Transcript Part 3

Monitoring of variable and
transient objects
Liu Liang & Qian Sheng-Bang
Yunnan Astronomical Observatory
April, 2010
Beijing
Stellar Observations Network Group
Some ideas about SONG
Part 1


To understand the phenomena of A-type and W-type
contact binaries
To understand the O’connell effect in close binaries
Part 2

To study the short time-scale dynamical process in close
binaries
Part 3

To monitor the transient objects
1 Flare events of M type active stars
2 Transit in the light curves
3 Some special flares

To search new variable stars
A-type and W-type contact binary

A-type (normal type，the
deeper minimum is respond to
the more massive component
(primary star) be covered，the
effective temperature of the
primary star is higher, its
spectral type always to be A-F).

W-type (abnormal type，the
deeper minimum is respond to
the less massive component
(secondary star) be covered，
the effective temperature of the
secondary star is higher, its
spectral type always to be G-K).
Part 1
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The phenomena of A-type and
W-type contact binaries
Part 1
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The O’connell effect in close binaries
 definition：
The brightness of maximum in
the light curve is not equal
 causes：
1 Asymmetry of the common
envelope
2 Stellar dark spots model
3 Hot spots model
 problems：
1 We don’t know which mechanism is dominant
2 We don’t know the reason(s) which caused the O’connell
effect type changes
Part 1
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The short time-scale dynamical
process in close binaries
 To get a series of
times of minima
 To know the period
changes in each cycle
 To get information of
tidal effect
 To get information of
dynamical effect
 To get information of
orbital stability
Part 2
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Flares in active M stars
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Transit in light curves and
unknown type variable
Part 3
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