The SPM Catalog 2.0 provides positions, absolute proper motions and photographic BV photometry for over 320,000 stars and galaxies. The Catalog covers an area of ~3700 square degrees in an irregularly bounded band between declinations of -43 and -22 degrees, with a slight extension near the South Galactic Pole, but excluding fields in the plane of the Milky Way. Stars cover the magnitude range 5<V<18.5. The standard errors for the best measured stars are as follows: 20 mas for positions in each coordinate; 2mas/yr for absolute proper motions and 0.05mag for B and V magnitudes. Standard error estimates of positions, absolute proper motions and magnitudes are given for each individual object. In addition to the Catalog, a list of CCD calibrating sequences is provided. Note that all fields (and objects) contained in the 1.0 version of the Catalog are also included in this version. The values of the astrometric parameters for these objects, however, may be different due to refinements in the reduction procedure, (i.e. the SGP fields were re-reduced for inclusion in the SPM catalog 2.0).
The SPM4 Catalog contains absolute proper motions, celestial coordinates, and B,V photometry for 103,319,647 stars and galaxies between the south celestial pole and -20 degrees declination. The catalog is roughly complete to V=17.5. It is based on photographic and CCD observations taken with the Yale Southern Observatory's double-astrograph at Cesco Observatory in El Leoncito, Argentina. The first-epoch survey, taken from 1965 to 1979, was entirely photographic. The second-epoch survey is approximately 1/3 photographic (taken from 1988 to 1998) and 2/3 CCD-based (taken from 2004 through 2008). Full details about the creation of the SPM4.0 catalog can be found in the paper, and also in the document "spm4_doc.txt" file which describes the original files, accessible from http://www.astro.yale.edu/astrom/spm4cat/
We have combined near-infrared data from the Two Micron All Sky Survey with ancillary optical data to identify previously unrecognized proper-motion stars that have colors and magnitudes consistent with nearby M dwarfs. We present follow-up observations of 392 stars from that sample, including ~200 stars discussed here for the first time. Our distance estimates, based primarily on spectroscopic parallaxes, place 123 stars within 20pc of the Sun. One hundred and seventy-six stars exhibit H{alpha} emission, and 82 stars have plausible X-ray counterparts from ROSAT observations.
1214 individual measurements of radial velocities made with CORAVEL-type spectrometer (Tokovinin, 1987AZh....64..196T) are presented for 1134 stars in 19 northern Kapteyn's areas. Precise coordinates are given for all these stars. Proper motions of stars are taken from NLTT (Luyten, 1979, Cat. <I/98>), PPM (Roser, Bastian, 1991, Cat. <I/146> and <I/193>), NPM1 (Klemola, Hanson, Jones, 1987, Cat. <I/200>) and Four-million catalog (Kuimov, 1992, In: On the four-million catalog of stars, eds. Izd. MGU, Moscow, P.27.; Glushkova et al., 1996PAZh...22..850G). A list of suspected binary stars and stars with variable radial velocities is also given. Two-dimensional spectral classification for these area is available (Bartaya, 1979AbaOB..51....1B).
We obtain the basic properties of the nuclear cluster of the Milky Way. First, we investigate the structural properties by constructing a stellar density map of the central 1000" using extinction-corrected old star counts from VISTA, WFC3/IR, and VLT/NACO data. We describe the data using two components. The inner, slightly flattened (axis ratio of q=0.80+/-0.04) component is the nuclear cluster, while the outer component corresponds to the stellar component of the circumnuclear zone. For the nuclear cluster, we measure a half-light radius of 178+/-51"~7+/-2pc and a luminosity of M_Ks_=-16.0+/-0.5. Second, we measure detailed dynamics out to 4pc. We obtain 10351 proper motions from AO data, and 2513 radial velocities from VLT/SINFONI data. We determine the cluster mass by means of isotropic spherical Jeans modeling. We fix the distance to the Galactic Center and the mass of the supermassive black hole. We model the cluster either with a constant M/L or with a power law. For the latter case, we obtain a slope of 1.18+/-0.06. We get a cluster mass within 100" of M_100"_=(6.09+/-0.53|_fixR_0_+/-0.97|_R_0_)x10^6^M_{sun}_ for both modeling approaches. A model which includes the observed flattening gives a 47% larger mass (see Chatzopoulos et al. 2015MNRAS.447..948C). Our results slightly favor a core over a cusp in the mass profile. By minimizing the number of unbound stars within 8", we obtain a distance of R_0_=8.53_-0.15_^+0.21^kpc when using an R0 supermassive black hole mass relation from stellar orbits. Combining our results, we obtain M/L=0.51+/-0.12M_{sun}/L_{sun},Ks_, which is roughly consistent with a Chabrier IMF.
Using 26 plates taken over the course of more than half a century, we present proper motions and photometry for 1177 stars in the central region of the Sculptor dwarf spheroidal galaxy, down to a limiting magnitude of V~20.25 at the level of the horizontal branch. The proper-motion cleaned color-magnitude diagram retained a broad giant branch, further supporting an intrinsic spread in metallicity. We determined an absolute proper motion for Sculptor, relative to background galaxies, of mu_alpha=+0.036+/-0.022arcsec/century and mu_delta=0.043+/-0.025arcsec/century after correcting for the LSR and peculiar solar motions. Our proper-motion uncertainty is similar to or smaller than those obtained by different groups for other distant satellites of the Galaxy. When combined with Sculptor's distance and radial velocity, this measurement shows the dwarf spheroidal to have a space velocity of roughly 220+/-125km/s. Although our measurement is less than twice its uncertainty, the direction of Sculptor's motion is significant because it rules out motion along the Magellanic Stream. A 2.5 sigma error allows for motion in a direction toward the Fornax dwarf spheroidal galaxy, so Sculptor remains a possible member of the proposed Fornax-Leo-Sculptor stream.
