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61. ACRONYM. III. Candidate young low-mass stars
ID:
ivo://CDS.VizieR/J/AJ/157/234
Title:
ACRONYM. III. Candidate young low-mass stars
Short Name:
J/AJ/157/234
Date:
21 Oct 2021
Publisher:
CDS
Description:
Young, low-mass stars in the solar neighborhood are vital for completing the mass function for nearby, young coeval groups, establishing a more complete census for evolutionary studies, and providing targets for direct-imaging exoplanet and/or disk studies. We present properties derived from high-resolution optical spectra for 336 candidate young nearby, low-mass stars. These include measurements of radial velocities and age diagnostics such as H{alpha} and Li {lambda}6707 equivalent widths. Combining our radial velocities with astrometry from Gaia DR2 (Cat. I/345), we provide full 3D kinematics for the entire sample. We combine the measured spectroscopic youth information with additional age diagnostics (e.g., X-ray and UV fluxes, color-magnitude diagram positions) and kinematics to evaluate potential membership in nearby, young moving groups and associations. We identify 77 objects in our sample as bona fide members of 10 different moving groups, 14 of which are completely new members or have had their group membership reassigned. We also reject 44 previously proposed candidate moving group members. Furthermore, we have newly identified or confirmed the youth of numerous additional stars that do not belong to any currently known group and find 69 comoving systems using Gaia DR2 astrometry. We also find evidence that the Carina association is younger than previously thought, with an age similar to the {beta} Pictoris moving group (~22 Myr).
62. ACRONYM II. The {beta} Pictoris Moving Group
ID:
ivo://CDS.VizieR/J/AJ/154/69
Title:
ACRONYM II. The {beta} Pictoris Moving Group
Short Name:
J/AJ/154/69
Date:
21 Oct 2021
Publisher:
CDS
Description:
We confirm 66 low-mass stellar and brown dwarf systems (K7-M9) plus 19 visual or spectroscopic companions of the {beta} Pictoris moving group (BPMG). Of these, 41 are new discoveries, increasing the known low-mass members by 45%. We also add four objects to the 14 known with masses predicted to be less than 0.07 M_{sun}_. Our efficient photometric + kinematic selection process identified 104 low-mass candidates, which we observed with ground-based spectroscopy. We collected infrared observations of the latest spectral types (>M5) to search for low-gravity objects. These and all <M5 candidates were observed with high-resolution optical spectrographs to measure the radial velocities and youth indicators, such as lithium absorption and H{alpha} emission, needed to confirm BPMG membership, achieving a 63% confirmation rate. We also compiled the most complete census of BPMG membership, with which we tested the efficiency and false-membership assignments using our selection and confirmation criteria. Using the new census, we assess a group age of 22+/-6 Myr, consistent with past estimates. With the now-densely sampled lithium depletion boundary, we resolve the broadening of the boundary by either an age spread or astrophysical influences on lithium-burning rates. We find that 69% of the now-known members with AFGKM primaries are M stars, nearing the expected value of 75%. However, the new initial mass function for the BPMG shows a deficit of 0.2-0.3 M_{sun}_ stars by a factor of ~2. We expect that the AFGK census of the BPMG is also incomplete, probably due to biases of searches toward the nearest stars.
63. ACS Fornax Cluster Survey. XI. GC candidates
ID:
ivo://CDS.VizieR/J/ApJS/221/13
Title:
ACS Fornax Cluster Survey. XI. GC candidates
Short Name:
J/ApJS/221/13
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present catalogs of globular cluster (GC) candidates for 43 galaxies from the ACS Fornax Cluster survey, a program designed to carry out imaging of early-type members of the Fornax cluster using the Advanded Camera for Surveys (ACS) on board the Hubble Space Telescope. The procedure to select bona fide GC candidates from the full list of detections is based on model-based clustering methods, similar to those adopted for a survey of 100 galaxies in the Virgo cluster, the ACS Virgo Cluster Survey. For each detected source, we measure its position, magnitudes in the F475W (~Sloan g) and F850LP (~Sloan z) bandpasses, half-light radii obtained by fitting point-spread function-convolved King models to the observed light distribution, and an estimate of the probability {rho}_GC_ that each cataloged source is a GC. These measurements are presented for 9136 sources, of which 6275 have {rho}_GC_>=0.5, and are thus likely GCs.
