Some General Aspects of Geomagnetically Trapped Radiation

Physical principles of radiation belts and entrapment of radiation by geomagnetic field

Geomagnetically Trapped Radiation Produced by a High-Altitude Nuclear Explosion on July 9, 1962

Geomagnetically trapped radiation produced by a high altitude nuclear explosio

Observation of about 500 KeV protons in interplanetary space with Mariner IV

Mariner IV observations of protons in interplanetary spac

Observations of the solar particle event of 5 to 12 February 1965 with Mariner IV AND Injun IV

Solar energetic particle intensities obtained with Mariner IV and Injun IV during 5-12 February 1965 cosmic ray even

Geomagnetically trapped alpha particles

Geomagnetically trapped alpha particles from Injun IV satellite measurement

A photodissociation model for the morphology of the HI near OB associations in M33

We present an approach for analysing the morphology and physical properties of Hi features near giant OB asso- ciations in M33, in the context of a model whereby the Hi excess arises from photodissociation of the molecular gas in remnants of the parent Giant Molecular Clouds (GMCs). Examples are presented here in the environs of NGC604 and CPSDPZ204, two prominent Hii regions in M33. These are the first results of a detailed analysis of the environs of a large number of OB associations in that galaxy. We present evidence for "diffusion" of the far-UV radiation from the OB association through a clumpy remnant GMC, and show further that enhanced CO(1-0) emission appears preferentially associated with GMCs of higher volume density.Comment: Accepted to Ap

Impulsive emission of approximately 40 KeV electrons from the sun

Impulsive emission of high energy electrons from sun and diffusive propagation through interplanetary medium observed by Mariner IV PARTICLE detector

Observation of approximately 500 KeV protons in interplanetary space with Mariner IV

Proton detection of approximately 500 KeV kinetic energy by Mariner IV Space Probe during interplanetary fligh

A new method for obtaining the star formation law in galaxies

We present a new observational method to evaluate the star formation law as formulated by Schmidt: the power-law expression assumed to relate the rate of star formation in a volume of space to the local total gas volume density. Volume densities in the clouds surrounding an OB association are determined with a simple model which considers atomic hydrogen as a photodissociation product on cloud surfaces. The photodissociating flux incident on the cloud is computed from the far-UV luminosity of the OB association and the geometry. We have applied this "PDR Method" to a sample of star-forming regions in M33 using VLA 21-cm data for the HI and GALEX imagery in the far-UV. It provides an estimate of the total volume density of hydrogen (atomic + molecular) in the gas clouds surrounding the young star cluster. A logarithmic graph of the cluster UV luminosity versus the surrounding gas density is a direct measure of the star formation law. However, this plot is severely affected by observational selection, rendering large areas of the diagram inaccessible to the data. An ordinary least-squares regression fit therefore gives a strongly biased result. Its slope primarily reflects the boundary defined when the 21-cm line becomes optically thick, no longer reliably measuring the HI column density. We use a maximum-likelihood statistical approach which can deal with truncated and skewed data, taking into account the large uncertainties in the derived total gas densities. The exponent we obtain for the Schmidt law in M33 is 1.4 \pm 0.2.Comment: Accepted for publication in Ap

Automating the Synthetic Field Method:Application to Sextans A

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 counts of background galaxies seen through the foreground system. The Sextans A results are consistent with the observational relation found by Cuillandre et al. (2001) between dust opacity and HI column density in the outer parts of M31.Comment: 4 pages, 6 figures, submitted for the proceedings of The Dynamics, Structure and History of Galaxies: A Workshop in Honour of Prof. Ken Freema