M. A. Guerrero

University of Guadalajara, Guadalajara, Jalisco, Mexico

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Publications (98)216.94 Total impact

  • Source
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    ABSTRACT: We present results from the most recent set of observations obtained as part of the Chandra X-ray observatory Planetary Nebula Survey (ChanPlaNS), the first comprehensive X-ray survey of planetary nebulae (PNe) in the solar neighborhood (i.e., within ~1.5 kpc of the Sun). The survey is designed to place constraints on the frequency of appearance and range of X-ray spectral characteristics of X-ray-emitting PN central stars and the evolutionary timescales of wind-shock-heated bubbles within PNe. ChanPlaNS began with a combined Cycle 12 and archive Chandra survey of 35 PNe. ChanPlaNS continued via a Chandra Cycle 14 Large Program which targeted all (24) remaining known compact (R_neb <~ 0.4 pc), young PNe that lie within ~1.5 kpc. Results from these Cycle 14 observations include first-time X-ray detections of hot bubbles within NGC 1501, 3918, 6153, and 6369, and point sources in HbDs 1, NGC 6337, and Sp 1. The addition of the Cycle 14 results brings the overall ChanPlaNS diffuse X-ray detection rate to ~27% and the point source detection rate to ~36%. It has become clearer that diffuse X-ray emission is associated with young (<~5x10^3 yr), and likewise compact (R_neb<~0.15 pc), PNe with closed structures and high central electron densities (n_e>~1000 cm^-3), and rarely associated with PNe that show H_2 emission and/or pronounced butterfly structures. Hb 5 is one such exception of a PN with a butterfly structure that hosts diffuse X-ray emission. Additionally, of the five new diffuse X-ray detections, two host [WR]-type CSPNe, NGC 1501 and NGC 6369, supporting the hypothesis that PNe with central stars of [WR]-type are likely to display diffuse X-ray emission.
    07/2014;
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    ABSTRACT: We present the first results of our search for new, extended Planetary Nebulae (PNe) based on careful, systematic, visual scrutiny of the imaging data from the INT Photometric H-alpha Survey of the Northern Galactic Plane (IPHAS). The newly uncovered PNe will help to improve the census of this important population of Galactic objects that serve as key windows into the late stage evolution of low to intermediate mass stars. They will also facilitate study of the faint end of the ensemble Galactic PN luminosity function. The sensitivity and coverage of IPHAS allows PNe to be found in regions of greater extinction in the Galactic Plane and/or those PNe in a more advanced evolutionary state and at larger distances compared to the general Galactic PN population. Using a set of newly revised optical diagnostic diagrams in combination with access to a powerful, new, multi-wavelength imaging database, we have identified 159 true, likely and possible PNe for this first catalogue release. The ability of IPHAS to unveil PNe at low Galactic latitudes and towards the Galactic Anticenter, compared to previous surveys, makes this survey an ideal tool to contribute to the improvement of our knowledge of the whole Galactic PN population
    07/2014;
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    ABSTRACT: We present radio observations of water masers toward the planetary nebula (PN) IRAS 15103-5754 (I15103), obtained during several campaigns at the Australia Telescope Compact Array (ATCA) and the Parkes antenna. I15103 is one of the rare planetary nebulae (PNe) exhibiting water maser emission. The follow-up of water masers is crucial in PNe, since the lifetime expected for this emission is very short, and it might trace the youngest stages of a star in the PN phase. The maser components detected in this source trace a jet with possible precession, which could be shaping its circumstellar envelope. Extraordinarily bright water maser emission reaching 1600 Jy was observed during our last observation campaigns, making I15103 the PN with the most intense water maser emission ever detected. The rapid evolution of its radio continuum emission associated to this unusual water maser activity indicates that this source could be one of the youngest PN known up to now.
