Transcript Mass determinations of PMS stars with the

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
The main aim of our work:
to test and calibrate the PMS
evolutionary tracks
★
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)
Knowledge of PMS stars masses
up to now
Mass determination
•
•
•
•
SB2 + AMBER data
SB1 + AMBER data + distance
SB1 → SB2 CRIRES
Future PRIMA
We need an input catalogue of suitable
binaries
Our survey in the southern sky
• 122 late pms investigated in five star-forming
regions:
Chamaeleon d ~ 165 pc
Corona Australis d ~ 170 pc
ρ Ophiuchi 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
Observations: FEROS spectrograph
ESO La Silla Site (Chile)
ESO 1.52 m telescope
8 years , 11 runs, ~ 50 nights,
~1500 spectra for 120 targets.
Spectral coverage : λ= 3500  9200 Å
Resolution: R  48000
MPG/ESO 2.2 m telescope
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@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
Results: the 14 targets (+1)
HD 113449
0.13±0.01 G5 5.51±0.02 13 03 50 -05 09 42 SB1
double system discovered with HARPS (during exo-planet survey)
215
The SB1 that will be observed in
the P79 with AMBER
Orbital
Mass-determination:
parameters:
PV=2 →
215.0±
Sr and
0.7days
Sd
e =0.281 ± 0.03
aSr
= BX
i =0.243
+ GY ± 0.05 AU
1 sin
f(m)
Sd==0.042
AX + FY
± 0.003
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
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