- ID:
- ivo://CDS.VizieR/J/A+A/562/A24
- Title:
- Cool carbon stars in the halo and Fornax dSph
- Short Name:
- J/A+A/562/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The population of cool carbon (C) stars located far from the galactic plane is probably made of debris of small galaxies such as the Sagittarius dwarf spheroidal galaxy (Sgr), which are disrupted by the gravitational field of the Galaxy. We aim to know this population better through spectroscopy, 2MASS photometric colours, and variability data. When possible, we compared the halo results to C star populations in the Fornax dwarf spheroidal galaxy, Sgr, and the solar neighbourhood. We first present a few new discoveries of C stars in the halo and in Fornax. The number of spectra of halo C stars is now 125. Forty percent show H{alpha} in emission. The narrow location in the JHK diagram of the halo C stars is found to differ from that of similar C stars in the above galaxies. The light curves of the Catalina and LINEAR variability databases were exploited to derive the pulsation periods of 66 halo C stars. A few supplementary periods were obtained with the TAROT telescopes. We confirm that the period distribution of the halo strongly resembles that of Fornax, and we found that it is very different from the C stars in the solar neighbourhood. There is a larger proportion of short-period Mira/SRa variables in the halo than in Sgr, but the survey for C stars in this dwarf galaxy is not complete, and the study of their variability needs to be continued to investigate the link between Sgr and the cool halo C stars.
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- ID:
- ivo://CDS.VizieR/J/ApJ/843/76
- Title:
- Cool-core clusters with Chandra obs.
- Short Name:
- J/ApJ/843/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive and compare the fractions of cool-core clusters in the Planck Early Sunyaev-Zel'dovich sample of 164 clusters with z<=0.35 and in a flux- limited X-ray sample of 100 clusters with z<=0.30, using Chandra observations. We use four metrics to identify cool-core clusters: (1) the concentration parameter, which is the ratio of the integrated emissivity profile within 0.15 r_500_ to that within r_500_; (2) the ratio of the integrated emissivity profile within 40kpc to that within 400kpc; (3) the cuspiness of the gas density profile, which is the negative of the logarithmic derivative of the gas density with respect to the radius, measured at 0.04 r_500_; and (4) the central gas density, measured at 0.01 r_500_. We find that the sample of X-ray-selected clusters, as characterized by each of these metrics, contains a significantly larger fraction of cool-core clusters compared to the sample of SZ-selected clusters (44%+/-7% versus 28%+/-4% using the concentration parameter in the 0.15-1.0 r_500_ range, 61%+/-8% versus 36%+/-5% using the concentration parameter in the 40-400 kpc range, 64%+/-8% versus 38%+/-5% using the cuspiness, and 53%+/-7% versus 39+/-5% using the central gas density). Qualitatively, cool-core clusters are more X-ray luminous at fixed mass. Hence, our X-ray, flux-limited sample, compared to the approximately mass-limited SZ sample, is overrepresented with cool-core clusters. We describe a simple quantitative model that uses the excess luminosity of cool-core clusters compared to non-cool-core clusters at fixed mass to successfully predict the observed fraction of cool-core clusters in X-ray-selected samples.
- 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.
- ID:
- ivo://CDS.VizieR/J/PASP/106/452
- Title:
- Cool Dwarfs - Temperatures
- Short Name:
- J/PASP/106/452
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The file contains values of Cousins R-I and theta [= 5040/T(eff)] for 417 F-K stars which are on or near the main sequence.
3885. Cool DZ white dwarfs. I.
- ID:
- ivo://CDS.VizieR/J/MNRAS/467/4970
- Title:
- Cool DZ white dwarfs. I.
- Short Name:
- J/MNRAS/467/4970
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- White dwarfs with metal lines in their spectra act as signposts for post-main-sequence planetary systems. Searching the Sloan Digital Sky Survey (SDSS) Data Release 12, we have identified 231 cool (<9000K) DZ white dwarfs with strong metal absorption, extending the DZ cooling sequence to both higher metal abundances and lower temperatures, and hence longer cooling ages. Of these 231 systems, 104 are previously unknown white dwarfs. Compared with previous work, our spectral fitting uses improved model atmospheres with updated line profiles and line-lists, which we use to derive effective temperatures and abundances for up to eight elements. We also determine spectroscopic distances to our sample, identifying two halo members with tangential space velocities >300km/s. The implications of our results on remnant planetary systems are to be discussed in a separate paper.
