1981/01/01 by Eric D. Feigelson, William M. DeCampli · 4 citations
Physics and Astronomy · Engineering · #Stellar, planetary, and galactic studies #Astronomical Observations and Instrumentation #Astrophysics and Star Formation Studies
paper · doi:10.1086/183449
openalex publication_date 1981/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
Observations of 28 T Tauri stars with the Imaging Proportional Counter on board the Einstein (HEAO 2) X-ray Observatory are reported. Eight are detected with soft X-ray luminosities of approximately 10 to the 30th ergs/sec in the Taurus cloud and approximately 10 to the 31st ergs/sec in the Orion cloud. One star, DG Tauri, is found to be highly variable, increasing in brightness by an order of magnitude in 35 minutes, with a significant rise within 4 minutes. Theoretical considerations indicate the X-rays are not produced in the entire envelope emitting the hydrogen Balmer lines, and the rapid variability suggests the emission occurs close to the photosphere rather than far from the star.