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261. PS1 proper-motion survey for brown dwarfs. I. Taurus
ID:
ivo://CDS.VizieR/J/ApJ/858/41
Title:
PS1 proper-motion survey for brown dwarfs. I. Taurus
Short Name:
J/ApJ/858/41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We are conducting a proper-motion survey for young brown dwarfs in the Taurus-Auriga molecular cloud based on the Pan-STARRS1 3{pi} Survey. Our search uses multi-band photometry and astrometry to select candidates, and is wider (370deg^2^) and deeper (down to ~3M_Jup_) than previous searches. We present here our search methods and spectroscopic follow-up of our high-priority candidates. Since extinction complicates spectral classification, we have developed a new approach using low-resolution (R~100) near-infrared spectra to quantify reddening-free spectral types, extinctions, and gravity classifications for mid-M to late-L ultracool dwarfs (<=100-3M_Jup_ in Taurus). We have discovered 25 low-gravity (VL-G) and the first 11 intermediate-gravity (INT-G) substellar (M6-L1) members of Taurus, constituting the largest single increase of Taurus brown dwarfs to date. We have also discovered 1 new Pleiades member and 13 new members of the Perseus OB2 association, including a candidate very wide separation (58kau) binary. We homogeneously reclassify the spectral types and extinctions of all previously known Taurus brown dwarfs. Altogether our discoveries have thus far increased the substellar census in Taurus by ~40% and added three more L-type members (<~5-10M_Jup_). Most notably, our discoveries reveal an older (>10Myr) low-mass population in Taurus, in accord with recent studies of the higher-mass stellar members. The mass function appears to differ between the younger and older Taurus populations, possibly due to incompleteness of the older stellar members or different star formation processes.
262. Radial Velocities from Objective Prism Plates
ID:
ivo://CDS.VizieR/III/172
Title:
Radial Velocities from Objective Prism Plates
Short Name:
III/172
Date:
21 Oct 2021
Publisher:
CDS
Description:
Accurate positions and radial velocities are determined from 32 objective-prism plates for two areas. Each field is observed twice with opposite dispersion, allowing adjustment of coordinates for spectra not at the plate centers. From the adjusted coordinates and plate overlap, positions are determined with average mean errors: 0.0135 s in RA and 0.177 arcsec in Dec for Area I (near the South Galactic Pole); 0.0315 s in RA, 0.144 arcsec in Dec for Area II (near the galactic plane). Observations were taken by J.D. MacConnell and G. Araya with a six degree prism on the Curtis Schmidt telescope at Cerro Tololo.
263. Radial Velocities of Galactic O-type stars I.
ID:
ivo://CDS.VizieR/J/AJ/142/146
Title:
Radial Velocities of Galactic O-type stars I.
Short Name:
J/AJ/142/146
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present radial velocities for 18 Galactic O-type stars. These stars display small radial velocity scatter over timescales of one to two weeks. Some of them are long-period binaries while others are probably single stars. By fitting model spectra to our observed spectra we obtain estimates for effective temperature, log g, rotational velocity, and average radial velocity for each target.
264. Radial velocities of HD 96511, HR 7578, and KZ And
ID:
ivo://CDS.VizieR/J/AJ/154/120
Title:
Radial velocities of HD 96511, HR 7578, and KZ And
Short Name:
J/AJ/154/120
Date:
21 Oct 2021
Publisher:
CDS
Description:
From an extensive number of newly acquired radial velocities we determine the orbital elements for three late-type dwarf systems, HD 96511, HR 7578, and KZ And. The orbital periods are 18.89737+/-0.00002, 46.81610+/-0.00006, and 3.0329113+/-0.0000005 days, respectively, and all three systems are eccentric, although KZ And is just barely so. We have detected lines of the secondary of HD 96511 for the first time. The orbital dimensions (a_1_ sin i and a_2_ sin i) and minimum masses (m_1_ sin^3^i and m_2_ sin^3^i) of the binary components all have accuracies of 0.2% or better. Extensive photometry of the chromospherically active binary HR 7578 confirms a rather long rotation period of 16.446+/-0.002 days and that the K3 V components do not eclipse. We have estimated the basic properties of the stars in the three systems and compared those results with evolutionary tracks. The results for KZ And that we computed with the revised Hipparcos parallax of van Leeuwen (Cat. I/311) produce inconsistencies. That parallax appears to be too large, and so, instead, we used the original Hipparcos parallax of the common proper motion primary, which improves the results, although some problems remain.
