- ID:
- ivo://CDS.VizieR/J/AJ/158/87
- Title:
- 86 cool dwarfs observed during K2 Campaigns 1-17
- Short Name:
- J/AJ/158/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present revised stellar properties for 172 K2 target stars that were identified as possible hosts of transiting planets during Campaigns 1-17. Using medium-resolution near-infrared spectra acquired with the NASA Infrared Telescope Facility/SpeX and Palomar/TripleSpec, we found that 86 of our targets were bona fide cool dwarfs, 74 were hotter dwarfs, and 12 were giants. Combining our spectroscopic metallicities with Gaia parallaxes and archival photometry, we derived photometric stellar parameters and compared them to our spectroscopic estimates. Although our spectroscopic and photometric radius and temperature estimates are consistent, our photometric mass estimates are systematically {Delta}M_*_=0.11 M_{sun}_ (34%) higher than our spectroscopic mass estimates for the least massive stars (M_*,phot_<0.4 M_{sun}_). Adopting the photometric parameters and comparing our results to parameters reported in the Ecliptic Plane Input Catalog, our revised stellar radii are {Delta}R_*_=0.15 R_{sun}_ (40%) larger, and our revised stellar effective temperatures are roughly {Delta}T_eff_=65 K cooler. Correctly determining the properties of K2 target stars is essential for characterizing any associated planet candidates, estimating the planet search sensitivity, and calculating planet occurrence rates. Even though Gaia parallaxes have increased the power of photometric surveys, spectroscopic characterization remains essential for determining stellar metallicities and investigating correlations between stellar metallicity and planetary properties.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/131/582
- Title:
- Cool white dwarfs in the SDSS
- Short Name:
- J/AJ/131/582
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A reduced proper motion diagram utilising Sloan Digital Sky Survey (SDSS) photometry and astrometry and USNO-B plate astrometry is used to separate cool white dwarf candidates from metal-weak, high-velocity, main-sequence Population II stars (subdwarfs) in the SDSS Data Release 2 imaging area. Follow-up spectroscopy using the Hobby-Eberly Telescope, the MMT, and the McDonald 2.7m telescope is used to demonstrate that the white dwarf and subdwarf loci separate cleanly in the reduced proper motion diagram and that the contamination by subdwarfs is small near the cool white dwarf locus.
- ID:
- ivo://CDS.VizieR/J/A+A/521/A39
- Title:
- Cordoba Carte du Ciel-Astrographic Catalog, CCAC
- Short Name:
- J/A+A/521/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on stellar positions and proper motions, we aim to re-analyse the region of the controversial open cluster Collinder 132. Methods. We have developed a model which analyse the proper motion distribution and the stellar density to find moving groups. The astrometric data was obtained from four Carte du Ciel (CdC) and one Astrogaphic Catalogue (AC) plates of the Cordoba Astronomical Observatory collection (Argentina). We detected an open cluster from the field stars and calculated the mean proper motion and the membership probabilities of the stars of the region. We report new coordinates of its centre RAc=108.347deg, DEc=-31.011deg, the components of mean proper motion mu_RA_cosDE=-2.62+/-0.44mas/yr, mu_DE_=4.79+/-0.88mas/yr. 11 stars are astrometric members giving a value of 370 for the cluster angular diameter. 6 stars fullfill astrometric and photometric analysis for being cluster members and locate the cluster at 360pc from the Sun. An over-density in the VPD was found after removing the cluster members, consequently a simple model for the proper motion distribution of an association and of the field was adopted. We report the components of the association mean proper motion mu_RA_cosDE=-1.38+/-0.14mas/yr, mu_DE_=2.26+/-0.16mas/yr. 174 astrometric members were found while 11 members have been located between 417 and 660pc from the Sun by Tycho-2 photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A98
- Title:
- Corona-Australis DANCe. I.
- Short Name:
- J/A+A/634/A98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Corona-Australis is one of the nearest regions to the Sun with recent and ongoing star formation, but the current picture of its stellar (and substellar) content is not complete yet. We take advantage of the second data release of the Gaia space mission to revisit the stellar census and search for additional members of the young stellar association in Corona-Australis. We applied a probabilistic method to infer membership probabilities based on a multidimensional astrometric and photometric data set over a field of 128deg^2^ around the dark clouds of the region. We identify 313 high-probability candidate members to the Corona-Australis association, 262 of which had never been reported as members before. Our sample of members covers the magnitude range between G>~5mag and G<~20mag, and it reveals the existence of two kinematically and spatially distinct subgroups. There is a distributed 'off-cloud' population of stars located in the north of the dark clouds that is twice as numerous as the historically known 'on-cloud' population that is concentrated around the densest cores. By comparing the location of the stars in the HR-diagram with evolutionary models, we show that these two populations are younger than 10Myr. Based on their infrared excess emission, we identify 28 Class II and 215 Class III stars among the sources with available infrared photometry, and we conclude that the frequency of Class~II stars (i.e. `disc-bearing' stars) in the on-cloud region is twice as large as compared to the off-cloud population. The distance derived for the Corona-Australis region based on this updated census is d=149.4^+0.4^_-0.4_pc, which exceeds previous estimates by about 20 pc. In this paper we provide the most complete census of stars in Corona-Australis available to date that can be confirmed with Gaia data. Furthermore, we report on the discovery of an extended and more evolved population of young stars beyond the region of the dark clouds, which was extensively surveyed in the past.
