The origins of fluorescent H 2 emission from T tauri stars

Gregoky J. Herczeg; Jeffrey L. Linsky; Frederick M. Walter; Gösta F. Gahm; Christopher M. Johns-Krull

doi:10.1086/503558

The origins of fluorescent H ₂ emission from T tauri stars

Gregoky J. Herczeg
, Jeffrey L. Linsky
, Frederick M. Walter
, Gösta F. Gahm
, Christopher M. Johns-Krull

Physics and Astronomy

University of Colorado Boulder
California Institute of Technology
Stockholm University
Rice University

Research output: Contribution to journal › Article › peer-review

85 Scopus citations

Abstract

We survey fluorescent H ₂ emission in HST STIS spectra of the classical T Tauri stars (CTTSs) TW Hya, DF Tau. RU Lupi, T Tau, and DG Tau, and the weak-lined T Tauri star (WTTS) V836 Tau. From each of those sources we detect between 41 and 209 narrow H ₂ emission lines, most of which are pumped by strong Lyα emission. H ₂ emission is not detected from the WTTS V410 Tau. The fluorescent H ₂ emission appears to be common to circumstellar environments around all CTTSs, but high spectral and spatial resolution STIS observations reveal diverse phenomenon. Blueshifted H ₂ emission detected from RU Lupi, T Tau, and DG Tau is consistent with an origin in an outflow. The H ₂ emission from TW Hya, DF Tau, and V836 Tau is centered at the radial velocity of the star and is consistent with an origin in a warm disk surface. The H ₂ lines from RU Lupi, DF Tau, and T Tau also have excess blueshifted H ₂ emission that extends to as much as -100 km s ^-1. The strength of this blueshifted component from DF Tau and T Tau depends on the upper level of the transition. In all cases, the small aperture and attenuation of H ₂ emission by stellar winds restricts the H ₂ emission to be formed close to the star. In the observation of RU Lupi, the Lyα emission and the H ₂ emission that is blueshifted by 15 km s ^-1 are extended to the SW by ∼0″07, although the faster H ₂ gas that extends to ∼100 km s ^-1 is not spatially extended. We also find a small reservoir of H ₂ emission from TW Hya and DF Tau consistent with an excitation temperature of ∼2.5 × 10 ⁴ K.

Original language	English
Pages (from-to)	256-282
Number of pages	27
Journal	Astrophysical Journal, Supplement Series
Volume	165
Issue number	1
DOIs	https://doi.org/10.1086/503558
State	Published - Jul 2006

Keywords

Accretion, accretion disks
Circumstellar matter
Line: identification
Stars: pre-main-sequence
Ultraviolet: stars

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10.1086/503558

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@article{b91573262edd494188b5d53a373c3de4,

title = "The origins of fluorescent H 2 emission from T tauri stars",

abstract = "We survey fluorescent H 2 emission in HST STIS spectra of the classical T Tauri stars (CTTSs) TW Hya, DF Tau. RU Lupi, T Tau, and DG Tau, and the weak-lined T Tauri star (WTTS) V836 Tau. From each of those sources we detect between 41 and 209 narrow H 2 emission lines, most of which are pumped by strong Lyα emission. H 2 emission is not detected from the WTTS V410 Tau. The fluorescent H 2 emission appears to be common to circumstellar environments around all CTTSs, but high spectral and spatial resolution STIS observations reveal diverse phenomenon. Blueshifted H 2 emission detected from RU Lupi, T Tau, and DG Tau is consistent with an origin in an outflow. The H 2 emission from TW Hya, DF Tau, and V836 Tau is centered at the radial velocity of the star and is consistent with an origin in a warm disk surface. The H 2 lines from RU Lupi, DF Tau, and T Tau also have excess blueshifted H 2 emission that extends to as much as -100 km s -1. The strength of this blueshifted component from DF Tau and T Tau depends on the upper level of the transition. In all cases, the small aperture and attenuation of H 2 emission by stellar winds restricts the H 2 emission to be formed close to the star. In the observation of RU Lupi, the Lyα emission and the H 2 emission that is blueshifted by 15 km s -1 are extended to the SW by ∼0″07, although the faster H 2 gas that extends to ∼100 km s -1 is not spatially extended. We also find a small reservoir of H 2 emission from TW Hya and DF Tau consistent with an excitation temperature of ∼2.5 × 10 4 K.",

keywords = "Accretion, accretion disks, Circumstellar matter, Line: identification, Stars: pre-main-sequence, Ultraviolet: stars",

author = "Herczeg, \{Gregoky J.\} and Linsky, \{Jeffrey L.\} and Walter, \{Frederick M.\} and Gahm, \{G{\"o}sta F.\} and Johns-Krull, \{Christopher M.\}",

year = "2006",

month = jul,

doi = "10.1086/503558",

language = "English",

volume = "165",

pages = "256--282",

journal = "Astrophysical Journal, Supplement Series",

issn = "0067-0049",

number = "1",

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TY - JOUR

T1 - The origins of fluorescent H 2 emission from T tauri stars

AU - Herczeg, Gregoky J.

