Detection of a 23.6 min periodic modulation in the optical counterpart of 3XMMJ051034.6–670353

¹ Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG, UK
e-mail: gavin.ramsay@armagh.ac.uk
² Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
³ Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
⁴ Department of Physics & Astronomy, University of Sheffield, Sheffield, S3 7RH, UK
⁵ Instituto de Astrofísica de Canarias, 38205 La Laguna, Tenerife, Spain
⁶ Inter-University Institute for Data Intensive Astronomy, Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch, 7701 South Africa
⁷ Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL, Nijmegen, Netherlands

Received: 25 April 2018
Accepted: 7 June 2018

Abstract

We present high speed optical photometric observations made using the NTT and ULTRACAM of the optical counterpart of 3XMMJ051034.6–670353, which was recently identified as an X-ray source showing a modulation on a period of 23.6 min. Although the optical counterpart is faint (g = 21.4), we find that the u′g′r′ light curves show a periodic modulation on a period which is consistent with the X-ray period. We also obtained three low resolution spectra of 3XMMJ051034.6–670353 using the Gemini South Telescope and GMOS. There is no evidence for strong emission lines in the optical spectrum of 3XMMJ051034.6–670353. We compare and contrast the optical and X-ray observations of 3XMMJ051034.6–670353 with the ultra compact binaries HM Cnc and V407 Vul. We find we can identify a distribution of binary masses in which stable direct impact accretion can occur.