ASCA Observations of Class I Protostars in the Rho OPH Dark Cloud
Abstract
With the ASCA PV phase, we detected hard X-rays from class I sources deeply embedded in the Rho-Oph cloud. From these objects, we found bipolar flows with the radio observations. These put the sources to be protostars at dynamical mass accretion phase. One of the sources (EL29) shows a flare associated with a heat-up and cooling, while another (WL6) exhibits sinusoidal variation with no large spectral change. The later would be due to the spin rotation of the protostar. The sinusoidal period is about 1 day, which is shorter than the spin period of T Tauri stars (TTSs) of ~3--7 day, which are more evolved than protostars. The averaged spectrum from protostars implies an extremely hot temperature feature (> 10 keV), associated with 6.9 keV H-like Fe line. In fact, the temperature is significantly larger than that of TTSs of several keV. The central region of the cloud would be observed on 02-Mar-1997 again, to make clear whether WL6 has regular sinusoidal variation or not, as well as to obtain a higher spatial resolution images. This will enable us to partly resolve source confusion and to search for X-rays from other protostars in the Rho-Oph cloud. We will report on the X-rays from protostars including new results obtained with the second observations.
- Publication:
-
The Hot Universe
- Pub Date:
- 1998
- Bibcode:
- 1998IAUS..188..236T