AU - Linsky, Jeffrey L.

AU - Walter, Frederick M.

AU - Gahm, Gösta F.

AU - Johns-Krull, Christopher M.

PY - 2006/7

Y1 - 2006/7

N2 - We survey fluorescent H 2 emission in HST STIS spectra of the classical T Tauri stars (CTTSs) TW Hya, DF Tau. RU Lupi, T Tau, and DG Tau, and the weak-lined T Tauri star (WTTS) V836 Tau. From each of those sources we detect between 41 and 209 narrow H 2 emission lines, most of which are pumped by strong Lyα emission. H 2 emission is not detected from the WTTS V410 Tau. The fluorescent H 2 emission appears to be common to circumstellar environments around all CTTSs, but high spectral and spatial resolution STIS observations reveal diverse phenomenon. Blueshifted H 2 emission detected from RU Lupi, T Tau, and DG Tau is consistent with an origin in an outflow. The H 2 emission from TW Hya, DF Tau, and V836 Tau is centered at the radial velocity of the star and is consistent with an origin in a warm disk surface. The H 2 lines from RU Lupi, DF Tau, and T Tau also have excess blueshifted H 2 emission that extends to as much as -100 km s -1. The strength of this blueshifted component from DF Tau and T Tau depends on the upper level of the transition. In all cases, the small aperture and attenuation of H 2 emission by stellar winds restricts the H 2 emission to be formed close to the star. In the observation of RU Lupi, the Lyα emission and the H 2 emission that is blueshifted by 15 km s -1 are extended to the SW by ∼0″07, although the faster H 2 gas that extends to ∼100 km s -1 is not spatially extended. We also find a small reservoir of H 2 emission from TW Hya and DF Tau consistent with an excitation temperature of ∼2.5 × 10 4 K.

AB - We survey fluorescent H 2 emission in HST STIS spectra of the classical T Tauri stars (CTTSs) TW Hya, DF Tau. RU Lupi, T Tau, and DG Tau, and the weak-lined T Tauri star (WTTS) V836 Tau. From each of those sources we detect between 41 and 209 narrow H 2 emission lines, most of which are pumped by strong Lyα emission. H 2 emission is not detected from the WTTS V410 Tau. The fluorescent H 2 emission appears to be common to circumstellar environments around all CTTSs, but high spectral and spatial resolution STIS observations reveal diverse phenomenon. Blueshifted H 2 emission detected from RU Lupi, T Tau, and DG Tau is consistent with an origin in an outflow. The H 2 emission from TW Hya, DF Tau, and V836 Tau is centered at the radial velocity of the star and is consistent with an origin in a warm disk surface. The H 2 lines from RU Lupi, DF Tau, and T Tau also have excess blueshifted H 2 emission that extends to as much as -100 km s -1. The strength of this blueshifted component from DF Tau and T Tau depends on the upper level of the transition. In all cases, the small aperture and attenuation of H 2 emission by stellar winds restricts the H 2 emission to be formed close to the star. In the observation of RU Lupi, the Lyα emission and the H 2 emission that is blueshifted by 15 km s -1 are extended to the SW by ∼0″07, although the faster H 2 gas that extends to ∼100 km s -1 is not spatially extended. We also find a small reservoir of H 2 emission from TW Hya and DF Tau consistent with an excitation temperature of ∼2.5 × 10 4 K.

KW - Accretion, accretion disks

KW - Circumstellar matter

KW - Line: identification

KW - Stars: pre-main-sequence

KW - Ultraviolet: stars

UR - https://www.scopus.com/pages/publications/33748578572

U2 - 10.1086/503558

DO - 10.1086/503558

M3 - Article

AN - SCOPUS:33748578572

SN - 0067-0049

VL - 165

SP - 256

EP - 282

JO - Astrophysical Journal, Supplement Series

JF - Astrophysical Journal, Supplement Series

IS - 1

ER -

The origins of fluorescent H ₂ emission from T tauri stars

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