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Everything about Astronomy & Astrophysics.
Questions related to Astronomy & Astrophysics
In textbooks on astronomy, we can find information that the radius of the habitable zone is influenced by the luminosity of the star, the sperctral class, and metallicity. But are there any formulas or equations, using which, knowing these parameters, you can find the radius of the habitable zone?
I would like to publish my Scientific Preprint Paper free-of-charge in an international Astrophysics journal with a satisfactory Impact Factor. Can you please suggest such a journal?
I have published my Research Results on a New Orbital Model for Moving Bodies in the Universe that I am asserting as a result of my scientific analysis, which can be found below:
"Everything Is A Circle: A New Model For Orbits Of Bodies In The Universe"
(Paperback Book) https://www.amazon.com/gp/product/B08NYG14X8
(Kindle eBook) https://www.amazon.com/gp/product/B08PVS2FBW
I will be presenting this work to the general scientific community at #COSPAR in Sydney, Australia, which will be broadcast Live according to Congress schedule on February 2, 2021
and will be available as Video-On-Demand in more detail.
To provide an introductory idea for readers and scientific community in general, here is a short video giving an overview description of the main and most significant findings:
The offended paper is here:
This is a rhetorical question since, in my mind, that is utterly non-acceptable.
I say that while accepting the reality that it takes time to write a few paragraphs in a rejection letter.
That said, it might take years to polish the arguments contained in a paper.
In my case, it took 16 years.
My issue is that, on purpose, I chose to tackle the Big Bang Theory first. It is the weakest model in the whole Physics. There are "Crisis in Cosmology" articles written by everyone and their cats. There is Hubble Tension, S8 tension... Missing Dark Matter, Early Galaxy Formation Conundrum...
Not to mention the lack of any evidence of a False Vacuum, Inflaton Field or Inflaton Particle, etc, etc.
My theory starts with a new model for matter, where matter is made of shapeshifting deformations of the metric (so, it is not Mass Deforms Metric, but modulated metric is mass).
It cannot be simpler. It allows the Universe to have just space, deformed space and time - the simplest possible model.
Occam's Razor will tell you that this model should be part of the conversation.
The Universe starts from a Heisenberg-Dictated Metric Hyperspherical Fluctuation, which after partial recombination is left with an Inner Dilation Layer (IDL) and the Outermost Contraction Layer (OCL).
As one would expect OCL breaks apart when it starts to move, pushed by the IDL. This process has a physical analogy in the Prince Rupert Drop
SO, the model is disappointly simple. No metrics, nothing for you to polish... just a simple model that explains EVERYTHING.
It also debunks General Relativity (Einstein's equations do not describe the Universe expansion). And replicates all Einstein's successes, while providing simpler explanations (instead of time dilation, we have the weakening of forces with absolute velocity).
What about ABSOLUTE VELOCITY? Well, we all know we can define absolute velocity using the CMB. Period. So, absolute velocity (and the breakdown of Relativity) shouldn't be a surprise.
So, my theory also challenges the current Cosmic Distance Ladder and in doing so (using an epoch-dependent law of Gravitation), it parameterless predicts the distances using just the redshifts. The predictions are attached.
So, in doing so, it attacks Dark Matter and Dark Energy and all the sordid interests behind them. I say sordid in the sense that I believe that all these entrenched interests are at play in this summary rejection of my work.
Why would I say that? There is a simple reason. If an editor (and all the other editors) don't bother to justify their actions, one is left with nothing to do other than speculate on the WHY.
Why is it ok for preprint repositories to block my already published work?? That is happening (and happened during the last 16 years) at the Los Alamos Archives.
Why would it be ethical for an editor not to write a single paragraph pointing to an specific scientific reason for yanking a paper out of the review process?
How calous these people can be with respect to Science and Mankind's Future? Science is the key to the Future. It shouldn't be at the mercy of unconfessable motivations.
Dear all members of RS,
considering the high tecnology that characterizes in this moment the space era, i have a question about the exoplanets and their studies. Now, in space there will be the JWST (James Webb Space Telescope) which will study exoplanets also. In geology is more important the carthography of surfaces for understand their evolution (and the history of the planetary body). With the JWSP will be able to cartograph exoplanets' surfaces?
Thank you all that will answer
Will man, thanks to technological progress, colonize the orbit of outer space in the 21st century?
Please reply
Best wishes
Dear Researchers in the field :
Does anyone know what the KAGRA Gravitational Waves Observatory it's been up to ?
KAGRA announced at the end of last year (2019) that they were ready for the kick off. And that in February this year (2020) they were turn to the sky for the first (real) observations and be ready to joing the efforts of the LIGO-Virgo collaboration.
But I haven't hear anything about KAGRA since that time.
I'm sure they had to close due to the COVID-19 pandemic, probably since March.
But, now in December, almost the end of the year, I would have expected to hear news about Observatory.
Does anyone know what is it status nowadays ? Maybe the explanation is that the facilities kept shut down almost the whole year since the pandemic.
If someone know fresh news, I'll appreciate the sharing.
Best Regards all ! :)
Do such measurements make sense? Do they exist?
Comparing redshift and luminosity distances, if that is a sensible question, may bear on the 4/3 scaling hypothesis as it relates to dark energy.
I'm trying to simulate light scattering of a Gaussian random sphere recently, but I don't quite understand how the [slm] in the second formula is calculated? Are there any GRS open source routines on the Internet?
