XRISM PIERCING THE DENSE STELLAR WIND OF LUMINOUS BLUE VARIABLE IN ETA CARINAE
Mass-loss is widely recognized as a key parameter to understand a stellar chemical evolution following supernova. However, a mass loss rate of Luminous Blue Variables (LBVs) are very difficult to measure due to their dense wind and understood only with digit precision of 10^-3 Mo / yr. In order to improve this accuracy, we propose to observe Eta Carinae at around the periastron passage. Eta Carinae is a long period binary of a primary LBV star and a secondary WR or O star with 5.5 yr period. During the periastron passage, the X-ray plasma heated by wind-wind collision becomes compact, the X-rays from which pierces the LBV wind with narrow beam size. Using the Fe-K absorption edge, the narrow beam enables promising us to pursue to measure the mass-loss rate of the LBV.
TELESCOP= 'XRISM ' / Mission name INSTRUME= 'XTEND ' / Instrument name OBS_ID = '201037010' / Observation identification string OBJECT = 'ETA_CARINAE' / Object name OBSERVER= 'YOSHITOMO MAEDA' / PI name OBS_MODE= 'POINTING' / POINTING or SLEW or ALL RA_OBJ = 161.2648 / [deg] Object Right ascension DEC_OBJ = -59.6845 / [deg] Object Declination RA_PNT = 161.270567815501 / Pointing RA DEC_PNT = -59.6868654964125 / Pointing DEC RA_NOM = 161.266656627641 / [deg] Nominal aspect point R.A. DEC_NOM = -59.6852201402521 / [deg] Nominal aspect point Dec. PA_NOM = 0.00600610118608813 / [deg] Nominal aspect point roll. TELAPSE = 220431 / Elapsed time DATE-OBS= '2025-08-05T09:14:24' / Start date DATE-END= '2025-08-07T22:28:15' / Stop date ONTIME = 85979.456433 / On-source time EXPOSURE= 85979.456433 / Exposure time PROCVER = '03.02.014.010' / Processing script version MKFFF = 'ISAS/JAXA' / Origin of First FITS file ORIGIN = 'GSFC/NASA' / Origin of Processed FITS file SOFTVER = 'Hea_12Mar2025_V6.35_XRISM_28Feb2025_V002' / Version of HEADAS used CALDBVER= 'gen20241115_xtd20241115_rsl20241115' / Version of CALDB used DATE = '2025-08-15T09:01:46' / Date and time this file was created or updated SIB2_VER= 'V04.00 ' / SIB2 version JAXA