265. Radial velocities of stars in NGC 2264
ID:
ivo://CDS.VizieR/J/AJ/149/119
Title:
Radial velocities of stars in NGC 2264
Short Name:
J/AJ/149/119
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an expanded kinematic study of the young cluster NGC 2264 based upon optical radial velocities measured using multi-fiber echelle spectroscopy at the 6.5m MMT and Magellan telescopes. We report radial velocities for 695 stars, of which approximately 407 stars are confirmed or very likely members. Our results more than double the number of members with radial velocities from Furesz et al., resulting in a much better defined kinematic relationship between the stellar population and the associated molecular gas. In particular, we find that there is a significant subset of stars that are systematically blueshifted with respect to the molecular (^13^CO) gas. The detection of Lithium absorption and/or infrared excesses in this blueshifted population suggests that at least some of these stars are cluster members; we suggest some speculative scenarios to explain their kinematics. Our results also more clearly define the redshifted population of stars in the northern end of the cluster; we suggest that the stellar and gas kinematics of this region are the result of a bubble driven by the wind from O7 star S Mon. Our results emphasize the complexity of the spatial and kinematic structure of NGC 2264, important for eventually building up a comprehensive picture of cluster formation.
266. Radial velocities of stars in the Galactic Center
ID:
ivo://CDS.VizieR/J/ApJ/681/1254
Title:
Radial velocities of stars in the Galactic Center
Short Name:
J/ApJ/681/1254
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from K-band slit scan observations of a ~20"x20" region of the Galactic center (GC) in two separate epochs more than 5 years apart. The high-resolution (R={lamda}/{Delta}{lambda}>=14000) observations allow the most accurate radial velocity and acceleration measurements of the stars in the central parsec of the Galaxy. Detected stars can be divided into three groups based on the CO absorption band heads at ~2.2935um and the HeII lines at ~2.0581 and ~2.112, 2.113um: cool, narrow-line hot, and broad-line hot. The radial velocities of the cool, late-type stars have approximately a symmetrical distribution with its center at ~-7.8+/-10.3km/s and a standard deviation ~113.7+/-10.3km/s. Although our statistics are dominated by the brightest stars, we estimate a central black hole mass of (3.9+/-1.1)x10^6^M_{sun}_, consistent with current estimates from complete orbits of individual stars. Our surface density profile and the velocity dispersion of the late-type stars support the existence of a low-density region at the Galactic center suggested by earlier observations.
267. Radial Velocities with Astrometric Data
ID:
ivo://CDS.VizieR/III/239
Title:
Radial Velocities with Astrometric Data
Short Name:
III/239
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue of radial velocities of Galactic stars with high precision astrometric data (CRVAD) is the result of a merging of star lists from the General Catalog of Mean Radial Velocities (GCRV, Cat. III/213) and from the All-sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5, Cat. I/280). The cross identification of GCRV and ASCC-2.5 objects was carried out with help of coordinate, magnitude, colour and/or spectral type criteria. Data from the Catalogue of Components of Double and Multiple Stars (CCDM, Cat. I/274) were taken into account for the identification of multiple system components. 34553 stars of the ASCC-2.5 were identified with 33509 stars of the GCRV, i.e. 33509 stars of the GCRV have one entry in the ASCC-2.5, and 1044 objects have two entries. The catalogue includes accurate equatorial coordinates J2000, proper motions and trigonometric parallaxes in the Hipparcos system, B and V magnitudes in Johnson system, spectral classes, multiplicity and variability flags from the ASCC-2.5, and radial velocities, stellar magnitudes and spectra from the GCRV. Stars are sorted in right ascension J2000 order. 3967 stars were selected as radial velocity standard candidates (file rv_std.dat). These stars: - do not have any multiplicity and/or variability flags both in the GCRV and ASCC-2.5; - have standard errors of equatorial coordinates e <= 40 mas; - have standard errors of proper motions e_pm <= 4 mas/yr; - have standard errors of V magnitude e_V <= 0.05 mag and (B-V) colour e_(B-V) <= 0.07 mag; - have standard errors of radial velocity e_RV <= 2 km/s or quality index A or B, which corresponds to e_RV 0.74 and 1.78 km/s; - have at least four RV observations N_RV.