From the 1998 book Seeing Red by Halton Arp, at page 274.
Is that consistent with nullius in verba?
Do you agree with Halton Arp?
Has anyone ever measured the velocity of light or gamma photons coming in from remote sources ?
Dear Sirs,
This question, it seems to me, may arise in the first meeting with general relativity theory. Free falling box with its locally inertial coordinate system, e.g. in the Earth gravity field, moves the same as space particles of the real spacetime continuum. So we can imagine that around us there is "a fluid" of space particles which moves towards to the Earth center. The imaginary fluid penetrates freely through the matter.
Have the space particles some dimensions (maybe the minimal one as real water, e.g.), any properties or even any forces accociated with them, does the motion look like the viscous or ideal or non Newtonian fluid?
I would be grateful of any comments on spacetime as fluid.
Will as a result of the continuation of technological progress in the twenty-first century more perfect telescopes or other astronomical instruments that will allow to know what is on the surface of the nearest exoplanets, and above all the guilty star systems similar to the Earth exoplanets located in other planetary systems circulating around other suns?
Please reply
Best wishes
If a black hole swallows an object of mass "m" and the initial mass of the black hole being "M", then does the total mass of black hole be = M + m?
Will the Schwarzschild radius change accordingly?
Dear Sirs,
The elevator example in general relativity is used to show that gravitational force and an inertial force are not distinguishable. In other words the 2nd Newton's law is the same in the two frames: inertial frame with homogenous gravitational field and the elevator's frame without gravitational field which has constant acceleration in respect to the inertial frame.
But every one knows that an inertial force is a force which does not obey the 3rd Newton's law. For example such forces are cetrifugal force and Coriolis force existing in the Earth reference frame. Gravitational force satisfies the 3rd Newton's law. So one can conclude that the gravitational force is not inertial.
Could you clarify the above controversy.
Do you think that there is life beyond our Solar System?
Please, answer, comments.
I invite you to the discussion.
Best wishes
Recently, I have written a research article. I want to produce preprint of it. I found various platforms for creating preprints of articles, including arXiv and Researchsquare. Personally, which platform do you prefer?
Why in spite of the many years of listening to radio waves emitted from various parts of the cosmos, did not there appear such, which would mean the possibility of existence in another cosmos of intelligent creatures?
For several dozen years, various astronomical programs have been running radio-frequency listening programs of various emission ranges to diagnose those that could be a testimony that somewhere in another constellation there is or has existed the civilization of other intelligent beings.
However, up to now, it has not been possible to diagnose such waves that could confirm the existence of other intelligent beings in the cosmos and thus other, developed forms of life.
Why has not it worked so far?
Why in spite of the many years of listening to radio waves emitted from various parts of the cosmos, did not there appear such, which would mean the possibility of existence in another cosmos of intelligent creatures?
Please, answer, comments. I invite you to the discussion.
Black Holes out of a galaxy: do they exist???
➣➣The question is as follow.
Are there black holes outside the confines of a galaxy{*}, in the spaces between one galaxy and another???
{*}Galaxy is not meant only the Milky Way but any type of galaxy.
In what way can be identified and/or measured these hypothetical extragalactic black holes???
➢➢Il quesito è il seguente.
Esistono buchi neri al di fuori dei confini di una galassia{*}, negli spazi tra una galassia e l'altra???
{*}Galassia non viene intesa la sola Via Lattea ma qualsiasi tipo di galassia.
in che modo possono essere individuati e/o misurati questi ipotetici buchi neri extragalattici???
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Is dark matter real, or have we misunderstood gravity? PHYS June 22 2021.
For many years now, astronomers and physicists have been in a conflict. Is the mysterious dark matter that we observe deep in the Universe real, or is what we see the result of subtle deviations from the laws of gravity as we know them? In 2016, Dutch physicist Erik Verlinde proposed a theory of the second kind: emergent gravity. New research, published in Astronomy & Astrophysics this week, pushes the limits of dark matter observations to the unknown outer regions of galaxies, and in doing so re-evaluates several dark matter models and alternative theories of gravity. Measurements of the gravity of 259,000 isolated galaxies show a very close relation between the contributions of dark matter and those of ordinary matter, as predicted in Verlinde's theory of emergent gravity and an alternative model called Modified Newtonian Dynamics. However, the results also appear to agree with a computer simulation of the Universe that assumes that dark matter is 'real stuff'.
The new research was carried out by an international team of astronomers, led by Margot Brouwer (RUG and UvA). Further important roles were played by Kyle Oman (RUG and Durham University) and Edwin Valentijn (RUG). In 2016, Brouwer also performed a first test of Verlinde's ideas; this time, Verlinde himself also joined the research team.
Matter or gravity?
So far, dark matter has never been observed directly—hence the name. What astronomers observe in the night sky are the consequences of matter that is potentially present: bending of starlight, stars that move faster than expected, and even effects on the motion of entire galaxies. Without a doubt all of these effects are caused by gravity, but the question is: are we truly observing additional gravity, caused by invisible matter, or are the laws of gravity themselves the thing that we haven't fully understood yet?
To answer this question, the new research uses a similar method to the one used in the original test in 2016. Brouwer and her colleagues make use of an ongoing series of photographic measurements that started ten years ago: the KiloDegree Survey (KiDS), performed using ESO's VLT Survey Telescope in Chile. In these observations one measures how starlight from far away galaxies is bent by gravity on its way to our telescopes. Whereas in 2016 the measurements of such 'lens effects' only covered an area of about 180 square degrees on the night sky, in the mean time this has been extended to about 1000 square degrees—allowing the researchers to measure the distribution of gravity in around a million different galaxies.
