Physics
Scientific paper
Aug 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005noao.prop..258h&link_type=abstract
NOAO Proposal ID #2005B-0258
Physics
Scientific paper
Our understanding of galaxy formation is severely limited by our lack of knowledge about the mass profiles of galaxies. We know that disk galaxies are surrounded by dark matter halos, but from rotation curves alone, it is impossible to decouple the gravitational contribution of a halo from that of the visible disk mass. Most analyses are therefore forced to rely on the ``maximal disk'' assumption, which requires that the mass-to-light ratio of a galactic disk be constant with radius. Absorption-line spectroscopy has shown that the constant M/L hypothesis is reasonable in a galaxy's inner regions. However, only one galaxy, M33, has any data more than ~1.5 scale lengths from its nucleus. Its kinematic measurements extend to ~ 5 infrared disk scale lengths, and imply a matter scale length that is more than twice that inferred from K-band surface photometry. We propose to learn more about the distribution of disk mass in normal spiral galaxies by measuring the z-motions of planetary nebulae (PNe) in a sample of face-on spirals. This specific proposal is to image M74 in [O III] (lambda) 5007, off-band (lambda) 5290, H(alpha), and B, in order to identify a sample of ≳ 100 PNe for follow- up spectroscopy. This would allow us to measure the system's disk surface-density and mass-to-light ratio over ≳ 5 disk scale lengths, thereby constraining models of galactic dark halos. As a by- product, our M74 measurements will also produce the first precision distance estimate to the galaxy.
Ciardullo Robin
Feldmeier John . J.
Herrmann Kimberly
Jacoby George
No associations
LandOfFree
The Planetary Nebula System of M74 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 The Planetary Nebula System of M74, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Planetary Nebula System of M74 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-796898