- ID:
- ivo://CDS.VizieR/J/A+A/635/A33
- Title:
- Galactic classical Cepheids Per-Lbol-Rad
- Short Name:
- J/A+A/635/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectral energy distributions (SEDs) were constructed for a sample of 477 classical cepheids (CCs); including stars that have been classified in the literature as such but are probably not. The SEDs were fitted with a dust radiative transfer code. Four stars showed a large mid- or far-infrared excess and the fitting then included a dust component. These comprise the well-known case of RS Pup, and three stars that are (likely) Type-II cepheids (T2Cs), AU Peg, QQ Per, and FQ Lac. The infrared (IR) excess in FQ Lac is reported for the first time in this work. The remainder of the sample was fitted with a stellar photosphere to derive the best-fitting luminosity and effective temperature. Distance and reddening were taken from the literature. The stars were plotted in a Hertzsprung-Russell diagram (HRD) and compared to evolutionary tracks for cepheids and theoretical instability strips. For the large majority of stars, the position in the HRD is consistent with the instability strip for a CC or T2C. About 5% of the stars are outliers in the sense that they are much hotter or cooler than expected. A comparison to effective temperatures derived from spectroscopy suggests in some cases that the photometrically derived temperature is not correct and that this is likely linked to an incorrectly adopted reddening. Two three-dimensional reddening models have been used to derive alternative estimates of the reddening for the sample. There are significant systematic differences between the two estimates with a non-negligible scatter. In this work the presence of a small near-infrared (NIR) excess, as has been proposed in the literature for a few well-known cepheids, is investigated. Firstly, this was done by using a sample of about a dozen stars for which a mid-infrared spectrum is available. This data is particularly con straining as the shape of the observed spectrum should match that of the photosphere and any dust spectrum, both dust continuum and any spectral features of, for example, silicates or aluminium oxide. This comparison provides constraints on the dust composition, in agreement with a previous work in the literature. Secondly, the SEDs of all stars were fitted with a dust model to see if a statistically significant better fit could be obtained. The results were compared to recent work. Eight new candidates for exhibiting a NIR excess are proposed, solely based on the photometric SEDs. Obtaining mid-infrared spectra would be needed to confirm this excess. Finally, period-bolometric luminosity and period-radius relations are presented for samples of over 370 fundamental-mode CCs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/235/41
- Title:
- Galactic EB stars with eccentric orbits based on ETDs
- Short Name:
- J/ApJS/235/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A comprehensive catalog of 623 galactic eclipsing binary (EB) systems with eccentric orbits is presented with more than 2830 times of minima determined from the archived photometric data by various sky-survey projects and new photometric measurements. The systems are divided into two groups according to whether the individual system has a GCVS name or not. All the systems in both groups are further classified into three categories (D, A, and A+III) on the basis of their eclipse timing diagrams: 453 D systems showing just constantly displaced secondary minima, 139 A systems displaying only apsidal motion (AM), and 31 A+III systems exhibiting both AM and light-time effects. AM parameters for 170 systems (A and A+III systems) are consistently calculated and cataloged with basic information for all systems. Some important statistics for the AM parameters are discussed and compared with those derived for the eccentric EB systems in the Large and Small Magellanic Clouds.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/89
- Title:
- 5 Galactic GC proper motions from Gaia DR1
- Short Name:
