SUMMARY OF PROPOSAL 51057
ISAS
KANAGAWA JAPAN 229
SAGANIHARA
YOSHINODAI 3-1-1
Tel: 0427-51-3911 Fax: 0427-59-4253
Medium: 2.5GB8MM
Subject: X-RAY BINARIES
SPECTROSCOPY OF AN X-RAY PULSAR OAO 1657-415 THROUGHOUT THE ECLIPSE TRANSITION
ABSTRACT
From recent Timing observation, the CGRO BASTE determined that the 38-s X-ray pulsar OAO 1657-415 is an eclipsing binary with an orbital period 10.4436, and eclipse duration 1.70 d. Hence, this binary pulsar, OAO 1657-415 is a system very similar with Vela X-1; they are just twin. We propose to observe this X-ray pulsar throughout its eclipse transition covering the phase of full eclipse, pre-eclipse ingress and post-eclipse egress. From the observation we investigate (1) iron emission during non-eclipse phase if it is 6.6 keV as was reported, (2) recombination emission lines from photo-ionization plasma during eclipse, (3) companion star atmosphere from eclipse transion, and (4) interstellar dust halo from soft-band image. These results will be compared with those of Vela X-1.
CO-INVESTIGATORS
| CO-I NAME | INSTITUTE | COUNTRY |
|---|
| TADAHARU DOTANI | ISAS | JAPAN |
| KAZUMI ASAI | ISAS | JAPAN |
| YASUTAKA KONNO | ISAS | JAPAN |
| TAKAO ENDO | ISAS | JAPAN |
TARGETS
| TARGET NAME | PRI | RA | DEC | TIME | TC | OFF | GIS | SIS CNT | OBS |
|---|
| 1)OAO 1657-415 | 2 | 255.1971 | -41.6502 | 80 ks | Y | Y | P | 5.00000 | 1 |
TARGET 1
Epoch: 48516.0000 Period: 10.44360000 Min: 0.8700Max: 0.2300