2021ApJ...922L..42D -
Astrophys. J., 922, L42-L42 (2021/December-1)
The remarkable spin-down and ultrafast outflows of the highly pulsed supersoft source of Nova Herculis 2021.
DRAKE J.J., NESS J.-U., PAGE K.L., LUNA G.J.M., BEARDMORE A.P., ORIO M., OSBORNE J.P., MROZ P., STARRFIELD S., BANERJEE D.P.K., BALMAN S., DARNLEY M.J., BHARGAVA Y., DEWANGAN G.C. and SINGH K.P.
Abstract (from CDS):
Nova Her 2021 (V1674 Her), which erupted on 2021 June 12, reached naked-eye brightness and has been detected from radio to γ-rays. An extremely fast optical decline of 2 magnitudes in 1.2 days and strong Ne lines imply a high-mass white dwarf. The optical pre-outburst detection of a 501.42 s oscillation suggests a magnetic white dwarf. This is the first time that an oscillation of this magnitude has been detected in a classical nova prior to outburst. We report X-ray outburst observations from Swift and Chandra that uniquely show (1) a very strong modulation of supersoft X-rays at a different period from reported optical periods, (2) strong pulse profile variations and the possible presence of period variations of the order of 0.1-0.3 s, and (3) rich grating spectra that vary with modulation phase and show P Cygni-type emission lines with two dominant blueshifted absorption components at ∼3000 and 9000 km s–1 indicating expansion velocities up to 11,000 km s–1. X-ray oscillations most likely arise from inhomogeneous photospheric emission related to the magnetic field. Period differences between reported pre- and post-outburst optical observations, if not due to other period drift mechanisms, suggest a large ejected mass for such a fast nova, in the range 2 x 10–5-2 x 10–4 M☉. A difference between the period found in the Chandra data and a reported contemporaneous post-outburst optical period, as well as the presence of period drifts, could be due to weakly nonrigid photospheric rotation.
Abstract Copyright:
© 2021. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Novae - Classical novae - Fast novae - X-ray novae - DQ Herculis stars - X-ray astronomy - X-ray transient sources - Cataclysmic variable stars - White dwarf stars - Stellar winds
Simbad objects:
9
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