Doppler imaging study of starspots and stellar non-radial pulsation using SONG network Sheng-hong Gu NAOC/Yunnan Observatory, Kunming, China Beijing  China

Content Doppler imaging SONG spectrograph Least-squares deconvolution Recent results Purposed programs for SONG network

Doppler imaging Indirect imaging method (Vogt & Penrod 1983, Donati & Collier Cameron 1997, Berdyugina 1998) Animation of Doppler imaging (Zs. Kovari)

Time series of line profiles  Surface map of the star Depend on Rotational velocity (vsini) Inclination of rotational axis Resolution (R) of spectrograph Phase coverage

SONG spectrograph Advantage High-resolution R= High efficiency Large wavelength region Long time coverage Disadvantage Smaller aperture -- 1m Limiting magnitude

Least-squares deconvolution (LSD) (Donati et al. 1997) Plenty of photospheric lines in the spectrum obtained by using echelle spectrograph  an ”average” profile with high S/N

One order of observed spectrum of V711 Tau and its LSD profile (Gu et al. 2010, in prep.)

Recent results Doppler imaging of non-radial pulsation on  Cep star  1 Sco (Berdyugina et al. 2003)

Doppler imaging of young star PW And (Gu et al. 2010)

Purposed programs for SONG network Remove the iodine cell from the light path Programs Stellar non-radial pulsation Typical magnetic active stars

Doppler imaging of stellar non-radial pulsation The time series of pulsating patterns on stellar surface Investigate pulsating mode Pulsation variation along with time Two possibilities: Add several pulsating stars (fast rotators) with non- radial pulsation to the main target list As an additional program

Doppler imaging of typical magnetic active stars Evolution of stellar magnetic activity, infer the accurate activity cycle of star Differential rotation along the latitude Meridional flow on stellar surface A potential additional program for SONG network

A time series of DI for V711 Tau (Strassmeier et al. 2000)

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