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J/ApJ/676/1109  Velocities of stars in the Orion Nebula Cluster  (Furesz+, 2008)

Kinematic structure of the Orion Nebula Cluster and its surroundings. Furesz G., Hartmann L.W., Megeath S.T., Szentgyorgyi A.H., Hamden E.T. <Astrophys. J., 676, 1109-1122 (2008)> =2008ApJ...676.1109F
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Radial velocities ; Photometry, H-alpha ; Equivalent widths ; Photometry, infrared Keywords: ISM: kinematics and dynamics - stars: formation - stars: kinematics - stars: pre-main sequence Abstract: We present results from 1351 high-resolution spectra of 1215 stars in the Orion Nebula Cluster (ONC) and the surrounding Orion 1c association, obtained with the Hectochelle multiobject echelle spectrograph on the 6.5m MMT. We confirmed 1111 stars as members, based on their radial velocity and/or Hα emission. The radial velocity distribution of members shows a dispersion of σ=3.1km/s. We found a substantial north-south velocity gradient and spatially coherent structure in the radial velocity distribution, similar to that seen in the molecular gas in the region. We also identified several binary and high velocity stars, a region exhibiting signs of triggered star formation, and a possible foreground population of stars somewhat older than the ONC. Description: The spectroscopic observations were carried out using the Hectochelle multiobject spectrograph at the 6.5m MMT telescope in Arizona. The first set of spectra was taken in 2004 December, when a total of 866 stars in four fields were observed. Initially we chose not to bin in the resolution direction, which resulted in low S/N values for the faintest targets. Therefore, we used a 2x2 binning in 2005 November in order to decrease the readout noise in the data and thus go fainter. Accordingly, the accuracy of RVs derived for the 485 stars observed in 2005 are comparable to the 2004 values. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 105 1111 Spectroscopy of member stars table3.dat 105 104 Spectroscopy of non-members stars
See also: J/ApJ/660/704 : Optical and X-ray variability of ONC PMS (Stassun+, 2007) J/ApJ/660/1462 : Abundances of ONC X-ray PMS stars (Maggio+, 2007) J/ApJ/671/605 : NGC 2264 and ONC PMS stars in the infrared (Cieza+, 2007) J/ApJS/183/261 : Optical photometry of the ONC (Da Rio+, 2009) Table1: Summary of Spectroscopic Observations -------------------------------------------------------------------------------- Date ID Field Center Exposures Binning Mode Number of Targets -------------------------------------------------------------------------------- 2004 Dec 01 F11 5 35 19 -04 49 27 3x20 min 1x1 224 2004 Dec 01 F21 5 35 13 -05 21 14 3x20 min 1x1 210 2004 Dec 01 F22 5 35 13 -05 21 14 3x20 min 1x1 219 2004 Dec 01 F31 5 35 26 -06 07 30 3x20 min 1x1 213 2005 Nov 15 S3 5 35 13 -05 33 10 3x15 min 2x2 161 2005 Nov 15 S2 5 35 11 -05 07 28 3x15 min 2x2 154 2005 Nov 15 S1 5 35 21 -05 18 50 3x15 min 2x2 170 Byte-by-byte Description of file: table[23].dat
Bytes Format Units Label Explanations
1- 14 A14 --- 2MASS 2MASS identification (HHMMSSS+DDMMSS) 16- 24 A9 --- ID This paper's identification (1) 26- 30 F5.2 mag Jmag 2MASS J band magnitude 32- 36 F5.2 mag J-K 2MASS J-K color index 38- 42 F5.2 mag H-K 2MASS H-K color index 44- 48 F5.2 mag 3.6-4.5 ? IRAC (3.6-4.5) micron band color index 50- 54 F5.2 mag 5.8-8.0 ? IRAC (5.8-8.0) micron band color index 56- 62 F7.2 km/s HRV ? Measured heliocentric radial velocity 64- 68 F5.2 km/s e_HRV ? Error estimate in HRV from xcsao 70- 73 F4.1 --- R Cross-correlation signal-to-noise 75- 78 F4.2 --- S Cross-correlation function peak height 80- 84 F5.1 0.1nm EWc ? Halpha absolute equivalent width (2) 86- 88 I3 km/s FW10 ? Hα full width at 10% of corrected maximum 90- 93 A4 --- Ha Halpha emission profile note (3) 95-103 A9 --- CCF Cross-correlation function note (4) 105 I1 --- N Number of observations
Note (1): ID specifies the field (see Table 1) and aperture of observation. * Hectochelle targets in ONC found to be members based on measured RV value or by detected Hα emission. The criteria of beeing RV member is to have at least one velocity measurement within 4σ of the cluster mean velocity: 13.7km/s<HRV<38.5km/s. RV members listed only with R>2, while stars with Hα emission are included regardless of R value, but with no velocity displayed. * Hectochelle targets in ONC found to be non-members based on measured RV value or lack of detected Hα emission. Stars are listed regardless of R value, but no velocity is displayed in case of very low R or undefined CCF. Note (2): Measured in Angstroems on the corrected Hα profile (see text for details). Note (3): CTTS/WTTS classification, as follows: C = classical T Tauri stars, CTTS W = nonaccreting, weak-emission T Tauri star, sWTTS CW = rather CTTS, but could be WTTS WC = rather WTTS, but could be CTTS W+ = assymetry in line profile/wing: likley WTTS W- = assymetry in wings, but wings at low intensity: could be WTTS D = resolved or unresolved double gaussian profile, no excess Hα emission (likley non-TTS) CD = resolved or unresolved double gaussian profile, likely CTTS WD = resolved or unresolved double gaussian profile, likely WTTS R = obviously shifted Hα absorption : high RV stars X = very wide Hα absorption with nebular emissions CX = CTTS, with strange emission profiles AE = stellar absorption and nebular emission together NS = very strong nebular component component, no wings, no asymmetry NSC = like NS, but if intensity logscaled wide wings/assymetry is visible and suggest CTTS emission signature under the strong nebular component NSW = like NS, but if intensity logscaled narrow wings/asymmetry is visible and suggest WTTS emission signature under the strong nebular component SAT = saturated, or neighbour saturated Note (4): Cross-correlation function flag as follows: w = wide peak, results large errors in RV l = very low peak, but still sticks out from surrounding u = almost undefined, very low/wide peak n = very noisy (several local peaks, almost as high as the one picked) s = side lobed, could be a spectroscopic binary d = double peak, spectroscopic binary dv = RV measured more than once, found different velocities, could be binary r = template spectra with highest peak in cross-correlation resulted non-realistic velocity, so the template resulting in highest R value was used instead to determine velocity c = clear, well-isolated peak ? = uncertainty in assigning the given note
History: * 05-Nov-2010: From electronic version of the journal * 31-Jan-2011: Label J-H corrected into J-K in tables 2,3.
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 25-Sep-2010
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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