Ronald J. Allen

Formation of OB Associations in Galaxies (2007)

The accuracy requirements on station-keeping for constellations of free-flying collectors coupled as (future) imaging arrays in space for astrophysics applications are examined. The basic imaging...

Shu, Frank H., Allen, Ronald J., Lizano, Susana, Galli, Daniele

We consider the formation of OB associations from two perspectives: (a) the fractional gas consumption in star formation,epsilon, per dynamical time scale t_dyn in a galaxy, and (b) the origin of the...

A Comparison between Anomalous 6-cm H$_2$CO Absorption and CO(1-0) Emission in the L1204/S140 (2007)

Rodriguez, Monica Ivette, Wiklind, Tommy, Allen, Ronald J., Escalante, Vladimir, Loinard, Laurent

We report observations of the dust cloud L1204 with the Onsala 25-m telescope in the 6 cm (1$_{11}-1_{10}$) transition of \htco. The observed region includes the S140 H${\alpha}$ arc. This spectral...

Anomalous H_2CO Absorption Towards the Galactic Anticenter: A Blind Search for Dense Molecular Clouds (2006)

Rodriguez, Monica Ivette, Allen, Ronald J., Loinard, Laurent, Wiklind, Tommy

We have carried out a blind search in the general direction of the Galactic Anticenter for absorption of the Cosmic Microwave Background (CMB) radiation near 4.83 GHz by molecular clouds containing...

The Narrative Fallacy, the Relative Plausibility Theory, and a Theory of the Trial (2006)

The Narrative Fallacy, the Relative Plausibility Theory, and a Theory of the Trial (2006)

The Narrative Fallacy, the Relative Plausibility Theory, and a Theory of the Trial (2006)

The Narrative Fallacy, the Relative Plausibility Theory, and a Theory of the Trial (2006)

The Opacity of Spiral Galaxy Disks VI: Extinction, stellar light and color (2005)

Holwerda, B. W., González, R. A., Van Der Kruit, P. C., Allen, Ronald J.

In this paper we explore the relation between dust extinction and stellar light distribution in disks of spiral galaxies. Extinction influences our dynamical and photometric perception of disks,...

The Opacity of Spiral Galaxy Disks: dust opacity from calibrated counts of distant galaxies (2005)

Holwerda, B. W., Gonzalez, R. A., Allen, Ronald J., Van Der Kruit, P. C.

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, Gonzalez et al (1998)...

The Opacity of Spiral Galaxy Disks V: dust opacity, HI distributions and sub-mm emission (2005)

Holwerda, B. W., González, R. A., Allen, Ronald J., Van Der Kruit, P. C.

The opacity of spiral galaxy disks, from counts of distant galaxies, is compared to HI column densities. The opacity measurements are calibrated using the ``Synthetic Field Method'' from Gonzalez et...

The Opacity of Spiral Galaxy Disks VII: the accuracy of galaxy counts as an extinction probe (2005)

Holwerda, B. W., Gonzalez, R. A., Allen, Ronald J., Van Der Kruit, P. C.

The ``Synthetic Field Method'' (SFM) was introduced by Gonzalez et al. (1998) to calibrate numbers of distant galaxies as a probe of extinction in a foreground spiral disk. Gonzalez et al. (2003)...

The Opacity of Spiral Galaxy Disks III: Automating the "Synthetic Field Method" (2004)

Holwerda, B. W., Gonzalez, R. A., Allen, Ronald J., Van Der Kruit, P. C.

The dust extinction in spiral disks can be estimated from the counts of background field galaxies, provided the deleterious effects of confusion introduced by structure in the image of the foreground...

The Opacity of Spiral Galaxy Disks IV: Radial Extinction Profiles from Counts of Distant Galaxies seen through Foreground Disks (2004)

Holwerda, B. W., Gonzalez, R. A., Allen, Ronald J., Van Der Kruit, P. C.

