Feigelson completed a dissertation at Harvard under Riccardo Giacconi, and took a post-doctoral position at MIT with Claude Canizares. In 2003, he started a faculty position at Penn State where he has remained. Here he teaches all levels of astronomy from Astro 001 to graduate level classes. He conducts research in two areas -- X-ray studies of star formation and the cross-disciplinary astrostatistics -- where he wrote seminal papers in the foundation of the subfields and continues to play a leading role.
- Using the Einstein and ROSAT observatories in the 1980-90s, he discovered high levels of magnetic activity in young solar-type stars, allowing X-ray telescopes to trace pre-main sequence populations. He authored a major review in 1999 on high-energy processes in young stars. The field was propelled forward by NASA's high-resolution Chandra X-ray Observatory. Feigelson and his collaborators conducted the Chandra Orion Ultradeep Project (2005 Special Issue of ApJSuppl) and the current MYStIX project (2013--). This combines X-ray and infrared surveys of massive star forming regions to trace young stellar populations. The work also has implications for meteoritics and planet formation.
For several years, Feigelson has been a Scientific Editor of the Astrophysical Journal specializing in X-ray astronomy, star and planet formation, exoplanets, and statistical methodology. He is also on organizing councils of the AAS Working Group on Astroinformatics and Astrostatisitcs, and the International Astrostatistics Association. He has recently been coappointed as Professor in the Department of Statistics at Penn State.