Spectral class distribution of circumstellar material in main-sequence stars

1988 ◽  
Vol 96 ◽  
pp. 1415 ◽  
Author(s):  
H. H. Aumann
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Circumstellar Material ◽  
Class Distribution ◽  
Spectral Class

scholarly journals On the Accuracy of Spectral Classifications of Main-Sequence Stars

1973 ◽  
Vol 50 ◽  
pp. 52-59
Author(s):  
W. Gliese
Keyword(s):  
Spectral Type ◽  
Main Sequence ◽  
Standard Errors ◽  
Main Sequence Stars ◽  
M Dwarfs ◽  
Spectral Class ◽  
Classification Errors ◽  
Nearby Stars

By examining the observed dispersion in (colour, spectral type) relations, classification errors have been derived from the data of nearby stars. The comparisons of the colour deviations observed in spectral regions of large variations of colour with type with the deviations in regions of small variations give the following standard errors in units of a tenth of a spectral class: For K dwarfs ±0.6 (MK), ±1.2 (Mt. Wilson), ±0.7 (Kuiper); for early M dwarfs ±0.9: (MK), ±0.7 (Mt. Wilson), ±0.5: (Kuiper); and for late M dwarfs ±0.7 (Kuiper).

Circumstellar material associated with solar-type pre-main-sequence stars - A possible constraint on the timescale for planet building

1989 ◽  
Vol 97 ◽  
pp. 1451 ◽  
Author(s):  
Karen M. Strom ◽  
Stephen E. Strom ◽  
Suzan Edwards ◽  
Sylvie Cabrit ◽  
Michael F. Skrutskie
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Circumstellar Material ◽  
Solar Type

scholarly journals On the Origin of the Algol Systems

1968 ◽  
Vol 1 ◽  
pp. 396-408
Author(s):  
M. Plavec
Keyword(s):  
Spectral Type ◽  
Main Sequence ◽  
Eclipsing Binaries ◽  
List Type ◽  
Type Number ◽  
Main Sequence Stars ◽  
Maximum Light ◽  
Spectral Class ◽  
Lagrangian Surfaces ◽  
Visual Binaries

The 4th edition of the Finding List for Observers of Eclipsing Variables (Koch et al, 1963) contains 145 sufficiently well-observed eclipsing binaries brighter than 8·5m at maximum light. Among them, 59 binaries, or 41%, are systems with both components on the main sequence. The second largest group, 52 binaries or 36% of all systems, are systems similar to Algol. These can be characterized as follows: (1)The primary (more massive) components are main-sequence stars, fitting well into the mass-luminosity relation defined by visual binaries and by eclipsing binaries with both components on the main sequence (detached systems).(2)The secondary components are of later spectral type than the primaries, and can be best characterized as subgiants. They are overluminous for their mass as well as for their spectral class.(3)As a rule, the secondary components fill their respective critical Roche lobes (innermost Lagrangian surfaces).

AKARI Pointed Detections of Circumstellar Material around Main Sequence Stars

2009 ◽  
Author(s):  
M. Fukagawa ◽  
H. Murakami ◽  
T. Hirao ◽  
T. Yamashita ◽  
T. Ootsubo ◽  
...  
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Circumstellar Material

scholarly journals Color-color diagrams in near infrared: (J-H)/(H-K). II.

2018 ◽  
Vol 2 (1) ◽  
pp. 21-26
Author(s):  
A. L. Gyulbudaghian ◽  
◽  
N. Baloian ◽  
I. A. Sanchez ◽  
◽  
...  
Keyword(s):  
Main Sequence ◽  
Near Infrared ◽  
Preceding Paper ◽  
Minimal Amount ◽  
Class Iii ◽  
Main Sequence Stars ◽  
Class V ◽  
Luminosity Class ◽  
Spectral Class ◽  
Class Iv

In the paper the color-color diagrams (J-H)/(H-K) for all stars with visible magnitudes B<11m (for which in the existing catalogs the magnitudes of J, H, K, and also their spectral types and luminosity classes are given) are presented. In the preceding paper the data for luminosity classes I, Ia, Ib, II and III were given. In this paper the data on luminosity classes IV (sub giants) and V (main sequence stars) are given. Among the diagrams of luminosity classes the most interesting are the diagrams for GII and GIV stars, each of these diagrams have two centers of concentrations. For stars of spectral class M the minimal amount of stars is at luminosity class IV, the maximal –at class III, which is not so for other spectral classes: for other classes the maximal amount is at class V. There is a tendency (seen in all diagrams)of increasing of the values of J-H and H-K along the sequence O-B-A-F-G-K-M.