    03/2014;
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    ABSTRACT: Water masers have been revealed as an important tool to study the jets that shape the circumstellar envelopes of Planetary Nebulae (PNe). Water fountains are evolved objects with water maser components expanding velocities larger than 100 km/s, and they represent one of the first manifestations of axisymmetric jets during the late AGB or post-AGB phases. The unexpected presence of water masers in PNe, and the recent finding of the first PN with water fountain characteristics lead us to propose an evolutionary sequence that could connect the evolved sources presenting this emission. Water masers disappear quickly with the beginning of the photoionisation during the PN phase, but their presence in the disk, in the lobes or tracing jets in these objects can give an estimation of the evolutionary stage of the PN.
    03/2014;
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    ABSTRACT: One of the most intriguing issues related with planetary nebulae (PNe) is their shaping process, since the most asymmetrical PNe defy the standard models for the formation of spherical, elliptical or slightly bipolar PNe. To observe the shaping mechanism, the use of high-resolution techniques is mandatory. Interferometric IR observations performed with the VLTI have revealed clear evidences of disks at the core of few PNe, nevertheless the use of the VLTI impose constraints in the sensitivity as well as in the spatial coverage, limiting the targets that can be observed with this technique. On the other hand, CRIRES-VLT high-resolution spectro-astrometry technique have proven its efficiency revealing the existence of protoplanetary disks.The spectro-astrometric observations using CRIRES-VLT are less time consuming and less constrained by the models used to interpret the data than VLTI observations. Inspired by these results and the less complicated spectro-astrometric observations, we have applied for the first time CRIRES-VLT spectro-astrometry to sources in transition to the PN phase to demonstrate the capabilities of this technique in the search of disks and compact structures at the innermost regions of these objects. We have used CRIRES-VLT commissioning data to develop the methodology and the tools to apply spectro-astrometric analysis to the proto-PN IRAS 17516-2525 and the young PN SwSt 1. In previous studies, the morphology of SwSt 1 is barely resolved and remains unresolved for IRAS 17516-252. Our exploratory study has revealed compact structures after the spectro-astrometric analysis. In the case of SwSt 1 we have investigated the line of [Fe III] at 2.145 microns and Br gamma line at 2.160 microns and we have detected small structures ~230 mas and 130 mas, respectively. As for IRAS 17516-252, the spectro-astrometric signature of the Br gamma line suggest the presence of a compact Keplerian-like disk structure of ~12 mas in size. Additionally, we have requested CRIRES-VLT observations devoted solely to spectro-astrometric analysis. We present preliminary results for the Red Rectangle (AFGL 915) in the CO fundamental band at 4.99 microns. We have found the spectro-astrometric signatures of the Keplerian gaseous CO disk detected in previous radio observations, but with smaller size (~100 mas = 35 AU). These CRIRES-VLT high-resolution spectro-astrometric results open a new window in the search of the shaping mechanism of the more complex morphologies of extremely asymmetric PNe.
    03/2014;
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    ABSTRACT: We present new high resolution narrow-band [OIII] λ5007 images, as well as long-slit high resolution echelle spectra of the planetary nebula NGC 6309 at unprecedented detail, comfirming the presence of a halo circumscribing the quadrupolar outflows and discovering two diffuse emission blobs, which seem to be related to collimated ejections from the central star. Radial velocities of these faint blobs are very low, but qualitatively correspond to the radial direction of the quadrupolar lobes. Some possible scenarios are discussed, including collimated outflows from the central star and interaction of wind with field material, among others.
    03/2014;
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    ABSTRACT: Many PNe show rings and shells related to the remnants of the circumstellar envelopes of the asymptotic giant branch phase (AGB). After an extensive search in the HST and Spitzer archives we found ring-like structures in several PNe. Following the image analysis described by Corradi et al. (2004), and unsharp masking techniques it was possible to effectively remove the underlying halo emission, enhancing the ring structures. We mention in the results some hypotheses about the origins of these rings.
