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J/ApJ/697/207     Cold stellar stream orbit fit           (Willett+, 2009)

An orbit fit for the Grillmair Dionatos cold stellar stream. Willett B.A., Newberg H.J., Zhang H., Yanny B., Beers T.C. <Astrophys. J., 697, 207-223 (2009)> =2009ApJ...697..207W
ADC_Keywords: Abundances, [Fe/H] ; Radial velocities ; Surveys ; Stars, halo ; Proper motions Keywords: Galaxy: kinematics and dynamics - Galaxy: structure Abstract: We use velocity and metallicity information from Sloan Digital Sky Survey and Sloan Extension for Galactic Understanding and Exploration stellar spectroscopy to fit an orbit to the narrow 63° stellar stream of Grillmair and Dionatos (GD; 2006ApJ...643L..17G). The stars in the stream have a retrograde orbit with eccentricity e=0.33 (perigalacticon of 14.4kpc and apogalacticon of 28.7kpc) and inclination approximately i∼35°. In the region of the orbit which is detected, it has a distance of about 7-11kpc from the Sun. Assuming a standard disk plus bulge and logarithmic halo potential for the Milky Way stars plus dark matter, the stream stars are moving with a large space velocity of approximately 276km/s at perigalacticon. Using this stream alone, we are unable to determine if the dark matter halo is oblate or prolate. The metallicity of the stream is [Fe/H]=-2.1±0.1. Observed proper motions for individual stream members above the main sequence turnoff are consistent with the derived orbit. None of the known globular clusters in the Milky Way have positions, radial velocities, and metallicities that are consistent with being the progenitor of the GD-1 stream. Description: In this work, we utilize newly available Sloan Extension for Galactic Understanding and Exploration (SEGUE; see Yanny et al. 2009AJ....137.4377Y) spectroscopy of stars identified along the stream, that are available in the SDSS Data Release 7 (DR7), to constrain the orbit of the stream and search for possible progenitors. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 123 48 Spectra of GD-1 stream candidates
See also: II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/ApJ/692/1464 : Spectroscopy of Segue 1 (Geha+, 2009) J/MNRAS/397/1748 : Spectroscopic study of Segue 2 (Belokurov+, 2009) : SDSS home page : SEGUE home page Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Plate SDSS plate number 5 A1 --- --- [-] 6- 10 I5 --- MJD SDSS Modified Julian Date 11 A1 --- --- [-] 12- 14 I3 --- Fiber SDSS fiber number 16 I1 --- Reg Stream Detection Region Number 18- 27 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000) 29- 37 F9.6 deg DEdeg Declination in decimal degrees (J2000) 39- 45 F7.3 deg Glon Galactic longitude 47- 52 F6.3 deg Glat Galactic latitude 54- 59 F6.1 km/s Vgsr Galactic standard of rest velocity (1) 61- 64 F4.1 km/s e_Vgsr Error in Vgsr 66- 71 F6.1 km/s RV Heliocentric radial velocity 73- 78 F6.3 mag gmag Dereddened g band magnitude 80- 84 F5.3 mag u-g Dereddened (u-g) color index 86- 91 F6.3 mag g-r Dereddened (g-r) color index 93- 97 F5.2 [Sun] [Fe/H] Metallicity 99-102 F4.2 [Sun] e_[Fe/H] Error in [Fe/H] 104-107 F4.2 [cm/s2] log(g) Log of the surface gravity 109-112 F4.2 [cm/s2] e_log(g) Error in log(g) 114-117 F4.1 mas/yr pmGlon Proper motion along galactic longitude 119-123 F5.1 mas/yr pmGlat Proper motion along galactic latitude
Note (1): Vgsr is computed from RV with the formula: Vgsr = RV + 10.1 cos(b)cos(l) + 224 cos(b)sin(l)+ 6.7 sin(b),
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 18-May-2011
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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