- ID:
- ivo://CDS.VizieR/J/ApJ/562/303
- Title:
- Old Stellar Populations of the SMC
- Short Name:
- J/ApJ/562/303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometry is given for six data sets of SMC photometry, all in the V and I bands. Field names in the file summary below are the names used in the STScI archive for the WFPC2 observations. WFPC2 observations of NGC 121 and the SMC fields reach limiting magnitudes of V=26 and I=25.5; ground-based observations cover a square region of 14.5 arcmin on a side and reach V=25.5 and I=24.5.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/530/A90
- Title:
- Optically bright post-AGB population of LMC
- Short Name:
- J/A+A/530/A90
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a catalogue of the optically bright post-AGB stars in the LMC. The sample forms an ideal testbed for stellar evolution theory predictions of the final phase of low- and intermediate-mass stars, because the distance and hence luminosity and also the current and initial mass of these objects is well constrained.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/94
- Title:
- Optical polarimetric catalog of stars in the SMC
- Short Name:
- J/ApJ/806/94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new optical polarimetric catalog for the Small Magellanic Cloud (SMC). It contains a total of 7207 stars, located in the northeast (NE) and Wing sections of the SMC and part of the Magellanic Bridge. This new catalog is a significant improvement compared to previous polarimetric catalogs for the SMC. We used it to study the sky-projected interstellar magnetic field structure of the SMC. Three trends were observed for the ordered magnetic field direction at position angles (PAs) of (65{deg}+/-10{deg}), (115{deg}+/-10{deg}), and (150{deg}+/-10{deg}). Our results suggest the existence of an ordered magnetic field aligned with the Magellanic Bridge direction and SMC's Bar in the NE region, which have PAs roughly at 115.4{deg} and 45{deg}, respectively. However, the overall magnetic field structure is fairly complex. The trends at 115{deg} and 150{deg} may be correlated with the SMC's bimodal structure, observed in Cepheids' distances and HI velocities. We derived a value of B_sky_=(0.497+/-0.079){mu}G for the ordered sky-projected magnetic field, and {delta}B=(1.465+/-0.069){mu}G for the turbulent magnetic field. This estimate of B_sky_ is significantly larger (by a factor of ~10) than the line of sight field derived from Faraday rotation observations, suggesting that most of the ordered field component is on the plane of the sky. A turbulent magnetic field stronger than the ordered field agrees with observed estimates for other irregular and spiral galaxies. For the SMC the B_sky_/{delta}B ratio is closer to what is observed for our Galaxy than other irregular dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/835/209
- Title:
- Orbital nature of 81 ellipsoidal red giant binaries
- Short Name:
- J/ApJ/835/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we collect a sample of 81 ellipsoidal red giant binaries in the Large Magellanic Cloud (LMC), and we study their orbital natures individually and statistically. The sample contains 59 systems with circular orbits and 22 systems with eccentric orbits. We derive orbital solutions using the 2010 version of the Wilson-Devinney code (Wilson & Devinney 1971ApJ...166..605W ; Wilson 1979ApJ...234.1054W, 1990ApJ...356..613W ; Wilson+ 2009, J/ApJ/702/403). The sample is selection-bias corrected, and the orbital parameter distributions are compared to model predictions for the LMC and to observations in the solar vicinity. The masses of the red giant primaries are found to range from about 0.6 to 9M_{sun}_ with a peak at around 1.5M_{sun}_, in agreement with studies of the star formation history of the LMC, which find a burst of star formation beginning around 4 Gyr ago. The observed distribution of mass ratios q=m_2_/m_1_ is more consistent with the flat q distribution derived for the solar vicinity by Raghavan+ (2010, J/ApJS/190/1) than it is with the solar vicinity q distribution derived by Duquennoy & Mayor (1991A&A...248..485D). There is no evidence for an excess number of systems with equal mass components. We find that about 20% of the ellipsoidal binaries have eccentric orbits, twice the fraction estimated by Soszynski+ (2004, J/AcA/54/347). Our eccentricity evolution test shows that the existence of eccentric ellipsoidal red giant binaries on the upper parts of the red giant branch (RGB) can only be explained if tidal circularization rates are ~1/100 the rates given by the usual theory of tidal dissipation in convective stars.
- ID:
- ivo://CDS.VizieR/J/A+A/560/A29
- Title:
- O-stars in VLT-FLAMES Tarantula Survey
- Short Name:
- J/A+A/560/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 30 Doradus (30 Dor) region of the Large Magellanic Cloud, also known as the Tarantula Nebula, is the nearest starburst region. It contains the richest population of massive stars in the Local Group and it is thus the best possible laboratory to investigate open questions in the formation and evolution of massive stars. Using ground based multi-object optical spectroscopy obtained in the framework of the VLT-FLAMES Tarantula Survey (VFTS), we aim to establish the (projected) rotational velocity distribution for a sample of 216 presumably single O-type stars in 30 Dor. The size of the sample is large enough to obtain statistically significant information and to search for variations among sub-populations - in terms of spectral type, luminosity class, and spatial location - in the field of view. We measured projected rotational velocities, Vrot, by means of a Fourier transform method and a profile fitting method applied on a set of isolated spectral lines. We also used an iterative deconvolution procedure to infer the probability density, P(Veq), of the equatorial rotational velocity, Veq. The distribution of Vrot shows a two-component structure: a peak around 80km/s and a high-velocity tail extending up to ~600km/s. This structure is also present in the inferred distribution P(Veq) with around 80% of the sample having 0<Veq<=300km/s and the other 20% distributed in the high-velocity region. The presence of the low-velocity peak is consistent with that found in other studies for late O- and early B-type stars. Most of the stars in our sample rotate with a rate less than 20% of their break-up velocity. For the bulk of the sample, mass-loss in a stellar wind and/or envelope expansion is not efficient enough to significantly spin down these stars within the first few Myr of evolution. If massive-star formation results in stars rotating at birth with a large fraction of their break-up velocities, an alternative braking mechanism, possibly magnetic fields, is thus required to explain the present day rotational properties of the O-type stars in 30 Dor. The presence of a sizeable population of fast rotators is compatible with recent population synthesis computations that investigate the influence of binary evolution on the rotation rate of massive stars. Despite the fact that we have excluded stars that show significant radial velocity variations, our sample may have remained contaminated by post-interaction binary products. The fact that the high-velocity tail may be preferentially (and perhaps even exclusively), populated by post-binary interaction products, has important implications for the evolutionary origin of systems that produce gamma-ray bursts.
