- ID:
- ivo://CDS.VizieR/J/A+A/628/A102
- Title:
- Carbon-rich (DQ) white dwarfs in SDSS
- Short Name:
- J/A+A/628/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among the spectroscopically identified white dwarfs, a fraction smaller than 2% have spectra dominated by carbon lines, mainly molecular C_2_, but also in a smaller group by CI and CII lines. These are together called DQ white dwarfs. We derive atmospheric parameters Teff, logg, and carbon abundances for a large sample of these stars and discuss implications for their spectral evolution. Sloan Digital Sky Survey spectra and ugriz photometry were used, together with Gaia Data Release 2 parallaxes and G band photometry. These were fitted to synthetic spectra and theoretical photometry derived from model atmospheres. We found that the DQs hotter than Teff ~10000K have masses ~0.4M_{sun}_ larger than the classical DQ, which have masses typical for the majority of white dwarfs (~0.6M_{sun}_). We found some evidence that the peculiar DQ below 10000K also have significantly larger masses and may thus be the descendants of the hot and warm DQs above 10000K. A significant fraction of the hotter objects with Teff>14500K have atmospheres dominated by carbon.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/390/967
- Title:
- Carbon-rich giants in the HR diagram
- Short Name:
- J/A+A/390/967
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are 513 entries corresponding to 513 SEDs of 410 carbon stars and related objects, and 70 Ba II stars. Absolute magnitude bolometric (Col. 7) are given for 348 348 (C & rel.) + 65 (Ba II) entries. Together with the effective temperatures previously obtained (Col. 5), they were used to draw the local HR diagram and the luminosity function for galactic carbon giants and related objects in the Sun vicinity. Also given in column 6, the apparent bolometric magnitudes, and in column 8 as ``remarks'', the variation phase information whenever available, the detection of circumstellar extinction and/or emission, the presence of Tc; the J-type, CH stars, carbon-Cepheids etc., are also shown. Our photometric solutions (photometric type in Col. 3 and interstellar extinction at J in Col. 4: to be multiplied by 1.145 to obtain E(B-V)).
- ID:
- ivo://CDS.VizieR/J/MNRAS/376/313
- Title:
- Carbon star in Magellanic Cloud
- Short Name:
- J/MNRAS/376/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dust radiative transfer models are presented for 60 carbon stars in the Magellanic Clouds (MCs) for which 535m Spitzer infrared spectrograph (IRS) spectra and quasi-simultaneous ground-based JHKL photometry are available. From the modelling, the luminosity and mass-loss rate are derived (under the assumption of a fixed expansion velocity and dust-to-gas ratio), and the ratio of silicon carbide (SiC) to amorphous carbon (AMC) dust is also derived. This ratio is smaller than observed in Galactic carbon stars, as has been noted before. Light curves for 36 objects can be retrieved from the massive compact halo object (MACHO) and optical gravitational lensing experiment (OGLE) data bases, and periods can be derived for all but two of these. Including data from the literature, periods are available for 53 stars.
- ID:
- ivo://CDS.VizieR/J/other/RAA/10.541
- Title:
- Carbon star list (90<l<270, |b|<6)
- Short Name:
- J/other/RAA/10.5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The availability of astrometric data and radial velocities of carbon stars near the Galactic plane enables us to investigate the kinematics of the Milky Way, especially the rotation curve. The recently published Third U.S. Naval Observatory CCD Astrograph Catalog (UCAC3) provides the opportunity to test this problem using three-dimensional velocity in order to obtain more reliable rotation curves. We intend to study the Galactic rotation curve up to 15kpc using the radial velocities and proper motions of carbon stars. The motivation for using UCAC3 is to provide high precision proper motions which have hardly been used in determining the rotation velocity of tracers. Seventy-four carbon stars and carbon-rich Mira variables toward the anti-center direction (90{deg}<l<270{deg}, |b|<6{deg}) are picked up from the literature then matched with UCAC3 carbon star candidates to obtain their proper motions. A rigorous geometrical method is employed to compute the rotation velocity of each object. Taking carbon stars as tracers, we find a flat rotation curve of 210+/-12km/s assuming R0=8.0kpc for the galactocentric distance and V0=220km/s for the rotation velocity of the Sun. Due to the uncertainties of distances, the rotation velocities are more dispersed if tangential velocities enter the calculation, compared to those derived from radial velocities only. However, the whole rotation curve shows coherence with previous results. Increasing observation and study of carbon stars would be desirable in order to provide more homogeneous data for the kinematical study of the Galactic disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/12
- Title:
- Carbon stars and DQ white dwarfs from SDSS-DR7+DR8
- Short Name:
- J/ApJ/765/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Among stars showing carbon molecular bands (C stars), the main-sequence dwarfs, likely in post-mass transfer binaries, are numerically dominant in the Galaxy. Via spectroscopic selection from the Sloan Digital Sky Survey, we retrieve 1220 high galactic latitude C stars, ~5 times more than previously known, including a wider variety than past techniques such as color or grism selection have netted, and additionally yielding 167 DQ white dwarfs. Of the C stars with proper motion measurements, we identify 69% clearly as dwarfs (dCs), while ~7% are giants. The dCs likely span absolute magnitudes M_i_ from ~6.5 to 10.5. "G-type" dC stars with weak CN and relatively blue colors are probably the most massive dCs still cool enough to show C_2_bands. We report Balmer emission in 22 dCs, none of which are G-types. We find 8 new DA/dC stars in composite spectrum binaries, quadrupling the total sample of these "smoking guns" for AGB binary mass transfer. Eleven very red C stars with strong red CN bands appear to be "N"-type AGB stars at large Galactocentric distances, one likely a new discovery in the dIrr galaxy Leo A. Two such stars within 30' of each other may trace a previously unidentified dwarf galaxy or tidal stream at ~40 kpc. We explore the multiwavelength properties of the sample and report the first X-ray detection of a dC star, which shows strong Balmer emission. Our own spectroscopic survey additionally provides the dC surface density from a complete sample of dwarfs limited by magnitude, color, and proper motion.
