scholarly journals Coronal C+3 in the LMC: Evidence for a Hot Halo

1999 ◽  
Vol 190 ◽  
pp. 56-60
Author(s):  
Bart Wakker
Keyword(s):  
Spectral Type ◽  
Active Regions ◽  
Sole Source ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Early Type ◽  
Hot Gas ◽  
Hα Emission ◽  
Early Type Stars ◽  
Photo Ionization

Observations of interstellar C IV toward six stars in the Large Magellanic Cloud are described. These data were obtained with the GHRS on HST and with IUE. They provide the first unambiguous evidence that C+3 exists in the Large Magellanic Cloud away from regions where it could have been produced locally, as the six stars are of spectral type later than 08, as well as away from hot early-type stars or active regions. Significant differences between the velocities of the C+3 absorption and those of Hα emission near the stars shows that these ions are not co-spatial, implying that the C+3 originates in the halo of the LMC. It is shown that photo-ionization is unlikely to be the sole source of the C+3 and that the LMC halo thus contains hot gas.

scholarly journals Mass loss from early-type stars

1970 ◽  
Vol 36 ◽  
pp. 209-212
Author(s):  
J. B. Hutchings
Keyword(s):  
Mass Loss ◽  
Spectral Type ◽  
Stellar Evolution ◽  
Early Type ◽  
High Luminosity ◽  
Spectroscopic Evidence ◽  
Ob Stars ◽  
Early Type Stars ◽  
Very High ◽  
Hr Diagram

Following the detailed study of four very high luminosity OB stars, a survey has been made for spectroscopic evidence of mass loss in a number of early-type supergiants. A list of spectroscopic criteria is given and the mass loss estimates for 24 stars plotted on the HR diagram. The dependence of the phenomenon on spectral type and luminosity is discussed as well as its significance in terms of stellar evolution.

scholarly journals The multiple system Sk-67°18 in the LMC

1995 ◽  
Vol 163 ◽  
pp. 251-253 ◽  
Author(s):  
V. S. Niemela ◽  
W. Seggewiss ◽  
A. F. J. Moffat
Keyword(s):  
Binary System ◽  
Radial Velocity ◽  
Spectral Type ◽  
Orbital Period ◽  
Large Magellanic Cloud ◽  
Primary Component ◽  
Magellanic Cloud ◽  
Bright Star ◽  
High Mass ◽  
Eclipsing Binary

The bright star Sk—67°18 (Brey 5) in the Large Magellanic Cloud (LMC) contains an eclipsing binary system. Our radial velocity study reveals that the orbital period is almost exactly two days. The spectra also show that the star's primary component is not of spectral type WN, but that the star is rather an Of+O type binary where the primary is probably of type O3f*. Furthermore, Sk—67°18 appears to be a high-mass multiple system.

scholarly journals The theory of winds in early type stars

1981 ◽  
Vol 59 ◽  
pp. 125-130 ◽  
Author(s):  
A.G. Hearn
Keyword(s):  
Mass Loss ◽  
Spectral Type ◽  
Stellar Evolution ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Optical Measurements ◽  
Early Type ◽  
Large Uncertainty ◽  
Early Type Stars ◽  
Loss Rates

I assume that the purpose of this review of the theory of winds from early type stars is to summarize the way in which the mass loss rate of a star may be included in a calculation of stellar evolution. Let me summarize my conclusions. It is not possible. One can only use estimates of mass loss rates obtained from the observations. Even these give a large uncertainty. The observed mass loss rates for different stars of the same spectral type vary. Further the mass loss rates obtained by different methods for the same star differ. An extreme example of this is 9 Sgr. The mass loss rate derived from the radio observations is forty times greater than that derived from the U.V. and optical measurements (Abbott et al. 1980).

scholarly journals Spectrophotometry of early type supergiants in the Large Magellanic Cloud