- ID:
- ivo://CDS.VizieR/J/A+A/434/89
- Title:
- Parameters of LMC detached eclipsing binaries
- Short Name:
- J/A+A/434/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a result of a careful selection of eclipsing binaries in the Large Magellanic Cloud using the OGLE-II photometric database, we present a list of 98 systems that are suitable targets for spectroscopic observations that would lead to the accurate determination of the distance to the LMC. For these systems we derive preliminary parameters combining the OGLE-II data with the photometry of MACHO and EROS surveys. In the selected sample, 58 stars have eccentric orbits. Among these stars we found fourteen systems showing apsidal motion. The data do not cover the whole apsidal motion cycle, but follow-up observations will allow detailed studies of these interesting objects.
- ID:
- ivo://CDS.VizieR/J/ApJS/117/135
- Title:
- Photometry of Cepheids in Magellanic Clouds
- Short Name:
- J/ApJS/117/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report BV(RI)C data for a select group of 14 Cepheids in the Large Magellanic Cloud and eight in the Small Magellanic Cloud that have preexisting radial velocity curves. The photometry was obtained as part of a program to determine distances to these Cepheids by means of the visual surface brightness technique and to improve significantly the optical BV(RI)C light curves of Magellanic Cloud Cepheids. The data were acquired on the 0.9 m telescope at Cerro Tololo Inter-American Observatory with the CFCCD instrument and with the 1 m photometric telescope at ESO using aperture photometry. The median number of measures per Cepheid is 46 in each band, and the uncertainty in the photometry is typically 0.01 mag. Using these data together with data from the literature, we determined improved periods for all variables. For most of the Cepheids, these revised periods lead to excellent, low-noise light curves, but for a few variables, the periods are obviously variable.
- ID:
- ivo://CDS.VizieR/J/AJ/119/2214
- Title:
- Photometry of Magellanic OB associations
- Short Name:
- J/AJ/119/2214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine new CCD UBV photometry and spectroscopy with those from the literature to investigate 19 Magellanic Cloud OB associations that contain Wolf-Rayet (W-R) and other types of evolved, massive stars. Our spectroscopy reveals a wealth of newly identified interesting objects, including early O-type supergiants, a high-mass, double-lined binary in the SMC, and, in the LMC, a newly confirmed luminous blue variable (LBV; R85), a newly discovered W-R star (Sk -69^deg^ 194), and a newly found luminous B[e] star (LH 85-10). We use these data to provide precise reddening determinations and construct physical H-R diagrams for the associations.
- ID:
- ivo://CDS.VizieR/J/A+A/301/396
- Title:
- Photometry of NGC 1962-65-66-70
- Short Name:
- J/A+A/301/396
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD data in the Johnson passbands B and V of the young association NGC 1962-65-66-70 in the Large Magellanic Cloud.
- ID:
- ivo://CDS.VizieR/J/AJ/149/95
- Title:
- Photometry of nova LMC 2012
- Short Name:
- J/AJ/149/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an intensive multiwavelength campaign on nova LMC 2012. This nova evolved very rapidly in all observed wavelengths. The time to fall two magnitudes in the V band was only 2days. In X-rays the super soft phase began 13+/-5days after discovery and ended around day 50 after discovery. During the super soft phase, the Swift/XRT and Chandra spectra were consistent with the underlying white dwarf (WD) being very hot, ~1MK, and luminous, ~10^38^erg/s. The UV, optical, and near-IR photometry showed a periodic variation after the initial and rapid fading had ended. Timing analysis revealed a consistent 19.24+/-0.03hr period in all UV, optical, and near-IR bands with amplitudes of ~0.3mag which we associate with the orbital period of the central binary. No periods were detected in the corresponding X-ray data sets. A moderately high inclination system, i=60+/-10{deg}, was inferred from the early optical emission lines. The HST/STIS UV spectra were highly unusual with only the N v (1240{AA}) line present and superposed on a blue continuum. The lack of emission lines and the observed UV and optical continua from four epochs can be fit with a low mass ejection event, ~10^-6^M_{sun}_, from a hot and massive WD near the Chandrasekhar limit. The WD, in turn, significantly illuminated its subgiant companion which provided the bulk of the observed UV/optical continuum emission at the later dates. The inferred extreme WD characteristics and low mass ejection event favor nova LMC 2012 being a recurrent nova of the U Sco subclass.
