[Normal Stars and WD -- Invited ]

X-ray studies of star and planet formation

Eric Feigelson, Penn State University

Although hardly conceived during the preparation of the satellite, the Chandra X-ray Observatory is playing a surprisingly strong role in studies of star and planet formation. Chandra high-resolution images of active molecular clouds often reveal hundreds of low-mass young stars, from Class I protostars through Class III disk-free pre-main sequence stars, as well as massive OB stars. Chandra time series and spectra provide insights into powerful magnetic flares that are unavailable at other wavelengths. Though not fully confirmed, the illumination of protoplanetary disks by high energy output of these flares may play critical roles in diverse processes of planet formation. Chandra's contributions to several broad themes in star and planet formation are briefly outlined: history and efficiency of star formation in molecular clouds; universality of the stellar Initial Mass Function; triggered star formation on the periphery of HII regions; stellar environment of OB stars; the large-scale effects of OB winds on molecular clouds; and the X-ray irradiation of protoplanetary disks.