Comparative testing
Brouwer and her colleagues selected over 259,000 isolated galaxies, for which they were able to measure the so-called 'Radial Acceleration Relation' (RAR). This RAR compares the amount of gravity expected based on the visible matter in the galaxy, to the amount of gravity that is actually present—in other words: the result shows how much 'extra' gravity there is, in addition to that due to normal matter. Until now, the amount of extra gravity had only been determined in the outer regions of galaxies by observing the motions of stars, and in a region about five times larger by measuring the rotational velocity of cold gas. Using the lensing effects of gravity, the researchers were now able to determine the RAR at gravitational strengths which were one hundred times smaller, allowing them to penetrate much deeper into the regions far outside the individual galaxies.
This made it possible to measure the extra gravity extremely precisely—but is this gravity the result of invisible dark matter, or do we need to improve our understanding of gravity itself? Author Kyle Oman indicates that the assumption of 'real stuff' at least partially appears to work: "In our research, we compare the measurements to four different theoretical models: two that assume the existence of dark matter and form the base of computer simulations of our universe, and two that modify the laws of gravity—Erik Verlinde's model of emergent gravity and the so-called 'Modified Newtonian Dynamics' or MOND. One of the two dark matter simulations, MICE, makes predictions that match our measurements very nicely. It came as a surprise to us that the other simulation, BAHAMAS, led to very different predictions. That the predictions of the two models differed at all was already surprising, since the models are so similar. But moreover, we would have expected that if a difference would show up, BAHAMAS was going to perform best. BAHAMAS is a much more detailed model than MICE, approaching our current understanding of how galaxies form in a universe with dark matter much closer. Still, MICE performs better if we compare its predictions to our measurements. In the future, based on our findings, we want to further investigate what causes the differences between the simulations."
Young and old galaxies
Thus it seems that, at least one dark matter model does appear to work. However, the alternative models of gravity also predict the measured RAR. A standoff, it seems—so how do we find out which model is correct? Margot Brouwer, who led the research team, continues: "Based on our tests, our original conclusion was that the two alternative gravity models and MICE matched the observations reasonably well. However, the most exciting part was yet to come: because we had access to over 259,000 galaxies, we could divide them into several types—relatively young, blue spiral galaxies versus relatively old, red elliptical galaxies." Those two types of galaxies come about in very different ways: red elliptical galaxies form when different galaxies interact, for example when two blue spiral galaxies pass by each other closely, or even collide. As a result, the expectation within the particle theory of dark matter is that the ratio between regular and dark matter in the different types of galaxies can vary. Models such as Verlinde's theory and MOND on the other hand do not make use of dark matter particles, and therefore predict a fixed ratio between the expected and measured gravity in the two types of galaxies—that is, independent of their type. Brouwer: "We discovered that the RARs for the two types of galaxies differed significantly. That would be a strong hint towards the existence of dark matter as a particle."
However, there is a caveat: gas. Many galaxies are probably surrounded by a diffuse cloud of hot gas, which is very difficult to observe. If it were the case that there is hardly any gas around young blue spiral galaxies, but that old red elliptical galaxies live in a large cloud of gas—of roughly the same mass as the stars themselves—then that could explain the difference in the RAR between the two types. To reach a final judgement on the measured difference, one would therefore also need to measure the amounts of diffuse gas—and this is exactly what is not possible using the KiDS telescopes. Other measurements have been done for a small group of around one hundred galaxies, and these measurements indeed found more gas around elliptical galaxies, but it is still unclear how representative those measurements are for the 259,000 galaxies that were studied in the current research.
Dark matter for the win?
If it turns out that extra gas cannot explain the difference between the two types of galaxies, then the results of the measurements are easier to understand in terms of dark matter particles than in terms of alternative models of gravity. But even then, the matter is not settled yet. While the measured differences are hard to explain using MOND, Erik Verlinde still sees a way out for his own model. Verlinde: "My current model only applies to static, isolated, spherical galaxies, so it cannot be expected to distinguish the different types of galaxies. I view these results as a challenge and inspiration to develop an asymmetric, dynamical version of my theory, in which galaxies with a different shape and history can have a different amount of 'apparent dark matter'."
Therefore, even after the new measurements, the dispute between dark matter and alternative gravity theories is not settled yet. Still, the new results are a major step forward: if the measured difference in gravity between the two types of galaxies is correct, then the ultimate model, whichever one that is, will have to be precise enough to explain this difference. This means in particular that many existing models can be discarded, which considerably thins out the landscape of possible explanations. On top of that, the new research shows that systematic measurements of the hot gas around galaxies are necessary. Edwin Valentijn formulates is as follows: "As observational astronomers, we have reached the point where we are able to measure the extra gravity around galaxies more precisely than we can measure the amount of visible matter. The counterintuitive conclusion is that we must first measure the presence of ordinary matter in the form of hot gas around galaxies, before future telescopes such as Euclid can finally solve the mystery of dark matter."
