New insights into the close circumstellar environment of the Herbig Ae/Be stars

• C. Catala, Observatoire de Paris,

• P. Feldman, JHU• A. Lecavelier des Etangs, IAP• C. Martin, LAM

• A. Roberge, Carnegie Institution of Washington

• T. Simon U. Hawaï • A. Vidal-Madjar, IAP

FUSE: a spectrograph in the FUVspectral range : 910 - 1180Å – R ~

15 000

3.63.844.24.44.6

4

1

3

Lo

g L

/ L

2

Log Teff

ßß Pictoris PictorisA5V, 20 Myr

AB AurAB AurA0V, 2.6 Myr

HD 100546HD 100546B9V, 9 Myr

HD 163296HD 163296 A1V, 4.7 Myr

HD 176386HD 176386B9V, 2.8 Myr

HD 250550HD 250550B7, 1 Myr

HD HD 8556785567

B5V, 1 Myr

HD HD 259431259431

B5, 1 Myr

HD 38087HD 38087B5, 0.5 Myr

HD 76534HD 76534B2, 0.5 Myr

Van den Ancker et al. (1997 & 1998)

20 Herbig Ae/Be stars and a few main sequence stars.

HD 141569AHD 141569AB9.5V, 4.7 Myr HR 5999HR 5999

A5Ve, 0.7 Myr

Evolved objects

7300K

8700K

9800K

10040K

10500K

10500K

10700K

12800K

Main sequence starsMain sequence stars : : emission lines in the FUV in stars with Teff ≤ 8200 K (Simon et al., 2002)

Pre-main sequence stars : : emission lines in stars with Teff ≤ 11 500 K

Bouret, Deleuil, Simon & Catala in preparation

C III

formation temperatures:

up to 300 000K

broad :

up to +/- 500 km/s

formation temperatures:

up to 300 000K

broad :

up to +/- 500 km/s

HD 100546

complex profiles:

bulk of the emission

redshifted

variations in intensity:

time scale > a few days

Deleuil, Lecavelier, Bouret et al., 2004

HD 100546 : OVI λ1032

Harper et al., 2001 ; Deleuil et al., 2004b

log10(F(C III))

log1

0(F

(O V

I))

Magnetic field detected in HD 104237

(Donati 1997)

some stars have a CS disk imaged; temperature of a few 106 K in

the shock region; variations in the line profiles.

the width of the observed lines is too large! at most equal to the free-fall velocity (Lamzin 1998)

mass loss additional veiling is expected needs to be investigated

disk

mass loss required; shock region extended with

temperature of a few 106 K variations in the line profiles.

Babel & Montmerle, 1997 X-rays emission in Ap and Bp stars

similarities of line widths in stars with different vsini !

additional veiling is expected

needs to be investigated

Log10

( F(

O V

I))

Log10( Age Myr)

Log10

( F(

O V

I))

V sini (km/s)Log10(1/2 M Vinf)● 2

Log10

(F(O

VI)

)

Log10(F(O VI))

Log10

(F(X

-rays)

)

Numerous lines in the FUV

The most abundant molecule in the CS environment of young stars

Constrains the reservoir of gas for planets building

Protected by " Self-Shielding "

Franck Le Petit, PhD Thesis (2002)

J v=0

H2 in the FUSE spectral domain:

Lyman transitions B-X ( )

Werner transitions C-X ( )

Airglow lines

OVI doublet 1032-1038 Å

Airglow lines

Green: Stellar Continuum

Blue : Intrinsic Profile

Red : Resulting Profile

Column densities

Radial velocities

Line widths (b)

Gas bound to the star

The OwensOwens Profile Fitting Procedure (M. Lemoine et al. 2002)

Martin et al. (2004)

H2 thermalized up to J=3H2 thermalized up to J=4

HH22 detected by FUSE: detected by FUSE:

Remnant of the original molecular cloud

Very extended disk with an inclination angle:

27° 35° from the plane of the sky

(Eisner et al. 2003, Mannings & Sargent 1997)

Excitation ConditionsExcitation Conditions ==

Interstellar MediumInterstellar MediumGry et al. (2002)

H2 thermalized up to J=2

Excitation temperature ~ 50K

HD 100546 & HD 163296HD 100546 & HD 163296

Stars surrounded by disks

H2 Thermalized up to J=4

Collisionally excited medium close to the star < 5 AU

(Lecavelier des Etangs, Deleuil et al. 2003)

Disks inclination angles tothe lines of sight:

(Grady et al. 2000; Augereau et al. 2001)

• HD 163296: = 60° 5°

• HD 100546: = 51° 3°

Extended chromosphere

located above the disk ?

HERBIG Be STARSHERBIG Be STARS

B8 – B2 stars

H2 Thermalized up to J=3

J=0-3 Temperature: ~100 K

Higher J-levels ~1300 K

Very similar to the HVery similar to the H22

excitationexcitation in PDRs in PDRs

Bouret, Martin et al. (2003)

RESULTS FOR HD 259431RESULTS FOR HD 259431

To reproduce the excitation diagram:

2 PDRs are needed:2 PDRs are needed:

• a large PDR with low density

for the lower J-levels

• a dense PDR close to the star

for the higher J-levels

Compatible with images:Compatible with images:

MSX (A band 8.8 µm): Hot dust close to the star

DSS2 (R and I bands): Very large dark cloud

Martin et al. (in prep)

PHOTODISSOCIATION REGIONS MODEL

J. Le Bourlot, "Molecules in the Universe" Team, Observatoire de Paris

Youngest stars of the sample - HBeEnvelopes: remnant of their original cloud

HD 259431: PDRs models with 2 componentsTBD : complete the analysis for the whole sample (under progress)

Stars with circumstellar disk Collisionally excited medium close to the star Goal: explain the excitation diagrams of stars with diskTBD: include radiative transfer of H2 in models of disk