J/AJ/129/363 Spectroscopy in Orion Nebula Cluster (Sicilia-Aguilar+, 2005)
Accretion, kinematics, and rotation in the Orion Nebula Cluster: initial results
from Hectochelle.
Sicilia-Aguilar A., Hartmann L.W., Szentgyorgyi A.H., Fabricant D.G.,
Furesz G., Roll J., Conroy M.A., Calvet N., Tokarz S., Hernandez J.
<Astron. J., 129, 363-381 (2005)>
=2005AJ....129..363S 2005AJ....129..363S
ADC_Keywords: Accretion ; Stars, pre-main sequence ; Clusters, open ;
Equivalent widths ; Radial velocities
Keywords: accretion, accretion disks - line: profiles -
stars: pre-main-sequence - stars: rotation
Abstract:
We present results from high-resolution spectra of 237 stars in the
Orion Nebula cluster (ONC) obtained during two engineering runs with
the Hectochelle multifiber echelle spectrograph on the 6.5m MMT. The
ONC is the nearest populous young (age ∼1Myr) cluster and is therefore
an important object for studies of the evolution of protoplanetary
disks. Using the high spectral resolution of Hectochelle, we are able
to distinguish stellar accretion and wind emission-line profiles from
nebular emission lines and identify accreting members of the cluster
from Hα profiles with greater accuracy than previously possible.
We find 15 new members on the basis of Li λ6707 absorption and
Hα emission. Line profiles of Hα of some objects that are
not too contaminated by nebular emission show features characteristic
of mass inflow and ejection. We also present rotational velocities as
part of an initial investigation into angular momentum evolution of
very young stars, confirming a difference between classical T Tauri
stars and weak-line T Tauri stars that had been found from period
analysis. Finally, we present an initial study of the radial velocity
dispersion of the brighter stars in the central cluster. The very
small dispersion derived, 1.8km/s, is in good agreement with estimates
from proper motions.
Description:
Hectochelle is a fiber-fed multiobject echelle spectrograph fed by a
robotic fiber positioner and mounted at the Cassegrain focus of the
MMT (Multiple Mirror Telescope) on Mount Hopkins, Arizona. The first
set of observations was taken on the night of 2003 December 8. The
second set of observations consisted of three 15 minute exposures in
the Hα order on 2004 March 10.
Objects:
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RA (2000) DE Designation(s)
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05 35 12.0 -05 24 06 Orion Nebula Cluster = GAL 208.9-19.4
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 75 185 Results from 2003 December
table2.dat 92 153 Results from March 2004
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See also:
J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997)
J/AJ/116/1816 : JHKLMNOPQ photometry in Orion cluster (Hillenbrand+, 1998)
J/A+A/396/513 : Stellar Rotation in the Orion Nebula Cluster (Herbst+, 2002)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- [H97b] ? Identification number (G1)
5- 6 A2 --- m_[H97b] Multiple components
8- 23 A16 --- 2MASS The 2MASS identification (HHMMSSss+DDMMSSs)
25- 38 A14 --- SpType Hillenbrand et al. (1998, Cat. J/AJ/116/1816)
spectral type
40- 41 A2 --- Type [CW: ] Type T Tauri star classification (G2)
43- 46 F4.2 0.1nm EW(Li) ? Equivalent width of Li (6707 Angstroms) in
Angstroms
47 A1 --- u_EW(Li) Uncertainty flag in EW(Li)
49- 52 I4 0.1nm EW(Ha) ? Equivalent width of Hα in Angstroms
54- 75 A22 --- Com Additional comments (1)
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Note (1): Proplyds named using their HST ID number as given in
Hillenbrand et al. 1998, Cat. J/AJ/116/1816) , Bally et al.
(1998AJ....116..293B 1998AJ....116..293B). Winds (denoted PC, or P-Cygni profiles)
and infall (denoted IPC, or inverse P-Cygni profiles) detected by
asymmetries in Hα profile. Broad or very broad He (written as
bHe or very bHe) refers to the detection of the broad component of the
He emission line at 5876Å. Low signal to noise spectra are marked
with the label lS/N. Colons have been added to uncertain values. Stars
with near-IR excess in 2MASS are labeled as nIR. An additional comment
has been included to distinguish stars with systematically broad lines
as possible fast rotators. The label "(2004)" indicate stars that were
observed again in March 2004, which have the additional information
corresponding to the 2004 run in Table2.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- [H97b] Identification number (G1)
5- 6 A2 --- m_[H97b] Multiple components
8- 23 A16 --- 2MASS The 2MASS identification (HHMMSSss+DDMMSSs)
25- 29 F5.1 km/s cz Heliocentric radial velocity
31- 34 F4.1 km/s e_cz Uncertainty in cz
36- 39 F4.1 --- S/N ? Signal-to-noise value of cross-correlation
peak (see text)
41- 45 F5.1 km/s vsini ? Rotational velocity
47- 50 F4.1 km/s e_vsini ? Uncertainty in vsini
52- 56 A5 --- Type T Tauri star classification (G2)
58- 63 F6.1 0.1nm EW(Ha) ? Equivalent width of Hα in Angstroms
64 A1 --- u_EW(Ha) Uncertainty flag in EW(Ha)
66- 77 A12 --- SpType Spectral type (1)
79- 92 A14 --- Com Additional comments (2)
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Note (1): From Hillenbrand (1997, Cat. J/AJ/113/1733) and subsequent updates
to electronically-available table except where noted:
P = Prosser & Stauffer, unpublished;
Sam = A.E. Samuel, 1993 unpublished PhD thesis;
D = Duncan (1993ApJ...406..172D 1993ApJ...406..172D); Strand (1958AJ.....63..152S 1958AJ.....63..152S);
Her = Herbig, quoted in Walker (1969ApJ...155..447W 1969ApJ...155..447W);
LR = Luhman et al. 2000, Cat. J/ApJ/540/1016;
e = Ca II infrared triplet emission;
: = uncertain values.
Note (2): Additional comments, defined as follows:
PC = P Cygni profile;
IPC = inverse P Cygni profile (see text);
SB2s = new double-lined binary;
nIR = star with near-IR excess in 2MASS;
NM = non-member from proper motions.
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Global Notes:
Note (G1): From Jones & Walker (1988AJ.....95.1755J 1988AJ.....95.1755J) number if < 2000,
otherwise from Hillenbrand (1997, Cat. J/AJ/113/1733) and subsequent
updates to electronically-available table. The objects are identified
by [H97b] NNNNa in Simbad.
Note (G2): Type T Tauri star classification, defined as follows:
C = classical T Tauri star;
W = weak T Tauri star.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 04-Jul-2005