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3381. Solar neighborhood. XXXV. Distances to M dwarfs
ID:
ivo://CDS.VizieR/J/AJ/149/5
Title:
Solar neighborhood. XXXV. Distances to M dwarfs
Short Name:
J/AJ/149/5
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present trigonometric, photometric, and photographic distances to 1748 southern ({delta}{<=}O{deg}) M dwarf systems with {mu}>=0.18''/yr, of which 1404 are believed to lie within 25pc of the Sun. The stars have 6.67{<=}V_J_{<=}21.38 and 3.50{<=}(V_J_-K_S_){<=}9.27, covering the entire M dwarf spectral sequence from M0.0 V through M9.5 V. This sample therefore provides a comprehensive snapshot of our current knowledge of the southern sky for the nearest M dwarfs that dominate the stellar population of the Galaxy. Roughly one-third of the 1748 systems, each of which has an M dwarf primary, have published high quality parallaxes, including 179 from the REsearch Consortium On Nearby Stars astrometry program. For the remaining systems, we offer photometric distance estimates that have well-calibrated errors. The bulk of these (~700) are based on new V_J_R_KC_I_KC_ photometry acquired at the CTIO/SMARTS 0.9m telescope, while the remaining 500 primaries have photographic plate distance estimates calculated using SuperCOSMOS B_J_R_59F_I_IVN_ photometry. Confirmed and candidate subdwarfs in the sample have been identified, and a census of companions is included.
3382. Solar neighborhood XXXVIII. Nearby M dwarf systems
ID:
ivo://CDS.VizieR/J/AJ/153/14
Title:
Solar neighborhood XXXVIII. Nearby M dwarf systems
Short Name:
J/AJ/153/14
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 160 new trigonometric parallaxes for 151 M dwarf systems from the REsearch Consortium On Nearby Stars (RECONS) group's long-term astrometry/photometry program at the CTIO/SMARTS 0.9m telescope. Most systems (124 or 82%) are found to lie within 25pc. The stars have 119mas/yr{<=}{mu}{<=}828mas/yr and 3.85{<=}(V-K){<=}8.47. Among these are 58 systems from the SuperCOSMOS-RECONS search, discovered via our proper motion trawls of the SuperCOSMOS digitized archival photographic plates, while the remaining stars were suspected via photometric distance estimates to lie nearby. Sixteen systems were newly discovered via astrometric perturbations to be binaries, many of which are ideal for accurate mass determinations due to their proximity and orbital periods on the order of a decade. A variability analysis of the stars presented, two-thirds of which are new results, shows six of the stars to vary by more than 20mmag. This effort brings the total number of parallaxes for M dwarf systems measured by RECONS to nearly 500 and increases by 26% the number of southern M dwarf systems with accurate trigonometric parallaxes placing them within 25pc.
3383. Solar neighborhood. XXXVI. VRI variability of M dwarfs
ID:
ivo://CDS.VizieR/J/AJ/150/6
Title:
Solar neighborhood. XXXVI. VRI variability of M dwarfs
Short Name:
J/AJ/150/6
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an analysis of long-term photometric variability for nearby red dwarf stars at optical wavelengths. The sample consists of 264 M dwarfs south of decl.=+30 with V-K=3.96-9.16 and M_V_~~10-20, corresponding to spectral types M2V-M8V, most of which are within 25pc. The stars have been observed in the VRI filters for ~4-14yr at the CTIO/SMARTS 0.9m telescope. Of the 238 red dwarfs within 25pc, we find that only ~8% are photometrically variable by at least 20mmag (~2%) in the VRI bands. Only four stars have been found to vary by more than 50mmag, including GJ 1207 at 8.6pc, which experienced a single extraordinary flare, and GJ 2006 A, TWA 8 A, and TWA 8 B, which are all young stars beyond 25pc linked to moving groups. We find that high variability at optical wavelengths over the long term can in fact be used to identify young stars. Overall, however, the fluxes of most red dwarfs at optical wavelengths are steady to a few percent over the long term. The low overall rate of photometric variability for red dwarfs is consistent with results found in previous work on similar stars on shorter timescales, with the body of work indicating that most red dwarfs are only mildly variable. As expected, we find that the degree of photometric variability is greater in the V band than in the R or I bands, but we do not find any obvious trends in variability over the long term with red dwarf luminosity or temperature. We highlight 17 stars that show long-term changes in brightness, sometimes because of flaring activity or spots, and sometimes because of stellar cycles similar to our Sun's solar cycle. Remarkably, two targets show brightnesses that monotonically increase (G 169-029) or decrease (WT 460AB) by several percent over a decade. We also provide long-term variability measurements for seven M dwarfs within 25pc that host exoplanets, none of which vary by more than 20mmag. Both as a population, and for the specific red dwarfs with exoplanets observed here, photometric variability is therefore often not a concern for planetary environments, at least at the optical wavelengths where they emit much of their light.
3384. Solar neighbourhood metallicity distribution
ID:
ivo://CDS.VizieR/J/MNRAS/325/1365
Title:
Solar neighbourhood metallicity distribution
Short Name:
J/MNRAS/325/1365
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a revised metallicity distribution of dwarfs in the solar neighbourhood. This distribution is centered on solar metallicity. We show that previous metallicity distributions, selected on the basis of spectral type, are biased against stars with solar metallicity or higher. A selection of G-dwarf stars is inherently biased against metal-rich stars and is not representative of the solar neighbourhood metallicity distribution. Using a sample selected on colour, we obtain a distribution where approximately half the stars in the solar neighbourhood have metallicities higher than [Fe/H]=0. The percentage of mid-metal-poor stars ([Fe/H}<-0.5) is approximately 4 per cent, in agreement with the present estimates of the thick disc.