More information: Margot M. Brouwer et al, The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000, Astronomy & Astrophysics (2021). DOI: 10.1051/0004-6361/202040108 ----- ABSTRACT. We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter (gbar) with the observed gravitational acceleration (gobs), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in gobs into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde’s emergent gravity (EG). We find that the measured relation between gobs and gbar agrees well with the MG predictions. In addition, we find a difference of at least 6σ between the RARs of early- and late-type galaxies (split by Sérsic index and u − r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant (Mgas ≈ M⋆) circumgalactic gaseous haloes. The observed behaviour is also expected in Λ-cold dark matter (ΛCDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a ΛCDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas; current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and ΛCDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.
Dear researcher,
I am looking for a detailed catalog of the yellow and blue supergiant stars. Could you please suggest some websites or related papers? Thanks. :)
Kennicutt (1994) proposed a simplest formula to estimate star formation rate (SFR) of the galaxies. I want to calculate SFR of some dwarf galaxies using SDSS spectroscopy and compare it with the SFR model for star forming dwarfs.
I read some papers which highlighted that when using the Hα flux for SFR estimates, we encounter the following difficulties, which may cause systematic errors: (i) contamination by [NII] emission lines, close to the Hα line, (ii) contamination by the other Hα emitters (e.g, other emission nebulae, non-thermal emitters, such as active galactic nuclei (AGN)), and (iii) internal extinction.
On the other hand, it is said that SDSS spectra data are well calibrated, so we do not need to perform any further corrections.
I am bit confused with this second statement.
Russian project to explore the moons of Jupiter after 2030 will be based on the nuclear propulsion spacecraft "Nuklon" with an electrical energy power of 0.5 MW. Such energy power gives the opportunity to significantly increase a data transfer performance to Earth. In my opinion, the speed of data transfer can be increase to 100 Mbit/sec. This value will be enough to use 4K Video for the investigation of dynamic processes in the atmosphere of Jupiter and moons. What is your opinion about this?
According to the principle of the general relativity theory, the gravity field equation should contain the field energy as a source of the field itself. Including the field energy-momentum tensor into the Einstein’s equation brings extra unknown quantities to the equation. Such equation is not suitable for a metric finding; however it allows – based on the known metric – calculating the whole energy-momentum tensor of both matter and gravitational field. As the gravity field metric, the metric of continuous field can be used, parameters of which are found from the generally covariant one-parametric equation. Here, the solutions are given of the equation for the spherically symmetric stationary problem. One of the solutions coincides practically with that by Schwarzschild for weak fields, while the other one describes an expulsive field.
Does the Solar System move in a meaningful pattern?
Will the new generation of astronomical instruments ever reach the farthest corners of the Universe, reach the edge of the universe and explain the essence of the boundlessness of what is possibly beyond the known Universe?
Perhaps someday in the future, thanks to the huge telescopes, we will discover the details of the distant planets in other planetary systems in other galaxies, i.e. exoplanets.
According to astronomers' forecasts, it will be technically possible to build such large telescopes in a few dozen years.
Astronomers have so far discovered a small part of the planets in our Andromeda Galaxy.
Billions of exoplanets existing in other constellations are still unknown.
However, even these known exoplanets are studied to a very limited extent.
In the case of the majority of exoplanets learned, apart from the knowledge of size and mass, little is known about them.
More and more perfect astronomical tools are being built, more and more telescopes provide new knowledge.
Thanks to more perfect astronomical instruments, we know more and more about the cosmos, but on the other hand we know that we still do not know more and more about the vastness of the Universe.
Will we ever know the answer to the question: Are there other forms of life somewhere in the Universe and how does life look like?
Will the new generation of astronomical instruments ever reach the farthest corners of the universe, reach the edge of the Universe and explain the essence of the boundlessness of what is possibly beyond the known Universe?
In view of the above, the current question is: Will the new generation of astronomical instruments ever reach the farthest corners of the Universe, reach the edge of the Universe and explain the essence of the boundlessness of what is possibly beyond the known Universe?
Please, answer, comments. I invite you to the discussion.
After surpassing electron degeneracy and supported by quantum degeneracy pressure, these kind of stars are composed mainly by neutrons, particles without electic charge. They posses nevertheless very strong magnetic fields. So, if they are composed mainly from electrically neutral particles, what is the origin of their strong magnetic fields?
I am stuck between Quantum mechanics and General relativity. The mind consuming scientific humor ranging from continuous and deterministic to probabilistic seems with no end. I would appreciate anyone for the words which can help me understand at least a bit, with relevance.
Thank you,
Regards,
Ayaz
Is anybody able to Imagine "Nothing" before the big bang? Does it mean no time and no space. Well, I cannot imagine there were nothing before the big bang. I think it might be something. But what about "something"? For me, this is the main question?
Dear Sirs,
The 1st law in Newton`s principia are now understood as two statements: the determination of inertial frame reference (if F=0 then a=0 and if F is not equal 0 then there is some body accelleration "a"); there is in nature at least one inertial frame reference. Theoretically I can understand it a little bit. As we have such a determination of inertial frame reference then the 2 nd Newton law is not directly followed from the 1 st law, or this determination is partly independent of the 2nd law. So it looks like logically good.
But what we have in experiment? I do not know whether there is any research on experimental determination of any particular inertial system (like International Celestial Reference System) using the 1 st Newton law. So in practice we use the 2 nd law (e.g. school example - foucault pendulum plane rotation). Could you clarify on the experimental and theoretical determination of inertial frame reference. You know there are teachers that see the 1st law as the consequence of the 2nd law.
