Astronomy and Astrophysics – Astrophysics
Scientific paper
2005-06-02
Astrophys.J. 627 (2005) L105-L108
Astronomy and Astrophysics
Astrophysics
ApJL, accepted
Scientific paper
10.1086/432417
We present VLA HI 21cm observations of HIJASS J1021+6842 which has been discovered in the direction of the M81 group. Our synthesis imaging reveals that the HI is distributed over a larger angular extent and velocity range than the single dish discovery observations. Assuming that HIJASS J1021+6842 is at the distance of the M81 group, we detect 1.5 x 10^8 M_sun of HI distributed over as much as 30 kpc, i.e., substantially larger than the biggest dwarf galaxies in the same group. At the depth of our imaging, the HI appears to be confined to at least 7 clouds. Peak HI column densities are ~1.8 x 10^20 atoms cm^-2 which is well below the canonical star formation threshold of ~10^21 atoms cm^-2 and therefore consistent with the fact that no optical counterpart has as yet been identified. A gradient in velocity is observed across the extent of the detected HI; assuming that the object is gravitationally bound we derive a dynamical mass of 7 x 10^9 M_sun and a dark-to-luminous mass ratio of >10. Alternatively, a tidal origin may also result in the observed velocity gradient which would lead to a considerably lower dynamical mass. Given the above properties and the absence of evidence of a stellar population, HIJASS J1021+6842 is unique amongst the other systems in the M81 group.
Brinks Elias
Skillman Evan
Walter Fabian
No associations
LandOfFree
VLA Imaging of the Intriguing HI Cloud HIJASS J1021+6842 in the M81 Group does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with VLA Imaging of the Intriguing HI Cloud HIJASS J1021+6842 in the M81 Group, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and VLA Imaging of the Intriguing HI Cloud HIJASS J1021+6842 in the M81 Group will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-435565