- ID:
- ivo://CDS.VizieR/J/ApJS/246/15
- Title:
- K2 periodic variables in M35 & NGC2158
- Short Name:
- J/ApJS/246/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 1143 periodic variables, compiled from our image-subtracted photometric analysis of the K2 Campaign-0 super stamp. This super stamp is centered on the open clusters M35 and NGC2158. Approximately 46% of our periodic variables were previously unreported. Of the catalog variables, we find that 331 are members of M35 and 56 are members of NGC 2158 (P_m_>0.5). Our catalog contains two new transiting exoplanet candidates, both of which orbit field stars. The smaller planet candidate has a radius of 0.35+/-0.04R_J_ and orbits a K dwarf (Kp=15.4mag) with a transit depth of 2.9mmag. The larger planet candidate has a radius of 0.72+/-0.02R_J_ and orbits a late G-type star (Kp=15.7mag) with a transit depth of 2.2mmag. The larger planet candidate may be an unresolved binary or a false alarm. Our catalog includes 44 eclipsing binaries (EBs), including ten new detections. Of the EBs, one is an M35 member and five are NGC 2158 members. Our catalog contains a total of 1097 nontransiting variable stars, including a field {delta} Cepheid exhibiting double mode pulsations, 561 rotational variables, and 251 pulsating variables (primarily {gamma} Doradus and {delta} Scuti types). The periods of our catalog sources range between 43 minutes to 24 days. The known ages of our reported cluster variables will facilitate investigations of a variety of stellar evolutionary processes.
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- ID:
- ivo://CDS.VizieR/J/ApJS/253/22
- Title:
- Ks absolute magnitudes from LAMOST for OB stars
- Short Name:
- J/ApJS/253/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a data-driven method to estimate absolute magnitudes for O- and B-type stars from the LAMOST spectra, which we combine with Gaia DR2 parallaxes to infer distance and binarity. The method applies a neural network model trained on stars with precise Gaia parallax to the spectra and predicts K_s_-band absolute magnitudes M_Ks_ with a precision of 0.25mag, which corresponds to a precision of 12% in spectroscopic distance. For distant stars (e.g., >5kpc), the inclusion of constraints from spectroscopic M_Ks_ significantly improves the distance estimates compared to inferences from Gaia parallax alone. Our method accommodates for emission-line stars by first identifying them via principal component analysis reconstructions and then treating them separately for the M_Ks_ estimation. We also take into account unresolved binary/multiple stars, which we identify through deviations in the spectroscopic M_Ks_ from the geometric M_Ks_ inferred from Gaia parallax. This method of binary identification is particularly efficient for unresolved binaries with near equal-mass components and thus provides a useful supplementary way to identify unresolved binary or multiple-star systems. We present a catalog of spectroscopic M_Ks_, extinction, distance, flags for emission lines, and binary classification for 16002 OB stars from LAMOST DR5. As an illustration, we investigate the M_Ks_ of the enigmatic LB-1 system, which Liu et al. 2019Natur.575..618L had argued consists of a B star and a massive stellar-mass black hole. Our results suggest that LB-1 is a binary system that contains two luminous stars with comparable brightness, and the result is further supported by parallax from the Gaia eDR3.
- ID:
- ivo://CDS.VizieR/J/A+A/438/377
- Title:
- Kyiv Meridian Axial Circle Catalogue, KMAC1
- Short Name:
- J/A+A/438/377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of astrometric observations of faint V<17mag stars in sky strip areas with ICRF objects obtained with the Kyiv meridian axial circle (D=180mm) equipped with a 1040x1160 CCD micrometer. Observations were carried out in a declination zone of 0+30 degrees. The work resulted in a compilation of a catalogue KMAC1 that presents an extension of the ICRF to faint stars in optical domain. The catalogue was obtained in the two versions: with reduction to the space catalogue Tycho2, <I/259>, (the version KMAC1-T, 159 ICRF fields, 104794 stars) and with reduction to the modern CCD catalogues CMC13 and UCAC2 (<I/289>) which are given also in the ICRF system (the version KMAC1-CU, 192 ICRF fields, 115032 stars). Due to a large number of CMC13 and UCAC2 stars used as reference, the version KMAC1-CU is of slightly better accuracy, though it may inherit local systematic errors of reference catalogues.
- ID:
- ivo://CDS.VizieR/J/ApJ/880/65
- Title:
- LAMOST K giants in Galactic halo substructures
- Short Name:
- J/ApJ/880/65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a large halo K-giant sample by combining the positions, distances, radial velocities, and metallicities of over 13000 LAMOST DR5 halo K giants with the Gaia DR2 proper motions, which covers a Galactocentric distance range of 5-120kpc. Using a position-velocity clustering estimator (the 6Distance), we statistically quantify the presence of position-velocity substructure at high significance: K giants have more close pairs in position-velocity space than a smooth stellar halo. We find that the amount of substructure in the halo increases with increasing distance and metallicity. With a percolation algorithm named friends-of-friends to identify groups, we identify members belonging to Sagittarius (Sgr) Streams, Monoceros Ring, Virgo Overdensity, Hercules-Aquila Cloud, Orphan Streams, and other unknown substructures and find that the Sgr streams account for a large part of grouped stars beyond 20kpc and enhance the increase of substructure with distance and metallicity. For the first time, we identify spectroscopic members of Monoceros Ring in the southern and northern Galactic hemispheres, which presents a rotation of about 185km/s and a mean metallicity of -0.66dex.
- ID:
- ivo://CDS.VizieR/J/ApJS/220/19
- Title:
- LAMOST obs. in the Kepler field. I.
