XRISM XTEND observation 201058010

Title

MASS MEASUREMENT OF THE WHITE DWARF IN EX HYA WITH HIGH RESOLUTION X-RAY SPECTROSCOPY

Abstract

The mass of white dwarfs (WDs) within binary systems is a crucial parameter for understanding their evolution into type-Ia supernovae. Among WD binary systems, we focus on the X-ray luminous object, the intermediate polars (IPs) for XRISM observations. The measurement of gravitational redshifts and the bulk Doppler shifts of atomic lines have proven to be robust tools for mass determination, as demonstrated by Hayashi et al.(2023) with Chandra HETG data. We propose a 75 ksec XRISM observation of the IP system EX Hya, to which we already applied the method for lighter elements, to ascertain the WD mass with 10% accuracy with Fe-K lines.

FITS header

TELESCOP= 'XRISM   '           / Mission name
INSTRUME= 'XTEND   '           / Instrument name
OBS_ID  = '201058010'          / Observation identification string
OBJECT  = 'EX_HYA  '           / Object name
OBSERVER= 'TAICHI ICHIKAWA'    / PI name
OBS_MODE= 'POINTING'           / POINTING or SLEW or ALL
RA_OBJ  =             193.1009 / [deg] Object Right ascension
DEC_OBJ =             -29.2489 / [deg] Object Declination
RA_PNT  =     193.103979673339 / Pointing RA
DEC_PNT =    -29.2477929085498 / Pointing DEC
RA_NOM  =     193.101334499172 / [deg] Nominal aspect point R.A.
DEC_NOM =    -29.2489232954401 / [deg] Nominal aspect point Dec.
PA_NOM  =     294.100314904517 / [deg] Nominal aspect point roll.
TELAPSE =               163248 / Elapsed time
DATE-OBS= '2025-07-12T19:26:45' / Start date
DATE-END= '2025-07-14T16:47:33' / Stop date
ONTIME  =         76612.566095 / On-source time
EXPOSURE=         76612.566095 / 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    = '2025-07-19T02:24:58' / Date and time this file was created or updated
SIB2_VER= 'V04.00  '           / SIB2 version JAXA

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