A Search for Optical Circular Polarization in White Dwarfs and Late-Type Stars with Circumstellar Shells

1973 ◽  
Vol 180 ◽  
pp. L123 ◽  
Author(s):  
A. Rich ◽  
W. L. Williams
Keyword(s):  
Circular Polarization ◽  
White Dwarfs ◽  
Late Type ◽  
Circumstellar Shells

scholarly journals Atlas of Main-line OH Masers in the Galactic Longitude Range 3° to 60°

1983 ◽  
Vol 36 (3) ◽  
pp. 417 ◽  
Author(s):  
JL Caswell ◽  
RF Haynes
Keyword(s):  
Star Formation ◽  
Circular Polarization ◽  
Galactic Plane ◽  
Hii Regions ◽  
Main Line ◽  
Late Type ◽  
Circumstellar Shells ◽  
Many Sources ◽  
First Time ◽  
Galactic Longitude

We tabulate all 55 OH main-line masers discovered to date in the galactic plane between longitude 3� and 60�. For most of these we show current spectra, which have been taken with the Parkes 64 m radio telescope, in both senses of circular polarization on the 1665 MHz and/or 1667 MHz transitions; for some sources we give new position estimates, and several sources are reported for the first time. We discuss many sources individually and note that while most of the main-line OH masers probably pinpoint compact HII regions and sites of current star formation, a few appear to be unusual varieties occurring in circumstellar shells, possibly associated with late-type stars.

Faint Sources in theEUVESurvey: Identification of White Dwarfs, Active Late‐Type Stars, and Galactic Nuclei

1997 ◽  
Vol 486 (1) ◽  
pp. 179-196 ◽  
Author(s):  
Elisha Polomski ◽  
Stephane Vennes ◽  
John R. Thorstensen ◽  
Mihalis Mathioudakis ◽  
Emilio E. Falco
Keyword(s):  
White Dwarfs ◽  
Galactic Nuclei ◽  
Late Type

The Effect of Magnetic Field Spread and Temperature and Density Variations in Cyclotron Emission Regions

1987 ◽  
Vol 7 (2) ◽  
pp. 123-127 ◽  
Author(s):  
D. T. Wickramasinghe ◽  
Lilia Ferrario
Keyword(s):  
Magnetic Field ◽  
Point Source ◽  
Circular Polarization ◽  
White Dwarfs ◽  
Type Systems ◽  
Polar Cap ◽  
Cyclotron Radiation ◽  
Cyclotron Emission ◽  
Source Models ◽  
Accretion Shocks

AbstractWe discuss the properties of cyclotron radiation from accretion shocks located above the atmospheres of magnetic white dwarfs taking into account the effects of field spread and density and temparture structure. The models which are an improvement on previous point source models are shown to have characteristics that are in better overall agreement with the properties of AM Herculis type systems. Our calculations of the polarization properties of large polar cap emission regions are used to discuss the recent null measurements of circular polarization in DQ Herculis type systems.

Faint Sources in the EUVE Survey. II. Identification of Two White Dwarfs and Four Late-Type Active Stars.

1997 ◽  
Vol 114 ◽  
pp. 1567 ◽  
Author(s):  
Stephane Vennes ◽  
Eric Korpela ◽  
Stuart Bowyer
Keyword(s):  
White Dwarfs ◽  
Late Type ◽  
Active Stars

scholarly journals On the Separations of Common Proper Motion Binaries Containing White Dwarfs

1989 ◽  
Vol 114 ◽  
pp. 454-457
Author(s):  
T.D. Oswalt ◽  
E.M. Sion
Keyword(s):  
Mass Loss ◽  
White Dwarf ◽  
Proper Motion ◽  
White Dwarfs ◽  
Main Sequence ◽  
Late Type ◽  
Class A ◽  
Color Class

Luyten [1,2] and Giclas et al. [3,4] list over 500 known common proper motion binaries (CPMBs) which, on the basis of proper motion and estimated colors, are expected to contain at least one white dwarf (WD) component, usually paired with a late type main sequence (MS) star. Preliminary assessments of the CPMBs suggest that nearly all are physical pairs [5,6]. In this paper we address the issue of whether significant orbital expansion has occurred as a consequence of the post-MS mass loss expected to accompany the formation of the WDs in CPMBs.Though the CPMB sample remains largely unobserved, a spectroscopic survey of over three dozen CPMBs by Oswalt [5] found that nearly all faint components of Luyten and Giclas color class “a-f” and “+1”, respectively, or bluer were a WD. This tendency was also evident in a smaller sample studied by Greenstein [7]. Conversely, nearly all CPMBs having two components of color class “g-k” and “+3” or redder were MS+MS pairs. With the caveat that such criteria discriminate against CPMBs containing cool (but rare) WDs, they nonetheless provide a crude means of obtaining statistically significant samples for the comparison of orbital separations: 209 highly probable WD+MS pairs and 109 MS+MS pairs.

scholarly journals Mass-Loss from Late-Type Stars: New Observational Evidence

1983 ◽  
Vol 103 ◽  
pp. 292-292
Author(s):  
P. G. Wannier ◽  
R. Sahai
Keyword(s):  
Mass Loss ◽  
Central Star ◽  
Ir Absorption ◽  
Late Type ◽  
Ir Radiation ◽  
Loss Mechanism ◽  
Continuum Source ◽  
Near Ir ◽  
Molecular Lines ◽  
Circumstellar Shells

Rapid mass-loss is observed in many late-type stars, yet the mass-loss mechanisms operating are not well understood. A survey of molecular emission from circumstellar shells has been carried out using millimeterwave molecular lines and suggests that radiation pressure alone may be inadequate to explain the observed mass-loss, especially in the case of carbon-rich objects which may display rates in excess of 10−5 M⊙/yr. Recent near-IR molecular line observations provide evidence for ejected material at several different velocities along the line-of-sight and may indicate the additional mass-loss mechanism at work. Resonantly scattered IR radiation spatially displaced from the central IR continuum source has now been observed for the first time and sheds new light on the IR absorption-line results, providing information about material within 1016 cm of the central star. These results are discussed along with recent high-resolution millimeterwave observations.

scholarly journals CCD Parallaxes for Southern Very Low Luminosity Stars

1993 ◽  
Vol 156 ◽  
pp. 75-78
Author(s):  
Philip A. Ianna
Keyword(s):  
White Dwarfs ◽  
Late Type ◽  
M Dwarfs ◽  
Dwarf Stars ◽  
Ccd Observations ◽  
Trigonometric Parallaxes ◽  
M Dwarf Stars ◽  
M Dwarf

Trigonometric parallaxes based on CCD observations are presented here for six southern very late-type M dwarf stars and three white dwarfs. The M dwarfs RG0050-2722, ESO207-61, MH2115-4518, MH2124-4228, and LHS3003 are among the very lowest luminosity stars known.

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