    03/2014;
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    ABSTRACT: We describe the evolution of of Swift J1644+57, whose unique X-ray properties have led several groups to interpret its behavior as corresponding to an extraordinary event of tidal disruption of a star by a supermassive black hole in the nucleus of a (z = 0.3545) galaxy, as derived by GTC. Multiwavelength observations (X-rays, optical, millimetre, centimitre) are proving to be essential to reveal the long term nature of the emission in this source. In particular, we identify for the first time the properties of a forming relativistic jet. In our interpretation of the phenomenon, we leave the still open possibility that it may correspond to the onset of a dormant AGN, but this may only be tested with longer term X-ray, millimetre and centimetre monitoring.
    12/2013;
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    ABSTRACT: The shaping process of planetary nebulae (PNe) takes place during the short transition from the asymptotic giant branch (AGB) phase to the white dwarf stage. The young PN K 3-35 represents a unique case where a small-sized water maser ring has been linked to the launch of collimated outflows that shape the nebula. The contrasting optical and radio continuum morphologies of K 3-35 indicate that they disclose different structural components that are apparently unconnected. To bridge the gap between optical and radio continuum observations, we present here new broadband and narrowband near-and mid-IR images of K 3-35. These images, and their comparison with optical and radio continuum images, are revealing. The radio continuum and mid-IR images are dominated by a compact source at the core of K 3-35 whose emission gives evidence of very dense ionized material embedded within a dust cocoon. The emission from the core, obscured at optical wavelengths, is faintly detected in the K s band. We suggest that the dust may shield the water molecules at the inner ring from the central star ionizing radiation. The precessing collimated outflows, very prominent in radio continuum, are also detected in mid-IR, very particularly in the [S iv] image. The mid-IR emission from these outflows consist mostly of ionized material, although the broadband filter at 11.85 μm seems to imply that a small amount of dust may be carried out by the outflow. The interactions of these outflows with the nebular shell result in shocks that excite the emission of H 2 as well as low-excitation lines from ionized species, such as [N ii] at the tips of the outflows.
    Astronomy and Astrophysics 10/2013; 561(A81). · 5.08 Impact Factor
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    ABSTRACT: We analyze Chandra observations of the Wolf-Rayet (WR) bubble NGC 6888. This WR bubble presents similar spectral and morphological X-ray characteristics to those of S 308, the only other WR bubble also showing X-ray emission. The observed spectrum is soft, peaking at the N VII line emission at 0.5 keV with additional line emission at 0.7 - 0.9 keV and a weak tail of harder emission up to ~1.5 keV. This spectrum can be described by a two-temperature optically thin plasma emission model (T_{1}~1.4x10^{6} K, T_{2}~7.4x10^{6} K). We confirm the results of previous X-ray observations that no noticeable temperature variations are detected in the nebula. The X-ray-emitting plasma is distributed in three apparent morphological components: two caps along the tips of the major axis and an extra contribution toward the northwest blowout not reported in previous analysis of the X-ray emission toward this WR nebula. Using the plasma model fits of the Chandra ACIS spectra for the physical properties of the hot gas and the ROSAT PSPC image to account for the incomplete coverage of Chandra observations, we estimate a luminosity of L_X = (7.7\pm0.1)x10^{33} erg/s for NGC 6888 at a distance of 1.26 kpc. The average rms electron density of the X-ray-emitting gas is >= 0.4 cm^{-3} for a total mass >= 1.2 Msun.
