Linear polarization observations of T Tauri stars. II - A sample of objects fainter than 13th magnitude

1992 ◽  
Vol 103 ◽  
pp. 564 ◽  
Author(s):  
Francois Menard ◽  
Pierre Bastien
Keyword(s):  
Linear Polarization ◽  
T Tauri Stars ◽  
T Tauri

scholarly journals A polarization outburst in the T Tauri star UY Aurigae

1987 ◽  
Vol 122 ◽  
pp. 133-134 ◽  
Author(s):  
F. Ménard ◽  
P. Bastien
Keyword(s):  
Linear Polarization ◽  
T Tauri Stars ◽  
Tauri Star ◽  
Monitoring Programme ◽  
Strong Polarization ◽  
Visual Binary ◽  
T Tauri ◽  
First Time

During the course of a monitoring programme of the linear polarization of various T Tauri stars, UY Aur was observed to undergo a strong polarization burst between 1984 October and 1985 January. The linear polarization rised from about 1.5% early in 1984 to a maximum of 7.6% in 1984 October and declined back to the earlier value after 3 to 4 months. It is the first time that such a large increase in linear polarization is reported in a T Tauri star. However the interpretation is complicated by the fact that UY Aur is a visual binary with a separation of 0.8 and both components were included in the measurements.

scholarly journals Circular polarization in T Tauri stars

1987 ◽  
Vol 122 ◽  
pp. 131-132
Author(s):  
P. Bastien ◽  
R. Nadeau
Keyword(s):  
Circular Polarization ◽  
Linear Polarization ◽  
T Tauri Stars ◽  
T Tauri

We report the detection of circular polarization in three T Tauri stars with known intrinsic linear polarization. A circumstellar origin is required.

Linear polarization of T Tauri stars. I - Variability of southern stars

1989 ◽  
Vol 97 ◽  
pp. 814 ◽  
Author(s):  
Laurent Drissen ◽  
Pierre Bastien ◽  
Nicole St.-Louis
Keyword(s):  
Linear Polarization ◽  
T Tauri Stars ◽  
T Tauri

scholarly journals Linear polarization of T Tauri stars

1981 ◽  
Vol 195 (2) ◽  
pp. 429-436 ◽  
Author(s):  
J. H. Hough ◽  
J. Bailey ◽  
E. C. Cunningham ◽  
A. McCall ◽  
D. J. Axon
Keyword(s):  
Linear Polarization ◽  
T Tauri Stars ◽  
T Tauri

scholarly journals Polarization measurements of some T Tauri stars

1987 ◽  
Vol 122 ◽  
pp. 135-136
Author(s):  
U. C. Joshi ◽  
M. R. Deshpande ◽  
A. K. Kulshrestha
Keyword(s):  
Systematic Study ◽  
Linear Polarization ◽  
Wavelength Dependence ◽  
Position Angle ◽  
T Tauri Stars ◽  
Time Variability ◽  
Specific Mechanism ◽  
Polarization Measurements ◽  
T Tauri ◽  
University Of Arizona

T Tauri stars show linear polarization typically between 1–3%. A two band linear polarization survey of some T Tauri star was reported earlier by Bastien (1982). Most of the stars show pronounced time variability in polarization and position angle (Bastien, 1980; 1982). Wavelength dependence of polarization is important in determining the specific mechanism(s) producing polarization. For a systematic study of polarization in T Tauri stars, we have taken up an observing programme to measure linear polarization of some stars in Taurus-Auriga region. Polarization measurements of 9 T Tauri stars are reported here. Observations were made on January 8–11, 1984 with MINIPOL (Frecker and Serkowski, 1976) on 61“ telescope of University of Arizona.

