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J/A+A/426/81        Kinematic analysis of the Minispiral      (Paumard+, 2004)

Kinematic and structural analysis of the Minispiral in the Galactic Center from BEAR spectro-imagery. Paumard T., Maillard J.-P., Morris M. <Astron. Astrophys. 426, 81 (2004)> =2004A&A...426...81P
ADC_Keywords: H II regions ; Infrared sources ; Space velocities Keywords: Galaxy: center - ISM: individual objects: Sgr A West - ISM: kinematics and dynamics - infrared: ISM - instrumentation: interferometers - line: profiles Description: We have obtained BEAR spectro-imaging data of the Galactic Center HII region "Sgr A West", also known as the "Minispiral", in the hydrogen Brackett γ line (2.166 microns). Through multi-component line fitting, we have decomposed this HII region into nine overlapping velocity structures, for which we have extracted the line flux and radial velocity maps. We have then fitted a set of Keplerian orbits onto the radial velocity map of the most extended structure (the "Northern Arm"), assuming that it was orbiting the central black hole candidate Sgr A*. This fit allows us to propose a three-dimensional kinematic model for this structure, which is hereby given as a set of FITS files. In this model, the central mass, its location in the field, and the distance to the Galactic Center are fixed: we use a mass of 3e6 solar masses and a distance of 8kpc; the pixel scale is 0.353 arcsec/pix, Sgr A* is considered to be located at pixel (59.2538, 38.9849) (IDL notation: (0, 0) is the center of the lower-left pixel, add 1 for FITS convention). Objects: ------------------------------------------ RA (2000) DE Designation(s) ------------------------------------------ 17 45 39.95 -29 00 28.2 Sgr A West ------------------------------------------ Note: The position given here is that of the radio source and supermassive black hole candidate Sgr A*, at the focus of the orbits in our model. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file 2880 82 *Three-dimensional velocity map in km/s 2880 82 *Error bars for in km/s 2880 28 *Line-of-sight distance in mas 2880 28 *Error bars for in mas
Note on Three-dimensional velocity map, a stack of three images (on the third axis of the FITS file) giving, in km/s, the velocity in each of the three dimensions: eastwards (V_alpha), northwards (V_delta), and outwards (V_radial). Note on Line-of-sight distance relative to the plane containing the central mass (Sgr A*), in equivalent milli-arcseconds on the sky. Positive for points of the structure further away from the observer than the central mass. Note on and The error bars are evaluated as follows: each fitting parameter is slightly moved within the range where moving it does not change Chi2 by more than 2 sigma. For each point of the field, we keep the highest and lowest values for each of the 4 variables we are interested in (LOS distance plus 3D velocity). The error bar is then (highest value-lowest value)/2.
Acknowledgements: Thibaut Paumard, paumard(at) References: Maillard, J. P., 1995, 3D-Spectroscopy with a Fourier Transform Spectrometer, in Tridimensional Optical Spectroscopic Methods in Astrophysics, ed. G. Comte & M. Marcelin, ASP Conf. Ser., 71, 316, 1995tosm.conf..316M Maillard, J. P. 2000, BEAR Imaging FTS: High Resolution Spectroscopy in Infrared Emission Lines, in Imaging the Universe in Three Dimensions, ed. W. van Breugel & J. Bland-Hawthorn, ASP Conf. Ser., 195, 185, 2000iutd.conf..185M
(End) Paumard [Max-Planck-Institut fuer extraterrestrische Physik] 09-Jul-2004
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