Astronomy and Astrophysics – Astrophysics
Scientific paper
Nov 1994
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994apj...436..292h&link_type=abstract
Astrophysical Journal, Part 1 (ISSN 0004-367X), vol. 436, no. 1, p. 292-300
Astronomy and Astrophysics
Astrophysics
22
Emission Spectra, Galactic Evolution, Infrared Stars, Iron, Morphology, Radial Velocity, Stellar Luminosity, Astronomical Observatories, Celestial Bodies, Flux Density, Mass
Scientific paper
We present flux-calibrated profiles of the (Fe II) 1.53 and 1.64 micron lines in five pre-main-sequence stars, PV Cep, V1331 Cyg, R Mon, and DG and HL Tau. The line centroids are blueshifted in all five sources, and four of the five have only blueshifted flux. In agreement with previous studies, we attribute the line asymmetries to local obscuration by dusty circumstellar disks. The absence of redshifted flux implies a minimum column density of obscuring material. The largest limit, NH greater than 3 x 1022/sq cm, derived for V1331 Cyg, suggests disk surface densities greater than 0.05 g/sq cm and disk masses greater than 0.001 solar mass within a radius of approximately 200 AU. The narrow high-velocity lines in PV Cep, V1331 Cyg, and HL Tau require formation in well collimated winds. The maximum full opening angles of their winds range from less than 20 deg in V1331 Cyg to less than 40 deg in HL Tau. The (Fe II) data also yield estimates of the electron densities (ne approximately 104/cu cm), hydrogen ionization fractions (fH(+) approximately 1/3), mass-loss rates (approximately 10-7 to 2 x 10-6 solar mass/yr), and characteristic radii of the emitting regions (approximately 32 to approximately 155 AU). The true radial extents will be larger, and the mass-loss rates smaller, by factors of a few for the outflows with limited opening angles. In our small sample the higher mass stars have stronger lines, larger emitting regions, and greater mass-loss rates. These differences are probably limited to the scale and energetics of the envelopes, because the inferred geometries, kinematics and physical conditions are similar. The measured (Fe II) profiles samples both 'high'- and 'low'-velocity environments. Recent studies indicate that these regions have some distinct physical properties and may be spatially separate. The (Fe II) data show that similar sizes and densities can occur in both environments.
Carr John S.
Hamann Fred
Prato Lisa
Simon} Michal
No associations
LandOfFree
(Fe II) 1.53 and 1.64 micron emission from pre-main-sequence stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with (Fe II) 1.53 and 1.64 micron emission from pre-main-sequence stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and (Fe II) 1.53 and 1.64 micron emission from pre-main-sequence stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1022666