Raul Michel

Raul Michel
Universidad Nacional Autónoma de México | UNAM · Institute of Astronomy

PhD

About

168
Publications
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Introduction
My main projects are: Development of new detectors, the SPM UBVRI photometric survey of Galactic clusters, and the study of variable stars with special emphasis on contact and cataclysmic variables.

Publications

Publications (168)
Preprint
Full-text available
We present new observations of the cataclysmic variable DW Cancri, after the system recovered from a low state. We performed a power spectrum analysis that reveals a clear signal of the 38 min spin period in our photometric data. Our spectroscopic power spectrum search was consistent with studies performed before the low state, showing the orbital...
Preprint
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During the last years and decades several individual studies and large-scale spectroscopic surveys significantly improved our knowledge of the Galactic metallicity distribution based on open clusters. The availability of Gaia data provided a further step forward in our knowledge. However, still some open issues remain, for example the influence of...
Article
During the last years and decades several individual studies and large-scale spectroscopic surveys significantly improved our knowledge of the Galactic metallicity distribution based on open clusters. The availability of Gaia data provided a further step forward in our knowledge. However, still some open issues remain, for example the influence of...
Article
New multi-color photometric observations were carried out on 22 nights in three observation missions between Oct. 2015 and Feb. 2016 for eclipsing binary HIP 7666. High- and low-resolution spectroscopic observations were also carried out in the winters of 2015, 2016, and 2019, respectively. The fully phase-covered light curves and radial velocity c...
Article
The multi-color passband CCD light curves of ASAS J124343+1531.7 and LINEAR 2323566 were first obtained by the 0.84 m Ritchey–Chrétien telescope with follow up observations by the WIYN 0.90 m Cassegrain telescope. The data from the Transiting Exoplanet Survey Satellite of ASAS J124343+1531.7 was also applied for subsequent analysis. By analyzing th...
Preprint
Full-text available
The multi-color passband CCD light curves of ASAS J124343+1531.7 and LINEAR 2323566 were first obtained by the 0.84-m Ritchey-Chr\'{e}tien telescope with follow up observations by the WIYN 0.90m Cassegrain telescope. The data from the $Transiting\quad Exoplanet\quad Survey\quad Satellite\quad (TESS)$ of ASAS J124343+1531.7 was also applied for subs...
Article
Spectroscopic observations of AH Herculis during a deep quiescent state are put forward. We found the object in a rare long minima, allowing us to derive accurately the semi-amplitudes: K1 = 121 ± 4 km s−1 and K2 = 152 ± 2 km s−1 and its mass functions MWsin 3i = 0.30 ± 0.01 M⊙ and MRsin 3i = 0.24 ± 0.02 M⊙, while its binary separation is given by...
Preprint
Spectroscopic observations of AH Herculis during a deep quiescent state are put forward. We found the object in a rare long minima, allowing us to derive accurately the semi-amplitudes: $K_1 =121 \pm \, 4$ \kms\ and $K_2 =152 \pm 2$ \kms\ and its mass functions $M_W{ \sin }^{ 3 }i=0.30 \pm 0.01$ M$_{\odot}$ and $M_R{ \sin }^{ 3 }i=0.24 \pm 0.02$ M$...
Article
Full-text available
The multicolour CCD light curves of the eclipsing binary systems CRTS J213033.6+213159 and 1SWASP J212454.61+203030.8 are presented for the first time, the observations are analyzed using the latest version of the WilsonDevinney code. Both the systems are found to be W UMa contact binaries belonging two different subtypes. All the light curves show...
Article
Photometric BVRc observations of the stars CSS J223614+311343, V523 Aur and V783 And were carried out and their absolute parameters (masses, radii and luminosities) were determined based on light curve modeling and Gaia distances. The main results are: (i) The components of CSS J223614+311343 and V783 And are of K spectral type while those of V523...
