- ID:
- ivo://CDS.VizieR/J/ApJS/224/36
- Title:
- The AllWISE motion survey (AllWISE2)
- Short Name:
- J/ApJS/224/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the AllWISE Data Release to continue our search for Wide-field Infrared Survey Explorer (WISE)-detected motions. In this paper, we publish another 27846 motion objects, bringing the total number to 48000 when objects found during our original AllWISE motion survey are included. We use this list, along with the lists of confirmed WISE-based motion objects from the recent papers by Luhman (2014, J/ApJ/781/4) and by Schneider et al. (2016, J/ApJ/817/112), and candidate motion objects from the recent paper by Gagne et al. (2014, J/ApJ/783/121), to search for widely separated, common-proper-motion systems. We identify 1039 such candidate systems. All 48000 objects are further analyzed using color-color and color-mag plots to provide possible characterizations prior to spectroscopic follow-up. We present spectra of 172 of these, supplemented with new spectra of 23 comparison objects from the literature, and provide classifications and physical interpretations of interesting sources. Highlights include: (1) the identification of three G/K dwarfs that can be used as standard candles to study clumpiness and grain size in nearby molecular clouds because these objects are currently moving behind the clouds, (2) the confirmation/discovery of several M, L, and T dwarfs and one white dwarf whose spectrophotometric distance estimates place them 5-20pc from the Sun, (3) the suggestion that the Na I "D" line be used as a diagnostic tool for interpreting and classifying metal-poor late-M and L dwarfs, (4) the recognition of a triple system including a carbon dwarf and late-M subdwarf, for which model fits of the late-M subdwarf (giving [Fe/H]~-1.0) provide a measured metallicity for the carbon star, and (5) a possible 24pc distant K5 dwarf + peculiar red L5 system with an apparent physical separation of 0.1pc.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/754/44
- Title:
- The AstraLux Large M-dwarf Survey
- Short Name:
- J/ApJ/754/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- These tables contain the results from a multiplicity survey of 701 M-type and 60 K-type stars (among which 182 new and 37 previously known companions were detected in 205 systems) using the Lucky Imaging cameras AstraLux Norte at the Calar Alto 2.2m and AstraLux Sur at the ESO NTT. Most of the targets have been observed during two or more epochs, and could be confirmed as physical companions through common proper motion, often with orbital motion being confirmed in addition. One table lists general properties of all the stars in the sample, another the observational parameters of each confirmed or suspected binary, a third lists the derived physical parameters of each confirmed or suspected binary, the fourth lists astrometric data points of all binary candidates for which multiple epochs have been collected (also including literature measurements for previously resolved binaries) and a final table lists observational properties of confirmed or suspected background stars.
- ID:
- ivo://CDS.VizieR/J/AJ/149/158
- Title:
- The BUD sample. I. L dwarf activity sample
- Short Name:
- J/AJ/149/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the colors and activity of ultracool (M7-L8) dwarfs from the Tenth Data Release of the Sloan Digital Sky Survey (SDSS). We combine previous samples of SDSS M and L dwarfs with new data obtained from the Baryon Oscillation Sky Survey (BOSS) to produce the BOSS Ultracool Dwarf (BUD) sample of 11820 M7-L8 dwarfs. By combining SDSS data with photometry from 2MASS and the Wide-field Infrared Sky Explorer (WISE) mission, we present ultracool dwarf colors from i-z to W2-W3 as a function of spectral type, and extend the SDSS-2MASS-WISE color locus to include ultracool dwarfs. The i-z, i-J, and z-J colors provide the best indication of spectral type for M7-L3 dwarfs. We also examine ultracool dwarf chromospheric activity through the presence and strength of H{alpha} emission. The fraction of active dwarfs rises through the M spectral sequence until it reaches ~90% at spectral type L0. The fraction of active dwarfs then declines to 50% at spectral type L5; no H{alpha} emission is observed in the late-L dwarfs in the BUD sample. The fraction of active L0-L5 dwarfs is much higher than previously observed. The strength of activity declines with spectral type from M7 through L3, after which the data do not show a clear trend. Using one-dimensional chromosphere models, we explore the range of filling factors and chromospheric temperature structures that are consistent with H{alpha} observations of M0-L7 dwarfs. M dwarf chromospheres have a similar, smoothly varying range of temperature and surface coverage, while L dwarf chromospheres are cooler and have smaller filling factors.
