We present and analyse a catalogue of 233 pulsars with proper motion measurements. The sample contains a wide variety of pulsars including recycled objects and those associated with globular clusters or supernova remnants. After taking the most precise proper motions for those pulsars for which multiple measurements are available, the majority of the proper motions (58 per cent) are derived from pulsar timing methods, 41% using interferometers and the remaining 1% using optical telescopes.
We report new photometry and radial velocities for almost 500 stars from the Lowell Proper Motion Catalog. We combine these results with our prior sample and rederive stellar temperatures based on the photometry, reddening, metallicities (using Chi^2 matching of our 22,500 low S/N high resolution echelle spectra with a grid of synthetic spectra), distances, space motions, and Galactic orbital parameters for 1269 (kinematics) and 1261 (metallicity) of the 1464 stars in the complete survey. The frequency of spectroscopic binaries for the metal-poor ([m/H]<=-1.2) stars with periods shorter than 3000 days is at least 15%. The spectroscopic binary frequency for metal-rich stars ([m/H]>-0.5) appears to be lower, about 9%, but this may be a selection effect. We also discuss special classes of stars, including treatment of the double-lined spectroscopic binaries, and identification of subgiants. Four possible new members of the class of field blue stragglers are noted. We point out the detection of three possible new white dwarfs, six broad-lined (binary) systems, and discuss briefly the three already known nitrogen-rich halo dwarfs.
Proper Motions, UBV Photometry, Four Open Clusters
Short Name:
V/28
Date:
21 Oct 2021
Publisher:
CDS
Description:
Proper motions were determined for 2169 stars with limiting magnitude B = 16.5 mag and located within a 60x60' area centered at RA = 23h54.2min, Dec = 60deg57arcmin (1950.0). Three plate pairs with a mean epoch difference of 49 years were used. The first epoch plates were taken with the Tashkent normal astrograph during 1923-1925 and the second epoch plates with the Pulkovo normal astrograph. The proper motions have a mean error +/-0.0030 arcsec (B < 14.5 mag) and +/-0.0036 arcsec (B > 14.5 mag) and were measured relative to reference stars with 13.5 mag <= B <= 14.5 mag. Photographic UBV magnitudes were measured using Sandages photoelectric standards. The U, B and V magnitudes were determined for 1930, 2165 and 1734 stars respectively, with the corresponding mean errors +/-0.03 mag, +/-0.06 mag and +/-0.05 mag. In the measured area there are three known open clusters (NGC 7788, NGC 7790 and Berkeley 58) and a previously unknown open cluster, discovered by the author, centered at RA =23 h 54.9 min, Dec = 61 deg 21 arcmin (1950.0). The cluster members were selected on the basis of the proper motion (vector diagram) and photometric (V ~ B-V and U-B ~ B-V) criteria. Stars within areas with 4 arcmin radii centered on NGC 7788 and NGC 7790 and 6 arcmin radii centered on Berkeley 58 and the anonymous cluster were investigated for cluster membership. The method of reduction of the observational data and the results obtained have been published in Izv. Pulkovo 195, 80, 1977 and 196, 69, 1979.
Proper Motions, UBV-Phot. & Spectral Class Region 7092
Short Name:
I/203
Date:
21 Oct 2021
Publisher:
CDS
Description:
A catalogue of positions, proper motions and photographic UBV-magnitudes for 7931 stars in and around the open cluster NGC 7092 (M39) is presented. The Catalogue is complete down to B=16.0m and covers an area with diameter of ~110'. The spectral types are provided for 511 stars generally brighter than B=13.0m. For convenience, basic cross-identifications are also included. Refer to the file "intro.txt" for full details about the catalogue.
We measured 304 absorption features in the ultraviolet and visible spectra of the star 51 Oph, which is known to have a debris disk with a high inclination. We analyzed the relative populations of atoms in excited fine-structure and metastable levels that are maintained by optical pumping and collisional excitation by electrons, and we found that most of the gas is situated at about 6 au from the star, has an electron volume density 10^5^<n(e)<3x10^6^cm^-3^, and a temperature T=8000K. Our interpretations reveal that the gas is partly ionized, has a column density of neutral hydrogen equal to 10^21^cm^-2^, and has a composition similar to that of a mildly depleted interstellar medium or that of Jupiter-family comets. Compared to results for disks around some other stars, such as {beta} Pic and 49 Cet, we find surprisingly little neutral carbon. No molecular features were detected, which indicates that our line of sight misses the molecule-rich central plane of the disk. The tilt of the disk is also validated by our being able to detect resonant scattering of the starlight by oxygen atoms.
We investigate the extent to which the Palomar-Green (PG) Bright Quasar Survey (BQS) is complete and representative of the general quasar population by comparing it with imaging and spectroscopy from the Sloan Digital Sky Survey (SDSS).
