scholarly journals Two-Dimensional Spectral Classification of M Stars by Narrow-Band Photometry

1978 ◽  
Vol 80 ◽  
pp. 451-454
Author(s):  
Robert F. Wing ◽  
Nathaniel M. White
Keyword(s):  
Spectroscopic Data ◽  
Near Infrared ◽  
Narrow Band ◽  
Classification Criteria ◽  
Spectral Classification ◽  
Color System ◽  
Effects Of Temperature ◽  
M Stars ◽  
Filter Photometry

To place a star on the HR diagram by means of spectroscopic data alone-i.e., without knowledge of the parallax-one must separate the spectroscopic effects of temperature and luminosity as cleanly as possible. Here we discuss the use of the red and near-infrared bands of TiO, VO, CN, and CaH as classification criteria for M stars. Our eight-color system of filter photometry (Wing 1971; White 1971a) has provided data on the first three molecules.

scholarly journals Narrow-Band Photometry of Red Variables in Globular Clusters

1973 ◽  
Vol 21 ◽  
pp. 164-177
Author(s):  
Robert F. Wing
Keyword(s):  
Radial Velocity ◽  
Globular Clusters ◽  
Near Infrared ◽  
Narrow Band ◽  
Small Range ◽  
Mira Variables ◽  
Color System ◽  
Red Giant ◽  
M Stars

AbstractFourteen red variables in the southern globular clusters 47 Tuc, ω Cen, and NGC 362 have been observed on an eight-color system of narrow-band photometry in the near infrared. Temperatures are derived from blackbody fits to the calibrated fluxes, and spectral types are given for the M stars. The types observed for the three Mira variables in 47 Tuc range from M3.1 to M7.5; two small-range variables in the same cluster are later than M4. The variables in ω Cen are mostly earlier than K5, but spectra of types M3 and MO were also encountered among radial-velocity members. In both the metal-rich 47 Tuc and the metal-poor ω Cen, the relation between TiO band strength and temperature is approximately normal. Several of these stars fall well above or below the red giant branches of their clusters in diagrams of infrared magnitude against temperature. Comparisons are made with recent results obtained at Radcliffe Observatory on some of the same stars.

scholarly journals UV Spectral Classification of B Stars

1985 ◽  
Vol 111 ◽  
pp. 411-413
Author(s):  
Janet Rountree ◽  
George Sonneborn ◽  
Robert J. Panek
Keyword(s):  
Classification System ◽  
Classification Criteria ◽  
High Dispersion ◽  
Spectral Classification ◽  
Early Type ◽  
B Stars ◽  
Dimensional Classification ◽  
Early Type Stars ◽  
Comprehensive Classification

Previous studies of ultraviolet spectral classification have been insufficient to establish a comprehensive classification system for ultraviolet spectra of early-type stars because of inadequate spectral resolution. We have initiated a new study of ultraviolet spectral classification of B stars using high-dispersion IUE archival data. High-dispersion SWP spectra of MK standards and other B stars are retrieved from the IUE archives and numerically degraded to a uniform resolution of 0.25 or 0.50 Å. The spectra (in the form of plots or photowrites) are then visually examined with the aim of setting up a two-dimensional classification matrix. We follow the method used to create the MK classification system for visual spectra. The purpose of this work is to examine the applicability of the MK system (and in particular, the set of standard stars) in the ultraviolet, and to establish classification criteria in this spectral region.

scholarly journals Quantitative spectral classification of Galactic O stars

2018 ◽  
Vol 616 ◽  
pp. A135 ◽  
Author(s):  
F. Martins
Keyword(s):  
Spectral Range ◽  
Spectral Resolution ◽  
Equivalent Width ◽  
Classification Criteria ◽  
High Spectral Resolution ◽  
Spectral Classification ◽  
Class V ◽  
Luminosity Class ◽  
Spectral Class

Our goal is to provide a quantification of several spectral classification criteria for O stars. We collect high-spectral resolution spectra of 105 Galactic O-type stars from various archives. We measured equivalent widths of classification lines. We defined average values of classification criteria for given spectral types and luminosity classes. We find that the ratio He I 4471 to He II 4542 well matches the published ratios for spectral types. We have quantified equivalent width ratios of helium and silicon lines among O8–O9.7 stars to refine spectral class typing in this spectral range. We present quantitative criteria to separate between luminosity class V, IV–III–II (grouped), and I among O3–O8.5 stars, mainly based on the strength of He II 4686. We find that these criteria also define very well the f, (f), and ((f)) classes for O3–O7.5 stars. Among O9–O9.7 stars we quantify the ratios of He II 4686 to He I 4713 and Si IV 4089 to He I 4026 for all luminosity classes. The tabulated values of the classification criteria should help classify any new O-type stars. The final step of the classification process should rely on a direct comparison to standard stars of the assigned spectral type or luminosity class.