scholarly journals Far-ultraviolet intensities of Orion stars

1970 ◽  
Vol 36 ◽  
pp. 100-108
Author(s):  
George R. Carruthers
Keyword(s):  
Wavelength Range ◽  
Main Sequence ◽  
Photometric Data ◽  
Orion Nebula ◽  
Main Sequence Stars ◽  
Spectral Class ◽  
Color Excess ◽  
Far Ultraviolet ◽  
Spectral Intensities ◽  
Good Agreement

Photometric data in the 1050–1180 Å and 1230–1350 Å wavelength ranges, and electronographic spectra in the 1000–1600 Å wavelength range, were obtained in an Aerobee rocket flight on January 30, 1969. The spectral intensities derived from these data for main-sequence stars are in good agreement with the model atmospheres of Morton and co-workers. Giant and supergiant stars, however, appear to be up to one magnitude weaker, at 1115 Å, than main-sequence stars of the same spectral class.The correction for interstellar reddening appears to be not inconsistent with a 1/λ extrapolation of earlier determinations of Smith (1967) and Stecher (1965), except in the case of θ Ori, in which the predicted color excess appears to be much too great, confirming the existence of a peculiar reddening law in the Orion Nebula region.

Distribution of Dust in the Disk Around Beta Pictoris

1991 ◽  
Vol 126 ◽  
pp. 421-424
Author(s):  
Takenori Nakano
Keyword(s):  
Thermal Radiation ◽  
Main Sequence ◽  
Planet Formation ◽  
Far Infrared ◽  
Main Sequence Stars ◽  
Circumstellar Material ◽  
Stellar Radiation ◽  
Beta Pictoris ◽  
Infrared Astronomical Satellite ◽  
Astronomical Satellite

Large far-infrared excesses in some nearby main-sequence stars, revealed by theInfrared Astronomical Satellite (IRAS), have been interpreted as being due to thermal radiation from dust orbiting the stars, heated to about 100K by the stellar radiation (Aumannet al.1984; Aumann 1985; Sadakane and Nishida 1986). The existence of solid circumstellar material is commonly interpreted in the context of planet formation, and the dust has been suggested to be formed by collisions of planetesimals (Nakano 1987, 1988).

scholarly journals ISO Observations of Circumstellar Material

1998 ◽  
Vol 11 (2) ◽  
pp. 1140-1141
Author(s):  
H.J. Habing
Keyword(s):  
Main Sequence ◽  
Circumstellar Matter ◽  
Young Stars ◽  
Main Sequence Stars ◽  
Circumstellar Material

Circumstellar matter is found almost exclusively around young stars that have not yet reached the main sequence and around old stars that have left this sequence. Some main sequence stars still carry the remnants of a disk of dustlike material as a remnant of their time of formation.

Chromospheric activity as a function of age in main-sequence stars

1966 ◽  
Vol 24 ◽  
pp. 40-43
Author(s):  
O. C. Wilson ◽  
A. Skumanich
Keyword(s):  
Main Sequence ◽  
The Sun ◽  
Main Sequence Stars ◽  
Tentative Conclusion ◽  
Chromospheric Activity ◽  
General Field ◽  
Large Clusters

Evidence previously presented by one of the authors (1) suggests strongly that chromospheric activity decreases with age in main sequence stars. This tentative conclusion rests principally upon a comparison of the members of large clusters (Hyades, Praesepe, Pleiades) with non-cluster objects in the general field, including the Sun. It is at least conceivable, however, that cluster and non-cluster stars might differ in some fundamental fashion which could influence the degree of chromospheric activity, and that the observed differences in chromospheric activity would then be attributable to the circumstances of stellar origin rather than to age.

On The Radii of Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 49-55 ◽  
Author(s):  
F.A. Catalano ◽  
G. Strazzulla
Keyword(s):  
Observational Data ◽  
Line Width ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Ap Stars

SummaryFrom the analysis of the observational data of about 100 Ap stars, the radii have been computed under the assumption that Ap are main sequence stars. Radii range from 1.4 to 4.9 solar units. These values are all compatible with the Deutsch's period versus line-width relation.

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