- ID:
- ivo://CDS.VizieR/III/140
- Title:
- Carbon stars from Baldone telescope
- Short Name:
- III/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains data on 318 cool carbon stars discovered on objective prism photographs taken with the Schmidt Telescope (80/120/240 cm) of the Radioastrophysical Observatory at Baldone near Riga. Green-yellow survey (BC Nos 1-217) is made on the ortochromatic astronomical films A-600. Reciprocial dispersion of the spectra: 600 A/mm or 1130 A/mm at H-gamma. The region of the sky covered by the survey: 1) 4.5 degrees wide zones centered on the galactic latitudes +7 and -7 degrees between longitudes 68 and 200 degrees, 2) equatorial zone at longitudes 84-96 degrees and 172-180 degrees, 3) several other separate fields with five degrees diameter. Infrared survey (BC Nos 218-318) made on the infrared Kodak plates 1N with the filter Schott RG1. Reciprocial dispersion: 2500 A/mm at the atmospheric A-band. The region of the sky covered: 1) 4.5 degrees wide zone centered on the galactic latitude +7 degrees between longitudes 128 and 140 degrees, 2) region between latitudes +9.5 and -9.5 degrees and longitudes between 80 and 96 degrees.
- ID:
- ivo://CDS.VizieR/J/AJ/93/663
- Title:
- Carbon stars from IRAS-LRS spectra
- Short Name:
- J/AJ/93/663
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The authors have classified 176 IRAS sources as carbon stars based on the presence of the SiC emission feature at 11.2 micron in their low-resolution spectra (LRS). Accurate positions were found by B. Skiff (Lowell Obs.), using visible-light (DSS), 2MASS, and WISE images to identify the carbon stars. Many of the stars are large-amplitude variables, whether designated or not, so sometimes the magnitudes are rounded to a whole magnitude so as to be representative of the brightness. Some notes are added about close companions and two stars where the existing position is significantly in error.
- ID:
- ivo://CDS.VizieR/J/ApJS/226/1
- Title:
- Carbon stars from LAMOST DR2 data
- Short Name:
- J/ApJS/226/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we present the new catalog of carbon stars from the LAMOST DR2 catalog. In total, 894 carbon stars are identified from multiple line indices measured from the stellar spectra. We are able to identify the carbon stars by combining the CN bands in the red end with C_2_ and other lines. Moreover, we also classify the carbon stars into spectral sub-types of C-H, C-R, and C-N. These sub-types show distinct features in the multi-dimensional line indices, implying that in the future they can be used to identify carbon stars from larger spectroscopic data sets. While the C-N stars are clearly separated from the others in the line index space, we find no clear separation between the C-R and C-H sub-types. The C-R and C-H stars seem to smoothly transition from one to another. This may hint that the C-R and C-H stars may not be different in their origins, instead their spectra look different because of different metallicities. Due to the relatively low spectral resolution and lower signal-to-noise ratio, the ratio of ^12^C/^13^C is not measured and thus the C-J stars are not identified.
- ID:
- ivo://CDS.VizieR/J/ApJS/234/31
- Title:
- Carbon stars from LAMOST using machine learning
- Short Name:
- J/ApJS/234/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work, we present a catalog of 2651 carbon stars from the fourth Data Release (DR4) of the Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST). Using an efficient machine-learning algorithm, we find these stars from more than 7 million spectra. As a by-product, 17 carbon-enhanced metal- poor turnoff star candidates are also reported in this paper, and they are preliminarily identified by their atmospheric parameters. Except for 176 stars that could not be given spectral types, we classify the other 2475 carbon stars into five subtypes: 864 C-H, 226 C-R, 400 C-J, 266 C-N, and 719 barium stars based on a series of spectral features. Furthermore, we divide the C-J stars into three subtypes, C-J(H), C-J(R), and C-J(N), and about 90% of them are cool N-type stars as expected from previous literature. Besides spectroscopic classification, we also match these carbon stars to multiple broadband photometries. Using ultraviolet photometry data, we find that 25 carbon stars have FUV detections and that they are likely to be in binary systems with compact white dwarf companions.
- ID:
- ivo://CDS.VizieR/J/A+A/375/366
- Title:
- Carbon stars from the Hamburg/ESO survey
- Short Name:
- J/A+A/375/366
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains 403 Faint High Latitude Carbon (FHLC) stars selected from the digitized objective prism plates of the Hamburg/ESO Survey (HES). Because of the ~15{AA} spectral resolution and high signal-to-noise ratio of the HES prism spectra, our automated procedure based on the detection of C_2_ and CN molecular bands permits high-confidence identification of carbon stars without the need for follow-up spectroscopy. 329 plates (87% of the survey) were examined, covering 6400deg^2^ to a magnitude limit of V~16.5. The catalog lists coordinates, photometry, and carbon band indices for 403 FHLC stars found in the Hamburg/ESO survey. B_J_ magnitudes are accurate to better than +/-0.2mag, including zero point errors. V magnitudes, B-V and U-B colors were derived by the procedure described in Christlieb et al. (2001A&A...366..898C). We also list an object classification for the sources, where "stars", "bright" and "ext" refer to point sources, sources above a saturation threshold, and sources detected as extended in DSS I images, respectively. We do not list V, B-V and U-B for saturated objects, because our color calibrations are not valid for them. Finally, we list two selection flags.
