- ID:
- ivo://CDS.VizieR/III/150A
- Title:
- Perkins Revised MK Types for the Cooler Stars
- Short Name:
- III/150A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The original catalog of standard stars classified on the Revised MK system published in 1989 contains 1054 standard stars of spectral types G0 and later (G, K, M, and a few S stars) classified at the Perkins Observatory. The present version of the catalog takes into account the revisions (before 14h of RA) presented by Philip C. Keenan and Gerald H. Newsom at the Department of Astronomy of the Ohio State University (http://www-astronomy.mps.ohio-state.edu/MKCool) dated 2000 January; the Sun (G2V star) has been omitted from the catalog. Accurate positions were added in 2003. The revised MK system is described by Keenan (1987PASP...99..713K). The spectrograms used for the classification were taken at four different observatories; hence, extensive comparisons have been made to ensure consistency between the Northern and Southern Hemispheres. The list provides a consistent set of standards in most parts of the sky and over a considerable range in magnitude, for stars later than G0. The catalog is not a survey complete to any magnitude and is not intended for statistical studies.
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- ID:
- ivo://CDS.VizieR/V/92A
- Title:
- Photometric and Spectroscopic Databases for LSS Stars
- Short Name:
- V/92A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains databases of published photoelectric UBVbeta data, MK-system spectral classifications, and Stroemgren four-color uvby photometry for objects in the Stephenson-Sanduleak "Luminous Stars in the Southern Milky Way" catalog (LSS catalog). The catalog contains mostly OB stars and A and F supergiants. These databases have been compiled from the literature.
- ID:
- ivo://CDS.VizieR/V/125
- Title:
- Photometry and Spectroscopy for Luminous Stars
- Short Name:
- V/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- of the paper: The birthrate of stars of masses >=10M_{sun}_ is estimated from a sample of just over 400 O3-B2 dwarfs within 1.5kpc of the Sun and the result extrapolated to estimate the Galactic supernova rate contributed by such stars. The solar-neighborhood Galactic-plane massive star birthrate is estimated at ~176stars/kpc^3^/Myr. On the basis of a model in which the Galactic stellar density distribution comprises a "disk+central hole" like that of the dust infrared emission (as proposed by Drimmel and Spergel), the Galactic supernova rate is estimated at probably not less than ~1 nor more than ~2 per century and the number of O3-B2 dwarfs within the solar circle at ~200000.
- ID:
- ivo://CDS.VizieR/J/AJ/109/1379
- Title:
- Praesepe & M 67 spectral standards
- Short Name:
- J/AJ/109/1379
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a grid of stellar classification spectra of moderate resolution (R~1500) in the range lambda lambda 5600-9000A, compiled from high signal-to-noise spectra of 275 stars, most in the open clusters Praesepe and M 67. The grid covers dwarfs from types B8 through M5, giants from G8 through M7, and subgiants from F5 through K0. We catalog atomic and molecular absorption features useful for stellar classification, and demonstrate the use of luminosity-sensitive features to distinguish between late-type dwarf and giant stars.
- ID:
- ivo://CDS.VizieR/J/AJ/121/2148
- Title:
- Precise spectral types for 372 A, F & G stars
- Short Name:
- J/AJ/121/2148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the first in a series of two papers that address the problem of the physical nature of luminosity classification in the late A-, F-, and early G-type stars. In this paper, we present precise spectral classifications of 372 stars on the MK system. For those stars in the set with Stroemgren uvby{beta} photometry, we derive reddenings and present a calibration of MK temperature types in terms of the intrinsic Stroemgren (b-y)_0_ index. We also examine the relationship between the luminosity class and the Stroemgren c_1_ index, which measures the Balmer jump. The second paper will address the derivation of the physical parameters of these stars, and the relationships between these physical parameters and the luminosity class. Stars classified in this paper include one new {lambda} Bootis star and 10 of the F- and G-type dwarfs with recently discovered planets.
