scholarly journals Actvity on T Tauri Stars

1995 ◽  
Vol 151 ◽  
pp. 221-222
Author(s):  
Erik Gullbring ◽  
Gösia F. Gahm ◽  
Heinz Barwig ◽  
Peicheng Chen
Keyword(s):  
Time Scales ◽  
High Speed ◽  
T Tauri Stars ◽  
Young Stars ◽  
Tauri Star ◽  
Emission Lines ◽  
Base Line ◽  
Short Term ◽  
T Tauri ◽  
Short Term Variability

We have made a detailed investigation of the short-term variability of the classical T Tauri star BP Tauri in UBVRI. Data were collected from the Wendelstein Observatory in 1991, 1992 and 1993 with time resolutions down to 1 sec. The 0.8m telescope was equipped with a fiber-fed fifteen channel high-speed photometer (Barwig et al. 1987). Observations (in UBV) were also collected in China at the Yunnan and Shanghai Observatories to get a long base line in time. To search for differences in the properties between the brightness variations of classical T Tauri stars (CTTS) and T Tauri stars with weak emission lines (WTTS) we performed simultaneous photometry (in the UBV and Strömgren systems) and spectroscopy of 6 young stars during two observing periods at ESO La Silla. The study concerned mainly short-term variability on time-scales of minutes to a few hours. The sample contained two CTTS, SY Ori and VW Cha; three WTTS, San 1, SZ Cha and ADA 481 and one post-T Tauri candidate, HD 70309B.

Short Term Variations in the Spectrum of the T Tauri Star DI Cep

1979 ◽  
Vol 46 ◽  
pp. 369-370
Author(s):  
R. Mundt ◽  
U. Bastian
Keyword(s):  
Time Scales ◽  
Time Resolution ◽  
Equivalent Width ◽  
Tauri Star ◽  
Emission Lines ◽  
Short Term ◽  
Spectroscopic Observations ◽  
T Tauri ◽  
Time Variations ◽  
Short Time

AbstractExtended spectroscopic observations of the T Tauri star DI Cep with a time resolution of 10 to 15 minutes have been carried out. On 2 of 6 observing nights the star showed significant variations of the strengths of its emission lines on time scales down to the time resolution of the observations. The most drastic event is shown in Figure 1. The equivalent width of the Hα line increased by a factor of 7 within two hours. Even faster variations, but of smaller amplitude, were observed in the strengths of the Hβ and Till 82 (λ 4572 Å) lines on another night. Obviously strong short time variations are not always present in DI Cep, as in 4 nights no significant variations could be detected.

scholarly journals High Quality Echelle Observations of T Tauri Stars

1988 ◽  
Vol 132 ◽  
pp. 99-104
Author(s):  
G. Basri
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
T Tauri Stars ◽  
Young Stars ◽  
Emission Lines ◽  
Current Understanding ◽  
General Nature ◽  
High Quality ◽  
T Tauri ◽  
Made In

This is a very brief review of the high resolution line profile work that has been done on very young stars. The spectral anamolies peculiar to these stars are mentioned, with some discussion of what may give rise to them. The Hα line is discussed most extensively, as the most work has been done with it. While progress has been made in understanding the general nature of T Tauri spectra, there are very large gaps in our current understanding of the emission lines from these stars.

Can complex T Tauri star light curves be modelled with star-spots?

2020 ◽  
Vol 500 (1) ◽  
pp. 1366-1379
Author(s):  
C Koen
Keyword(s):  
Ridge Regression ◽  
Young Stars ◽  
Light Curves ◽  
Stellar Surface ◽  
Tauri Star ◽  
T Tauri ◽  
Almost All

ABSTRACT ‘Transiting Exoplanet Survey Satellite’ photometry of 10 young stars with very complex periodic light curves is considered. Previous findings that these cannot be due to dark surface spots are re-evaluated by allowing arbitrarily shaped areas on the stellar surface to have sub-photospheric fluxes. This is done by approximating flux integrals by sums over surface elements. The unknown ratios of spot to photospheric fluxes are determined by lasso or ridge regression procedures. It is found that almost all light curves can be modelled very accurately in this way. The usual, if rarely stated, caveat applies – star-spot models presented in the paper are not unique.

scholarly journals Variability of young stars: Determination of rotational periods of weak-line T Tauri stars in the Cepheus-Cassiopeia star-forming region

2009 ◽  
Vol 330 (5) ◽  
pp. 482-492
Author(s):  
A. Koeltzsch ◽  
M. Mugrauer ◽  
St. Raetz ◽  
T.O.B. Schmidt ◽  
T. Roell ◽  
...  
Keyword(s):  
T Tauri Stars ◽  
Young Stars ◽  
Weak Line ◽  
Star Forming ◽  
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 Oh Observations Near the Reflection Nebulae Ngc 2068 and Ngc 2071