64. ACS Galactic Globular Cluster Survey (ACSGGCT)
ID:
ivo://mast.stsci/acsggct
Title:
ACS Galactic Globular Cluster Survey (ACSGGCT)
Short Name:
HST.ACSGGCT
Date:
22 Jul 2020 22:26:50
Publisher:
Space Telescope Science Institute Archive
Description:
The ACSGGCT program used the HST ACS/WFC instrument to obtain uniform imaging of 65 of the nearest globular clusters to provide an extensive homogeneous dataset for a broad range of scientific investigations. An overview of the project was published by Sarajedini, A. et al. 2007, "The ACS Survey of Galactic Globular Clusters. I. Overview and Clusters Without Previous Hubble Space Telescope Photometry" AJ, 133, 1658.
65. ACS Virgo Cluster Survey. XIII.
ID:
ivo://CDS.VizieR/J/ApJ/655/144
Title:
ACS Virgo Cluster Survey. XIII.
Short Name:
J/ApJ/655/144
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ACS Virgo Cluster Survey consists of HST-ACS Advance Camera for Surveys) imaging for 100 early-type galaxies in the Virgo Cluster, observed in the F475W (~SDSS g) and F850LP (~SDSS z) filters. We derive distances for 84 of these galaxies using the method of surface brightness fluctuations (SBFs), present the SBF distance catalog, and use this database to examine the three-dimensional distribution of early-type galaxies in the Virgo Cluster. The SBF distance moduli have a mean (random) measurement error of 0.07mag (0.5Mpc), or roughly 3 times better than previous SBF measurements for Virgo Cluster galaxies. Five galaxies lie at a distance of d~23Mpc and are members of the W' cloud. The remaining 79 galaxies have a narrow distribution around our adopted distance of <d>=16.5+/-0.1 (random mean error) +/-1.1Mpc (systematic). The rms distance scatter of this sample is {sigma}(d)=0.6+/-0.1Mpc, with little or no dependence on morphological type or luminosity class (i.e., 0.7+/-0.1 and 0.5+/-0.1Mpc for the giants and dwarfs, respectively). The back-to-front depth of the cluster measured from our sample of early-type galaxies is 2.4+/-0.4Mpc (i.e., +/-2{sigma} of the intrinsic distance distribution). The M87 (cluster A) and M49 (cluster B) subclusters are found to lie at distances of 16.7+/-0.2 and 16.4+/-0.2Mpc, respectively. There may be a third subcluster associated with M86. A weak correlation between velocity and line-of-sight distance may be a faint echo of the cluster velocity distribution not having yet completely virialized. In three dimensions, Virgo's early-type galaxies appear to define a slightly triaxial distribution, with axis ratios of (1:0.7:0.5). The principal axis of the best-fit ellipsoid is inclined ~20{deg}-40{deg} from the line of sight, while the galaxies belonging to the W' cloud lie on an axis inclined by ~10{deg}-15{deg}.
66. Activity-rotation relationship in stars
ID:
ivo://CDS.VizieR/J/A+A/397/147
Title:
Activity-rotation relationship in stars
Short Name:
J/A+A/397/147
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a new study on the relationship between coronal X-ray emission and stellar rotation in late-type main-sequence stars. We have selected a sample of 259 dwarfs in the B-V range 0.5-2.0, including 110 field stars and 149 members of the Pleiades, Hyades, {alpha} Persei, IC 2602 and IC 2391 open clusters. All the stars have been observed with ROSAT, and most of them have photometrically-measured rotation periods available. Our results confirm that two emission regimes exist, one in which the rotation period is a good predictor of the total X-ray luminosity, and the other in which a constant saturated X-ray to bolometric luminosity ratio is attained; we present a quantitative estimate of the critical rotation periods below which stars of different masses (or spectral types) enter the saturated regime.