3385. Sombrero galaxy globular clusters
ID:
ivo://CDS.VizieR/J/MNRAS/417/1823
Title:
Sombrero galaxy globular clusters
Short Name:
J/MNRAS/417/1823
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a large sample of over 200 integrated-light spectra of confirmed globular clusters (GCs) associated with the Sombrero (M104) galaxy taken with the Deep Imaging Multi-Object Spectrograph (DEIMOS) instrument on the Keck telescope. A significant fraction of the spectra have signal-to-noise ratio levels high enough to allow measurements of GC metallicities using the method of Brodie & Huchra. We find a distribution of spectroscopic metallicities in the range -2.2<[Fe/H]<+0.1 that is bimodal, with peaks at [Fe/H]~-1.4 and -0.6. Thus, the GC system of the Sombrero galaxy, like a few other galaxies now studied in detail, reveals a bimodal spectroscopic metallicity distribution supporting the long-held belief that colour bimodality reflects two metallicity subpopulations. This further suggests that the transformation from optical colour to metallicity for old stellar populations, such as GCs, is not strongly non-linear. We also explore the radial and magnitude distribution with metallicity for GC subpopulations but small number statistics prevent any clear trends in these distributions.
3386. S4 0954+658 outburst in 2011 March-April
ID:
ivo://CDS.VizieR/J/AJ/148/42
Title:
S4 0954+658 outburst in 2011 March-April
Short Name:
J/AJ/148/42
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of optical (R-band) photometric and polarimetric monitoring and Very Long Baseline Array imaging of the blazar S4 0954+658, along with Fermi {gamma}-ray data during a multi-waveband outburst in 2011 March-April. After a faint state with a brightness level R~17.6mag registered in the first half of 2011 January, the optical brightness of the source started to rise and reached ~14.8mag during the middle of March, showing flare-like behavior. The most spectacular case of intranight variability was observed during the night of 2011 March 9, when the blazar brightened by ~0.7mag within 7hr. During the rise of the flux, the position angle of the optical polarization rotated smoothly over more than 300{deg}. At the same time, within 1{sigma} uncertainty, a new superluminal knot appeared with an apparent speed of 19.0+/-0.3c. We have very strong evidence that this knot is associated with the multi-waveband outburst in 2011 March-April. We also analyze the multi-frequency behavior of S4 0954+658 during a number of minor outbursts from 2008 August to 2012 April. We find some evidence of connections between at least two additional superluminal ejecta and near-simultaneous optical flares.
3387. Southern binary galaxies. I.
ID:
ivo://CDS.VizieR/J/A+AS/110/371
Title:
Southern binary galaxies. I.
Short Name:
J/A+AS/110/371
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
3388. Southern emission-line stars multiphotometry
ID:
ivo://CDS.VizieR/J/A+A/380/609
Title:
Southern emission-line stars multiphotometry
Short Name:
J/A+A/380/609
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents a catalogue of previously unpublished optical and infrared photometry for a sample of 162 emission-line objects and shell stars visible from the southern hemisphere. The data were obtained between 1978 and 1997 in the Walraven (WULBV), Johnson/Cousins UBV(RI)_c_ and ESO and SAAO near-infrared (JHKLM) photometric systems. Most of the observed objects are Herbig Ae/Be (HAeBe) stars or HAeBe candidates appearing in the list of HAeBe candidates of The et al. (1994, Cat. <J/A+AS/104/315>), although several B[e] stars, LBVs and T Tauri are also included in the sample. For many of the stars the data presented here are the first photo-electric measurements in the literature. The resulting catalogue consists of 1809 photometric measurements. Optical variability was detected in 66 out of the 116 sources that were observed more than once. 15 out of the 50 stars observed multiple times in the infrared showed variability at 2.2 microns (K band). Table 1 contains the stars identifiers, positions, types and a summary of the observational data on each star. Tables 2, 3 and 4 contain all obtained photometry in the Walraven WULBV, Johnson/Cousins UBV(RI)_c and ESO and SAAO near-infrared (JHKLM) photometric systems.
3389. Southern isolated triple systems of galaxies
ID:
ivo://CDS.VizieR/J/AZh/77/569
Title:
Southern isolated triple systems of galaxies
Short Name:
J/AZh/77/569
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the ESO/SERC and POSS-I surveys we selected 76 isolated triple systems of galaxies with DE<-3{deg}. For each triplet the equatorial coordinates, type of configuration, angular diameters, apparent angular separation of the components, morphological types, total magnitudes and other characteristics are presented.
3390. Southern MK Standards 5800-10200A
ID:
ivo://CDS.VizieR/III/179
Title:
Southern MK Standards 5800-10200A
Short Name:
III/179
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spectra are presented for MK standards in the wavelength range 580-1020nm. The stars cover the normal spectral types O to M and luminosity types I, III, and V. In addition, a small number of peculiar stars are included. The data are in 137 FITS files, in the "fits" subdirectory. The list of the 137 stars is included in the "stars.dat" file; note that the list is not identical to the stars listed in Table1 of the paper.