- ID:
- ivo://CDS.VizieR/J/A+A/618/A5
- Title:
- Radial velocity survey of low-mass binaries
- Short Name:
- J/A+A/618/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The identification and characterisation of low-mass binaries is of importance for a range of astrophysical investigations. Low-mass binaries in young (~10-100Myr) moving groups (YMGs) in the solar neighborhood are of particular significance as they provide unique opportunities to calibrate stellar models and evaluate the ages and coevality of the groups themselves. Low-mass M-dwarfs have pre-main sequence life times on the order of ~100Myr and therefore are continually evolving along a mass-luminosity track throughout the YMG phase, providing ideal laboratories for precise isochronal dating, if a model-independent dynamical mass can be measured. AstraLux lucky imaging multiplicity surveys have recently identified hundreds of new YMG low-mass binaries, where a subsample of M-dwarf multiples have estimated orbital periods less than 50 years. We have conducted a radial velocity survey of a sample of 29 such targets to complement the astrometric data. This will allow enhanced orbital determinations and precise dynamical masses to be derived in a shorter timeframe than possible with astrometric monitoring alone, and allow for a more reliable isochronal analysis. Here we present radial velocity measurements derived for our sample over several epochs. We report the detection of the three-component spectroscopic multiple 2MASS J05301858-5358483, for which the C component is a new discovery, and forms a tight pair with the B component. Originally identified as a YMG member, we find that this system is a likely old field interloper, whose high chromospheric activity level is caused by tidal spin-up of the tight BC pair. Two other triple systems with a tight pair exist in the sample, 2MASS J04244260-0647313 (previously known) and 2MASS J20163382-0711456, but for the rest of the targets we find that additional tidally synchronized companions are highly unlikely, providing further evidence that their high chromospheric activity levels are generally signatures of youth.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/648/629
- Title:
- Radio observations of late M, L, and T dwarfs
- Short Name:
- J/ApJ/648/629
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I present radio observations of 90 dwarf stars and brown dwarfs of spectral type M5-T8. Three sources exhibit radio activity, in addition to the six objects previously detected in quiescence and outburst, leading to an overall detection rate of ~10% for objects later than M7.
- ID:
- ivo://CDS.VizieR/J/ApJ/746/23
- Title:
- Radio observations of ultracool dwarf stars
- Short Name:
- J/ApJ/746/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new radio survey of about 100 late-M and L dwarfs undertaken with the Very Large Array. The sample was chosen to explore the role of rotation in the radio activity of ultracool dwarfs. As part of the survey we discovered radio emission from three new objects, 2MASS J0518113-310153 (M6.5), 2MASS J0952219-192431 (M7), and 2MASS J1314203+132001 (M7), and made an additional detection of LP 349-25 (M8). Combining the new sample with results from our previous studies and from the literature, we compile the largest sample to date of ultracool dwarfs with radio observations and measured rotation velocities.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A131
- Title:
- Radio survey of ultracool dwarfs
- Short Name:
- J/A+A/549/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to increase the sample of ultracool dwarfs studied in the radio domain to allow a more statistically significant understanding of the physical conditions associated with these magnetically active objects. We conducted a volume-limited survey at 4.9GHz of 32 nearby ultracool dwarfs with spectral types covering the range M7-T8. A statistical analysis was performed on the combined data from the present survey and previous radio observations of ultracool dwarfs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/2003
- Title:
- Red supergiant population in Perseus arm
- Short Name:
- J/MNRAS/475/2003
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of cool supergiants in a section of the Perseus arm, most of which had not been previously identified. To generate it, we have used a set of well-defined photometric criteria to select a large number of candidates (637) that were later observed at intermediate resolution in the infrared calcium triplet spectral range, using a long-slit spectrograph. To separate red supergiants from luminous red giants, we used a statistical method, developed in previous works and improved in the present paper. We present a method to assign probabilities of being a red supergiant to a given spectrum and use the properties of a population to generate clean samples, without contamination from lower luminosity stars. We compare our identification with a classification done using classical criteria and discuss their respective efficiencies and contaminations as identification methods. We confirm that our method is as efficient at finding supergiants as the best classical methods, but with a far lower contamination by red giants than any other method. The result is a catalogue with 197 cool supergiants, 191 of which did not appear in previous lists of red supergiants. This is the largest coherent catalogue of cool supergiants in the Galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/727/53
- Title:
- Red supergiant stars in the LMC. I.