- Short Name:
- J/ApJS/220/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nearly continuous light curves with micromagnitude precision provided by the space mission Kepler are revolutionizing our view of pulsating stars. They have revealed a vast sea of low-amplitude pulsation modes that were undetectable from Earth. The long time base of Kepler light curves allows for the accurate determination of the frequencies and amplitudes of pulsation modes needed for in-depth asteroseismic modeling. However, for an asteroseismic study to be successful, the first estimates of stellar parameters need to be known and they cannot be derived from the Kepler photometry itself. The Kepler Input Catalog provides values for the effective temperature, surface gravity, and metallicity, but not always with sufficient accuracy. Moreover, information on the chemical composition and rotation rate is lacking. We are collecting low-resolution spectra for objects in the Kepler field of view with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, Xinglong observatory, China). All of the requested fields have now been observed at least once. In this paper, we describe those observations and provide a useful database for the whole astronomical community.
- ID:
- ivo://CDS.VizieR/J/MNRAS/328/45
- Title:
- Late-type stars members of young groups
- Short Name:
- J/MNRAS/328/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first paper of a series aimed at studying the properties of late-type members of young stellar kinematic groups. We concentrate our study on classical young moving groups such as the Local Association (Pleiades moving group, 2-150Myr), IC 2391 supercluster (35Myr), Ursa Major group (Sirius supercluster, 300Myr), and Hyades supercluster (600Myr), as well as on recently identified groups such as the Castor moving group (200Myr). In this paper we compile a preliminary list of single late-type possible members of some of these young stellar kinematic groups. Stars are selected from previously established members of stellar kinematic groups based on photometric and kinematic properties as well as from candidates based on other criteria such as their level of chromospheric activity, rotation rate and lithium abundance. Precise measurements of proper motions and parallaxes taken from the Hipparcos Catalogue, as well as from the Tycho-2 Catalogue, and published radial velocity measurements are used to calculate the Galactic space motions (U, V, W) and to apply Eggen's kinematic criteria in order to determine the membership of the selected stars to the different groups.
- ID:
- ivo://CDS.VizieR/I/130
- Title:
- LDS Catalogue: Doubles with Common Proper Motion
- Short Name:
- I/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains all double stars with common proper motion discovered by Luyten since 1940 up to 1987 (references below). When Luyten had noticed that an entry was duplicated (ref. 8 and 9), only the former LDS number was kept in the data file but with the data given for the latter. The unique exception is LDS 6166, which is a duplicate of LDS 5662, but with an additional component. The systems classified as optical by Luyten were also rejected from the main data files. All the rejected data were put together in a separate file. All coordinates are for the equinox 1950; when the original publication gave another equinox (this is the case for ref. 1), the 1950-coordinates were calculated. The catalogue contains all the systems, sorted by increasing LDS numbers. Duplicate entries and optical systems listed by Luyten were rejected. The catalogue contains 6121 systems, including 87 triple and 1 quadruple systems. The number of records is thus 6210, since each triple system occupies 2 records and the quadruple system 3.
298. LFT Catalogue
- ID:
- ivo://CDS.VizieR/I/54A
- Title:
- LFT Catalogue
- Short Name:
- I/54A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue, published in 1955, provides data about stars known to have proper motions exceeding 0.5" annually. Note that a more recent version, known as the "LHS" catalogue and containing 4471 stars, was published later in 1987 (catalogue I/87)
- ID:
- ivo://CDS.VizieR/I/87B
- Title:
- LHS Catalogue, 2nd Edition
- Short Name:
- I/87B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue gathers stars with large proper motions, the large majority coming out of the Bruce Proper Motion Survey (W.J. Luyten). 804 fields in the Palomar Survey have been hand-blinked or processed by an automated blink-machine; 160 low galactic latitude fields could not be handled. There are therefore many less stars with high proper motion south of -33 degrees (limit of the Palomar Survey) compared to the Northern hemisphere. Stars with proper motions larger than 2arcsec/yr are numbered 1 to 100; stars with proper motions between 1 and 2arcsec/yr are numbered 101 to 1000 ; numbers 1001 through 5000 are assigned to stars with proper motions between 0.5 and 1arcsec/yr. The stars which appear to have motions between 0.480 and 0.499arcsec/yr have been assigned numbers larger than 5000. Numbers larger than 6000 refer to Appendix II of the printed publication, containing stars for which at one time or another a value larger than 0.49arcsec/yr was published; these numbers are not listed in the printed version of the catalogue. All proper motions have been reduced to the Palomar-Bruce system. The catalogue supersedes the "Catalogue of Stars with Motions exceeding 0.5" annually" (LFT) published in 1955 (CDS ref. <I/54>)
- ID:
- ivo://CDS.VizieR/J/PASP/117/676
- Title:
- LHS faint proper-motion stars
- Short Name:
- J/PASP/117/676
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present low-resolution spectroscopic observations of faint proper-motion stars from the LHS Catalogue, concentrating on stars with m_r_>16.5 and {mu}>0.5"/yr. The present paper includes observations and spectral classifications for 294 M dwarfs, M subdwarfs (sdM), and extreme M subdwarfs (esdM). We also identify white dwarfs among the faintest LHS stars. We have cross-referenced this sample against the Two Micron All Sky Survey (2MASS) sources, and list data for the detected objects. We discuss stars of individual interest, as well as the characteristics of the overall sample. As expected, a significant number of the stars in this proper-motion-selected sample are halo subdwarfs, including an esdM dwarf, LHS 3481, that is likely to lie within 20pc of the Sun. None of the subdwarfs show H{alpha} emission.