We analyzed images of comet 49P/Arend-Rigaux on 33 nights between 2012 January and May and obtained R-band lightcurves of the nucleus. Through usual phasing of the data, we found a double-peaked lightcurve having a synodic rotation period of 13.450+/-0.005 hr. Similarly, phase dispersion minimization and the Lomb-Scargle method both revealed rotation periods of 13.452 hr. Throughout the 2011/2012 apparition, the rotation period was found to increase by a small amount, consistent with a retrograde rotation of the nucleus. We also reanalyzed the publicly available data from the 1984/1985 apparition by applying the same techniques, finding a rotation period of 13.45+/-0.01 hr. Based on these findings, we show that the change in rotation period is less than 14 s per apparition. Furthermore, the amplitudes of the lightcurves from the two apparitions are comparable, to within reasonable errors, even though the viewing geometries differ, implying that we are seeing the comet at a similar sub-Earth latitude. We detected the presence of a short-term jet-like feature in 2012 March, which appears to have been created by a short-duration burst of activity on March 15. Production rates obtained in 2004/2005, along with reanalysis of the previous results from 1984/1985, imply a strong seasonal effect and a very steep fall-off after perihelion. This, in turn, implies that a single source region, rather than leakage from the entire nucleus, dominates activity.
Properties of dwarf galaxies from the ALFALFA survey
Short Name:
J/AJ/143/133
Date:
21 Oct 2021
Publisher:
CDS
Description:
We examine the global properties of the stellar and HI components of 229 low HI mass dwarf galaxies extracted from the ALFALFA survey ({alpha}.40; Haynes et al., 2011, Cat. J/AJ/142/170), including a complete sample of 176 galaxies with HI masses<10^7.7^M_{sun}_and HI line widths<80km/s. Sloan Digital Sky Survey (SDSS; Cat . II/294 superseded by Cat. V/139) data are combined with photometric properties derived from Galaxy Evolution Explorer (GALEX; GR5, Cat. II/312) to derive stellar masses (M_*_) and star formation rates (SFRs) by fitting their UV-optical spectral energy distributions (SEDs). In optical images, many of the ALFALFA dwarfs are faint and of low surface brightness; only 56% of those within the SDSS footprint have a counterpart in the SDSS spectroscopic survey. A large fraction of the dwarfs have high specific star formation rates (SSFRs), and estimates of their SFRs and M_*_ obtained by SED fitting are systematically smaller than ones derived via standard formulae assuming a constant SFR. The increased dispersion of the SSFR distribution at M_*_<~10^8^M_{sun}_ is driven by a set of dwarf galaxies that have low gas fractions and SSFRs; some of these are dE/dSphs in the Virgo Cluster. The imposition of an upper HI mass limit yields the selection of a sample with lower gas fractions for their M_*_ than found for the overall ALFALFA population. Many of the ALFALFA dwarfs, particularly the Virgo members, have HI depletion timescales shorter than a Hubble time. An examination of the dwarf galaxies within the full ALFALFA population in the context of global star formation (SF) laws is consistent with the general assumptions that gas-rich galaxies have lower SF efficiencies than do optically selected populations and that HI disks are more extended than stellar ones.
Positional, structural, and dynamical parameters for all dwarf galaxies in and around the Local Group are presented, and various aspects of our observational understanding of this volume-limited sample are discussed. Over 100 nearby galaxies that have distance estimates reliably placing them within 3Mpc of the Sun are identified. This distance threshold samples dwarfs in a large range of environments, from the satellite systems of the MW and M31, to the quasi-isolated dwarfs in the outer regions of the Local Group, to the numerous isolated galaxies that are found in its surroundings. It extends to, but does not include, the galaxies associated with the next nearest groups, such as Maffei, Sculptor, and IC 342. Our basic knowledge of this important galactic subset and their resolved stellar populations will continue to improve dramatically over the coming years with existing and future observational capabilities, and they will continue to provide the most detailed information available on numerous aspects of dwarf galaxy formation and evolution. Basic observational parameters, such as distances, velocities, magnitudes, mean metallicities, as well as structural and dynamical characteristics, are collated, homogenized (as far as possible), and presented in tables that will be continually updated to provide a convenient and current online resource. As well as discussing the provenance of the tabulated values and possible uncertainties affecting their usage, the membership and spatial extent of the MW sub-group, M31 sub-group, and the Local Group are explored. The morphological diversity of the entire sample and notable sub-groups is discussed, and timescales are derived for the Local Group members in the context of their orbital/interaction histories. The scaling relations and mean stellar metallicity trends defined by the dwarfs are presented, and the origin of a possible "floor" in central surface brightness (and, more speculatively, stellar mean metallicity) at faint magnitudes is considered.
We compare the physical and morphological properties of z~2 Ly{alpha} emitting galaxies (LAEs) identified in the HETDEX Pilot Survey and narrow band studies with those of z~2 optical emission line selected galaxies (oELGs) identified via HST WFC3 infrared grism spectroscopy. Both sets of galaxies extend over the same range in stellar mass (7.5<logM/M_{sun}_<10.5), size (0.5<R<3.0kpc), and star formation rate (~1<SFR<100M_{sun}_/yr). Remarkably, a comparison of the most commonly used physical and morphological parameters - stellar mass, half-light radius, UV slope, SFR, ellipticity, nearest neighbor distance, star formation surface density, specific SFR, [OIII] luminosity, and [OIII] equivalent width - reveals no statistically significant differences between the populations.