Article
We present the results of our investigation and first analysis of the geometrical and physical parameters of the 1SWASP J15133589-3725239 and 1SWASP J22310605-1940584 W UMa-type binary systems. Light curve analysis was performed with the PHOEBE0.31a interface program based on the Wilson-Devinney code. New times of minima and light elements have bee...
Preprint
In this paper, we present the first light curve synthesis and orbital period change analysis of nine contact binaries around the short period limit. It is found that all these systems are W-subtype contact binaries. One of them is a medium contact system while the others are shallow contact ones. Four of them manifest obvious O'Connell effect expla...
Article
The CCD UBV(RI)KC photometry of the poorly studied open clusters Juchert 9 (Juc 9) and Berkeley 97 (Be 97), which are observed with the 0.84 m telescope at the San Pedro Mártir National Observatory, México has been analyzed. For the likely cluster members, we determined the reddenings, E(B‐V) = 0.82 ± 0.04 (Juc 9) and E(B‐V) = 0.87 ± 0.05 (Be 97),...
Article
Full-text available
We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013–2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well a...
Preprint
Full-text available
The CCD UBV(RI)KC photometry of the poorly studied open clusters Juchert 9 (Juc 9) and Berkeley 97 (Be 97), which are observed with the 0.84 m telescope at the San Pedro M\'artir National Observatory, M\'exico has been analysed. For the likely cluster members, we determined the reddenings, E(B-V)=0.82 +- 0.04 (Juc 9) and E(B-V)=0.87 +- 0.05 (Be 97)...
Preprint
Full-text available
We present the results of our study of the eclipsing binary systems CSS J112237.1+395219, LINEAR 1286561 and LINEAR 2602707 based on new CCD $B$, $V$, $R_c$ and $I_c$ complete light curves. The ultra-short period nature of the stars \citep{Drake2014} is confirmed and the system's periods are revised. The light curves were modelled using the 2005 ve...
Article
Full-text available
The poorly studied Berkeley 8 (Be 8) open cluster is analysed from CCD U BV RI photometric data taken with the 0.90 m telescope at the Sierra Nevada Observatory. The Z = +0.008 PARSEC isochrone gave us a reddening of E(B-V) = 0.69 ± 0.03, a distance of 3410 ± 300 pc and an age of 2.8 ± 0.2 Gyr. Its median Gaia DR2 distance, d = 3676 ± 810 pc is in...
Preprint
Full-text available
We present a multiwavelength study of the flat-spectrum radio quasar CTA 102 during 2013-2017. We use radio-to-optical data obtained by the Whole Earth Blazar Telescope, 15 GHz data from the Owens Valley Radio Observatory, 91 and 103 GHz data from the Atacama Large Millimeter Array, near-infrared data from the Rapid Eye Monitor telescope, as well a...
Article
Full-text available
We report the development of a high-time resolution, 3-colour, simultaneous optical imaging system for the 2.1 m telescope in the San Pedro Mártir Observatory, México. OPTICAM will be equipped with three 2,048×2,048 pixel Andor Zyla 4.2-Plus sCMOS cameras and a set of SDSS filters allowing optical coverage in the 320–1,100 nm range. OPTICAM will no...
Preprint
Full-text available
The poorly studied Berkeley 8 (Be8) open cluster is analysed from CCD UBVRI photometric data taken with the 0.90 m telescope at the Sierra Nevada Observatory. The Z = +0.008 PARSEC isochrone gave us a reddening of E(B-V) = 0.69 +- 0.03, a distance of 3410 +- 300 pc and an age of 2.8 +- 0.2 Gyr. Its median Gaia DR2 distance, d = 3676 +- 810 pc is in...
Preprint
Full-text available
We report the development of a high-time resolution, 3-colour, simultaneous optical imaging system for the 2.1 m telescope in San Pedro M\'artir Observatory, M\'exico. OPTICAM will be equipped with three Andor Zyla 4.2-Plus sCMOS cameras and a set of SDSS filters allowing optical coverage in the 320-1,100 nm range. OPTICAM will nominally allow sub-...
