NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Cold, warm, and hot gas in the late-stage merger NGC 7252We present the first observations of the neutral hydrogen distribution and x-ray emission in the prototypical merger remnant NGC 7252, the 'Atoms-for-Peace' galaxy. These data are supplemented by accurate B and R surface photometry, reaching a limit of mu(sub B) = 26.5 mag/sq arcsec, and images taken through a narrow-band H alpha filter. We find all of the 2 x 10(exp 9)/sq h solar mass of atomic gas to be restricted to the outer, tidal regions of this system (H(sub zero) = 100 h km/s/Mpc). By contrast, the molecular gas traced by the (12)CO(1 approaches zero) map of Wang et al. (1992) is confined to an inner rotating disk of radius 7 seconds and has an H alpha counterpart. The gap between the atomic and molecular gas distributions is filled in by diffuse H alpha emission and perhaps by x-ray emission. The velocity field of the atomic gas in the tidal tails indicates that they are swinging through space in the same sense as the rotation of the inner gas disk. The H I at the apparent base of the northwestern tail seems to be falling back toward the main body of the galaxy, yet there is no H I associated with this main stellar body: This suggests ongoing efficient conversion of the atomic gas into other phases in this region. The H alpha velocity anomalies previously found in the remnant body may be produced in part by the combination of tail-related, noncircular motions and the inner gas-disk rotation. Both tidal tails have bluer B-R colors than the main body of the remnant, with the bluest regions coinciding with peaks in the gas column density. Each tail contains one giant H II region near the end of its optical light distribution. These H II regions are associated with large concentrations of gas and stars that approach the sizes and gas contents of dwarf galaxies. The H I extends beyond the end of the optical tails and reaches projected distances of 62/h kpc east and 120/h kpc northwest from the center. We discuss the possible relevance of these data to : (1) the transformation of merged spirals into ellipticls; (2) the generation of ripples by returning tidal material; and (3) the formation of bound stellar systems from tidally torn material.
Document ID
19950033114
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hibbard, J. E.
(Columbia Univ. New York, NY, United States)
Guhathakurta, Puragra
(Princeton Univ. Princeton, NJ, United States)
Van Gorkom, J. H.
(Columbia Univ. New York, NY, United States)
Schweizer, Francois
(Carnegie Inst. of Washington, Washington, DC United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1994
Publication Information
Publication: The Astronomical Journal
Volume: 107
Issue: 1
ISSN: 0004-6256
Subject Category
Astrophysics
Accession Number
95A64713
Funding Number(s)
CONTRACT_GRANT: NAG5-1618
CONTRACT_GRANT: NSF AST-89-17744
CONTRACT_GRANT: NSF AST-90-23254
CONTRACT_GRANT: NAS5-26555
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available