- Short Name:
- J/ApJ/727/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From previous samples of red supergiants (RSGs) by various groups, 191 objects are assembled to compose a large sample of RSG candidates in LMC. For 189 of them, the identity as an RSG is verified by their brightness and color indexes in several near- and mid-infrared bands related to the Two Micron All Sky Survey (2MASS) JHKs bands and the Spitzer/IRAC and Spitzer/MIPS bands. From the visual time-series photometric observations by the ASAS and MACHO projects which cover nearly 8-10 years, the period and amplitude of light variation are analyzed carefully using both the phase dispersion minimization and Period04 (Lenz, 2004CoAst.144...41L) methods.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A175
- Title:
- Red supergiant stars in the LMC. II.
- Short Name:
- J/A+A/616/A175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characteristics of infrared properties and mid-infrared (MIR) variability of red supergiant (RSG) stars in the Large Magellanic Cloud (LMC) are analyzed based on 12 bands of near-infrared (NIR) to MIR co-added data from 2MASS, Spitzer and WISE, and ~6.6 years of MIR time-series data collected by the ALLWISE and NEOWISE-R projects. 773 RSGs candidates are compiled from the literature and verified by using the color-magnitude diagram (CMD), spectral energy distribution (SED) and MIR variability. About 15% of valid targets in the IRAC1-IRAC2/IRAC2-IRAC3 diagram may show Polycyclic Aromatic Hydrocarbon (PAH) emission. We show that arbitrary dereddening Q parameters related to the IRAC4, S9W, WISE3, WISE4 and MIPS24 bands could be constructed based on a precise measurement of MIR interstellar extinction law. Several peculiar outliers in our sample are discussed, in which one outlier might be a RSG right before the explosion or an extreme asymptotic giant branch (AGB) star in the very late evolutionary stage based on the MIR spectrum and photometry. There are 744 identified RSGs in the final sample having both the WISE1- and WISE2-band time-series data. The results show that the MIR variability is increasing along with the increasing of brightness. There is a relatively tight correlation between the MIR variability, mass loss rate (MLR; in terms of K_S-WISE3 color) and the warm dust/continuum (in terms of WISE4 magnitude/flux), where the MIR variability is evident for the targets with K_S-WISE3>1.0mag and WISE4<6.5mag, while the rest of the targets show much smaller MIR variability. The MIR variability is also correlated with the MLR for which targets with larger variability also show larger MLR with an approximate upper limit of -6.1M_{sun}_/yr. The variability and luminosity may both be important for the MLR since the WISE4-band flux is increasing exponentially along with the degeneracy of luminosity and variability. The identified RSG sample has been compared with the theoretical evolutionary models and shown that the discrepancy between observation and evolutionary models can be mitigated by considering both variability and extinction.
- ID:
- ivo://CDS.VizieR/J/ApJ/754/35
- Title:
- Red supergiant stars in the SMC. II.