1984 ◽  
Vol 210 (1) ◽  
pp. 131-139 ◽  
Author(s):  
K. Nandy ◽  
G. I. Thompson ◽  
D. H. Morgan ◽  
L. Houziaux
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Early Type

scholarly journals The Large Magellanic Cloud R CrB Star - HV 12842

1985 ◽  
Vol 87 ◽  
pp. 225-228
Author(s):  
D.H. Morgan ◽  
K. Nandy ◽  
N. Kameswara Rao
Keyword(s):  
Spectral Type ◽  
Large Magellanic Cloud ◽  
Variable Stars ◽  
Magellanic Cloud ◽  
Schmidt Telescope ◽  
Maximum Light ◽  
The North ◽  
North Eastern ◽  
The Uk ◽  
North Eastern Part

The star HV12842 is one of the 5 R CrB stars listed in the catalogue of variable stars in the LMC (Payne-Goposchkin 1971) and is located 4 deg. to the north of 30 Doradus. At this location it falls in the north-eastern part of one of two standard LMC fields used by the UK 1.2 m Schmidt Telescope. Since 1976 a series of I-plates (normally 90 minute exposures of hypersensitized Kodak IV-N emulsion through a Schott RG 715 filter) has been obtained on both the standard fields (LMC (N) and LMC (S)). This paper describes the behaviour of HV 12842 during the period 1976-1985 as it appears on the 38-I-plates of LMC(N) taken with the UK 1.2 m Schmidt Telescope. Earlier, the UBV magnitude at maximum light are given as V=13.65, B−V=0.51, U−B=−0.11 (Sherwood 1974) and the spectral type as F (Feast 1979).

scholarly journals Steps to a New Calibration of the Spectral Type — Effective Temperature Relationship for Early-type Stars

1986 ◽  
Vol 116 ◽  
pp. 111-112
Author(s):  
B. Bohannan ◽  
D. C. Abbott ◽  
S. A. Voels ◽  
D. G. Hummer
Keyword(s):  
Spectral Type ◽  
Effective Temperature ◽  
Massive Stars ◽  
Temperature Relationship ◽  
Temperature Calibration ◽  
Early Type ◽  
Bolometric Luminosity ◽  
Early Type Stars

The spectral type - effective temperature calibration is a cornerstone of our understanding of massive stars and their environment. Any uncertainty in determining their effective temperature is directly reflected in an uncertainty in defining the bolometric luminosity and the number of ionizing photons. We suggest that previous calibrations of bolometric luminosity and the number of ionizing photons as a function of spectral type may be uncertain by at least a factor of 3 for the early 0-type stars (Table 1).

scholarly journals Optical Observations of four Balmer-Dominated Supernova Remnants in the Large Magellanic Cloud

1983 ◽  
Vol 101 ◽  
pp. 559-565
Author(s):  
I. R. Tuohy ◽  
M. A. Dopita ◽  
D. S. Mathewson ◽  
K. S. Long ◽  
D. J. Helfand
Keyword(s):  
Supernova Remnants ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Optical Observations ◽  
Type I ◽  
Radiative Shock ◽  
Neutral Gas ◽  
The Galaxy ◽  
Hα Emission ◽  
Very High

We report the optical identification of four Balmer-dominated supernova remnants (SNRs) in the Large Magellanic Cloud. Both the Balmer-dominated spectra and the presence of a broad Hα component in one remnant can be understood in terms of a very high velocity non-radiative shock encountering gas which is partially neutral, as proposed originally by Chevalier and Raymond to account for the similar spectra of the galactic remnants, Tycho and SN1006. From a consideration of the optical and X-ray luminosities of the SNR with broad Hα emission, we infer that the fraction of neutral gas in the medium is ≲ 30%. Radio observations of the LMC remnants show that their surface brightnesses are anomalously low; this could be intrinsic to the supernova themselves, or a result of their environment. Finally, we argue that the four SNRs all resulted from Type I supernovae, in which case they are the first such remnants to be identified outside the Galaxy.

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