X-Ray Emission from Candidate Stellar Merger Remnant TYC 2597-735-1 and Its Blue Ring Nebula

Creators: Günther, Hans Moritz; Hoadley, Keri; Günther, Maximilian N.; Metzger, Brian D.; Schneider, P. C.; Shen, Ken J.

Abstract

Tight binary or multiple-star systems can interact through mass transfer and follow vastly different evolutionary pathways than single stars. The star TYC 2597-735-1 is a candidate for a recent stellar merger remnant resulting from a coalescence of a low-mass companion with a primary star a few thousand years ago. This violent event is evident in a conical outflow ("Blue Ring Nebula") emitting in UV light and surrounded by leading shock filaments observed in Hα and UV emission. From Chandra data, we report the detection of X-ray emission from the location of TYC 2597-735-1 with a luminosity log(L_X / L_(bol) = -5.5. Together with a previously reported period of ~14 days, this indicates ongoing stellar activity and the presence of strong magnetic fields on TYC 2597-735-1. Supported by stellar evolution models of merger remnants, we interpret the inferred stellar magnetic field as dynamo action associated with a newly formed convection zone in the atmosphere of TYC 2597-735-1, though internal shocks at the base of an accretion-powered jet cannot be ruled out. We speculate that this object will evolve into an FK Com–type source, i.e., a class of rapidly spinning magnetically active stars for which a merger origin has been proposed but for which no relic accretion or large-scale nebula remains visible. We also detect likely X-ray emission from two small regions close to the outer shock fronts in the Blue Ring Nebula, which may arise from inhomogeneities either in the circumstellar medium or in the mass and velocity distribution in the merger-driven outflow.

Additional Information

© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 October 2; revised 2022 February 10; accepted 2022 February 10; published 2022 March 16. This research has made use of data obtained from the Chandra Data Archive and the Chandra Source Catalog and software provided by the Chandra X-ray Center (CXC) in the application packages CIAO and Sherpa. This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. We acknowledge the use of TESS High-Level Science Products (HLSP) produced by the Quick-Look Pipeline (QLP) at the TESS Science Office at MIT, which are publicly available from the Mikulski Archive for Space Telescopes (MAST). Funding for the TESS mission is provided by NASA's Science Mission directorate. This research made use of lightkurve, a Python package for Kepler and TESS data analysis (Lightkurve Collaboration et al. 2018). This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. H.M.G. was supported by the National Aeronautics and Space Administration through Chandra Award No. GO9-20018X issued by the Chandra X-ray Observatory Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. K.H. was supported by the David & Ellen Lee Prize Postdoctoral Fellowship in Experimental Physics at Caltech and the National Aeronautics and Space Administration Astrophysics Research and Analysis (APRA) grant No. 80NSSC20K0395. M.N.G. acknowledges support from MIT's Kavli Institute as a Juan Carlos Torres Fellow and from the European Space Agency (ESA) as an ESA Research Fellow. B.D.M. is supported in part by the National Science Foundation (grant AST-2009255). P.C.S. acknowledges support by DLR 50 OR 2102. K.J.S. is supported by NASA through the Astrophysics Theory Program (NNX17AG28G and 80NSSC20K0544). We thank the referee for thoughtful and detailed comments. Facilities: Chandra/ACIS - , TESS - . Software: AstroPy (Astropy Collaboration et al. 2013, 2018), CIAO (Fruscione et al. 2006), NumPy (Van Der Walt et al. 2011; Harris et al. 2020), Matplotlib (Hunter 2007), Sherpa (Doe et al. 2007; Burke & Laurino 2021), Lightkurve (Lightkurve Collaboration et al. 2018), Tesscut (Brasseur et al. 2019), Eleanor (Feinstein et al. 2019).

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