Mass determinations of PMS stars with the VLTI

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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?r Astronomie,
  Hiedelberg, Germany
• E.Covino, J.M.Alcalà Osservatorio
  Astronomico di Capodimonte, Napoli, Italy

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The main aim of our work to test and calibrate
the PMS evolutionary tracks
?
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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)
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Knowledge of PMS stars masses up to now
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Mass determination

• SB2 AMBER data
• SB1 AMBER data distance
• SB1 ? SB2 CRIRES
• Future PRIMA
• We need an input catalogue of suitable
  binaries

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Our survey in the southern sky

• 122 late pms investigated in five star-forming
  regions
• Chamaeleon d 165 pc
• Corona Australis d 170 pc
• ? Ophiuchi d 160 pc
• Lupus d 150 pc
• Sco-Cen d 140 pc
• PMS fainter that K10 mag or that are visual
  binaries or have a v sin i gt 50 km/s are
  unsuitable

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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 ? 3500 ? 9200 Å Resolution
R ? 48000
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What do we mean for suitable ?

• The stars of the SBs should be well separeted to
  be observed with AMBER
• ( 4 mas, 0.6 AU_at_150 pc, P 120 d m1 m2
  1M?)? should have orbital periods
• gt 50 days to be resolvable with AMBER
• lt 3000 days to try to cover a whole period

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Results the 14 targets (1)
HD 113449 0.130.01 G5
5.510.02 13 03 50 -05 09 42 SB1 215
double system discovered with
HARPS (during exo-planet survey)
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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 Xcos E e YsinE(1-e2)½ B,G,A,F
(a, ?, O, 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
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Results and future prospectives

• In an 8 years campaign of spectroscopical
  observations we have discovered 9 PMS SB with
  period gt 50 days that are suitable for
  observations with AMBER
• We already had observations of BS Indi (K6.6
  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