    The Astronomical Journal 10/2013; 147(2). · 4.97 Impact Factor
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    J. A. Toalá, M. A. Guerrero
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    ABSTRACT: We present the analysis of XMM-Newton archival observations towards the Wolf-Rayet (WR) bubble around WR16. Despite the closed bubble morphology of this WR nebula, the XMM-Newton observations show no evidence of diffuse emission in its interior as in the similar WR bubbles NGC6888 and S308. We use the present observations to estimate a 3-\sigma upper limit to the X-ray luminosity in the 0.3-1.5 keV energy band equal to 7.4x10^{32} erg s^{-1} for the diffuse emission from the WR nebula, assuming a distance of 2.37 kpc. The WR nebula around WR16 is the fourth observed by the current generation of X-ray satellites and the second not detected. We also examine FUSE spectra to search for nebular O VI absorption lines in the stellar continuum of WR16. The present far-UV data and the lack of measurements of the dynamics of the optical WR bubble do not allow us to confirm the existence of a conductive layer of gas at T~3x10^5 K between the cold nebular gas and the hot gas in its interior. The present observations result in an upper limit of n_e < 0.6 cm^-3 on the electron density of the X-ray emitting material within the nebula.
    Astronomy and Astrophysics 09/2013; · 5.08 Impact Factor
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    ABSTRACT: The propagation of a shock wave into a medium is expected to heat the material beyond the shock, producing noticeable effects in intensity line ratios such as [O III]/Halpha. To investigate the occurrence of shocks in planetary nebulae (PNe), we have used all narrowband [O III] and Halpha images of PNe available in the HST archive to build their [O III]/Halpha ratio maps and to search for regions where this ratio is enhanced. Regions with enhanced [O III]/Halpha emission ratio can be ascribed to two different types of morphological structures: bow-shock structures produced by fast collimated outflows and thin skins enveloping expanding nebular shells. Both collimated outflows and expanding shells are therefore confirmed to generate shocks in PNe. We also find regions with depressed values of the [O III]/Halpha ratio which are found mostly around density bounded PNe, where the local contribution of [N II] emission into the F656N Halpha filter cannot be neglected.
    Astronomy and Astrophysics 07/2013; · 5.08 Impact Factor
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    ABSTRACT: This White Paper, submitted to the recent ESA call for science themes to define its future large missions, advocates the need for a transformational leap in our understanding of two key questions in astrophysics: 1) How does ordinary matter assemble into the large scale structures that we see today? 2) How do black holes grow and shape the Universe? Hot gas in clusters, groups and the intergalactic medium dominates the baryonic content of the local Universe. To understand the astrophysical processes responsible for the formation and assembly of these large structures, it is necessary to measure their physical properties and evolution. This requires spatially resolved X-ray spectroscopy with a factor 10 increase in both telescope throughput and spatial resolving power compared to currently planned facilities. Feedback from supermassive black holes is an essential ingredient in this process and in most galaxy evolution models, but it is not well understood. X-ray observations can uniquely reveal the mechanisms launching winds close to black holes and determine the coupling of the energy and matter flows on larger scales. Due to the effects of feedback, a complete understanding of galaxy evolution requires knowledge of the obscured growth of supermassive black holes through cosmic time, out to the redshifts where the first galaxies form. X-ray emission is the most reliable way to reveal accreting black holes, but deep survey speed must improve by a factor ~100 over current facilities to perform a full census into the early Universe. The Advanced Telescope for High Energy Astrophysics (Athena+) mission provides the necessary performance (e.g. angular resolution, spectral resolution, survey grasp) to address these questions and revolutionize our understanding of the Hot and Energetic Universe. These capabilities will also provide a powerful observatory to be used in all areas of astrophysics.
    06/2013;
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    ABSTRACT: Stars over a wide range of masses and evolutionary stages are nowadays known to emit X-rays. This X-ray emission is a unique probe of the most energetic phenomena occurring in the circumstellar environment of these stars, and provides precious insight on magnetic phenomena or hydrodynamic shocks. Owing to its large collecting area, Athena+ will open up an entirely new window on these phenomena. Indeed, Athena+ will not only allow us to study many more objects with an unprecedented spectral resolution, but will also pioneer the study of the dynamics of these objects via time-resolved high-resolution spectroscopy. In this way, Athena+ will be a unique tool to study accretion processes in TTauri stars, flaring activity in young stars, dynamos in ultra-cool dwarfs, small and large-scale structures in the winds of single massive stars, wind interactions in massive binary systems, hot bubbles in planetary nebula... All these studies will lead to a deeper understanding of yet poorly understood processes which have profound impact in star and planetary system formation as well as in feedback processes on Galactic scale.