- ID:
- ivo://CDS.VizieR/J/other/Ser/182.35
- Title:
- Corrected proper motion for HIP stars
- Short Name:
- J/other/Ser/182.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- During the last century, there were many so-called independent latitude (IL) stations with the observations which were included into data of a few international organizations (like Bureau International de l'Heure - BIH, International Polar Motion Service - IPMS) and the Earth rotation programmes for determining the Earth Orientation Parameters - EOP. Because of this, nowadays, there are numerous astrometric ground-based observations (made over many decades) of some stars included in the Hipparcos Catalogue (ESA 1997, Cat. <A HREF="http://cdsarc.u-strasbg.fr/cgi-bin/Cat?I/239">I/239</A>). We used these latitude data for the inverse investigations - to improve the proper motions in declination µ<SUB>δ</SUB> of the mentioned Hipparcos stars. We determined the corrections Δµ<SUB>δ</SUB> and investigated agreement of our µ<SUB>δ</SUB> and those from the catalogues Hipparcos and new Hipparcos (van Leeuwen 2007, Cat. <A HREF="http://cdsarc.u-strasbg.fr/cgi-bin/Cat?I/311">I/311</A>). To do this we used the latitude variations of 7 stations (Belgrade, Blagoveschtschensk, Irkutsk, Poltava, Pulkovo, Warsaw and Mizusawa), covering different intervals in the period 1904.7-1992.0, obtained with 6 visual and 1 floating zenith telescopes (Mizusawa). On the other hand, with regard that about two decades have elapsed since the Hipparcos ESA mission observations (the epoch of Hipparcos catalogue is 1991.25), the error of apparent places of Hipparcos stars has increased by nearly 20mas because of proper motion errors. Also, the mission lasted less than four years which was not enough for a sufficient accuracy of proper motions of some stars (such as double or multiple ones). Our method of calculation, and the calculated µ<SUB>δ</SUB> for the common IL/Hipparcos stars are presented here. We constructed an IL catalogue of 1200 stars: there are 707 stars in the first part (with at least 20 years of IL observations) and 493 stars in the second one (less than 20 years). In the case of µ<SUB>δ</SUB> of IL stars observed at some stations (Blagoveschtschensk, Irkutsk, Mizusawa, Poltava and Pulkovo) we find the formal errors less than the corresponding Hipparcos ones and for some of them (stations Blagoveschtschensk and Irkutsk) even less than the new Hipparcos ones.
- ID:
- ivo://CDS.VizieR/J/AN/341/770
- Title:
- Corrected proper motion for HIP stars
- Short Name:
- J/AN/341/770
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Independent Latitude Stations (INDLS) catalog of proper motion in declination {mu}_{delta}_ for 682 bright Hipparcos (HIP) stars is presented. It is obtained in the Hipparcos reference frame, and only the Hipparcos mean position at epoch 1991.25 is used for INDLS data to calculate independent {mu}_{delta}$ (the HIP {mu}_{delta}_ values are not entering the INDLS data). Catalog comparisons were made in pairs for the four catalogs (HIP, new Hipparcos -- NHIP, Gaia DR2, INDLS) to look for possible systematic differences as a function of brightness, color, position coordinates ({alpha}, {delta}). All catalogs were found in agreement, except: 0.21mas/yr for differences INDLS-DR2 in line with the brightness, -0.13mas/yr and 0.24mas/yr for differences HIP-DR2 in line with the free term and brightness respectively, -0.16mas/yr, 0.23mas/yr and 0.13mas/yr for differences NHIP$-$DR2 in line with the free term, brightness and color respectively. A slightly better consistency is in the cases INDLS-NHIP and INDLS-DR2 than HIP-DR2 and NHIP-DR2. The systematic error is in line with brightness on the level 0.1mas/yr in DR2, and near 0.1mas/yr in line with color. An indication that the bright reference frame of DR2 rotates by about 0.1mas/yr relative to the faint quasar frame is in line with a presented sinusoidal curve of differences {mu}_{delta}_ as a function of {alpha}. Its amplitude is A=0.53+/-0.11mas/yr for INDLS-DR2 (0.26+/-0.07 for INDLS-NHIP); about 0.2 belongs to DR2. The level of formal errors is near 1.9mas/yr for the case INDLS-DR2, and near 1.5 for: INDLS-NHIP, HIP-DR2, NHIP-DR2. The values {mu}_{delta}_ of bright DR2 stars could be underestimated; the astrometry is unreliable for G<=6mag due to detector saturation.