1974 ◽  
Vol 60 ◽  
pp. 301-302
Author(s):  
L. E. B. Johansson ◽  
B. Höglund ◽  
A. Winnberg ◽  
Nguyen-Q-Rieu ◽  
W. M. Goss
Keyword(s):  
Dust Cloud ◽  
T Tauri Stars ◽  
Emission Lines ◽  
Class I ◽  
Reflection Nebula ◽  
Cosmic Background ◽  
T Tauri ◽  
Reflection Nebulae

Narrow OH emission lines at 1667 MHz, apparently from a Class I source, have been observed near the reflection nebula NGC 2071. The region contains many T Tauri stars. OH emission corresponding to the dust cloud north and east of NGC 2024 is also seen. At 1720 MHz the dust cloud component appears in absorption; presumably the isotropic 2.7 K cosmic background is being absorbed.

scholarly journals Flares on T Tauri stars

1990 ◽  
Vol 137 ◽  
pp. 193-207
Author(s):  
G. F. Gahm
Keyword(s):  
Qualitative Difference ◽  
T Tauri Stars ◽  
Strong Line ◽  
Short Term ◽  
T Tauri ◽  
Ultraviolet Spectral Region ◽  
Total Energies ◽  
Light Variability ◽  
Circumstellar Environment ◽  
Powerful Flare

An overview of the characteristics of short-term light variability on T Tauri stars is given. The evidence of the occurrence of flares comes from observations mainly at X-ray energies and from patrole observations in the ultraviolet spectral region. From such observations some limits on the peak fluxes and total energies of the largest flare-like events can be set. In addition, the frequency of such events can be deduced for a number of stars. It is demonstrated that there appears to be a qualitative difference between powerful flare-like events on the weak-line T Tauri stars (NTTs) and those on strong-line stars (CTTs). While it appears that the concept of surface flares occurring on NTTs may be correct there is the evidence that the disk-stars in addition produce flare-like events of a different nature. These events could be related to processes occurring not on the stars but in their circumstellar environment, for instance in a circumstellar disk. We also point at observations that could be of importance in clarifying the cause of flare-like activity on T Tauri stars and also comment on how this activity changes with stellar age.

scholarly journals Quasicyclic Light Changes in Three Low Mass T Tauri Stars

1977 ◽  
Vol 42 ◽  
pp. 66-71
Author(s):  
H. Mauder
Keyword(s):  
Variable Stars ◽  
T Tauri Stars ◽  
Emission Lines ◽  
T Tauri ◽  
Cyclic Variations ◽  
Low Mass ◽  
Photographic Survey ◽  
Objective Prism

During a photographic survey of the Chamaeleon T association in 1971/1972, evidence was found for quasiperiodic light changes of three variable stars, see Mauder and Sosna (1975). The period of 6.2 days for SY Cha is well seen, the periods of 7 days for VZ Cha and of 8 days for TW Cha are less pronounced. Intrinsic variations are present in addition to the cyclic variations. The three stars were classified by Hoffmeister (1963) as T Tauri type stars from their light variations. Objective prism spectra obtained by Henize and Mendoza (1973) confirm this classification, they found conspicuous emission lines. For SY Cha and TW Cha they got slit spectra, too, which show the typical veiling. The stars SY Cha, TW Cha and VZ Cha have been observed in the UBV system from 1974 March 12 until 1974 March 22, using the ESO standard photometer. In Figures 1 - 3 the light and colour curves are given for SY Cha, TH Cha and VZ Cha. Each point is a mean of generally 8 to 12 integrations, each integration lasting 5 seconds.

scholarly journals The Infrared Companions of T Tauri Stars: Clues to the Formation and Early Evolution of Binaries

2001 ◽  
Vol 200 ◽  
pp. 265-274 ◽  
Author(s):  
Chris D. Koresko ◽  
Christoph Leinert
Keyword(s):  
T Tauri Stars ◽  
Young Stars ◽  
Early Evolution ◽  
Young Stellar Objects ◽  
Physical Status ◽  
Stellar Objects ◽  
T Tauri ◽  
Mode Of Development ◽  
Source Of Information

Infrared companions are young stellar objects with unusual properties gravitationally bound to more or less typical T Tauri stars. As such they promise to be the source of information on either a particular phase in the development of young stars or on a particular mode of development. We discuss the observed properties of infrared companions as well as attempts to explain their physical status with the aim to see how much of solid conclusion has been obtained so far.

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