Download A HOT WIND FROM TW HYA: IMPLICATIONS FOR X-RAYS

A HOT WIND FROM TW HYA:
IMPLICATIONS FOR X-RAYS
IR and Ultraviolet (FUSE) spectroscopy
Hot (300,000K), Fast ( 100’s km/s) wind
Structures in wind
Most probably from star itself
Andrea Dupree and Nancy Brickhouse, CfA
Star Formation and Great Observatories: 13 July 2005
TW Hya: Perfect orientation to
seek a wind…..
Accretion Disk face-on
(Krist et al 2000)
Star and its magnetic
dipole almost ‘pole-on’
In the Sun, open magnetic
fields allow corona to escape
in the fast solar wind…
TW Hya: He I (λ10830) indicates
fast, warm wind
He I IR line a sensitive
marker of mass flow:
metastable level is
decoupled from local
conditions.
NIRSPEC/KECK
spectra show
P Cygni profile with
wind extension to
-250 to -300 km/s
Far UV Spectra indicate hotter wind
FUSE spectra
show C III wind
absorption
to -350 km/s
(80,000K)
O VI profile is also
asymmetric..
(300,000K)
Dupree et al. 2005, ApJ, 625, L131
Profiles of High Temperature Lines
Indicate Wind Absorption
Asymmetry typical of wind
absorption occurs in strong
resonance lines of C III
(977A) and O VI (1032A)
measured with FUSE.
(Similar asymmetries found
in HST/STIS profiles of
C IV and N V.)
Absorption revealed with
Gaussian fit to line profile
Accelerating wind detected in TW Hya
Absorption profile
reveals accelerating
wind with increasing
temperature:
He I 260 km/s 20,000K
C III 325 km/s 80,000K
O VI 440 km/s 300,000K
For τSobolev ~ 1, Mass loss =
10-12 to 10-11 M~/yr
Smaller than ‘accretion rate’
Wind is constant, exhibits structures
Variability on the ‘red’ side
(accretion side) of H-alpha
and O VI.
Structure apparent on
‘blue’ (wind) side of profiles
of H-alpha.
H-alpha from Magellan/MIKE
O VI from FUSE
Structure apparent in outflow
Magellan/MIKE
H-alpha spectra
over 2 epochs
suggest periodicity.
KECK/NIRSPEC
spectra indicate
wind variations at
higher temperatures.
Dupree & G. Smith, 2005, in prep.
CONCLUSIONS/IMPLICATIONS
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Hot winds (80000K300,000K) are present in
accreting T Tau stars
Continuously increasing T and
acceleration from star
Appear to originate from
star itself
May provide link to optical
jets
Broad uv lines suggest source
of uv distinct from x-rays
Wind can affect angular
momentum loss