- J/ApJ/839/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a pilot study of Galactic globular cluster (GC) proper motion (PM) determinations using Gaia data. We search for GC stars in the Tycho-Gaia Astrometric Solution (TGAS) catalog from Gaia Data Release 1 (DR1), and identify five members of NGC 104 (47 Tucanae), one member of NGC 5272 (M3), five members of NGC 6121 (M4), seven members of NGC 6397, and two members of NGC 6656 (M22). By taking a weighted average of member stars, fully accounting for the correlations between parameters, we estimate the parallax (and, hence, distance) and PM of the GCs. This provides a homogeneous PM study of multiple GCs based on an astrometric catalog with small and well-controlled systematic errors and yields random PM errors similar to existing measurements. Detailed comparison to the available Hubble Space Telescope (HST) measurements generally shows excellent agreement, validating the astrometric quality of both TGAS and HST. By contrast, comparison to ground-based measurements shows that some of those must have systematic errors exceeding the random errors. Our parallax estimates have uncertainties an order of magnitude larger than previous studies, but nevertheless imply distances consistent with previous estimates. By combining our PM measurements with literature positions, distances, and radial velocities, we measure Galactocentric space motions for the clusters and find that these also agree well with previous analyses. Our analysis provides a framework for determining more accurate distances and PMs of Galactic GCs using future Gaia data releases. This will provide crucial constraints on the near end of the cosmic distance ladder and provide accurate GC orbital histories.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/1725
- Title:
- Galactic globular clusters SDSS photometry
- Short Name:
- J/MNRAS/437/1725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present g' and z' aperture photometry for 96 Galactic globular clusters, making this the largest homogeneous catalogue of photometry for these objects in the Sloan Digital Sky Survey (SDSS) filter system. For a subset of 56 clusters, we also provide photometry in r' and i'. We carry out comparisons with previous photometry as well as with the SDSS data set. The data will be useful for a series of applications in Galactic and extragalactic astrophysics. Future papers will analyse the colour-metallicity relation, colour-magnitude diagrams and structural parameters. The compilation of results based on this data set will be collected in the Galactic Globular Cluster Catalog (G2C2).
- ID:
- ivo://CDS.VizieR/J/ApJ/731/4
- Title:
- Galactic halo as seen by the CFHTLS
- Short Name:
- J/ApJ/731/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Canada-France-Hawaii Telescope Legacy Survey data for 170deg^2^, recalibrated and transformed to the Sloan Digital Sky Survey ugri photometric system, to study the distribution of near-turnoff main-sequence stars in the Galactic halo along four lines of sight to heliocentric distances of ~35kpc. We find that the halo stellar number density profile becomes steeper at Galactocentric distances greater than R_gal_~28kpc, with the power-law index changing from n_inner_=-2.62+/-0.04 to n_outer_=-3.8+/-0.1. In particular, we test a series of single power-law models and find them to be strongly disfavored by the data. The parameters for the best-fit Einasto profile are n=2.2+/-0.2 and R_e_=22.2+/-0.4kpc. We measure the oblateness of the halo to be q=c/a=0.70+/-0.01 and detect no evidence of it changing across the range of probed distances. The Sagittarius stream is detected in the l=173{deg} and b=-62{deg} direction as an overdensity of [Fe/H]~-1.5dex stars at R_gal_~32kpc, providing a new constraint for the Sagittarius stream and dark matter halo models. We also detect the Monoceros stream as an overdensity of [Fe/H]>-1.5dex stars in the l=232{deg} and b=26{deg} direction at R_gal_<~25kpc. In the two sight lines where we do not detect significant substructure, the median metallicity is found to be independent of distance within systematic uncertainties ([Fe/H]~-1.5+/-0.1dex).
