Optical rotation curves beyond the HI cut-off in spirals

Details Optical rotation curves beyond the HI cut-off in spirals Optical rotation curves beyond the HI cut-off in spirals

1997-12-07

arxiv.org/abs/astro-ph/9712105v1

Astronomy and Astrophysics

Astrophysics

8 pages (3 figures). To appear in the Proceedings of the UC Santa Cruz Workshop on Galactic Halos, ed. D. Zaritsky, held at UC

Scientific paper

In the best observed spiral galaxies, the HI is observed to decline slowly with radius for up to 90% of the maximum extent, before experiencing a rapid truncation. Early models predicted that the outer parts of spirals would be fully ionized by a metagalactic UV field at column depths of roughly 10^{19} atoms cm^{-2}. Weak optical line emission has now been observed beyond the HI edge in a number of cases and, furthermore, this warm gas has been used to trace the dark halo far beyond the HI cut-off. But the observed emission measures (40-90 mR) are higher than expected for a cosmic origin. A more likely explanation is ionization of the warped outer disk by the blue stellar population at smaller radius. There are many implications of ionized warped edges, in particular, severe HI warps may be greatly under represented in current HI surveys. We briefly discuss the implications of this model for the Galactic warp.

Affiliated with

Also associated with

No associations

Rating

Optical rotation curves beyond the HI cut-off in spirals 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 Optical rotation curves beyond the HI cut-off in spirals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical rotation curves beyond the HI cut-off in spirals will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-224024