Astronomy and Astrophysics – Astrophysics
Scientific paper
Mar 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003a%26a...400..137c&link_type=abstract
Astronomy and Astrophysics, v.400, p.137-143 (2003)
Astronomy and Astrophysics
Astrophysics
3
Stars: Early-Type, Stars: Formation, Stars: Kinematics, Galaxies: Starburst, Galaxies: Individual: Ngc 253
Scientific paper
We present observations of J004804.8-251749, a blue object in the direction of the halo of NGC 253 with (B-V) = -0.16 +/- 0.08, V = 22.09 +/- 0.06 and a stellar spectrum showing the Balmer lines redshifted to a velocity of 279 +/- 15 km s-1. These data are consistent with a B5/B8 supergiant star with a mass M = 12 M_sun and a maximum age tau =~ 20 Myr in the halo of NGC 253. Based on its position, radial velocity, and inferred maximum age, we consider the possibility that J004804.8-251749 may be a runaway star ejected from the disk of NGC 253. We derive a lower limit of 172 km s-1 for the ejection velocity, or 148 km s-1 if the lower limit of the distance fork to NGC 253 is adopted. While being within the range of velocities accessible to runaway stars through the dynamical ejection mechanism, such high velocities are rather unlikely, especially since the inferred value is only a lower limit. This leads us to consider in situ formation as a possible alternative scenario, in which the formation of J004804.8-251749 would have been triggered by the interaction between the starburst-driven superwind stemming from the center of NGC 253 and a cloud of cold hydrogen in the halo. Such a formation mechanism would be consistent with our previous finding of an excess of blue point sources in the direction of the halo of NGC 253, which we interpreted as indicating the existence of superwind-triggered star formation.
Based on observations obtained at the European Southern Observatory using the Very Large Telescope in Cerro Paranal (programme 69.D-0109(A)).
Comeron Fernando
Gomez Ana E.
Torra Jordi
No associations
LandOfFree
A bright early-type star in the halo of NGC 253: Runaway or in situ formation 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 A bright early-type star in the halo of NGC 253: Runaway or in situ formation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A bright early-type star in the halo of NGC 253: Runaway or in situ formation will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1881441