KIAA-Cambridge Workshop

The Formation of Peculiar Stars

Zhanwen Han

(Kunming)

KIAA-Cambridge Workshop

KIAA-Cambridge Workshop

Kunming

Beijing

Nanjing Shanghai

KIAA-Cambridge Workshop

正心问天 寻道兴文

KIAA-Cambridge Workshop

正心问天 寻道兴文

KIAA-Cambridge Workshop

Current Projects

Stellar Evolution Binary Related Objects

Applications of Stellar Evolution

Symbiotics

Blue Stragglers

Hot Subdwarfs

Progenitors of SNe Ia,Companion Stars of SNe Ia 、

CEMP

Contact Binaries

Rapid Mass Loss Model

Initial-Final Mass Relation

Stellar Evolution with Alpha elements enhanced

EPS model

Stellar Populations of Galaxies

Far-UV excess of early-type galaxies

Chemical Yields of Stellar Population

Gravitational Wave Radiation Background of

the Galaxy

Brown Dwarfs

KIAA-Cambridge Workshop

Progenitor Model:

Single Degenerate Model

CO WD + MS

CO WD + RG

Double Degenerate

CO WD + CO WD

KIAA-Cambridge Workshop

Birthrates of SNe Ia from WD+MS

Birth

rate

time

Han, Podsiadlowski, 2004, MNRAS

KIAA-Cambridge Workshop

Humuy: I ½

Livio: DD

WD+AGB

WD+Mira

Delayed dynamically unstable RLOF

Hamuy et al. 2003, Nature

SN Ia 2002ic ， Different Progenitor ?

KIAA-Cambridge Workshop

2002ic-like SNe Ia——delayed dynamical unstable RLOF model

Han, Podsiadlowski, 2006, MNRAS

KIAA-Cambridge Workshop

Com

p. Mass

Orb. Period

KIAA-Cambridge Workshop

Properties of Companion Stars of SNe IaHan, 2008, ApJL

Space Velocity

Com

p. Mass

Eff. Temperature

Gravity

KIAA-Cambridge Workshop

Rot. Velocity

Com

p. M

ass

KIAA-Cambridge Workshop

hot subdwarfs

KIAA-Cambridge Workshop

Why hot subdwarfs important ?

• Stellar evolutionary theory

• Stellar seismology

• Distance indicator

• Structure and evolution of the Galaxy

• Far-UV excess (UV-upturn) of early type galaxies (age indicator ?)

KIAA-Cambridge Workshop

Binary model

To explain binary and single hot subdwarfs .

• Han, Podsiadlowski, Maxted, Marsh, Ivanova, 2002, MNRAS, 336, 449

• Han, Podsiadlowski, Maxted, Marsh, 2003, MNRAS, 341, 669

• Han, 2008, A&A, 484, L31

KIAA-Cambridge Workshop

KIAA-Cambridge Workshop

Hot subdwarfs in globular clusters

Extreme Horizontal Branch (EHB) stars

Han, 2008, A&A, Letter

KIAA-Cambridge Workshop

Han, Podsiadlowski, Lynas-Gray, 2007, MNRAS

KIAA-Cambridge Workshop

Brown et al. 2003

KIAA-Cambridge Workshop

GALEX Observations

KIAA-Cambridge Workshop

• Despite its simplicity, our model can reproduce lots of observations

• UV-upturn is universal (from dwarf to giant ellipticals)

• The magnitude of UV-upturn does NOT depend much on metallicity or redshift.

• UV-upturn is NOT an age indicator !

UV-upturn is explained naturally !

KIAA-Cambridge Workshop

Thanks !

KIAA-Cambridge Workshop

Composite Populations:old dominant + younger minor

FUV~ f

Given tmajor, variable f, tminor

8 supernovae in 6 of the 10 quiescent

galaxies