If quantum information is stored on the Event horizon of the black hole (according to the Holographic principle), What happens to information when black holes evaporate or merge?
According to Weyl and Chandrasekhar, general relativity (GR) is a triumph of speculative thought. But it is a well-known fact that GR is initiated by two analogies. Analogy is known to be a weak reasoning in science and philosophy. To redress the case this type of reasoning is renamed as Equivalence Principle (EP) in relativistic physics. The renaming, however, could not hide the fact that the presented analogy was not flawless. Irrefutable disproves were side-stepped and the analogy was instated to be the seed of new kind of physics. EP was defended by reducing the size of the lab and the duration of the experiment. This type of defending is like the proponents of flat-earth idea defend their case by reducing the patch of the land for examination until their pseudo-science theory is proven.
The attached document is a short description of EP analogies and its well-known critics. The document also introduces a new EP based on Uniform Deceleration of a spaceship in open space. This new analogy results in a different curvature of light in comparison to what original EP has established using uniform acceleration. The author believes that none of the conclusions from EPs should be allowed in science as they are based on inconclusive comparison/analogy and they ignore glaring flaws in the argument.
The author would like to present this new EP for discussion and criticism.
Hello,
can anyone suggest from where can I get hands-on experience on astropy except Coursera's data-driven astronomy course !!!
The fact that the measurement of vanishing distances is physically impossible, which preempts continuity, may lead us to not consider renormalization as a proper procedure in particle physics.
Also, it may lead us to disconsider it, as not needed to define derivatives using infinitesimals, and use Galois fields instead.
We may be pushing our equations too close, to limits where they probably do not apply, and renormalization just tries to solve the symptoms -- to avoid infinities. But the "problem" remains -- there are no infinitesimals in Nature, nor can be created.
Can we not use a concept that we cannot find nor encounter? Infinitesimals do not exist? Then, is renormalization necessary?
Dear Researchers,
I want to buy a telescope and request for the suggestions. Which one should I buy with better resolution?
Thank you
A team led by students probes the mass-radius relation of white dwarf stars, observing in their data evidence of quantum mechanics and Einstein’s theory of general relativity.
This puzzling relationship between a white dwarf’s mass and size, called the mass-radius relation, was first theorized by Nobel Prize-winning astrophysicist Subrahmanyan Chandrasekhar in the 1930s. Now, a team of Johns Hopkins astrophysicists has developed a method to observe the phenomenon itself using astronomical data collected by the Sloan Digital Sky Survey and a recent dataset released by the Gaia Space Observatory. The combined datasets provided more than 3,000 white dwarfs for the team to study.
A report of their findings, led by Hopkins senior Vedant Chandra, is now published in The Astrophysical Journal.
I'm currently working on SRc Alf Ori and its Bolometric Magnitudes. I do have the light curve estimates (From AAVSO but the SDSS doesn't seem to have an available data set for Alf Ori) and I'm wondering if I can utilize the V-band optical photometric band to obtain the MBOL assuming that I got the adopted values of Teff, R and Distance D?
If so, is there a program/software/inlist that I can use to get those?
Recommendations/suggestions are highly accepted.
Best regards,
Generich Capuli | CGHA
Can anybody please share the IDL source code for Hapke photometric modeling?
Thank you,
The gravitational shielding hypothesis may be checked with height observations of a geostationary satellite. If Earth canceles acceleration of free fall toward the Sun, the satellite should fly away from Earth at a distance of up to about 40 km during 1-hour shadowing (s=g_sun*t^2/2). If no, such an observation may be the independent confirmation of high penetration ability of gravity forces.
What does it actually mean to exist? How is it different from non-existence? How can we be sure if something exists or does not exist? I have made a case that these questions are more fundamental than the usually dubbed first question "Why is there something rather than nothing"? Here is a ready link for which I would appreciate your comments.
Please do feel free to share the link with your colleagues and friends who you think might be interested in this topic.
When stars as primary radiation sources are placed at rather large mutual distances and are embedded in a dissipative intergalactic medium I expect that line of sight is substantially limited (maybe around 14 Gly) and dissipative medium will stay at rather low equilibrium temperatures (maybe around 3 K).
Some petroleum and geophysics companies use controlled-source seismology for Mineral Inspection and cavity detection. These methods based on impulsive source controllers such as (dynamite, air gun seismic source, etc.). More efficient techniques use a Seismic vibrator for seismic wave generator such as chirp, sine or square seismic waves.
I wonder if recents detections of Gravitational Waves coming from earth or space using optical interferometry, and how to distinguish between each of them, especially when seismic wave have a same chirp form such as Gravitational Waves?
Example of Seismic Source: http://seismicsource.com/html/index.php
I was once told that stable isotopes of lighter elements such as H, N C , etc are found in stars, planets, etc. Can anyone suggest any literature which talks about the formation of these isotopes?