The Infancy of Solar-Type Stars and its Relevance for the Origin of Life

1997 ◽  
Vol 161 ◽  
pp. 267-282 ◽  
Author(s):  
Thierry Montmerle
Keyword(s):  
Main Sequence ◽  
Solar Nebula ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Necessary Condition ◽  
Sequence Evolution ◽  
T Tauri ◽  
Solar Type ◽  
Optical Domain ◽  
The Origin Of Life

AbstractFor life to develop, planets are a necessary condition. Likewise, for planets to form, stars must be surrounded by circumstellar disks, at least some time during their pre-main sequence evolution. Much progress has been made recently in the study of young solar-like stars. In the optical domain, these stars are known as «T Tauri stars». A significant number show IR excess, and other phenomena indirectly suggesting the presence of circumstellar disks. The current wisdom is that there is an evolutionary sequence from protostars to T Tauri stars. This sequence is characterized by the initial presence of disks, with lifetimes ~ 1-10 Myr after the intial collapse of a dense envelope having given birth to a star. While they are present, about 30% of the disks have masses larger than the minimum solar nebula. Their disappearance may correspond to the growth of dust grains, followed by planetesimal and planet formation, but this is not yet demonstrated.

The Bright Accretion Rings on Magnetic T Tauri Stars

1998 ◽  
Vol 497 (1) ◽  
pp. 342-353 ◽  
Author(s):  
Andisheh Mahdavi ◽  
Scott J. Kenyon
Keyword(s):  
T Tauri Stars ◽  
T Tauri

scholarly journals Very Low-Luminosity Objects in Star-Forming Regions

1998 ◽  
Vol 11 (1) ◽  
pp. 423-424
Author(s):  
Motohide Tamura ◽  
Yoichi Itoh ◽  
Yumiko Oasa ◽  
Alan Tokunaga ◽  
Koji Sugitani
Keyword(s):  
Brown Dwarfs ◽  
Mass Function ◽  
T Tauri Stars ◽  
Initial Mass Function ◽  
Formation Mechanisms ◽  
Star Forming ◽  
Star Forming Regions ◽  
T Tauri ◽  
Low Mass ◽  
Stellar Sources

Abstract In order to tackle the problems of low-mass end of the initial mass function (IMF) in star-forming regions and the formation mechanisms of brown dwarfs, we have conducted deep infrared surveys of nearby molecular clouds. We have found a significant population of very low-luminosity sources with IR excesses in the Taurus cloud and the Chamaeleon cloud core regions whose extinction corrected J magnitudes are 3 to 8 mag fainter than those of typical T Tauri stars in the same cloud. Some of them are associated with even fainter companions. Follow-up IR spectroscopy has confirmed for the selected sources that their photospheric temperature is around 2000 to 3000 K. Thus, these very low-luminosity young stellar sources are most likely very low-mass T Tauri stars, and some of them might even be young brown dwarfs.

scholarly journals Aperture synthesis CS and 98 GHz continuum observations of protostellar IRAS sources in Taurus

1991 ◽  
Vol 147 ◽  
pp. 353-356
Author(s):  
N. Ohashi ◽  
R. Kawabe ◽  
M. Hayashi ◽  
M. Ishiguro
Keyword(s):  
Molecular Cloud ◽  
Total Mass ◽  
T Tauri Stars ◽  
Continuum Emission ◽  
Beam Size ◽  
Dust Grains ◽  
Dynamical Mass ◽  
T Tauri ◽  
Cloud Cores ◽  
The Continuum

The CS (J = 2 — 1) line and 98 GHz continuum emission have been observed for 11 protostellar IRAS sources in the Taurus molecular cloud with resolutions of 2.6″−8.8″ (360 AU—1200 AU) using the Nobeyama Millimeter Array (NMA). The CS emission is detected only toward embedded sources, while the continuum emission from dust grains is detected only toward visible T Tauri stars except for one embedded source, L1551-IRS5. This suggests that the dust grains around the embedded sources do not centrally concentrate enough to be detected with our sensitivity (∼4 m Jy r.m.s), while dust grains in disks around the T Tauri stars have enough total mass to be detected with the NMA. The molecular cloud cores around the embedded sources are moderately extended and dense enough to be detected in CS, while gas disks around the T Tauri are not detected because the radius of such gas disks may be smaller than 70 (50 K/Tex) AU. These results imply that the total amount of matter within the NMA beam size must increase when the central objects evolve into T Tauri stars from embedded sources, suggesting that the compact and highly dense disks around T Tauri stars are formed by the dynamical mass accretion during the embedded protostar phase.

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