- ID:
- ivo://CDS.VizieR/J/AJ/142/103
- Title:
- Cool evolved stars in SAGE-SMC and SAGE-LMC
- Short Name:
- J/AJ/142/103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the infrared (IR) properties of cool, evolved stars in the Small Magellanic Cloud (SMC), including the red giant branch (RGB) stars and the dust-producing red supergiant (RSG) and asymptotic giant branch (AGB) stars using observations from the Spitzer Space Telescope Legacy program entitled "Surveying the Agents of Galaxy Evolution in the Tidally Stripped, Low Metallicity SMC", or SAGE-SMC. The survey includes, for the first time, full spatial coverage of the SMC bar, wing, and tail regions at IR wavelengths (3.6-160um). We identify evolved stars using a combination of near-IR and mid-IR photometry and point out a new feature in the mid-IR color-magnitude diagram that may be due to particularly dusty O-rich AGB stars. We find that the RSG and AGB stars each contribute ~20% of the global SMC flux (extended + point-source) at 3.6um, which emphasizes the importance of both stellar types to the integrated flux of distant metal-poor galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A143
- Title:
- Cool, evolved stars PACS and SPIRE spectroscopy
- Short Name:
- J/A+A/618/A143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At the end of their lives AGB stars are prolific producers of dust and gas. The details of this mass-loss process are still not understood very well. Herschel PACS and SPIRE spectra which cover the wavelength range from ~55 to 670um almost continuously, offer a unique way of investigating properties of AGB stars in general and the mass-loss process in particular as this is the wavelength region where dust emission is prominent and molecules have many emission lines. We present the community with a catalogue of AGB stars and red supergiants (RSGs) with PACS and/or SPIRE spectra reduced according to the current state of the art. The Herschel Interactive Processing Environment (HIPE) software with the latest calibration is used to process the available PACS and SPIRE spectra of 40 evolved stars. The SPIRE spectra of some objects close to the Galactic plane require special treatment because of the weaker fluxes in combination with the strong and complex background emission at those wavelengths. The spectra are convolved with the response curves of the PACS and SPIRE bolometers and compared to the fluxes measured in imaging data of these sources. Custom software is used to identify lines in the spectra, and to determine the central wavelengths and line intensities. Standard molecular line databases are used to associate the observed lines. Because of the limited spectral resolution of the PACS and SPIRE spectrometers (~1500), several known lines are typically potential counterparts to any observed line. To help identifications in follow-up studies the relative contributions in line intensity of the potential counterpart lines are listed for three characteristic temperatures based on local thermodynamic equilibrium (LTE) calculations and assuming optically thin emission. The following data products are released: the reduced spectra, the lines that are measured in the spectra with wavelength, intensity, potential identifications, and the continuum spectra, i.e. the full spectra with all identified lines removed. As simple examples of how this data can be used in future studies we have fitted the continuum spectra with three power laws (two wavelength regimes covering PACS, and one covering SPIRE) and find that the few OH/IR stars seem to have significantly steeper slopes than the other oxygen- and carbon-rich objects in the sample, possibly related to a recent increase in mass-loss rate. As another example we constructed rotational diagrams for CO (and HCN for the carbon stars) and fitted a two-component model to derive rotational temperatures.
- ID:
- ivo://CDS.VizieR/III/156
- Title:
- Cool Galactic Carbon Stars, 2nd Edition
- Short Name:
- III/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is intended to list all 5987 cool carbon stars having known positions of at least roughly the precision of The Henry Draper Catalogue. Cool carbon stars are defined as stars whose spectra at low dispersion (say a resolution no better than 1-2 angstroms) are known to show bands of the Swan system of the C2 molecule; or, if the spectral region of the Swan system is inadequately observed, they show the red or infrared bands of CN in strength adequate to infer that the Swan bands almost certainly would be seen if their presence could be tested. The closing date for literature search was 1989 June 30, defined by literature received in the author's library by that date. The catalog includes equatorial coordinates (B1900.0); photographic, visual, and infrared magnitudes; spectral types, galactic coordinates, and cross identifications to various other designation systems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/292/419
- Title:
- Cooling flows in 207 clusters of galaxies
- Short Name:
- J/MNRAS/292/419
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we present an X-ray image deprojection analysis of Einstein Observatory imaging data on 207 clusters of galaxies. The resulting radial profiles for luminosity, temperature and electron density variations are determined from the cluster surface-brightness profiles according to gravitational potential constraints from average X-ray temperatures and optical velocity dispersions. This enables us to determine cooling flow and other cluster properties, such as baryon fractions, Sunyaev-Zel'dovich microwave decrements and Thomson depths. From the results we have compiled a catalogue of the detected cooling flows, and investigated their effects on general cluster properties.
- ID:
- ivo://CDS.VizieR/J/ApJS/213/5
- Title:
- Cool KOIs. VI. H- and K- band spectra
- Short Name:
- J/ApJS/213/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present H- and K-band spectra for late-type Kepler Objects of Interest (the "Cool KOIs"): low-mass stars with transiting-planet candidates discovered by NASA's Kepler Mission that are listed on the NASA Exoplanet Archive. We acquired spectra of 103 Cool KOIs and used the indices and calibrations of Rojas-Ayala et al. (2012, Cat. J/ApJ/748/93) to determine their spectral types, stellar effective temperatures, and metallicities, significantly augmenting previously published values. We interpolate our measured effective temperatures and metallicities onto evolutionary isochrones to determine stellar masses, radii, luminosities, and distances, assuming the stars have settled onto the main sequence. As a choice of isochrones, we use a new suite of Dartmouth predictions that reliably include mid-to-late M dwarf stars. We identify five M4V stars: KOI-961 (confirmed as Kepler 42), KOI-2704, KOI-2842, KOI-4290, and the secondary component to visual binary KOI-1725, which we call KOI-1725B. We also identify a peculiar star, KOI-3497, which has Na and Ca lines consistent with a dwarf star but CO lines consistent with a giant. Visible-wavelength adaptive optics imaging reveals two objects within a 1 arcsec diameter; however, the objects' colors are peculiar. The spectra and properties presented in this paper serve as a resource for prioritizing follow-up observations and planet validation efforts for the Cool KOIs.