Spectrophotometric properties of the nearest pre-main sequence stars

2009. 10. 07

A-Ran Lyo

HR diagram

Lu

min

osi

ty

Temperature

Pre-main

sequence

Lyo et al. 2004a

Hα emission line : accretion disk & chromospheric activity Li I absorption line : age indicator because Li I is diminished fast during the very early phase of stellar evolution.

ε Chamaelentis cluster : t = 3 - 5 Myr (Feigelson et al. 2003)

~ 6 Myr (Luhman 2004)

η Cha cluster : t = 5 - 8 Myr (Luhman & Steeghs 2004)

= 7 - 9 Myr (Lyo et al. 2004)

TW Hydrae association : t ~ 8 - 10 Myr (Webb et al. 1999)

β Pictoris Moving group : t ~ 20±10 Myr (Barrado y Navascues 2001)

Lower Centaurus Crux : t = 17 ~ 23 Myr (Mamajek et al. 2002)

a common kinematic link with the Ophiuchus-Scorpius- Centaurus OB Association

Lawson & Feigelson 2000

Pre-main sequence evolutionary models

Spectral lines

: Effective temperature (spectral type): Luminosity (surface gravity): Chemical composition (metallicity)

valuable input for understanding PMS stellar structure and evolution.

Chamaeleontis

Lyo et al. 2004b

η Chamaeleontis

Comparison of η Cha cluster members and dwarfs

PC3 PC4 PC5

CaHTiO

CaOH

Lyo et al. 2004b

Temperature-sensitive indices

Lyo et al. 2004b

Gravity-sensitive indices

Lyo et al. 2004b

Lyo et al. 2008

Lawson, Lyo, & Bessell 2009, accepted

Lawson, Lyo, & Bessell 2009, accepted

Thank you