Dust extinction can be determined from the number of distant field galaxies seen through a spiral disk. To calibrate this number for the crowding and confusion introduced by the foreground image,...

Total Opacity of Local Group Galaxies and Large Scale Structure behind the Galactic Bulge (2004)

Gonzalez, Rosa A., Holwerda, Benne, Loinard, Laurent, Allen, Ronald J., Muller, Sebastien

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 distant background field...

Photodissociation and the Morphology of HI in Galaxies (2004)

Cold Molecular Gas as a Possible Component of Dark Matter in the Outer Parts of Disk Galaxies (2004)

Young massive stars produce Far-UV photons which dissociate the molecular gas on the surfaces of their parent molecular clouds. Of the many dissociation products which result from this...

Allen, Ronald J., Diaz-Miller, Rosa

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 precursor molecular...

The Error of Expected Loss Minimization (2003)

The Opacity of Nearby Galaxies from Counts of Background Galaxies: II. Limits of the Synthetic Field Method (2002)

Considerable effort has been expended by legal scholars attempting to apply formal approaches such as Bayes' Theorem or decision theory to various aspects of the litigation process. These efforts...

Gonzalez, Rosa A., Loinard, Laurent, Allen, Ronald J., Muller, Sebastien

Recently, we have developed and calibrated the Synthetic Field Method (SFM) to derive the total extinction through disk galaxies. The method is based on the number counts and colors of distant...

On The Origin of HI in Galaxies: Photodissociation and the ``Schmidt Law'' for Global Star Formation (2002)

On The Origin Of HI In Galaxies: The Sizes and Masses of HI Photodissociation Regions (2002)

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 Far-UV photons...

Automating the Synthetic Field Method:Application to Sextans A (2002)

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. Simple estimates...

Holwerda, Benne W., Allen, Ronald J., Van Der Kruit, Pieter C.

We have automated the ``Synthetic Field Method'' developed by Gonzalez et al.(1998) and used it to measure the opacity of the ISM in the Local Group dwarf galaxy Sextans A by using the changes in...

106th IAU Symposium on the Milky Way Galaxy (2001)

Allen, Ronald J, Burton, W Butler, Van Woerden, Hugo

The confusion limit on astrometry with SIM (2001)

Rajagopal, Jayadev, Boeker, Torsten, Allen, Ronald J.

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 measure proper...

The Formation of Molecular Clouds (2001)

Pringle, J. E., Allen, Ronald J., Lubow, S. H.

In a recent paper, Elmegreen (2000) has made a cogent case, from an observational point of view, that the lifetimes of molecular clouds are comparable to their dynamical timescales. If so, this has...

Cold Molecular Gas, PDRs, and the Origin of HI in Galaxies (2001)

Gas, Dust, and Young Stars in the Outer Disk of M 31 (2001)

In the currently-accepted model for star formation out of the interstellar gas in galaxies, the basic construction material is assumed to be large clouds of atomic hydrogen (HI). These clouds are...

Cuillandre, Jean-Charles, Lequeux, James, Allen, Ronald J., Mellier, Yannick, Bertin, Emmanuel

Using the Canada-France-Hawaii Telescope we have obtained deep high-resolution CCD images in V and I of a 28'x28' field in the outer disk of M 31 at ~ 116' from the center along the major axis to the...

A New Probe of the Molecular Gas in Galaxies: Application to M101 (2000)

Smith, Denise A., Allen, Ronald J., Bohlin, Ralph C., Nicholson, Natalya, Stecher, Theodore P.

Recent studies of nearby spiral galaxies suggest that photodissociation regions (PDRs) are capable of producing much of the observed HI in galaxy disks. In that case, measurements of the HI column...

Observations of several discrete radio sources at 3.64 and 1.94 centimeters /--by Ronald John Allen. (1967)

Observations of several discrete radio sources at 3.64 and 1.94 centimeters. (1967)

Photocopy of typescript.