MKT J170456.2–482100: the first transient discovered by MeerKAT. Issue 1 (30th October 2019)

• Record Type: Journal Article
• Authors: Driessen, L N; McDonald, I; Buckley, D A H; Caleb, M; Kotze, E J; Potter, S B; Rajwade, K M; Rowlinson, A; Stappers, B W; Tremou, E; Woudt, P A; Fender, R P; Armstrong, R; Groot, P; Heywood, I; Horesh, A; van der Horst, A J; Koerding, E; McBride, V A; Miller-Jones, J C A; Mooley, K P; Wijers, R A M J
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 491:Issue 1(2020)
• Page Start: 560
• Page End: 575
• Publication Date: 2019-10-30
• Subjects: stars: activity -- binaries: spectroscopic -- stars: flare -- stars: peculiar; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz3027
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We report the discovery of the first transient with MeerKAT, MKT J170456.2–482100, discovered in ThunderKAT images of the low-mass X-ray binary GX339–4. MKT J170456.2–482100 is variable in the radio, reaching a maximum flux density of $0.71\pm 0.11\, \mathrm{mJy}$ on 2019 October 12, and is undetected in 15 out of 48 ThunderKAT epochs. MKT J170456.2–482100 is coincident with the chromospherically active K-type sub-giant TYC 8332-2529-1, and $\sim 18\, \mathrm{yr}$ of archival optical photometry of the star shows that it varies with a period of $21.25\pm 0.04\, \mathrm{d}$ . The shape and phase of the optical light curve changes over time, and we detect both X-ray and UV emission at the position of MKT J170456.2–482100, which may indicate that TYC 8332-2529-1 has large star spots. Spectroscopic analysis shows that TYC 8332-2529-1 is in a binary, and has a line-of-sight radial velocity amplitude of $43\, \mathrm{km\, s^{-1}}$ . We also observe a spectral feature in antiphase with the K-type sub-giant, with a line-of-sight radial velocity amplitude of $\sim 12\pm 10\, \mathrm{km\, s^{-1}}$, whose origins cannot currently be explained. Further observations and investigation are required to determine the nature of the MKT J170456.2–482100 system.