- ID:
- ivo://CDS.VizieR/J/other/Ser/177.109
- Title:
- Corrections to HIP proper motions
- Short Name:
- J/other/Ser/177.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the data on latitude variations obtained from observations with 10 classical photographic zenith tubes (PZT) in order to improve the Hipparcos proper motions in declinations µ<SUB>δ</SUB> for 807 stars. Part of observing programmes, carried out during the last century for the purpose of studying the Earth's rotation, were realized by using PZT instruments. These observations were performed within in the intervals (tens of years) much longer than that of the Hipparcos mission (less than 4 years). In addition, the annual number of observations for every PZT- programme star is several hundreds on the average. Though the accuracy of the star coordinates in the Hipparcos Catalogue is by two orders of magnitude better than that of the star coordinates from the PZT observations, the large number of observations performed a much longer time interval makes it possible to correct the Hipparcos proper motions and to improve their accuracy with respect to the accuracy given in the Hipparcos Catalogue. Long term examinations of latitude and time variations were used to form the Earth Orientation Catalogue (EOC-2), aimed at a more accurate determination of positions and proper motions for the stars included. Our method of calculating the corrections of the proper motions in declination from the latitude variations is different from the method used in obtaining the EOC-2 Catalogue. Comparing the results we have established a good agreement between our µ<SUB>δ</SUB> and the EOC-2 ones for the star sample used in the present paper.
138. CPMDS catalogue
- ID:
- ivo://CDS.VizieR/J/A+A/521/A4
- Title:
- CPMDS catalogue
- Short Name:
- J/A+A/521/A4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalogue of 2572 new double stars with common proper motion and angular separation smaller than 2 arcminutes, found in PM2000 proper motion catalogue. To this catalogue we add an annex of 259 of common proper motion doublestars with angular separation between 2 and 5 arcminutes and proper motion larger than 50mas/yr. A by-product of this work was the identification in PM2000 and remeasurement of 926 WDS double stars.
- ID:
- ivo://CDS.VizieR/IV/30
- Title:
- Cross-id. of stars with high-proper motions. V2.
- Short Name:
- IV/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue of stars with high-proper motions (more than 0.04"/year) has been compiled using original definitions from catalogue FONAK 1.1, the data of catalogues Hipparcos, Tycho-2, CMC (STAR 11), PPM, NPM1, NPM2, UCAC2 (up to +40 degrees in declination and going up to +52 degrees in some areas), GCVS, XZ80Q, Pul-3, PUL2, NLTT, LHS, Lowell Proper Motion, Bruce Proper Motion as well as the data of about 770 other published sources. The list consist of 514100 such stars with limiting magnitude 16 (companions for multiple systems up to 17) in a declination zone from -2.5 to +90 degrees. Besides astrometric parameters (equatorial coordinates, proper motions, estimations of stars magnitudes) the catalogue includes some astrophysical characteristics (magnitudes in UBVRIJHK system, radial velocities, spectra, luminosity class, metallicity; flags of multiple system, of variable star and other). For convenience of usage original numbers of stars from different catalogues the author's lists of stars and basic sources are given too. At present the catalogue includes codes of 63 catalogues and author's lists of stars. Cross index list is given by a file of 493200 stars arranged on right ascension. Star information is recorded in a digital integer form with one line. Thus maximum amount of star numbers from catalogues and author's lists does not exceed 10 (if more, the number of next lines for star is increased by unit). Beginning the second line there are blanks in the column declination if star information is recorded in several lines. Cross index list is regularly supplemented.
- ID:
- ivo://CDS.VizieR/J/MNRAS/460/2593
- Title:
- Cygnus OB2 DANCe: Proper motion study
- Short Name:
- J/MNRAS/460/2593
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high-precision proper motion study of 873 X-ray and spectroscopically selected stars in the massive OB association Cygnus OB2 as part of the DANCe project. These were calculated from images spanning a 15-year baseline and have typical precisions <1mas/yr. We calculate the velocity dispersion in the two axes to be 13.0^+0.8^_-0.7_ and 9.1^+0.5^_-0.5_km/s, using a 2-component, 2-dimensional model that takes into account the uncertainties on the measurements. This gives a 3-dimensional velocity dispersion of 17.8+/-0.6km/s implying a virial mass significantly larger than the observed stellar mass, confirming that the association is gravitationally unbound. The association appears to be dynamically unevolved, as evidenced by considerable kinematic substructure, non-isotropic velocity dispersions and a lack of energy equipartition. The proper motions show no evidence for a global expansion pattern, with approximately the same amount of kinetic energy in expansion as there is in contraction, which argues against the association being an expanded star cluster disrupted by process such as residual gas expulsion or tidal heating. The kinematic substructures, which appear to be close to virial equilibrium and have typical masses of 40-400M_{sun}_, also do not appear to have been affected by the expulsion of the residual gas. We conclude that Cyg OB2 was most likely born highly substructured and globally unbound, with the individual subgroups born in (or close to) virial equilibrium, and that the OB association has not experienced significant dynamical evolution since then.