- ID:
- ivo://CDS.VizieR/J/ApJ/704/531
- Title:
- The coevality of young binary systems
- Short Name:
- J/ApJ/704/531
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiple star systems are commonly assumed to form coevally; they thus provide the anchor for most calibrations of stellar evolutionary models. In this paper, we study the binary population of the Taurus-Auriga association, using the component positions in an HR diagram in order to quantify the frequency and degree of coevality in young binary systems. After identifying and rejecting the systems that are known to be affected by systematic errors (due to further multiplicity or obscuration by circumstellar material), we find that the relative binary ages, |{Delta}log{tau}|, have an overall dispersion {sigma}_|{Delta}log{tau}|_~0.40dex.
- ID:
- ivo://CDS.VizieR/V/152
- Title:
- The DEBCat detached eclipsing binary catalogue
- Short Name:
- V/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detached eclipsing binary star systems are our primary source of measured physical properties of normal stars. I introduce DEBCat: a catalog of detached eclipsing binaries with mass and radius measurements to the 2% precision necessary to put useful constraints on theoretical models of stellar evolution. The catalog was begun in 2006, as an update of the compilation by Andersen (1991A&ARv...3...91A). It now contains over 195 systems (2017/10/10), and new results are added on appearance in the refereed literature.
- ID:
- ivo://CDS.VizieR/J/ApJ/718/683
- Title:
- The edge of the young Galactic disk
- Short Name:
- J/ApJ/718/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we report and discuss the detection of two distant diffuse stellar groups in the third Galactic quadrant. They are composed of young stars, with spectral types ranging from late O to late B, and lie at galactocentric distances between 15 and 20kpc. These groups are located in the area of two cataloged open clusters (VdB-Hagen 04 and Ruprecht 30), projected toward the Vela-Puppis constellations, and within the core of the Canis Major overdensity. Their reddening and distances have been estimated by analyzing their color-color and color-magnitude diagrams, derived from deep UBV photometry. The existence of young star aggregates at such extreme distances from the Galactic center challenges the commonly accepted scenario in which the Galactic disk has a sharp cutoff at about 14kpc from the Galactic center and indicates that it extends to much greater distances (as also supported by the recent detection of CO molecular complexes well beyond this distance). While the groups we find in the area of Ruprecht 30 are compatible with the Orion and Norma-Cygnus spiral arms, respectively, the distant group we identify in the region of VdB-Hagen 04 lies in the external regions of the Norma-Cygnus arm, at a galactocentric distance (~20kpc) where no young stars have been detected so far in the optical.
- ID:
- ivo://CDS.VizieR/J/AJ/157/177
- Title:
- The evolutionary status of GK subgiants
- Short Name:
- J/AJ/157/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Snowden & Young (2005ApJS..157..126S) suggested that the reason why there are GK subgiants is because they are members of binaries, which would bring them above the main sequence in an Hertzsprung-Russell (HR) diagram. They studied a sample of 30 G0-K1 IV stars and were disappointed to find only two to be spectroscopic binaries. With more accurate radial velocities I found seven binaries in their samples of subgiants and control stars; orbital elements are given for those seven. Using Hipparcos parallaxes and SIMBAD data, I found that nearly all of the G0-K1 IV stars fall on the evolutionary tracks by Girardi et al. (2000, J/A+AS/141/371) for Population I stars with masses of 0.9-1.9 M_{sun}_ and ages of up to 10^10^ yr, which are normal parameters for nearby field stars. Therefore there is no problem regarding the existence of GK subgiants.
