- ID:
- ivo://CDS.VizieR/J/ApJ/826/224
- Title:
- RSG and foreground candidates in M31
- Short Name:
- J/ApJ/826/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the red supergiant (RSG) population of M31, obtaining the radial velocities of 255 stars. These data substantiate membership of our photometrically selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B-V, V-R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolved from 25-30 M_{sun}_ stars, while the vast majority evolved from stars with initial masses of 20 M_{sun}_ or less. There is an interesting bifurcation in the distribution of RSGs with effective temperatures that increases with higher luminosities, with one sequence consisting of early K-type supergiants, and with the other consisting of M-type supergiants that become later (cooler) with increasing luminosities. This separation is only partially reflected in the evolutionary tracks, although that might be due to the mis-match in metallicities between the solar Geneva models and the higher-than-solar metallicity of M31. As the luminosities increase the median spectral type also increases; i.e., the higher mass RSGs spend more time at cooler temperatures than do those of lower luminosities, a result which is new to this study. Finally we discuss what would be needed observationally to successfully build a luminosity function that could be used to constrain the mass-loss rates of RSGs as our Geneva colleagues have suggested.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/900/118
- Title:
- RSGs in the LMC & sp. follow-up for LMC & SMC
- Short Name:
- J/ApJ/900/118
- Date:
- 20 Jan 2022 11:32:23
- Publisher:
- CDS
- Description:
- The binary fraction of unevolved massive stars is thought to be 70%-100% but there are few observational constraints on the binary fraction of the evolved version of a subset of these stars, the red supergiants (RSGs). Here we identify a complete sample of RSGs in the Large Magellanic Cloud (LMC) using new spectroscopic observations and archival UV, IR, and broadband optical photometry. We find 4090 RSGs with logL/L_{sun}_>3.5, with 1820 of them having logL/L_{sun}_>4, which we believe is our completeness limit. We additionally spectroscopically confirmed 38 new RSG + B-star binaries in the LMC, bringing the total known up to 55. We then estimated the binary fraction using a k-nearest neighbors algorithm that classifies stars as single or binary based on photometry with a spectroscopic sample as a training set. We take into account observational biases such as line-of-sight stars and binaries in eclipse while also calculating model- dependent corrections for RSGs with companions that our observations were not designed to detect. Based on our data, we find an initial result of 13.5_-6.67_^+7.56^% for RSGs with O- or B-type companions. Using the Binary Population and Spectral Synthesis models to correct for unobserved systems, this corresponds to a total RSG binary fraction of 19.5_-6.7_^+7.6^% . This number is in broad agreement with what we would expect given an initial OB binary distribution of 70%, a predicted merger fraction of 20%-30%, and a binary interaction fraction of 40%-50%.
113. RSGs in the SMC
- ID:
- ivo://CDS.VizieR/J/A+A/639/A116
- Title:
- RSGs in the SMC
- Short Name:
- J/A+A/639/A116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the most comprehensive red supergiant (RSG) sample for the Small Magellanic Cloud (SMC) to date, including 1239 RSG candidates. The initial sample was derived based on a source catalog for the SMC with conservative ranking. Additional spectroscopic RSGs were retrieved from the literature, and RSG candidates were selected based on the inspection of Gaia and 2MASS color-magnitude diagrams (CMDs). We estimate that there are in total ~1800 or more RSGs in the SMC. We purify the sample by studying the infrared CMDs and the variability of the objects, though there is still an ambiguity between asymptotic giant branch stars (AGBs) and RSGs at the red end of our sample. One heavily obscured target was identified based on multiple near-IR (NIR) and mid-IR (MIR) CMDs. The investigation of color-color diagrams (CCDs) shows that there are fewer RSGs candidates (~4%) showing PAH emission features compared to the Milky Way and LMC (~15%). The MIR variability of RSG sample increases with luminosity. We separate the RSG sample into two subsamples (risky and safe), and identify one M5e AGB star in the risky subsample based on simultaneous inspection of variabilities, luminosities, and colors. The degeneracy of mass loss rate (MLR), variability, and luminosity of the RSG sample is discussed, indicating that most of the targets with high variability are also the bright ones with high MLR. Some targets show excessive dust emission, which may be related to previous episodic mass loss events. We also roughly estimate the total gas and dust budget produced by entire RSG population as ~1.9^+2.4^_-1.1_x10^-6^M_{sun}_/yr in the most conservative case, according to the derived MLR from IRAC1-IRAC4 color. Based on the MIST models, we derive a linear relation between T_eff_ and observed J-Ks color with reddening correction for the RSG sample. By using a constant bolometric correction and this relation, the Geneva evolutionary model is compared with our RSG sample, showing a good agreement and a lower initial mass limit of ~7M_{sun}_ for the RSG population. Finally, we compare the RSG sample in the SMC and the LMC. Despite the incompleteness of LMC sample in the faint end, the result indicates that the LMC sample always shows redder color (except for the IRAC1-IRAC2 and WISE1-WISE2 colors due to CO absorption) and higher variability than the SMC sample, which is likely due to a positive relation between MLR, variability and the metallicity.
