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A New Transient Ultraluminous X-ray Source in NGC 7090
D. J. Walton, M. Heida, M. Bachetti +17
We report on the discovery of a new, transient ultraluminous X-ray source (ULX) in the galaxy NGC 7090. This new ULX, which we refer to as NGC 7090 ULX3, was discovered via monitor…
NIR Counterparts to ULXs (III): Completing the photometric survey and selected spectroscopic results
K. M. López, M. Heida, P. G. Jonker +5
We present results from the remaining sources in our search for near-infrared (NIR) candidate counterparts to ultraluminous X-ray sources (ULXs) within 10 Mpc. We observed…
A naked-eye triple system with a nonaccreting black hole in the inner binary
Th. Rivinius, D. Baade, P. Hadrava +2
Several dozen optical echelle spectra demonstrate that HR 6819 is a hierarchical triple. A classical Be star is in a wide orbit with an unconstrained period around an inner 40 d bi…
The binary mass ratio in the black hole transient MAXI J1820+070
M. A. P. Torres, J. Casares, F. Jiménez-Ibarra +5
We present intermediate resolution spectroscopy of the optical counterpart to the black hole X-ray transient MAXI J1820+070 (=ASASSN-18ey) obtained with the OSIRIS spectrograph on…
The (re)appearance of NGC 925 ULX-3, a new transient ULX
Hannah P. Earnshaw, Marianne Heida, Murray Brightman +8
We report the discovery of a third ULX in NGC 925 (ULX-3), detected in November 2017 by Chandra at a luminosity of erg s. Examination…
From SN2010da to NGC 300 ULX-1: Ten Years of Observations of an Unusual High Mass X-ray Binary in NGC 300
Breanna A. Binder, Stefania Carpano, Marianne Heida +1
In 2010 May, an intermediate luminosity optical transient was discovered in the nearby galaxy NGC 300 by a South African amateur astronomer. In the decade since its discovery, mult…