In the immediate future, ( a half century or less) , Mars Adventure will entail robots colonising Mars and the immense benefits, it will accrue to techpreneurs, will be mining Moon for lanthanides or so, will make them king like or trillionaires in the process. Aliens have remotely been encountered, physically, maybe once in 5000 years. If you consider us vs them theory , then it is 1:10000 or so, they should have colonised us long back.The odds are infinitely stacked in their favour. Problems do have a solution, for some, maybe, only in a long term one and so in the immediate scenario, it is impossible. Environmental problems are challenging , hence and some of it is gargantuam and are irreversible. Greta Thunberg has been rightly awarded " Person of the Year 2019" by TIME Magazine and this might instill eco-consciousness of the global society .I have revised special theory of relativity and concluded that: Cosmic Speed is one-third the speed of light.and this could be the reason for the above .Bernie Sanders, emergence as a Presidential contender, awakens the spirit of social consciousness that has been lagging in the past and need not bode well for the future as " Necessity is the mother of invention" . Welfare Economics need not produce or need not result in vibrant Innovative Economies.The Ultimate Adventure of the human species is to become a space- faring civilization could be termed a misadventure. An Endangered Planet's escapist nuances. The same tendencies that can cause extinction of this planet can as well destroy other colonised planets as well .It only needs a momentary lapse of reasoning. Does it mean we are waiting for the apocalypse.?
We are prematurely arriving at Hubble Constant and conclusion of acceleration of expansion in the Universe.
Nothing in Nature lasts for eve and follows DOB and DOD principles. Light propagating forever in Vaccum of Space, while not encountering any matter (though rare), has not been verified and likely to lose momentum to lowest frequency and lowest temperature (temperature and momentum of Photon are related at the time of emission and absorption). The Vaccum of Space itself at the lowest temperature will be the next place, beside the matter, for the photon to be absorbed. The CMB is the epoch just before that moment, and where the temperature is approaching 0 Kelvin.
My recent papers for the last 6 months have explored the different independent lines of thinkings, without wanting to prove the alternate source of Redshift theory, have come to the same surprising conclusion.
The Galaxies can also have retrograde movements like planets, where they are moving away and then moving towards.
We have been using GAIA data to study different types of stars, specifically non magnetic white dwarfs, most of the correlations were obtained for ratio of magnetic white dwarf to non magnetic white dwarfs with Mass, Temperature, Distance,Tangential velocity and Signal to Noise ratio.Are these variables either constant or have no trend? Are there any variables that affect what determines a magnetic white dwarf or any other correlations found in magnetic white dwarfs ?
Is there any online free course on planetary photometry (or photometry)? Pls, send me the link. Thanks!
A body thrown up, stalling and falling back in Earth’s gravitational field accelerates towards Earth. No new energy is created, it is potential energy converted into kinetic energy.
Space expansion accelerating seems to be not quite analogical. Where is the potential energy converting to kinetic energy expanding space? Is space falling back to where it started father out? It seems that space expanding is more analogical to a ball being thrown into the air, out it goes. Muscle potential energy sends the ball on its way. What potential energy has that effect on space? Is space in rebound mode, expanding outward, like a compressed spring? If potential energy does not account for expanding space, then could it be energy is being added to the universe resulting in space expanding? The expansion is accelerating constantly, so that would seem to require a constant addition of energy. But if our universe is self contained, there is no external source of energy to create a force to accelerate space.
These considerations suggest that so called accelerating space might instead be space expanding inertially, like a rocket gliding after fuel has run out. Suppose space plus (light) motion is 4 dimensions and empty space is 3 dimensions. Then an unchanging (invariant) ratio of dimensions, 4 : 3, would nor require adding energy to the universe. Three dimensional space would grow radially by 4/3 L when 4 dimensions grow by L.
Where does the energy for DE come from?
I RETRACTED THE SDSS DATA ANALYSIS AFTER @GEORGE DISHMAN ASKED ENOUGH PERTINENT QUESTIONS THAT MY MISTAKE BECAME EVIDENT. THE REASON IS THAT THE SDSS DATA WAS COLLECTED WITH A BIAS. THE PROTOCOL IS CALLED CMASS AND FOR A GIVEN Z, THEY ONLY COLLECTED DATA FROM GALAXIES OF THE SAME MASS.
THAT CREATED THE RECURRENCES AND THE SPHERICAL MASS DISTRIBUTION.
I AM WRITING THIS BECAUSE SOMEONE JUST ADDED ANOTHER COMMENT AND MISSED MY LAST ONE (WHERE I RETRACTED THE ANALYSIS).
SO, I WAS WRONG ABOUT THE SDSS.
THAT SAID, THE THEORY HAS PLENTY OF SUPPORT FROM EVERYTHING ELSE.
Here is the support from the Supernova Cosmology Project:
The posting refutes General Relativity by showing that the Universe is a lightspeed expanding hyperspherical hypersurface.
Here is the posting refuting L-CDM.
Here is the demonstration that HU Laws of Nature satisfies all SR and GR tests:
Here is the HU prediction of Tulley-Fisher Law:
Here is how I located Earth in a map that is impossible to even conceive in the current view: a map of the hyperspherical Universe.
Here is the 3D map of the Observable Universe:
I also created a replacement to the Big Bang and to Particle Physics...(so I created a replacement for the whole Physics):
and here is how the Universe started moving at c:
If we consider MIT Bag Model EOS, the square of speed of sound for quark star should be around 0.33. But whether this is true for an anisotropic quark star or not. So whether EOS from MIT Bag Model is for isotropic or anisotropic matter or for both?
In this part in addition to new subjects, I have highlighted some of responses from previous sections for further discussion. Please leave you comments to support/weaken any of the following statements:
1) @Harry ten Brink recapitulated a summary of a proof that CO2 is such an important Greenhouse component/gas. Here is a summary of this argument:
"a) Satellites' instruments measure the radiation coming up from the Earth and Atmosphere.
b) The emission of CO2 at the maximum of the terrestrial radiation at 15 micrometer.
b1. The low amount of this radiation emitted upwards: means that "back-radiation" towards the Earth is high.
b2. Else said the emission is from a high altitude in the atmosphere and with more CO2 the emission is from an even higher altitude where it is cooler. That means that the emission upwards is less. This is called in meteorology a "forcing", because it implies that less radiation /energy is emitted back into space compared to the energy coming in from the sun.
