T TAURI
V410 TAU
Analysis of MOST light curves of five young stars in Taurus–Auriga and
Lupus 3 star-forming regions†
Michal Siwak, Slavek M. Rucinski, Jaymie M. Matthews, Rainer Kuschnig, David B. Guenther, Anthony F. J.
Moffat, Dimitar Sasselov, Werner W. Weiss
Article first published online: 29 JUN 2011
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Pre Main Sequence – young, low mass stars that are contracting as they
evolve toward their main sequence stage.
Mostly made of Hydrogen, some Helium, and some trace elements. Of the
trace elements, Lithium appears which is an indicator of stellar youth.
Often have large protoplanetary accretion disks left over from stellar
formation.
Typical size and age: 0.2-3x’s Solar Mass and 100,000 – 1,000,000 years
Found in galactic clouds (like Taurus Auriga dark cloud) because they formed
more recently and haven’t had enough time to move far from where they
formed.
Spectra contain strong Balmer lines as well as forbidden lines … and … . The
low density of T Tauri stars allows these lines to appear.
LIGHT CURVE OF T TAURI
• Unlike many other types of variable stars, the behavior of T Tauri young stars is very
erratic.
• The variations in light of these stars are so irregular and unpredictable that
classification of T Tauri variables cannot be based upon their light-curves.
• Between 1864 and 1916, the brightness magitude of T Tauri was between 9.3 and 14.
• In 2009 and 2010, the Canadian Microvariability and Oscillations of Stars (MOST)
satellite observed V410 Tau in T Tauri system and obtained the maximum brightness
magnitude of 10.8.
• Doppler tomographic studies show that the light variations of V410 Tau is due to
rotational modulation by dark spots. The light curves systematic changes support the
observations of spots.
• To retain consistancy with the result, MOST assumed two dark spots: one close to the
pole and a second at low latitudes, and obtained the rotational period of 1.87 days.
• Theory: many variations in the star due to a magnetic
field
• A magnetic reconnection event
• Probability of flare detection is low
• Magnitudes of flares generally moderate in size 0.2-0.1
mag
PROBLEMS
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Some T Tauri stars have periodic non thermal radio emissions
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The long term stability of large spots is not explained by current theory
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Some T Tauri stars have dark spots that are higher in temperature than their surrounding
photosphere
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The magnetic fields of T Tauri stars are not well understood, though they are believed to
be similar to late Main Sequence stars
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The pattern of flare events is not well documented
POSSIBLE SOLUTIONS
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Extended Range Photometry – X-ray through Radio waves
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Better Models – both models to fit the data, to better explain the convective properties of
T Tauri stars, and to model large spots
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Increased sensitivity to small spots
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Longer Studies – most current studies only record a few periods