TY - JOUR
T1 - A micro-molecular bipolar outflow from HL Tauri
AU - Takami, Michihiro
AU - Beck, Tracy L.
AU - Pyo, Tae Soo
AU - McGregor, Peter
AU - Davis, Christopher
PY - 2007
Y1 - 2007
N2 - We present detailed geometry and kinematics of the inner outflow toward HL Tau observed using Near Infrared Integral Field Spectrograph (NIFS) at the Gemini-North 8 m Observatory. We analyzed H2 2.122 μm emission and [Fe II] 1.644 μm line emission as well as the adjacent continuum observed at a <0.2" resolution. The H2 emission shows (1) a bubblelike geometry to the northeast of the star, as briefly reported in the previous paper, and (2) faint emission in the southwest counterflow, which has been revealed through careful analysis. The emission on both sides of the star shows an arc 1.0" away from the star, exhibiting a bipolar symmetry. Different brightnesses and morphologies in the northeast and southwest flows are attributed to absorption and obscuration of the latter by a flattened envelope and a circumstellar disk. The H2 emission shows a remarkably different morphology from the collimated jet seen in [Fe ii] emission. The positions of some features coincide with scattering continuum, indicating that these are associated with cavities in the dusty envelope. Such properties are similar to millimeter CO outflows, although the spatial scale of the H 2 outflow in our image (∼150 AU) is strikingly smaller than the millimeter outflows, which often extend over 1000-10000 AU scales. The positionvelocity diagrams of the H2 and [Fe n] emission do not show any evidence for kinematic interaction between these flows. All results described above support the scenario that the jet is surrounded by an unseen wide-angled wind, which interacts with the ambient gas and produces the bipolar cavity and shocked H2 emission.
AB - We present detailed geometry and kinematics of the inner outflow toward HL Tau observed using Near Infrared Integral Field Spectrograph (NIFS) at the Gemini-North 8 m Observatory. We analyzed H2 2.122 μm emission and [Fe II] 1.644 μm line emission as well as the adjacent continuum observed at a <0.2" resolution. The H2 emission shows (1) a bubblelike geometry to the northeast of the star, as briefly reported in the previous paper, and (2) faint emission in the southwest counterflow, which has been revealed through careful analysis. The emission on both sides of the star shows an arc 1.0" away from the star, exhibiting a bipolar symmetry. Different brightnesses and morphologies in the northeast and southwest flows are attributed to absorption and obscuration of the latter by a flattened envelope and a circumstellar disk. The H2 emission shows a remarkably different morphology from the collimated jet seen in [Fe ii] emission. The positions of some features coincide with scattering continuum, indicating that these are associated with cavities in the dusty envelope. Such properties are similar to millimeter CO outflows, although the spatial scale of the H 2 outflow in our image (∼150 AU) is strikingly smaller than the millimeter outflows, which often extend over 1000-10000 AU scales. The positionvelocity diagrams of the H2 and [Fe n] emission do not show any evidence for kinematic interaction between these flows. All results described above support the scenario that the jet is surrounded by an unseen wide-angled wind, which interacts with the ambient gas and produces the bipolar cavity and shocked H2 emission.
KW - ISM: jets and outflows
KW - ISM: kinematics and dynamics
KW - Stars: formation
UR - http://www.scopus.com/inward/record.url?scp=42149092711&partnerID=8YFLogxK
U2 - 10.1086/524138
DO - 10.1086/524138
M3 - Article
SN - 0004-637X
VL - 670
SP - L33-L36
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1 PART 2
ER -