    06/2013;
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    ABSTRACT: Planetary nebulae (PNe), the endpoint of the evolution of low- and intermediate-mass stars, display a wild morphological variety. Observations indicate that the onset of asymmetry in PNe already originates at the end of the Asymptotic Giant Branch (AGB) phase or during the post-AGB phase. Therefore, objects in these transition stages provide us a unique opportunity to investigate the sculpting processes of PNe. Here we report VISIR mid-IR high angular resolution observations of a sample of young PNe and objects in their transition to the PN phase. The investigation of the shaping mechanisms requires even higher resolution observations. AMBER and MIDI at the VLTI may provide the required spatial resolution, but the imaging capabilities are limited and the observations are heavily time-consuming. On the other hand, spectro-astrometry using CRIRES-VLT can provide robust results at a lower observational cost. We report preliminary results of our CRIRES spectro-astrometry exploratory program in the search for disks inside PNe.
    05/2013;
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    ABSTRACT: We present the analysis of the hot plasma detected with XMM-Newton and Chandra X-ray observations toward the only two Wolf-Rayet bubbles so far detected: S 308 and NGC 6888. Both nebulae present spectra dominated by soft temperature plasmas of ˜10^{6} K with luminosities of L_{{X}}˜10^{33}-10^{34} erg s^{-1}, but with different X-ray-emitting plasma distribution. In the case of S 308 it presents a limb-brightened morphology, while in the case of NGC 6888, it shows three maxima localized at the Northeast and Southwest caps and another one extending toward the Northwest.
    05/2013;
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    ABSTRACT: Narrow-band Hα, [NII] λ6583, and [OIII] λ5007 images of Kn 26 were acquired on June 21, 2009 using ALFOSC (Andalucia Faint Object Spectrograph and Camera) at the 2.56m Nordic Optical Telescope (NOT) of the Observatorio de Roque de los Muchachos (ORM, La Palma, Spain). Narrow-band H2 2.1218um, Brγ 2.1658um, and K continuum at 2.270um images of Kn 26 were obtained on June 27, 2010 using LIRIS at the Cassegrain focus of the 4.2m William Herschel Telescope (WHT) at the ORM. Intermediate-resolution long-slit spectra of Kn 26 were obtained on October 5, 2011 using the ALBIREO spectrograph at the 1.5m telescope of the Observatorio de Sierra Nevada (OSN), Granada, Spain. Long-slit high-dispersion spectroscopy on the Hα and [NII] λ6583 lines of Kn 26 has been acquired on June 13, 2010 using the Manchester Echelle Spectrometer (MES) mounted on the 2.1m (f/7.5) telescope at the Observatorio Astronomico Nacional de San Pedro Martir (OAN-SPM, Mexico). (2 data files).
    VizieR Online Data Catalog. 03/2013;
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    ABSTRACT: The presence of O VI ions can be indicative of plasma temperatures of a few times 10^5 K that is expected in heat conduction layers between the hot shocked stellar wind gas at several 10^6 K and the cooler (~10,000 K) nebular gas of planetary nebulae (PNe). We have used FUSE observations of PNe to search for nebular O VI emission or absorption as a diagnostic of conduction layer to ensure the presence of hot interior gas. Three PNe showing nebular O VI, namely IC 418, NGC 2392, and NGC 6826, have been selected for Chandra observations and diffuse X-ray emission is indeed detected in each of these PNe. Among the three, NGC 2392 has peculiarly high diffuse X-ray luminosity and plasma temperature compared with those expected from its stellar wind's mechanical luminosity and terminal velocity. The limited effects of heat conduction on the plasma temperature of a hot bubble at the low terminal velocity of the stellar wind of NGC 2392 may partially account for its high plasma temperature, but the high X-ray luminosity needs to be powered by processes other than the observed stellar wind, probably caused by the presence of an unseen binary companion of the CSPN of NGC 2392. We have compiled relevant information on the X-ray, stellar, and nebular properties of PNe with a bubble morphology and found that the expectations of bubble models including heat conduction compare favorably with the present X-ray observations of hot bubbles around H-rich CSPNe, but have notable discrepancies for those around H-poor [WR] CSPNe. We note that PNe with more massive central stars can produce hotter plasma and higher X-ray surface brightness inside central hot bubbles.