The atmosphere warms so the energy out becomes equals the solar radiation coming in. Summary of the Greenhouse Effect."
At first glance, this reasoning seems plausible. Nevertheless, it is based on these assumptions that the contribution of CO2 is not negligible and any other gas like N2O and Ozone has minor effect. The structure of this argument is supported by an article by Schmidt et al., 2010:
By using the Goddard Institute for Space Studies (GISS) ModelE radiation module, the authors claim that "water vapor is the dominant contributor (∼50% of the effect), followed by clouds (∼25%) and then CO2 with ∼20%. All other absorbers play only minor roles. In a doubled CO2 scenario, this allocation is essentially unchanged, even though the magnitude of the total greenhouse effect is significantly larger than the initial radiative forcing, underscoring the importance of feedbacks from water vapour and clouds to climate sensitivity."
The following notions probably will shed light on the aforementioned argument for better understanding the premises:
Q1) Is there any observational data to support the overall upward/downward IR radiation because of CO2?
Q2) How can we separate practically the contribution of water vapor from anthropogenic CO2?
Q3) What are the deficiencies of the (GISS) ModelE radiation module, if any?
Q4) Some facts, causes, data, etc relevant to this argument, which presented by NASA, strongly support this argument (see: https://climate.nasa.gov/evidence/)
Q5) Stebbins et al, (1994) showed that there exists "A STRONG INFRARED RADIATION FROM MOLECULAR NITROGEN IN THE NIGHT SKY" (thanks to @Brendan Godwin for mentioning about this paper). As more than 78% of the dry air contains nitrogen, so the contribution of this element is not negligible.
2) The mean global temperature is not a good diagnostic to study the sensitivity to global forcing. Because given a change in this mean value, it is almost impossible to attribute it to global forcing. Zonal and meridional distribution of heat flux and temperature are not uniform on the earth, so the mean temperature value is misleading.
3) "The IPCC model outputs show that the equilibrium response of mean temperature to a doubling of CO2 is about 3C while for the other observational approaches this value is less than 1C." (R. Lindzen). What is wrong with these propositions?
4) What is the role of the thermohaline circulation (THC) in global warming (or the other way around)? It is known that during Heinrich events and Dansgaard‐Oeschger (DO) millennial oscillations, the climate was subject to a number of rapid cooling and warming with a rate much more than what we see in recent decades. In the literature, these events were most probably associated with north-south shifts in convection location of the THC. The formation speed of North Atlantic Deep Water (NADW) affects northerly advection velocity of the warm subtropical waters that would normally heat/cool the atmosphere of Greenland and western Europe.
I really appreciate all the researchers who have participated in these discussions with their useful remarks, particularly Harry ten Brink, Filippo Maria Denaro, Tapan K. Sengupta, Jonathan David Sands, John Joseph Geibel, Aleš Kralj, Brendan Godwin, Ahmed Abdelhameed, Jorge Morales Pedraza, Amarildo de Oliveira Ferraz, Dimitris Poulos, William Sokeland, John M Wheeldon, Joseph Tham, and Boris Winterhalter.
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Link to the discussions of Global Warming (Part 1):
Link to the discussions of Global Warming (Part 2):
Link to the discussions of Global Warming (Part 3):
I am working an a project which requires me to know the exact total amount of GCR flux between 10MeV to 1GeV. There are many papers on GCR flux but they only talk about flux at some specific energy but not the total flux of GCR.
In many cosmological theories, astronomers try to explain the essence of the unlimitedness of the Universe. But how can this unlimitedness be presented and defined in the most concise and clear way possible?
What can be compared to the unlimitedness of the Universe? Or maybe the essence of the problem goes beyond the scientific definition of the concept of the unlimitedness of the Universe?
The problem may be the understanding of this unlimitedness of the Universe by man, because everything that surrounds man in everyday life on Earth is limited.
Do you agree with my opinion on this matter?
In view of the above, I am asking you the following question:
How is the unlimitedness of the Universe explained now?
Please reply
I invite you to the discussion
Best wishes
Since Verlinde's proposal that gravitation is related to entropy, there have been many papers discussing or extending his hypothesis. In a recent paper, Basilakos and Sola reconsidered entropic-force dark energy (http://arxiv.org/pdf/1402.6594v3.pdf). They wrote: "We reconsider the entropic-force model in which both kind of Hubble terms appear in the effective dark energy (DE) density affecting the evolution of the main cosmological functions, namely the scale factor, deceleration parameter, matter density and growth of linear matter perturbations. However, we find that the entropic-force model is not viable at the background and perturbation levels due to the fact that the entropic formulation does not add a constant term in the Friedmann equations."
So do you think that entropic force can explain dark energy?
Did a certain type of space exist before the explosion took place? Even when the explosion itself created the space by its own strength, there had to be something that existed before the Big-Bang, or was there?
Dear all,
in accordance with Friedmann-Lemaitre-Equation there are three different possibilities of space curvature which can be described mathematically and imparted graphically or analogously (Closed, Openend or Flat Universe). In the attached poster a fourth graphic representation is shown, which is however only graphically derived.
