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Mass determinations of PMS stars with the VLTI

Mass determinations of PMS stars with the VLTI. F.Cusano, E.W.Guenther, M.Esposito, B.Stecklum TLS-Tautenburg, Germany R.Mundt Max-Planck-Institut f ϋ r Astronomie, Hiedelberg, Germany E.Covino, J.M.Alcalà Osservatorio Astronomico di Capodimonte, Napoli, Italy.

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Mass determinations of PMS stars with the VLTI

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  1. Mass determinations of PMS stars with the VLTI F.Cusano, E.W.Guenther, M.Esposito, B.Stecklum TLS-Tautenburg, Germany R.Mundt Max-Planck-Institut fϋr Astronomie, Hiedelberg, Germany E.Covino, J.M.Alcalà Osservatorio Astronomico di Capodimonte, Napoli, Italy

  2. The main aim of our work:to test and calibrate the PMS evolutionary tracks ★

  3. The importance to confirm the best theoretical model • to put constraints on stellar interior’ theories • to get the masses of PMS stars using the HR diagram • precise determination of the IMFs and age for the star forming regions and clusters → important step in the theories of stellar Galactic formation (Preibisch et al. 2002)

  4. Knowledge of PMS stars masses up to now

  5. Mass determination • SB2 + AMBER data • SB1 + AMBER data + distance • SB1 → SB2 CRIRES • Future PRIMA We need an input catalogue of suitable binaries

  6. Our survey in the southern sky • 122 late pms investigated in five star-forming regions: Chamaeleon d ~ 165 pc Corona Australis d ~ 170 pc ρOphiuchi d ~ 160 pc Lupus d ~ 150 pc Sco-Cen d ~ 140 pc • PMS fainter that K=10 mag or that are visual binaries or have a v sin i > 50 km/s are unsuitable

  7. Observations: FEROS spectrograph ESO La Silla Site (Chile) ESO 1.52 m telescope MPG/ESO 2.2 m telescope 8 years , 11 runs, ~ 50 nights, ~1500 spectra for 120 targets. Spectral coverage : λ= 3500  9200 Å Resolution: R  48000

  8. What do we mean forsuitable? • The stars of the SBs should be well separeted to be observed with AMBER ( ~ 4 mas, 0.6 AU@150 pc, P ~ 120 d m1= m2 = 1M◉)→ should have orbital periods: • > 50 days to be resolvable with AMBER • < 3000 days to try to cover a whole period

  9. Results: the 14 targets (+1) HD 113449 0.13±0.01 G5 5.51±0.02 13 03 50 -05 09 42 SB1 215 double system discovered with HARPS (during exo-planet survey)

  10. The SB1 that will be observed in the P79 with AMBER Orbital parameters: P = 215.0± 0.7days e =0.281 ± 0.03 a1 sin i =0.243 ± 0.05 AU f(m) =0.042 ± 0.003 Mass-determination: V2 → Sr and Sd Sr = BX + GY Sd= AX + FY X=cos E –e Y=sinE(1-e2)½ B,G,A,F (a”, ω, Ω, i) Thiele-Innes constans We know a sin i and f(m) with i and the distance, using also the 3° law of kepler→M1 and M2

  11. Results and future prospectives • In an 8 years campaign of spectroscopical observations we have discovered 9 PMS SB with period > 50 days that are suitable for observations with AMBER • We already had observations of BS Indi (K=6.6 mag) with AMBER but the signal resulted to be too faint (+ no standard observed) • In this period our brightest (HD113449) candidate will be observed with AMBER • We hope to observe all targets with the VLTI (UTs or ATs + fringe tracker) to put constraints on the PMS evolutionary tracks

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