- Short Name:
- J/ApJ/754/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The characteristics of light variation of red supergiant (RSG) stars in the Small Magellanic Cloud (SMC) are analyzed based on the nearly 8-10 year data collected by the ASAS and MACHO projects. The 126 identified RSGs are classified into five categories accordingly: 20 with poor photometry, 55 with no reliable period, 6 with semi-regular variation, 15 with a long secondary period (LSP) and distinguishable short period, and 30 with only an LSP. For the semi-regular variables and the LSP variables with distinguishable short period, the K_S_-band period-luminosity (P-L) relation is analyzed and compared with that of the Galaxy, the Large Magellanic Cloud, and M33. It is found that the RSGs in these galaxies obey a similar P-L relation except for those in the Galaxy. In addition, the P-L relations in the infrared bands, namely, the 2MASS JHK_S_, Spitzer/IRAC, and Spitzer/MIPS 24 {mu}m bands, are derived with high reliability. The best P-L relation occurs in the Spitzer/IRAC [3.6] and [4.5] bands. Based on the comparison with the theoretical calculation of the P-L relation, the mode of pulsation of RSGs in the SMC is suggested to be the first-overtone radial mode.
- ID:
- ivo://CDS.VizieR/III/237A
- Title:
- Revised Byurakan-IRAS stars (BIS) catalog
- Short Name:
- III/237A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Five lists of late-type stars were published in Astrophysics in 1997-2001, found in the First Byurakan Survey low-dispersion spectroscopic plates as optical identifications of unidentified IRAS sources. These identifications were carried out in the region with DE>+61 and |b|>15 with a surface of 1504deg^2^. As a result, the catalog of the Byurakan-IRAS Stars (BIS) was compiled. Its preliminary version was available at CDS since 2003, Cat. <III/237>. We have revised and updated the BIS catalog with the new data from recently published optical and infrared catalogs to give access to all available data and make possible further comparative studies of the properties of these objects. Cross-correlations of the BIS catalogue with the MAPS, USNO-B1.0 and 2MASS are made, updated SIMBAD data for the BIS objects are added, and accurate DSS1 and DSS2 positions and revised photometry are provided. The objects were checked for proper motion and variability as well. A refined classification from the Digitized First Byurakan Survey (DFBS) low-dispersion spectra was carried out. The revised and updated catalogue of 276 Byurakan-IRAS stars (BIS) is presented. The BIS catalogue can be used for a study of a complete sample of IRAS selected stars and for investigation of individual objects.
- ID:
- ivo://CDS.VizieR/III/266
- Title:
- Revised First Byurakan Survey of late-type stars
- Short Name:
- III/266
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Between 1990 and 2010, 15 lists of late-type stars found in the low-dispersion spectroscopic plates of the First Byurakan Survey (FBS) were published. The systematic search and selection was carried out on a surface of 16000 sq.deg. on almost the whole area of the FBS. As a result, a comprehensive catalogue of the late-type stars of the FBS was generated. Its preliminary version has been available at the CDS since 2007 (Cat. III/246). We have revised and updated the FBS catalogue of late-type stars with new data from recently published optical and multiwavelength catalogues to give access to all available data and to make further comparative studies of the properties of these objects possible. We have made cross-correlations with the Digitized First Byurakan Survey (DFBS, Cat. VI/116)), the United States Naval Observatory-B1.0 catalogue (Cat. I/284), the Guide Star Catalogue 2.3.2 (Cat. I/305), Tycho-2 (Cat. I/259), Sloan Digital Sky Survey Data Release 8 (Cat. II/306), the Two-Micron All-Sky Survey (2MASS, Cat. II/246)), the Wide-field Infrared Survey Explorer catalogue (WISE, Cat. II/311), the Infrared Astronomical Satellite Point Source Catalogue/Faint Source Catalogue (IRAS Catalogs II/125, II/156), the AKARI catalogue (Cat. II/297), the ROSAT Bright Source Catalogue (IX/10) and Faint Source (IX/29) Catalogues, the General Catalogue of Variable Stars (B/gcvs) and the Northern Sky Variability Survey. Also, we have added updated SIMBAD data for the objects. We present accurate Digitized Sky Survey 2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours and available proper motions for 1045 FBS late-type stars. The FBS revised and updated catalogue lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint carbon stars at high Galactic latitudes and M dwarfs in the vicinity of the Sun. We study the complete samples, as well as investigating individual interesting objects up to 16.0-16.5mag in visual.