Article
Full-text available
The open clusters NGC 2323 and NGC 2539 have been analysed using CCD \(U\!B\!V\!(R\!I)_{KC}\) photometric data, observed at the San Pedro Mártir Observatory. Cluster memberships have been determined with the proper motion and parallax measures from the GaiaDR2 astrometric data release. Photometric metal and heavy element abundances have been obtain...
Article
An increasing number of white dwarf stars shows atmospheric chemical composition polluted by heavy elements accreted from debris disc material. The existence of such debris discs strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The Z...
Preprint
Full-text available
The open clusters NGC 2323 and NGC 2539 have been analysed using CCD UBV(RI)KC photometric data, observed at the San Pedro Martir Observatory. Cluster memberships have been determined with the proper motion and parallax measures from the GaiaDR2 astrometric data release. Photometric metal and heavy element abundances have been obtained as (M/H, Z)...
Article
Full-text available
We present an in-depth photometric study of the 2013 superoutburst of the recently discovered cataclysmic variable V1838 Aql and subsequent photometry near its quiescent state. A careful examination of the development of the superhumps is presented. Our best determination of the orbital period is Porb = 0.05698(9) days, based on the periodicity of...
Article
Full-text available
The first multicolor observations and light curve solutions of the eclipsing binary systems V1009 Per and CRTS J031642.2+332639 are presented. Using the 2005 version of the Wilson-Devinney code, both systems are found to be W UMa contact binaries. V1009 Per has a mass ratio of q = 0.362±0.002 and a shallow fill out parameter of f = 11.8 ± 0.6% whil...
Preprint
Full-text available
An increasing number of white dwarf stars show atmospheric chemical composition polluted by heavy elements accreted from debris disk material. The existence of such debris disks strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The ZZ...
Article
We present photometric observations of the W UMa binaries OT UMa and UG Leo. Our results from the light curve solutions are: (i) The two targets show partial eclipses; (ii) The components OT UMa and UG Leo are of G spectral type; (iii) Detailed q-search analysis was carried out for determination of the mass ratios; (iv) The two binaries are of W su...
Article
Full-text available
The period distribution of contact binaries exhibits a very sharp short period cut-off at 0.22 d. In order to provide valuable information on this short period limit, we observed 10 totally eclipsing contact binaries with orbital periods near this cut-off. By detailed analysis using the W-D code, we determined that two of these systems are A-subtyp...
Preprint
Full-text available
The period distribution of contact binaries exhibits a very sharp short period cut-off at 0.22 days. In order to provide valuable information on this short period limit, we observed ten totally eclipsing contact binaries with orbital periods near this cut-off. By detailed analysis using W-D code, we determined that two of these systems are A-subtyp...
Article
Full-text available
W UMa-type binary stars have an apparent short-period cutoff around 0.2 days. Close binaries with orbital periods shorter than this limit are very useful for understanding the formation and evolution of this type of binaries. 2MASS J11553339+3544399 (hereafter J1155) is a red-dwarf binary with a period of 0.199724 days. Multicolor (V, R, R c , I, I...
Preprint
Full-text available
The first multicolor observations, and light curve solutions, of the eclipsing binary systems V1009~Per and CRTS~J031642.2+332639 are presented. Using the 2005 version of the Wilson-Devinney code, both systems are found to be W UMa contact binaries. V1009~Per has a mass ratio of $q = 0.362 \pm 0.002$ and a shallow fill out parameter of $f = 11.8 \p...
Preprint
Full-text available
New light curves and photometric solutions of FP Lyn, FV CVn and V354 UMa are presented. It is found that these three systems are W-subtype shallow contact binaries. In addition, it is obvious that the light curves of FP Lyn and V354 UMa are asymmetric. Therefore, a hot spot was added on the primary star of FP Lyn and a dark spot was added on the s...
