of Physics and Astronomy
Phone: (219) 464-5379
Education: University of Pennsylvania, Ph.D.
Major field: Astronomy and Astrophysics
Teaching specialty: astronomy, astrophysics, and NASA space science
Observational astronomy: studying the properties of evolved stars and binary stars, primarily at visible and infrared wavelengths.
Prof. Hrivnak has been actively engaged in the identification and study of "proto-planetary nebulae" (PPN), objects in transition between the asymptotic giant branch (AGB) and planetary nebula (PN) phases in the evolution of stars. This is a short-lived phase (few thousand years) near the end of the life of most stars. During this phase, the star, which had been losing mass during the previous AGB phase, becomes enshrouded in an expanding shell of gas and dust.
In collaboration with Dr. Sun Kwok (Hong Kong University), he has used data from the Infrared Astronomical Satellite (IRAS) to identify candidate PPNs on the basis of their large infrared excesses due to circumstellar dust. These have been the subject of follow-up studies using ground-based telescopes in Hawaii (CFHT,UKIRT,IRTF,Gemini), Arizona (KPNO), Chile (CTIO), and also space-based Hubble Space Telescope (HST), Infrared Space Observatory (ISO), and Spitzer Space Telescope. Spectacular high-resolution images of several bipolar PPN have been obtained with HST (see below).
A program to study the light variations of PPN is being carried out at the Valparaiso Univ. Observatory, with undergraduates actively participating in this research.
Prof. Hrivnak has also been involved in the study of binary star systems. By combining spectroscopic and photometric observations, he has determined the fundamental properties (mass, size, luminosity, temperature) of a number of these interacting binary stars.
2001 Rubel Lecture in Christianity and Higher Learning
"Glorious are the Works of the Lord: Studying the Heavens" (B. J. Hrivnak).