67. Activity type of AGN with SDSS spectra
ID:
ivo://CDS.VizieR/J/other/Ap/63.322
Title:
Activity type of AGN with SDSS spectra
Short Name:
J/other/Ap/63.32
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is a detailed spectral classification of 96 active galaxies from the Veron-Cetty and Veron catalog (2010, Version 13, Cat. VII/258) of active galaxies and quasars. These objects were identified as radio sources using standard radio catalogs. Those galaxies which had radio sources in at least 6 different radio bands and had been identified spectrally in the SDSS catalog were selected. The types of activity of these were determined using their SDSS spectra. Three diagnostic diagrams and a direct study of the spectra were used for more certain classification. As a result, the classifications of 85% of the objects were changed. The radio sources in different radio bands make it possible to construct the spectral distribution of the energy in the radio range and to compare it with the optical activity types.
68. Activity types of ROSAT/SDSS galaxies
ID:
ivo://CDS.VizieR/J/other/Ap/62.147
Title:
Activity types of ROSAT/SDSS galaxies
Short Name:
J/other/Ap/62.14
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this study we carry out detailed spectral classification of 173 AGN candidates from the Joint HRC/BHRC sample, which is a combination of HRC (Hamburg-ROSAT Catalogue) and BHRC (Byurakan-Hamburg-ROSAT Catalogue). These objects were revealed as optical counterparts for ROSAT X-ray sources, however spectra for 173 of them are given in SDSS without definite spectral classification. We studied these 173 objects using the SDSS spectra and revealed the detailed activity types for them. Three diagnostic diagrams and direct examination of the spectra were used to have more confident classification. We also made identification of these sources in other wavelength ranges and calculated some of their parameters.
69. A deep catalogue of classical Be stars
ID:
ivo://CDS.VizieR/J/MNRAS/446/274
Title:
A deep catalogue of classical Be stars
Short Name:
J/MNRAS/446/274
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of 247 photometrically and spectroscopically confirmed fainter classical Be stars (13<r<16) in the direction of the Perseus Arm of the Milky Way (1{deg}<b<+4{deg}, 120{deg}<l<140{deg}). The catalogue consists of 181 IPHAS-selected new classical Be stars, in addition to 66 objects that we studied in our previous work more closely, and three stars identified as classical Be stars in earlier work. This study more than doubles the number known in the region. Photometry spanning 0.6-5um, spectral types, and interstellar reddenings are given for each object. The spectral types were determined from low-resolution spectra ({lambda}/{Delta}_{lambda}~800-2000), to a precision of 1-3 subtypes. The interstellar reddenings are derived from the (r-i) colour, using a method that corrects for circumstellar disc emission. The colour excesses obtained range from E(B-V)=0.3 up to 1.6 a distribution that modestly extends the range reported in the literature for Perseus-Arm open clusters. For around half the sample, the reddenings obtained are compatible with measures of the total sightline Galactic extinction. Many of these are likely to lie well beyond the Perseus Arm.
70. AD Leo high resolution spectra
ID:
ivo://CDS.VizieR/J/A+A/637/A13
Title:
AD Leo high resolution spectra
Short Name:
J/A+A/637/A13
Date:
21 Oct 2021
Publisher:
CDS
Description:
Flares and coronal mass ejections (CMEs) are important for the evolution of the atmospheres of planets and their potential habitability, particularly for planets orbiting M stars at a distance <0.4AU. Detections of CMEs on these stars have been sparse, and previous studies have therefore modelled their occurrence frequency by scaling up solar relations. However, because the topology and strength of the magnetic fields on M stars is different from that of the Sun, it is not obvious that this approach works well. We used a large number of high-resolution spectra to study flares, CMEs, and their dynamics of the active M dwarf star AD Leo. The results can then be used as reference for other M dwarfs. We obtained more than 2000 high-resolution spectra (R~35000) of the highly active M dwarf AD Leo, which is viewed nearly pole on. Using these data, we studied the behaviour of the spectral lines H{alpha}, H{beta}, and HeI 5876 in detail and investigated asymmetric features that might be Doppler signatures of CMEs. We detected numerous flares. The largest flare emitted 8.32x10^31^erg in H{beta} and 2.12x10^32^erg in H{alpha}. Although the spectral lines in this and other events showed a significant blue asymmetry, the velocities associated with it are far below the escape velocity. Although AD Leo shows a high level of flare activity, the number of CMEs is relatively low. It is thus not appropriate to use the same flare-to-CME relation for M dwarfs as for the Sun.