scholarly journals Abundance Effects in the Classification of K Stars

1976 ◽  
Vol 72 ◽  
pp. 87-90
Author(s):  
P. M. Williams
Keyword(s):  
Spectral Type ◽  
Near Infrared ◽  
Narrow Band ◽  
Infrared Photometry ◽  
Metal Abundance ◽  
Metal Abundances ◽  
Effective Temperatures

The influence of metal abundance and gravity on the relation between spectral type and effective temperatures of late G and K type stars is investigated and calibrated using metal abundances from narrow-band photometry, near infrared photometry and independent luminosity estimates.

scholarly journals Scans and Narrow-Band Photometry of Late-Type Stars in the One-Micron Region

1974 ◽  
Vol 3 ◽  
pp. 285-306 ◽  
Author(s):  
R. F. Wing
Keyword(s):  
Near Infrared ◽  
Narrow Band ◽  
M Dwarfs ◽  
Mira Variables ◽  
Near Infrared Spectra ◽  
First Results ◽  
System 2 ◽  
M Stars ◽  
Band Sequence ◽  
The One

AbstractA summary is given of the molecular bands occurring in the near-infrared spectra of cool stars, especially those having sufficient strength and freedom from contamination to be measurable by narrow-band photometry. In some cases useful indices of both temperature and luminosity can be obtained from such measurements. Several bands remain unidentified, including the 9910 Å band in late M dwarfs and at least nine bands in cool S stars.Three topics of a spectroscopic nature are discussed. (1) In Mira variables, grossly different spectral types are sometimes obtained from zero-volt and excited TiO bands of the same band system. (2) A few M stars have been found to show bands of’ both VO and CN at the same time. They may be the coolest known supergiants, although there remains some doubt as to their luminosities. (3) The first results are given from a program of measuring crude C12/C13 ratios from narrow-band photometry of sensitive points on the profile of the ∆υ = + 2 band sequence of CN. The observations require only a few minutes per star, and the method can be applied to G and K giants and supergiants as well as to carbon stars.

scholarly journals Red supergiants in the Small Magellanic Cloud: The effects of metallicity on narrow-band classification indices

2004 ◽  
Vol 193 ◽  
pp. 317-321
Author(s):  
Robert F. Wing ◽  
Kyle M. Walker ◽  
D. Jack MacConnell ◽  
Edgardo Costa
Keyword(s):  
Near Infrared ◽  
Narrow Band ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Small Magellanic Cloud ◽  
Color System ◽  
The Galaxy ◽  
Red Supergiants

AbstractNarrow-band classification photometry, on a six-color system that measures near-infrared bands of TiO and CN, has been obtained for a set of red supergiants in the Small Magellanic Cloud. To investigate the effects of metallicity on the band-strength indices, comparisons are made to supergiants in the LMC and the Galaxy. Two new variable stars are reported.

Narrow-band photometric classification of eclipsing binaries

1966 ◽  
Vol 24 ◽  
pp. 190-210
Author(s):  
D. H. McNamara
Keyword(s):  
Temperature Scale ◽  
Narrow Band ◽  
Eclipsing Binaries ◽  
Spectral Classification ◽  
Uniform System ◽  
Fundamental Properties ◽  
Eclipsing Stars ◽  
Accurate Knowledge ◽  
Observational Program

Although a great deal of work has been devoted in recent years to the problem of improving our knowledge of the spectroscopic and light elements of the eclipsing stars, little effort has been expended on the problem of two-dimensional spectral classification of the component stars on a uniform system. The only serious attempt in this direction appears to be the MK classification of a number of eclipsing stars by Miss Roman (i). Since the light- and velocity-curves of eclipsing systems provide us with fundamental properties such as radii, masses, and densities it is extremely important to have accurate knowledge of the luminosities and spectral types of these objects. In this paper we describe the results of an observational program designed specifically to improve our knowledge of the luminosities and colors of these important stars. The luminosities and colors are then utilized in a discussion of the mass-luminosity relation and effective-temperature scale of stars brigher than the Sun.

scholarly journals New Standards for the Spectral Classification of M Dwarfs

1973 ◽  
Vol 50 ◽  
pp. 209-219
Author(s):  
R. F. Wing
Keyword(s):  
Spectral Type ◽  
Near Infrared ◽  
Color Temperature ◽  
Spectral Classification ◽  
M Dwarfs ◽  
Dwarf Stars ◽  
Photoelectric Measurements

Spectral types based upon photoelectric measurements of the strong TiO band near 7100 Å and having an internal accuracy of one-tenth of a subclass are presented for 26 dwarf stars in the range K4 to M6. For the calibration of the TiO index into spectral type, the MK scale for giants established by Wing and Keenan was adopted. Accordingly the types differ systematically from those previously published on any of the systems used for dwarfs, being closest to Joy's. The advantages of the MK giant scale are discussed, and it is suggested that the stars classified here be adopted as standards for a revised system of MK classification for dwarfs.The relation between TiO band strength and near-infrared color temperature for dwarfs differs significantly from the giant relation. The coolest dwarfs observed were Wolf 359 and Proxima Centauri; although Wolf 359 is both cooler and less luminous than Proxima, they have nearly identical TiO band strengths.

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