Query : 2004A&A...413..525B

2004A&A...413..525B - Astronomy and Astrophysics, volume 413, 525-534 (2004/1-2)

Kinematics of the faintest gas-rich galaxy in the Local Group: DDO210.


Abstract (from CDS):

We present deep, high velocity resolution (∼1.6km/s) Giant Meterwave Radio Telescope (GMRT) HI 21-cm synthesis images of the faint (MB~-10.6) local group dwarf galaxy DDO210. We find that the HI distribution in the galaxy is not axi-symmetric, but shows density enhancements in the eastern and southern halves of the galaxy. The optical emission is lopsided with respect to the HI, most of the bright optical emission arises from the eastern half of the HI disk. The velocity field of the galaxy is however quite regular and shows a systematic large scale pattern, consistent with the rotational motion. The rotation curve for the galaxy shows a peak (inclination corrected) rotation velocity of only ∼8km/s, comparable to the random motions in the HI gas. After correcting for the dynamical support provided by random motions (the ``asymmetric drift'' correction), we find the corrected peak rotation velocity of ∼16.0km/s. Mass modeling of the corrected rotation curve shows that the kinematics of DDO210 can be well fit with either a modified isothermal halo (with a central density ρ0∼29x10–3M/pc3 for a stellar mass to light ratio of 3.4) or an NFW halo. In the case of the NFW halo however, a good fit is obtained for a wide range of parameters; the halo parameters could not be uniquely determined from the fit. Density profiles with inner slope steeper than ∼1.2 however provide a poor fit to the data. Finally, the rotation curve derived using MOND also provides a reasonable fit to the observed rotation curve.

Abstract Copyright:

Journal keyword(s): galaxies: evolution - galaxies: dwarf - galaxies: kinematics and dynamics - galaxies: individual: DDO210 - lines: galaxies radio

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 3C 48 QSO 01 37 41.2996631208 +33 09 35.080388820   16.62 16.20     ~ 2673 2
2 3C 286 Sy1 13 31 08.2883506368 +30 30 32.960091564   17.51 17.25     ~ 4060 2
3 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2701 2
4 NAME Aquarius Dwarf G 20 46 51.7 -12 50 54 15.75 15.18 14.83 14.46   ~ 417 1
5 NAME Local Group GrG ~ ~           ~ 7639 0

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