Issue |
A&A
Volume 464, Number 1, March II 2007
AMBER: Instrument description and first astrophysical results
|
|
---|---|---|
Page(s) | 155 - 165 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20066023 | |
Published online | 29 November 2006 |
Stars and gas in the very large interacting galaxy NGC 6872
1
Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden e-mail: Cathy.Horellou@chalmers.se
2
Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia e-mail: Baerbel.Koribalski@csiro.au
Received:
12
July
2006
Accepted:
2
November
2006
The dynamical evolution of the
large (>100 kpc), barred spiral galaxy NGC 6872
and its small companion IC 4970 in the southern group Pavo
is investigated.
We present
N-body simulations with stars and gas and
21 cm Hi observations carried out with the Australia Telescope Compact Array
of the large-scale distribution and kinematics of atomic gas.
Hi is detected toward the companion, corresponding to a gas mass of
~.
NGC 6872 contains ∼
of Hi gas,
distributed in an extended rotating disk.
Massive concentrations of gas (∼
)
are found at the tip of both tidal
tails and towards the break seen in the optical northern arm near
the companion.
We detect no Hi counterpart to the X-ray trail
between NGC 6872 and NGC 6876, the dominant elliptical galaxy
in the Pavo group located ∼
to the southeast.
At the sensitivity and the resolution of the observations,
there is no sign in the overall Hi distribution that
NGC 6876 has affected the evolution of NGC 6872.
There is no evidence of ram pressure stripping either.
The X-ray trail could be due to gravitational focusing of
the hot gas in the Pavo group
behind NGC 6872 as the galaxy moves supersonically through the
hot medium.
The simulations of a gravitational interaction with a small
nearby companion on a low-inclination prograde passage
are able to reproduce most of the
observed features of NGC 6872, including the
general morphology of the galaxy, the inner bar,
the extent of the tidal tails and
the thinness of the southern tail.
Key words: galaxies: interactions / galaxies: ISM / ISM: kinematics and dynamics / galaxies: individual: NGC 6872 / galaxies: individual: IC 4970 / galaxies: individual: NGC 6876
© ESO, 2007
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