268. Radial velocity estimates of 4 stars with IGRINS
ID:
ivo://CDS.VizieR/J/AJ/161/283
Title:
Radial velocity estimates of 4 stars with IGRINS
Short Name:
J/AJ/161/283
Date:
08 Mar 2022
Publisher:
CDS
Description:
Application of the radial velocity (RV) technique in the near-infrared is valuable because of the diminished impact of stellar activity at longer wavelengths, making it particularly advantageous for the study of late-type stars but also for solar-type objects. In this paper, we present the IGRINS RV open-source python pipeline for computing infrared RV measurements from reduced spectra taken with IGRINS, an R~{lambda}/{Delta}{lambda}~45000 spectrograph with simultaneous coverage of the H-band (1.49-1.80{mu}m) and K-band (1.96-2.46{mu}m). Using a modified forward-modeling technique, we construct high-resolution telluric templates from A0 standard observations on a nightly basis to provide a source of common-path wavelength calibration while mitigating the need to mask or correct for telluric absorption. Telluric standard observations are also used to model the variations in instrumental resolution across the detector, including a yearlong period when the K-band was defocused. Without any additional instrument hardware, such as a gas cell or laser frequency comb, we are able to achieve precisions of 26.8m/s in the K-band and 31.1m/s in the H-band for narrow-line hosts. These precisions are empirically determined by a monitoring campaign of two RV standard stars, as well as the successful retrieval of planet-induced RV signals for both HD189733 and {tau}BooA; furthermore, our results affirm the presence of the Rossiter-McLaughlin effect for HD189733. The IGRINS RV pipeline extends another important science capability to IGRINS, with publicly available software designed for widespread use.
269. Radio observations of ultracool dwarf stars
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.
270. Red supergiant stars in M31 and M33
ID:
ivo://CDS.VizieR/J/AJ/161/79
Title:
Red supergiant stars in M31 and M33
Short Name:
J/AJ/161/79
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify red supergiants (RSGs) in our spiral neighbors M31 and M33 using near-IR (NIR) photometry complete to a luminosity limit of logL/L{odot}=4.0. Our archival survey data cover 5{deg}^2^ of M31, and 3{deg}^2^ for M33, and are likely spatially complete for these massive stars. Gaia is used to remove foreground stars, after which the RSGs can be separated from asymptotic giant branch (AGB) stars in the color-magnitude diagram. The photometry is used to derive effective temperatures and bolometric luminosities via MARCS stellar atmosphere models. The resulting H-R diagrams show superb agreement with the evolutionary tracks of the Geneva evolutionary group. Our census includes 6400 RSGs in M31 and 2850 RSGs in M33 within their Holmberg radii; by contrast, only a few hundred RSGs are known so far in the Milky Way. Our catalog serves as the basis for a study of the RSG binary frequency being published separately, as well as future studies relating to the evolution of massive stars. Here we use the matches between the NIR- selected RSGs and their optical counterparts to show that the apparent similarity in the reddening of OB stars in M31 and M33 is the result of Malmquist bias; the average extinction in M31 is likely higher than that of M33. As expected, the distribution of RSGs follows that of the spiral arms, while the much older AGB population is more uniformly spread across each galaxy's disk.

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