    The Astrophysical Journal 02/2013; 767(1). · 6.73 Impact Factor
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    ABSTRACT: Infrared photometry of the probable triple WC4(+O?)+O8I: Wolf-Rayet system HD 36402 (= BAT99-38) in the Large Magellanic Cloud (LMC) shows emission characteristic of heated dust. The dust emission is variable on a time-scale of years, with a period near 4.7 yr, possibly associated with orbital motion of the O8 supergiant and the inner P ~ 3.03-d WC4+O binary. The phase of maximum dust emission is close to that of the X-ray minimum, consistent with both processes being tied to colliding wind effects in an elliptical binary orbit. It is evident that Wolf-Rayet dust formation occurs also in metal-poor environments.
    Monthly Notices of the Royal Astronomical Society 02/2013; 431(2). · 5.52 Impact Factor
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    ABSTRACT: We report the discovery of extended X-ray emission within the young star cluster NGC 602 in the Wing of the Small Magellanic Cloud (SMC) based on observations obtained with the Chandra X-ray Observatory. X-ray emission is detected from the cluster core area with the highest stellar density and from a dusty ridge surrounding the HII region. We use a census of massive stars in the cluster to demonstrate that a cluster wind or wind-blown bubble is unlikely to provide a significant contribution to the X-ray emission detected from the central area of the cluster. We therefore suggest that X-ray emission at the cluster core originates from an ensemble of low- and solar-mass pre-main-sequence (PMS) stars, each of which would be too weak in X-rays to be detected individually. We attribute the X-ray emission from the dusty ridge to the embedded tight cluster of the new-born stars known in this area from infrared studies. Assuming that the levels of X-ray activity in young stars in the low-metallicity environment of NGC 602a are comparable to their Galactic counterparts, then the detected spatial distribution, spectral properties, and level of X-ray emission are largely consistent with those expected from low- and solar-mass PMS stars and young stellar objects (YSOs). This is the first discovery of X-ray emission attributable to PMS stars and YSOs in the SMC, which suggests that the accretion and dynamo processes in young, low-mass objects in the SMC resemble those in the Galaxy.
    The Astrophysical Journal 01/2013; 765(1). · 6.73 Impact Factor

Publication Stats

313 Citations
216.94 Total Impact Points

Institutions

  • 2014
    • University of Guadalajara
      • Instituto de Astronomía y Meteorología
      Guadalajara, Jalisco, Mexico
  • 2005–2014
    • Instituto De Astrofisica De Andalucia
      Granata, Andalusia, Spain
    • Spanish National Research Council
      • Andalusian Astrophysics Institute
      Madrid, Madrid, Spain
  • 2011
    • Rochester Institute of Technology
      • Center for Imaging Science
      Rochester, New York, United States
  • 2010
    • Autonomous University of Baja California
      Mexicali, Baja California, Mexico
  • 2008
    • The University of Sheffield
      • Department of Physics and Astronomy
      Sheffield, ENG, United Kingdom
  • 2000–2005
    • University of Illinois, Urbana-Champaign
      • Department of Astronomy
      Urbana, IL, United States
  • 1999
    • Instituto de Astrofísica de Canarias
      San Cristóbal de La Laguna, Canary Islands, Spain