- ID:
- ivo://CDS.VizieR/J/ApJ/696/1278
- Title:
- The extended star-forming environment of M17
- Short Name:
- J/ApJ/696/1278
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M17 is one of the youngest and most massive nearby star-formation regions in the Galaxy. It features a bright HII region erupting as a blister from the side of a giant molecular cloud (GMC). Combining photometry from the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) with complementary infrared (IR) surveys, we identify candidate young stellar objects (YSOs) throughout a 1.5x1{deg} field that includes the M17 complex. The long sightline through the Galaxy behind M17 creates significant contamination in our YSO sample from unassociated sources with similar IR colors. Removing contaminants, we produce a highly reliable catalog of 96 candidate YSOs with a high probability of association with the M17 complex. We fit model spectral energy distributions to these sources and constrain their physical properties. Extrapolating the mass function of 62 intermediate-mass YSOs (M_*_>3M_{sun}_), we estimate that >1000 stars are in the process of forming in the extended outer regions of M17. The remaining 34 candidate YSOs are found in a 0.17deg^2^ field containing the well-studied M17 HII region and photodissociation region (PDR), where bright diffuse mid-IR emission drastically reduces the sensitivity of the GLIMPSE point-source detections.
- ID:
- ivo://CDS.VizieR/J/ApJ/863/181
- Title:
- The fifth catalog of LMC Wolf-Rayet stars
- Short Name:
- J/ApJ/863/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We summarize the results of our 4yr survey searching for Wolf-Rayet (WR) stars in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud. Over the course of this survey we have discovered 15 new WR stars and 12 Of-type stars. In this last year we discovered two rare Of-type stars: an O6.5f?p and an O6nfp, in addition to the two new Of?p stars discovered in our first year and the three Onfp stars discovered in our second and third years. However, even more exciting was our discovery of a new type of WR star, ones we are calling WN3/O3s owing to their spectroscopic signatures. We describe the completeness limits of our survey and demonstrate that we are sensitive to weak-lined WRs several magnitudes fainter than any we have discovered, arguing that there is not a population of fainter WRs waiting to be discovered. We discuss the nature of the WN3/O3s, summarizing the results of our extensive spectroscopy and modeling. We also examine the important claim made by others that the WN3/O3s are isolated compared to other massive stars. We find that if we use a more complete sample of reference massive stars, the WN3/O3s show the same spatial distribution as other early WNs, consistent with a common origin. Finally, we use this opportunity to present the "Fifth Catalog of LMC Wolf-Rayet Stars," which includes revised coordinates and updated spectral types for all 154 known LMC WRs.
- ID:
- ivo://CDS.VizieR/J/AJ/158/13
- Title:
- The first 300 stars observed by the GPIES
- Short Name:
- J/AJ/158/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a statistical analysis of the first 300 stars observed by the Gemini Planet Imager Exoplanet Survey. This subsample includes six detected planets and three brown dwarfs; from these detections and our contrast curves we infer the underlying distributions of substellar companions with respect to their mass, semimajor axis, and host stellar mass. We uncover a strong correlation between planet occurrence rate and host star mass, with stars M_*_>1.5 M_{sun}_ more likely to host planets with masses between 2 and 13 M_Jup_ and semimajor axes of 3-100 au at 99.92% confidence. We fit a double power-law model in planet mass (m) and semimajor axis (a) for planet populations around high-mass stars (M_*_>1.5 M_{sun}_) of the form d^2^N/(dm da){prop.to}m^{alpha}^{alpha}^{beta}^, finding {alpha}=-2.4+/-0.8 and {beta}=-2.0+/-0.5, and an integrated occurrence rate of 9_-4_^+5^% between 5-13 M_Jup_ and 10-100 au. A significantly lower occurrence rate is obtained for brown dwarfs around all stars, with 0.8_-0.5_^+0.8^% of stars hosting a brown dwarf companion between 13-80 M_Jup_ and 10-100 au. Brown dwarfs also appear to be distributed differently in mass and semimajor axis compared to giant planets; whereas giant planets follow a bottom-heavy mass distribution and favor smaller semimajor axes, brown dwarfs exhibit just the opposite behaviors. Comparing to studies of short-period giant planets from the radial velocity method, our results are consistent with a peak in occurrence of giant planets between ~1 and 10 au. We discuss how these trends, including the preference of giant planets for high-mass host stars, point to formation of giant planets by core/pebble accretion, and formation of brown dwarfs by gravitational instability.