Preprint
Full-text available
We analyse new optical spectroscopic, direct-image and X-ray observations of the recently discovered a high proper motion cataclysmic variable V1838 Aql. The data were obtained during its 2013 superoutburst and when the source came back to quiescence. The object was detected as a weak X-ray source ($0.01103\pm0.0014$ counts s$^{-1}$) in the plateau...
Preprint
Full-text available
We present an in-depth photometric study of the 2013 superoutburst of the recently discovered cataclysmic variable V1838 Aql and subsequent photometry near its quiescent state. A careful examination of the development of the superhumps is presented. Our best determination of the orbital period is Porb = 0.05698(9) days, based on the periodicity of...
Preprint
Full-text available
We present an analysis of VI CCD time-series photometry of the globular cluster NGC 6171. The main goal is to determine individual physical parameters for single-mode RR Lyrae stars present in the field of view of our images, by means of light curve Fourier decomposition and well-established calibrations and zero-points. This leads to the estimatio...
Article
Multicolor photometric observations of the W UMa binaries CSS J113505.5+332031, ASAS J142124+1813.1 and HR Boo are presented. They led to improvement of the orbital periods of CSS J113505.5+332031 and HR Boo. The light curve solutions revealed that all the targets are overcontact binaries with moderate fill-out factors whose components are of G and...
Article
Full-text available
New multi-band CCD light curves of three binaries W UMa-type V1175 Her, NSVS 2669503, and 1SWASP J133417.80+394314.4 are presented. Spectroscopic data for V1175 Her and NSVS 2669503 show that their spectral types are G7V and K4V, respectively. Photometric solutions of these three objects were obtained with the help of the Wilson–Devinney program. W...
Preprint
Full-text available
This paper presents a photometric and spectroscopic study of the short-period binary star Cl*~Melotte~111~AV~1224. Measurements in the $B$, $V$, and $R$ passbands obtained during three observing runs between 2014 and 2017 and medium-resolution spectra secured in 2014, are analyzed together with public data from the SuperWASP and LAMOST projects. Ou...
Article
We present an analysis of VI CCD time series photometry of the globular cluster NGC 6171. The main goal is to determine individual physical parameters for single‐mode RR Lyrae stars present in the field of view of our images, by means of light curve Fourier decomposition and well‐established calibrations and zero points. This leads to the estimatio...
Article
Full-text available
Bi-site time-series photometric and high-resolution spectroscopic observations were made for the double-mode high-amplitude $\delta$ Scuti star VX\ Hya. The fundamental frequency $f_{0}=4.4763\ \rm{c\ days^{-1}}$, the first overtone $f_{1}=5.7897\ \rm{c\ days^{-1}}$ and 23 harmonics and linear combinations of $f_{0}$ and $f_{1}$ are detected by pul...
Preprint
Full-text available
Bi-site time-series photometric and high-resolution spectroscopic observations were made for the double-mode high-amplitude δ Scuti star VX Hya. The fundamental frequency f 0 = 4.4763 c days −1 , the first overtone f 1 = 5.7897 c days −1 and 23 harmonics and linear combinations of f 0 and f 1 are detected by pulsation analysis. From the spectroscop...
Article
Photometric observations in V, R c and I c bands of the ultrashort-period W UMa binaries 1SWASP J044132.96+440613.7, 1SWASP J052926.88+461147.5 and NSVS 2175434 are presented. The results from the modeling and analysis of our observations reveal that: (i) All targets undergo total eclipses and their pho-tometric mass ratios should be accepted with...
Preprint
Full-text available
Bi-site time-series photometric and high-resolution spectroscopic observations were made for the double-mode high-amplitude $\delta$ Scuti star VX\ Hya. The fundamental frequency $f_{0}=4.4763\ \rm{c\ days^{-1}}$, the first overtone $f_{1}=5.7897\ \rm{c\ days^{-1}}$ and 23 harmonics and linear combinations of $f_{0}$ and $f_{1}$ are detected by pul...