- ID:
- ivo://CDS.VizieR/J/ApJ/763/32
- Title:
- Galactic halo RRab stars from CSS
- Short Name:
- J/ApJ/763/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present analysis of 12227 type-ab RR Lyraes (RRLs; ~9400 are newly discovered) found among the 200 million public light curves in Catalina Surveys Data Release 1. These stars span the largest volume of the Milky Way ever surveyed with RRLs, covering ~20000deg^2^ of the sky (0{deg}<{alpha}<360{deg}, -22{deg}<{delta}<65{deg}) to heliocentric distances of up to 60kpc. Each of the RRLs is observed between 60 and 419 times over a six-year period. Using period finding and Fourier fitting techniques we determine periods and apparent magnitudes for each source. We find that the periods are generally accurate to {sigma}=0.002% in comparison to 2842 previously known RRLs and 100 RRLs observed in overlapping survey fields. We photometrically calibrate the light curves using 445 Landolt standard stars and show that the resulting magnitudes are accurate to ~0.05mag using Sloan Digital Sky Survey (SDSS) data for ~1000 blue horizontal branch stars and 7788 RRLs. By combining Catalina photometry with SDSS spectroscopy, we analyze the radial velocity and metallicity distributions for >1500 of the RRLs. Using the accurate distances derived for the RRLs, we show the paths of the Sagittarius tidal streams crossing the sky at heliocentric distances from 20 to 60kpc. By selecting samples of Galactic halo RRLs, we compare their velocity, metallicity, and distance with predictions from a recent detailed N-body model of the Sagittarius system. We find that there are some significant differences between the distances and structures predicted and our observations.
- ID:
- ivo://CDS.VizieR/J/A+A/518/A1
- Title:
- Galactic massive stars with AstraLux
- Short Name:
- J/A+A/518/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive stars have high-multiplicity fractions, and many of them have still undetected components, thus hampering the study of their properties. I study a sample of massive stars with high angular resolution to better characterize their multiplicity. I observed 138 fields that include at least one massive star with AstraLux, a lucky imaging camera at the 2.2m Calar Alto telescope. I also used observations of 3 of those fields with ACS/HRC on HST to obtain complementary information and to calibrate the AstraLux data. The results were compared with existing information from the Washington Double Star Catalog, Tycho-2, 2MASS, and other literature results.
1278. Galactic O star catalog
- ID:
- ivo://CDS.VizieR/V/116
- Title:
- Galactic O star catalog
- Short Name:
- V/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have produced a catalog of 378 Galactic O stars with accurate spectral classifications that is complete for V<8 but includes many fainter stars. The catalog provides cross-identifications with other sources; coordinates (obtained in most cases from Tycho-2 data); astrometric distances for 24 of the nearest stars; optical (Tycho-2, Johnson, and Stroemgren) and NIR photometry; group membership, runaway character, and multiplicity information; and a Web-based version with links to on-line services.
1279. Galactic O-type Stars
- ID:
- ivo://CDS.VizieR/II/82
- Title:
- Galactic O-type Stars
- Short Name:
- II/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a compilation from the literature of all O-type stars for which spectral types, luminosity classes, and UBV photometry exist. The catalog contains 765 stars, for each of which designation (HD, DM, etc.), spectral type, V, B-V, absolute visual magnitude, absolute bolometric magnitude, cluster membership, distance, galactic coordinates, and source references are given. In addition, the authors have included derived values of absolute visual and bolometric magnitudes, and distances. The Catalog of Galactic O-Type Stars (Garmany, Conti and Chiosi 1982) is a compilation from the literature of all O-type stars for which spectral types, luminosity classes and UBV photometry exist. Most of the entries come from Cruz-Gonzalez, et al. (1974) and Humphreys (1978), with additional stars from Garrison and Kormendy (1976), Garrison, Hiltner and Schild (1977), Garrison and Schild (1979), Feinstein, Marraco and Muzzio (1973), Feinstein, Marraco and Forte (1976), and Moffat, FitzGerald and Jackson (1979).
- ID:
- ivo://CDS.VizieR/J/ApJS/253/54
- Title:
- Galactic O-type stars from LAMOST spectra
- Short Name:
- J/ApJS/253/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper reports 209 O-type stars found with LAMOST. All 135 new O-type stars discovered so far with LAMOST are given. Among them, 94 stars are first presented in this sample. There are 1 Iafpe star, 5 Onfp stars, 12 Oe stars, 1 Ofc stars, 3 ON stars, 16 double-lined spectroscopic binaries, and 33 single-lined spectroscopic binaries. All O-type stars are determined based on LAMOST low-resolution spectra (R~1800), with their LAMOST median-resolution spectra (R~7500) as supplements.
