Tomography of X-ray Nova Muscae 1991: evidence for ongoing mass transfer and stream–disc overflow

• Published in: Monthly notices of the Royal Astronomical Society Vol. 449; no. 2; pp. 1584 - 1592
• Main Authors: Peris, Charith S., Vrtilek, Saeqa D., Steiner, James F., Vrtilek, Jan M., Wu, Jianfeng, McClintock, Jeffrey E., Longa-Peña, Penelope, Steeghs, Danny, Callanan, Paul, Ho, Luis C., Orosz, Jerome A., Reynolds, Mark T.
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 11.05.2015
• Subjects: Astronomy; Black holes; Black holes (astronomy); Disks; Doppler effect; Hot spots; Mass transfer; Nova; Spectrum analysis; Star & galaxy formation; Stars; Symbols; Telescopes; binaries: close; X-rays: binaries; accretion, accretion discs; stars: individual: Nova Muscae 1991
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stv407

We present a spectroscopic analysis of the black hole binary Nova Muscae 1991 in quiescence using data obtained in 2009 with Magellan Echelette on the Magellan Clay telescope and in 2010 with IMACS on the Magellan Baade telescope at the Las Campanas Observatory. Emission from the disc is observed in Hα, Hβ and Ca ii (λ8662). A prominent hotspot is observed in the Doppler maps of all three emission lines. The existence of this spot establishes ongoing mass transfer from the donor star in 2009–2010 and, given its absence in the 1993–1995 observations, demonstrates the presence of a variable hotspot in the system. We find the radial distance to the hotspot from the black hole to be consistent with the circularization radius. Our tomograms are suggestive of stream–disc overflow in the system. We also detect possible Ca ii (λ8662) absorption from the donor star.