A magnitude-limited photographic survey of relative proper-motion components and B, V photometry of 1.3x10^6^ stars brighter than apparent B magnitude 14.5+/-0.5 in the fourth Galactic quadrant is converted into a distance-limited survey of 3.26x10^5^ stars up to a distance of 500pc. A streaming motion of 13.5+/-0.5 km/s is detected in 4.1x10^4^ Population I stellar candidates with an orbital perigalactic center located at 6.8<=R<=7.2kpc, with a Sun location Rsol=8.5 kpc. A density perturbation of about 0.1M{sun}/pc^3^ in the Galactic field potential at Ro~6.8kpc is interpreted as resulting from the density wave connected with the Sagittarius-Carina spiral arm. A set of 1.4x10^4^ stars of mass about 1.5+/-0.75 M{sun} identify a pitch angle of 10+/-1{deg} and a migration time from the Sagittarius spiral arm into the greater solar neighborhood of about 35Myr.
We present the technique and results of a survey of stars within 8pc of the Sun with declinations {delta}>-35{deg} (J2000.00). The survey, designed to find without color bias faint companions, consists of optical coronagraphic images of the 1 field of view centered on each star and infrared direct images with a 32" field of view. The images were obtained through the optical Gunn r and z filters and the infrared J and K filters. The survey achieves sensitivities up to 4 absolute magnitudes fainter than the prototype brown dwarf, Gliese 229B. However, this sensitivity varies with the seeing conditions, the intrinsic brightness of the star observed, and the angular distance from the star. As a result, we tabulate sensitivity limits for each star in the survey. We used the criterion of common proper motion to distinguish companions and to determine their luminosities. In addition to the brown dwarf Gl 229B, we have identified six new stellar companions of the sample stars. Since the survey began, accurate trigonometric parallax measurements for most of the stars have become available. As a result, some of the stars we originally included should no longer be included in the 8pc sample. In addition, the 8pc sample is incomplete at the faint end of the main sequence, complicating our calculation of the binary fraction of brown dwarfs. We assess the sensitivity of the survey to stellar companions and to brown dwarf companions of different masses and ages.
The multiplicity fraction of stars, down to the substellar regime, is a parameter of fundamental importance for stellar formation, evolution, and planetology. The census of multiple stars in the solar neighborhood is however incomplete. The presence of a companion in orbit around a star affects its proper motion. We aim at detecting companions of Hipparcos catalog stars from the proper motion anomaly (PMa) they induce on their host star, that is, the difference between their long-term Hipparcos-Gaia and short-term Gaia proper motion vectors. We also aim at detecting resolved, gravitationally bound companions of the Hipparcos catalog stars (117955 stars), and of the Gaia EDR3 stars closer than 100 c (542232 stars). Using the Hipparcos and EDR3 data, we revise the PMa catalog for the Hipparcos stars. To identify gravitationally bound visual companions of our sample, we search the Gaia EDR3 catalog for common proper motion (CPM) candidates. The detection of tangential velocity anomalies with a median accuracy of 26cm/s per parsec of distance is demonstrated with the EDR3. This improvement by a factor 2.5 in accuracy compared to the Gaia DR2 results in PMa detection limits on companions well into the planetary mass regime for many targets. We identify 37515 Hipparcos stars presenting a PMa at significant level (S/N>3), that is, a fraction of 32% (compared to 30% for the DR2) and 12914 (11%) hosting CPM bound candidate companions. Including the Gaia EDR3 RUWE>1.4 as an additional indicator, 50,720 stars of the Hipparcos catalog (43%) exhibit at least one signal of binarity. Among the Gaia EDR3 stars located within 100 pc, we find CPM bound candidate companions for 39,490 stars (7.3% of the sample). The search for companions using a combination of the PMa, CPM and RUWE indicators significantly improves the exhaustivity of the multiplicity survey. The detection of CPM companions of very bright stars (heavily saturated on the Gaia detectors) that are classical benchmark objects for stellar physics provides a useful proxy to estimate their distance with a higher accuracy than Hipparcos.
We have identified stellar and substellar members in the nearby star cluster Coma Berenices, using photometry, proper motions, and distances of a combination of 2MASS, UKIDSS, URAT1, and Gaia/DR2 data. Those with Gaia/DR2 parallax measurements provide the most reliable sample to constrain the distance, averaging 86.7pc with a dispersion of 7.1pc, and age of ~800Myr, of the cluster. This age is older than the 400-600 Myr commonly adopted in the literature. Our analysis, complete within 5{deg} of the cluster radius, leads to identification of 192 candidates, among which, after field contamination is considered, about 148 are true members. The members have J~3mag to ~17.5mag, corresponding to stellar masses 2.3-0.06M_{sun}_. The mass function of the cluster peaks around 0.3M_{sun},_ and in the sense of dN/dm=m^-{alpha}^, where N is the number of members and m is stellar mass, with a slope {alpha}~=0.49+/-0.03 in the mass range 0.3-2.3M_{sun}_. This is much shallower than that of the field population in the solar neighborhood. The slope {alpha}=-1.69+/-0.14 from 0.3M_{sun}_ to 0.06M_{sun}_, the lowest mass in our sample. The cluster is mass-segregated and has a shape elongated toward the Galactic plane. Our list contains nine substellar members, including three new discoveries of an M8, an L1, and an L4 brown dwarfs, extending from the previously known coolest members of late-M types to even cooler types.
