VLMS & BD – Garching, October 13th 2011

Carlo Felice Manara1,2,4, Massimo Robberto2, Nicola Da Rio2,3,Giuseppe Lodato4

HST MEASURES OF MASS ACCRETION RATES IN THE ORION NEBULA CLUSTER

1ESO Garching; 2STScI, Baltimore; 3ESA ESTEC; 4Università degli Studi di Milano, Italy

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

OUTLINES

1.HST Treasury program on the ONC 2.Methods to estimate Lacc

• 2CD (U-band excess) • Ha luminosity

3.Results • Macc vs age • Macc vs M*

• Dependence on both age and M*

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

• Cycle: 13 • GO10246 •Year: 2004-2005 •Orbits: 104 •P.I.: Robberto •Instruments: - ACS (B,V,Ha,I,Z) - WFPC2 (U,B,Ha,I) - NICMOS (J,H) •Parralel observations: - WFI(U,B,V,Ha,I,TiO) - ISPI (J,H,K)

HST Treasury Program on the ONC

Credits: NASA, ESA, M. Robberto

1 pc

10 arcmin

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

HST Treasury Program on the ONC

Science team: M. Robberto (STScI, PI), D. Soderblom (STScI), C. R. O’Dell (Vanderbilt), L. A. Hillenbrand (Caltech), M. Simon (Stony Brook), E. D. Feigelson (Penn State), J. Najita (NOAO), K. G. Stassun (Vanderbilt), J. Stauffer (JPL-Caltech), M. Meyer (ETH), J. Krist (JPL), N. Panagia (STScI), M. Romaniello (ESO), F. Palla (Arcetri), I.N. Reid (STScI), P. McCullough (STScI), R. Makidon (STScI), N. Da Rio (ESA), M. Andersen (ESA). STScI team: E. Bergeron (STScI), M. McMaster (STScI), V. Kozhurina-Platais (STScI), H. McLaughlin (STScI), K. Smith (MPIA), W. Sherry (NOAO) Graduate students: L. Ricci (ESO/Caltech), M. Reggiani (ETH), G. Scandariato (INAF Catania), W. Oosterheert (Groeningen), C. F. Manara (ESO) , Sara Sans (Innsbruck), T. Ananna (Bryn Mawr College), A. Miotello (Univ. Milano) Recent papers: Andersen et al. 2011, A&A, 534:10; Reggiani et al. 2011, A&A, 534:83

HST Treasury Program on the ONC - Atlas

Poster by A. Miotello #31

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Robberto et al., 2011, in prep.

WFPC2 dataset

1643 sources

F336W (U) F439W (B) F656N (Ha) F814W (I)

Detected 1021 997 1342 1610

Upper limit 481 521 215 11

For 1131 of the WFPC2 sources Teff from

Hillenbrand 1997 (specctra), Da Rio et al. 2010, 2011 (narrowband photometry) available.

439 sources with U, B, I band photometry and Teff available. 339 of them are used (corrected for red

leak - no proplyds, binaries, big errors…)

1027 sources with Ha band photometry , Teff and AV available. 682 of them are used (no proplyds,

binaries, edge-on disks…)

2CD

LHa

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Method

UBI Diagram (2CD) with:

Two Colors Diagram

•Atmosphere Models (Allard et al.2010)

•Accretion spectrum (Calvet et al. 1998)

•75% optically thick emission (blackbody at 8000K) •25% optically thin emission (HII region with n=104 cm-3)

• Extinction law (Cardelli et al. 1989)

+ HII region (magnetospheric emission) (more important for low accretion rates)

Empirically calibrated

RV = 3.1

Method – (1) 2CD C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Two Colors Diagram – Accretion Spectrum

Observed 2CD

Method – (1) 2CD C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Two Colors Diagram – Accretion Spectrum

Method – (1) 2CD C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Observed 2CD

6000 K

5500 K

5000 K

4500 K

4000 K

3500 K

3200 K

Two Colors Diagram – Accretion Spectrum

Method – (1) 2CD C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Dereddened 2CD

6000 K

5500 K

5000 K

4500 K

4000 K

3500 K

3200 K

Two Colors Diagram – Accretion Spectrum

Method – (1) 2CD C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Basic accretion spectrum

6000 K

5500 K

5000 K

4500 K

4000 K

3500 K

3200 K

Two Colors Diagram – Accretion Spectrum

Method – (1) 2CD C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Basic + Magnetosphere

6000 K

5500 K

5000 K

4500 K

4000 K

3500 K

3200 K

Derivation of LACC and AV

The intersection of the reddening line (red) and the accretion curve (blue) determines simultaneously Lacc and AV.

Estimate of Lacc and AV obtained for 245 sources.

Method – (1) 2CD C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

LACC from LHa - calibration

Linear regression :

148 sources

Method – (2) Ha

528 sources with Lacc estimated from LHa

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

HR Diagram – Masses – Macc

Derivation of Ṁacc for 730 sources (244 with 2CD and 486 from LHa)

Method – HRD

2CD

Ha

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Results

Macc decreases with time

Ṁacc ~ t-(1.2±0.3)

Results

Hartmann et al., 1998: Ṁacc ~ t-1.5

2CD

Ha

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Muzerolle et al., 2003: Ṁacc ~ M*2

Natta et al., 2006: Ṁacc ~ M*1.8±0.2

Rigliaco et al., 2011: Ṁacc~ M*1.6±0.4

Ṁacc ~ M*1.5±0.6

Macc increases with Mstar

Results

2CD

Ha

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Macc depends on age & Mstar

Results

log M log Age

log

Mac

c

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Results

Macc depends on age & Mstar – new results

log

Mac

c

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Results

Macc depends on age & Mstar – new results lo

g M

acc

Mstar ~ 0.13 Msun Ṁacc ~ t-1.5

Mstar ~ 0.3 Msun Ṁacc ~ t-1.07

Mstar ~ 0.5 Msun Ṁacc ~ t-0.8

Slower decay for higher mass stars

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

Results

Macc depends on age & Mstar – new results lo

g M

acc

age ~ 1 Myr Ṁacc ~ M*1.24

age ~ 2 Myr Ṁacc ~ M*1.59

age ~ 5 Myr Ṁacc ~ M*2

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Manara et al., 2011, in prep.

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011

Macc estimate for 730 sources with two methods (2CD and Ha)

Fit of the the warped plane Macc – age – Mstar

Different behaviour for different mass and age ranges.

More massive stars evolve more slowly than less massive stars.

CONCLUSIONS

Thanks

C.F. Manara - HST Mass Accretion Rates Measures in the ONC – VLMS & BD, ESO, Garching, Oct 13 2011