8 papers
The Opacity of Spiral Galaxy Disks: dust opacity from calibrated counts of distant galaxies
B. W. Holwerda, R. A. Gonzalez, Ronald J. Allen +1
The opacity of foreground spiral disks can be probed from the number of distant galaxies seen through them. To calibrate this number for effects other than the dust extinction, Gon…
Total Opacity of Local Group Galaxies and Large Scale Structure behind the Galactic Bulge
Rosa A. Gonzalez, Benne Holwerda, Laurent Loinard +2
Recently, we have developed and calibrated the Synthetic Field Method to derive total extinction through disk galaxies. The method is based on the number counts and colors of dista…
Cold Molecular Gas as a Possible Component of Dark Matter in the Outer Parts of Disk Galaxies
Ronald J. Allen, Rosa Diaz-Miller
In the last few years new evidence has been presented for the presence of ongoing massive star formation in the outer HI disks of galaxies. These discoveries strongly suggest that…
On The Origin of HI in Galaxies: Photodissociation and the ``Schmidt Law'' for Global Star Formation
Ronald J. Allen
Young stars in the disks of galaxies produce HI from their parent H2 clouds by photodissociation. This process is widespread in late-type galaxies, and follows the distribution of…
On The Origin Of HI In Galaxies: The Sizes and Masses of HI Photodissociation Regions
Ronald J. Allen
Young stars in the disks of galaxies produce HI from their parent H2 clouds by photodissociation. This paper describes the observational evidence for and the morphology of such HI.…
The confusion limit on astrometry with SIM
Jayadev Rajagopal, Torsten Boeker, Ronald J. Allen
An important requirement for the Space Interferometry Mission (SIM) is to carry out precision astrometry in crowded fields. This capability is crucial, for example, to accurately m…