- ID:
- ivo://CDS.VizieR/J/A+A/325/693
- Title:
- Quantitative spectral classification
- Short Name:
- J/A+A/325/693
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New criteria of quantitative spectral classification have been introduced and the method of stepwise linear regression to these criteria for quantitative spectral classification of F-K stars has been applied to the Bochum photoelectric spectra (resolution 10A). Table 4 contains the averaged values of the classification criteria (indices) for 54 stars used in our analysis. Each measurement in our analysis refers to an area confined by the border wavelengths for an interval, the spectral energy distribution and the zero level. We chose the intervals for measurements in a such way that the sensitivity to spectral and/or luminosity effects were different for two adjacent or near-by intervals. The ratios of measurements in such intervals may then serve as classification criteria (indices) with minimum contamination by interstellar extinction. Table 2 contains the border wavelengths for the intervals with indications of the principal measured features. Table 3 contains the list of classification indices. Table 2. The border wavelengths for the intervals in Angstroems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/3344
- Title:
- Red-giant stars classification
- Short Name:
- J/MNRAS/466/3344
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Determining the ages of red-giant stars is a key problem in stellar astrophysics. One of the difficulties in this determination is to know the evolutionary state of the individual stars - i.e. have they started to burn Helium in their cores? That is the topic of this paper. Asteroseismic data provide a route to achieving this information. What we present here is a highly autonomous way of determining the evolutionary state from an analysis of the power spectrum of the light curve. The method is fast and efficient and can provide results for a large number of stars. It uses the structure of the dipole-mode oscillations, which have a mixed character in red-giant stars, to determine some measures that are used in the categorization. It does not require that all the individual components of any given mode be separately characterized. Some 6604 red-giant stars have been classified. Of these, 3566 are determined to be on the red-giant branch, 2077 are red-clump and 439 are secondary-clump stars. We do not specifically identify the low-metallicity, horizontal-branch stars. The difference between red-clump and secondary-clump stars is dependent on the manner in which Helium burning is first initiated. We discuss that the way the boundary between these classifications is set may lead to mis-categorization in a small number of stars. The remaining 522 stars were not classified either because they lacked sufficient power in the dipole modes (so-called depressed dipole modes) or because of conflicting values in the parameters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/2003
- Title:
- Red supergiant population in Perseus arm
- Short Name:
- J/MNRAS/475/2003
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalogue of cool supergiants in a section of the Perseus arm, most of which had not been previously identified. To generate it, we have used a set of well-defined photometric criteria to select a large number of candidates (637) that were later observed at intermediate resolution in the infrared calcium triplet spectral range, using a long-slit spectrograph. To separate red supergiants from luminous red giants, we used a statistical method, developed in previous works and improved in the present paper. We present a method to assign probabilities of being a red supergiant to a given spectrum and use the properties of a population to generate clean samples, without contamination from lower luminosity stars. We compare our identification with a classification done using classical criteria and discuss their respective efficiencies and contaminations as identification methods. We confirm that our method is as efficient at finding supergiants as the best classical methods, but with a far lower contamination by red giants than any other method. The result is a catalogue with 197 cool supergiants, 191 of which did not appear in previous lists of red supergiants. This is the largest coherent catalogue of cool supergiants in the Galaxy.
- ID:
- ivo://CDS.VizieR/J/AJ/126/2867
- Title:
- Red supergiants in Magellanic Clouds
- Short Name:
- J/AJ/126/2867
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the red supergiant (RSG) content of the SMC and LMC using multiobject spectroscopy on a sample of red stars previously identified by BVR CCD photometry. We obtained high-accuracy (<1km/s) radial velocities for 118 red stars seen toward the SMC and 167 red stars seen toward the LMC, confirming most of these (89% and 95%, respectively) as red supergiants. Spectral types were also determined for most of these RSGs.
- ID:
- ivo://CDS.VizieR/J/A+A/317/871
- Title:
- Revised spectral types of B-supergiants in the SMC
- Short Name:
- J/A+A/317/871
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The problem of the classification of metal poor stars, such as occur in the Small Magellanic Cloud (SMC), is discussed with reference to the applicability of the MK system in such an environment. An alternative method is presented here and applied to B-type supergiants in the SMC. A local reference system is first devised and then a transformation to MK spectral types is determined by comparing the trends of metal line strengths in these two systems. For the determination of the luminosity class, we emphasize the need to use the hydrogen Balmer line strengths independently of metal line-strength considerations. This method is used to determine new spectral types for 64 supergiants in the SMC, 75% of the sample requiring classifications different from previous findings. These new types result in much improved line strength - spectral type correlations for He, C, N, O, Mg and Si. Corresponding changes in the distribution of these stars in the Hertzsprung-Russell diagram of the SMC reveal more clearly than before the existence of a ridge which may be the SMC analogue of a similar feature found for the LMC by Fitzpatrick & Garmany (1990ApJ...363..119F). The group of very luminous supergiants lying above this ridge includes the LBV AV415 (R40), a property which this object has in common with LBVs in the Large Magellanic Cloud. Also, for the first time, clear examples of BN/BC supergiants are found in the SMC.