Preprint
Full-text available
There are several peculiar long-period dwarf-nova like objects, which show rare, low-amplitude outbursts with highly ionized emission lines. 1SWASP J162117$+$441254, BD Pav, and V364 Lib belong to this kind of objects. Some researchers even doubt whether 1SWASP J1621 and V364 Lib have the same nature as normal dwarf novae. We studied the peculiar o...
Article
Full-text available
We present \emph{Herschel} PACS observations of 8 Classical T Tauri Stars in the $\sim 7-10$ Myr old OB1a and the $\sim 4-5$ Myr old OB1b Orion sub-asscociations. Detailed modeling of the broadband spectral energy distributions, particularly the strong silicate emission at 10 $\mu$m, shows that these objects are (pre)transitional disks with some am...
Article
Multicolor photometric observations of the W UMa binaries CSS J015638.9+224640, CSS J073801.1+303139 and ROTSE1 J135749.66+361609.3 with periods of around 6 h are presented. The light curve solutions revealed that the components of each target are almost equal in temperature and are of G and K spectral types. CSS J015638.9+224640 and ROTSE1 J135749...
Article
Full-text available
The morphology and optical spectrum of IPHASXJ210205+471015, a nebula classified as a possible planetary nebula, are however strikingly similar to those of ATCnc, a classical nova shell around a dwarf nova. To investigate its true nature, we have obtained high-resolution narrow-band [O III] and [N II] images and deep GTC OSIRIS optical spectra. The...
Article
Full-text available
The first multicolor observations and light curve solutions of the stars 1SWASP J130111.22+420214.0 and 1SWASP J231839.72+352848.2 are presented. The estimated physical parameters of 1SWASP J130111.22+420214.0 are $M_1=1.0M_{\odot}$, $M_2=1.63M_{\odot}$, $R_1=0.77R_{\odot}$, $R_2=0.91R_{\odot}$, $L_1=0.59L_{\odot}$, and $L_2=0.68L_{\odot}$. While a...
Article
Light curve modeling for the newly discovered system 1SWASP J092328.76+435044 was carried out by using a new BVR complete light curves. A spotted model was applied to treat the asymmetry of the light curves. The output model was obtained by means of Wilson-Devinney code, which reveals that the massive component is hotter than the less massive one w...
Article
Observations for the δ Scuti star AN Lyn have been made between 2008 and 2016 with the 85- cm telescope at Xinglong station of National Astronomical Observatories of China, the 84-cm telescope at SPM Observatory of Mexico and the Nanshan One metre Wide field Telescope of Xinjiang Observatory of China. Data in V in 50 nights and in R in 34 nights ar...
Article
Full-text available
In this paper, CCD photometric light curves for the short-period eclipsing binary 1SWASP J140533.33+114639.1 (hereafter J1405) in the $BVR$ bands are presented and analyzed using the 2013 version of the Wilson-Devinney (W-D) code. It is discovered that the J1405 is a W-subtype shallow contact binary with a contact degree of $f$ = 7.9$\pm$ 0.5\% and...
Article
Full-text available
Blazar emission is dominated by non-thermal radiation from a relativistic jet pointing toward us, therefore undergoing Doppler beaming. This is responsible for flux enhancement and contraction of the variability time scales, so that most blazars appear as luminous sources characterized by noticeable and fast flux changes at all frequencies. The mec...
Article
Full-text available
The variability of young stellar objects is mostly driven by star-disk interactions. In long-term photometric monitoring of the accreting T Tauri star GI Tau, we detect extinction events with typical depths of $\Delta V \sim 2.5$ mag that last for days-to-months and often appear to occur stochastically. In 2014 - 2015, extinctions that repeated wit...
Article
We present the results of our investigation of the geometrical and physical parameters of the binary system LX Leo. Based on CCD BV Rc light curves, and their analyses with the Wilson-Devinney code, new times of minima and light elements have been determined. According to our solution, the system is a high mass-ratio, totally eclipsing, W-type W UM...