- ID:
- ivo://CDS.VizieR/J/A+A/395/97
- Title:
- RV and vsini of Ib supergiant stars
- Short Name:
- J/A+A/395/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotational velocity vsini and mean radial velocity are presented for a sample of 232 Ib supergiant stars covering the spectral region F, G and K. This work is the second part of the large survey carried out with the CORAVEL spectrometer to establish the behavior of the rotation for stars evolving off the main sequence (De Medeiros & Mayor, 1999, Cat. <J/A+AS/139/433>). These data will add constraints to the study of the rotational behavior in evolved stars, as well as solid information concerning tidal interactions in binary systems and on the link between rotation, chemical abundance and activity in stars of intermediate masses.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/2814
- Title:
- SAGE SMC evolved stars candidates
- Short Name:
- J/MNRAS/457/2814
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The life cycle of dust in the interstellar medium is heavily influenced by outflows from asymptotic giant branch (AGB) and red supergiant (RSG) stars, a large fraction of which is contributed by a few very dusty sources. We compute the dust input to the Small Magellanic Cloud (SMC) by fitting the multi-epoch mid-infrared spectral energy distributions of AGB/RSG candidates with models from the Grid of RSG and AGB ModelS grid, allowing us to estimate the luminosities and dust-production rates (DPRs) of the entire population. By removing contaminants, we guarantee a high-quality data set with reliable DPRs and a complete inventory of the dustiest sources. We find a global AGB/RSG dust-injection rate of (1.3+/-0.1)x10^-6^M_{sun}_/yr, in agreement with estimates derived from mid-infrared colours and excess fluxes. As in the Large Magellanic Cloud, a majority (66 per cent) of the dust arises from the extreme AGB stars, which comprise only ~7 per cent of our sample. A handful of far-infrared sources, whose 24{mu}m fluxes exceed their 8{mu}m fluxes, dominate the dust input. Their inclusion boosts the global DPR by ~1.5x, making it necessary to determine whether they are AGB stars. Model assumptions, rather than missing data, are the major sources of uncertainty; depending on the choice of dust shell expansion speed and dust optical constants, the global DPR can be up to ~10 times higher. Our results suggest a non-stellar origin for the SMC dust, barring as yet undiscovered evolved stars with very high DPRs.
116. S Dor variables
- ID:
- ivo://CDS.VizieR/J/A+A/366/508
- Title:
- S Dor variables
- Short Name:
- J/A+A/366/508
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The goal in writing this paper is five fold: (1) to summarize the scientific achievements in the 20th century on S Dor variables (or LBVs); (2) to present an inventory of these variables in the Galaxy and the Magellanic Clouds with a description of their physical state and instability properties; (3) to emphasize the photometric achievements of the various types of instabilities. Generally this seems to be a neglected item resulting in a number of misunderstandings continuously wandering through literature; (4) to investigate the structure of the S Dor-area on the HR-diagram; (5) to estimate the total numbers of S Dor variables in the three stellar systems.
- ID:
- ivo://CDS.VizieR/J/other/AstBu/65.150
- Title:
- Spectral line identification in 3 Pup
- Short Name:
- J/other/AstBu/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical spectra taken in 1997-2008 are used to analyze the spectral peculiarities and velocity field in the atmosphere of the peculiar supergiant 3 Pup.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A75
- Title:
- Spectra of 8 supergiants in nearby galaxies
- Short Name:
- J/A+A/562/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The role of episodic mass loss in massive star evolution is one of the outstanding questions of current stellar evolution theory. Episodic mass loss produces dust and therefore causes evolved massive stars to be very luminous in the mid-infrared and dim at optical wavelengths. We aim to increase the number of investigated luminous mid-IR sources to shed light on the late stages of these objects. To achieve this we explore mid-IR selection criteria to identity dusty evolved massive stars in two nearby galaxies. The method is based on mid-IR colors, using 3.6um and 4.5um photometry from archival Spitzer Space Telescope images of nearby galaxies and J-band from 2MASS. We apply our criteria to two nearby star-forming dwarf-irregular galaxies: Sextans A and IC 1613, selecting 8 targets, which we follow up with spectroscopy. Our spectral classification and analysis yielded the discovery of 2 M-type supergiants in IC 1613, 3 K-type supergiants and 1 candidate F-type giant in Sextans A, and 2 foreground M giants. We show that the proposed criteria provide an independent way for identifying dusty evolved massive stars, which can be extended to all nearby galaxies with available Spitzer/IRAC images at 3.6um and 4.5um.
- ID:
- ivo://CDS.VizieR/J/AN/320/105
- Title:
- Spectrophotometry of 26 supergiants in the LMC
- Short Name:
- J/AN/320/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New spectrophotometric data for 3 galactic and 23 LMC F to G supergiants are presented. The wavelength range of the spectra is 3400 to 6400{AA}, the resolution about 10{AA}. The mean transformational error of the fluxes is 0.03mag. The S/N ratio is about 100 and 30 for galactic and LMC stars, respectively. Details about the reduction one may found in Oestreicher & Schmidt-Kaler (1998MNRAS.299..625O) and Malyuto et al. (1997MNRAS.286..500M). The fluxes are given in magnitudes according to the system of Hayes & Latham (1975ApJ...197..593H). For each star an ASCII file is given with the name of the first identifier. In the first column the wavelength, in the second column the flux is given.
- ID:
- ivo://CDS.VizieR/J/A+A/400/1043
- Title:
- Spectroscopic atlas of Deneb 3826-5212{AA}
- Short Name:
- J/A+A/400/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic atlas of Deneb (A2 Iae) obtained with the long camera of the 1.22-m telescope of the Dominion Astrophysical Observatory using Reticon and CCD detectors. For {lambda}{lambda}3826-5212 the inverse dispersion is 2.4{AA}/mm with a resolution 0.072{AA}. At the continuum the mean signal-to-noise ratio is 1030. The wavelengths in the laboratory frame, the equivalent widths, and the identifications of the various spectral features are given. This atlas should provide useful guidance for studies of other stars with similar spectral types. The stellar and synthetic spectra with their corresponding line identifications can be examined at http://www.brandonu.ca/physics/gulliver/atlases.html .
