R. Viotti and P. Grandi, Istituto di Astrofisica Spaziale, CNR, Rome; L. A. Antonelli and S. Rebecchi, BeppoSAX Science Data Center (SDC), Rome; J. M. Muller, BeppoSAX SDC and Space Research Organization of the Netherlands, Utrecht; and M. Villada, Observatorio Astronomico, Cordoba, report: "eta Car was observed as a target-of-opportunity with LECS and MECS onboard BeppoSAX over Mar. 18.1-19.2 UT, during egress from the ongoing spectroscopic event (IAUC 6849). A preliminary comparison with the Dec. 1996 BeppoSAX observations revealed a large flux defect between 1.5 and 6 keV, indicating that the event was still in progress at high energies. The Fe-k line flux appears slightly weaker. The variation can be interpreted as due to a larger amount of absorbing matter (about 3 times) from a hot 4.7-keV component, with only minor changes of its unabsorbed flux. Simultaneous optical spectroscopy with the 2.15-m telescope of the Complejo Astronomico El Leoncito provided the following emission-line equivalent widths (in nm): [NII] 575.5-nm, 1.0; He I 587.6-nm, 0.9; He I 667.8-nm, 1.1; He I 706.5-nm, 1.6. This is about half of their intensity at maximum, confirming the ending of the deeper part of the event."
International Astronomical Union Circular
- Pub Date:
- April 1998