Is this sketch describable within Friedmann-Lemaitre-Equations? How can we interpret this sketch? A Universe that is truly infinite, although it has a defined start and a defined end point?
What would be a 3-Dimensional mathematical object to describe the plot (closed hypertorus, while closed means without a connection in the center?). And what numbers for curvature parameter k and density Parameter Ω make sense for this sketch?
I have created this plot purely graphically and wonder whether a mathematical interpretation of such a shaped space-time is possible, or whether it inevitably leads to paradoxes and is thus a graphic that can be drawn abstractly, but ultimately makes no mathematical sense.
Thank you!
Dear Sirs,
I would like to find out more precisely whether the 2nd Newton law is valid or not in wide range of masses, accelerations, forces. Particulary I have a question whether the inertial property of body (inertial mass) is able to stop the body for small external forces or not. I have found in the Internet the fresh articles with tests of the 2nd Newton law for small accelerations (10^-10), small forces (10^-13) and SMALL masses (about 1 kg). The articles deal with the question of dark matter and MOND theory in astrophysics.
But I am interested in BIG masses. Could the test be carried out in planetary scale? Maybe for the Moon or asteroids? Or for masses like 1000 kg? Thank you very much for any references.
Dear Sirs,
Inertia is opposite effect in some sence in respect to gravitation. But inertial and gravitational properties are unified in one body. Could inertial property of mass be explained by some processes related to space-time curvature?
Is the inertia of accelerating masses to be interpreted as due to interaction with the local gravitational potential originating from remote masses of the universe? A gravitational drag experiment proposed by J.C. Keith might help finding an answer.
I have found two different results for the effect of dark matter on the orbital speed of the Sun. One from Wikipedia suggests there is no effect while another one from astronomynotes suggests there is a substantial effect. Which one is correct? Both Figures and their captions are attached.
When are the first manned trips to Mars planned?
Considering technological development, when will it be possible to establish the first permanent research bases and residential colonies on Mars?
Please reply
Best wishes
Kepler-186f is the first earth-sized planet located in the habitable zone of another star that has been discovered. With this discovery, the search for life on other planets has entered into a new zone of discovery.
How does even Majorana Fermion exist ? Why any fermion can be written as a combination of two Majorana fermions? Is there any physical meaning in it? Why Majorana fermion can be used for topological quantum computation?
Dear Respectful Researchers,
Here come several "strange" and probably unique questions about deep space detection which is motivated by an important recent scientific discovery and publication (in the journal Nature) about Fast Radio Bursts, "A second source of repeating fast radio bursts" as referring to these links as follows:
Researchers at UBC, Canada, have discovered the second so-called “repeating fast radio burst” (FRB) recorded six times coming from the same location, 1.5 billion light-years away. It seems that, CHIME was able to record some of the bursts as low as 400 MHz. My quick and first question is, can we statistically exclude its origin from the extraterrestrial (ET) civilizations?
Here come my rudimentary thoughts and reasoning as an electronics/telecommunications engineer, just out of strong curiosity.
I’ve conducted some quick and simplistic calculation of the link budget from communication perspective. Assume that the 400 MHz radio signals (assuming constant without shifting although actually not) do not significantly suffer from planets/galaxies introduced (all types of) attenuation and are thus deemed in an ideal free-space propagation model.
1.5 billion light-years distance is equal to around 1.419e22 kilometers, which will introduce a Free Space Path Loss (FSPL) of 537.5 dB at 400 MHz. On the other hand, assume that the receiver at ground station is able to achieve an ultra-low sensitivity of -160 dBm thanks to very large high gain phased array antennas, which also means the power at the origin (output) is at least 377.5 dBm, or 5.62e33 Watts (56.2 Decillion Watts).
On the other hand, the Sun releases an estimated 384.6 Yotta Watts (3.846e26) of Energy [1], the power output of all power plants of the world in 2008 is only 2.31e12 Watts. Therefore, we may be talking about an Energy (1.5 billion light year away) equivalent to at least 14.6 millions times the Sun !
This comparison makes one feel that this energy resource can be hardly from an ET civilization, unless it is from the so-called Type-III civilization categorized in the Kardashev Scale [3]. Could it be ?
Another thing I am concerned with and would like to ask is, what could the "super-macro galaxy-level" propagation channel models look like? Would there be some multi-path fading effects? Would there be some time delay/frequency shifting among different bursts, and in the order of months/years?
Thanks for your correction, discussion, and suggestions.
References
Yours Sincerely,
Yiming Huo (Jimmy), Ph.D.,
Jan. 12, 2019
According to my understanding, a planet doesn't follow the visual position of its central star but simply advances perpendicular with respect to the permanent local gravitational field gradient of the central star.
The derivation of orbital velocity is presumably well understood. One method is to set the centripetal force equal to the gravitational force and solve for v.
Mv^2/r = GMm/r^2
for which orbital velocity becomes v = sqrt(GM/r)
Now let's assume we have a spacecraft in stable orbit around a body at some distance r(1) and want to move the craft to a higher orbit r(2), to do this it must fire it's engines, i.e. accelerate the craft (a) for some time (t), and presumably increase its velocity as ∆v = at, however Newtonian theory tells us that the velocity has indeed decreased as r(2) is larger than r(1).
So I would like to know what kind of Hokus Pokus is normally applied to explain this problem.
