161 research outputs found
The shell elliptical NGC2865: evolutionary population synthesis of a kinematically distinct core
We report on the discovery of a rapidly co-rotating stellar and gas component
in the nucleus of the shell elliptical NGC2865. The stellar component extends ~
0.51/h100 kpc along the major axis, and shows depressed velocity dispersion and
absorption line profiles skewed in the opposite sense to the mean velocity.
Associated with it is a young stellar population with enhanced \hbeta, lowered
Mg and same Fe indices relative to the underlying elliptical. Its recent star
formation history is constrained by considering ``bulge+burst'' models under 4
physically motivated scenarios, using evolutionary population synthesis.
Scenarios in which the nuclear component is formed over a Hubble time or
recently from continuous gas inflow are ruled out.
Our results argue for a gas-rich accretion or merger origin for the shells
and kinematic subcomponent in NGC2865. Arguments based on stellar populations
and gas dynamics suggest that one of the progenitors is likely a Sb or Sc
spiral. We demonstrate that despite the age and metallicity degeneracy of the
underlying elliptical, the age and metallicity of the kinematic subcomponent
can be constrained. This work strengthens the link between KDCs and shells, and
demonstrates that a KDC can be formed from a late merger.Comment: 26 pages, accepted for publication in MNRA
Magnetschwebeanordnung mit minimaler Leistungsaufnahme für berührungslose Fördersysteme
Versuche über Phagocytose in menschlichem Sputum, hauptsächlich in tuberkulösem Auswurf
The Free Energy, Entropy and Heat Capacity of Bromine and of Hydrogen Bromide from Spectroscopic Data
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