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The planets around NN Ser: still there

Marsh, TR, Parsons, SG, Bours, MCP, Littlefair, SP, Copperwheat, CM, Dhillon, VS, Breedt, E, Caceres, C and Schreiber, MR (2013) The planets around NN Ser: still there. Monthly Notices of the Royal Astronomical Society, 437 (1). pp. 475-488. ISSN 0035-8711

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We present 25 new eclipse times of the white dwarf binary NN Ser taken with the high-speed camera ULTRACAM on the WHT and NTT, the RISE camera on the Liverpool Telescope, and HAWK-I on the VLT to test the two-planet model proposed to explain variations in its eclipse times measured over the last 25 years. The planetary model survives the test with flying colours, correctly predicting a progressive lag in eclipse times of 36 seconds that has set in since 2010 compared to the previous 8 years of precise times. Allowing both orbits to be eccentric, we find orbital periods of 7.9 +/- 0.5 yr and 15.3 +/- 0.3 yr, and masses of 2.3 +/- 0.5 Mjup and 7.3 +/- 0.3 Mjup. We also find dynamically long-lived orbits consistent with the data, associated with 2:1 and 5:2 period ratios. The data scatter by 0.07 seconds relative to the best-fit model, by some margin the most precise of any of the proposed eclipsing compact object planet hosts. Despite the high precision, degeneracy in the orbit fits prevents a significant measurement of a period change of the binary and of N-body effects. Finally, we point out a major flaw with a previous dynamical stability analysis of NN Ser, and by extension, with a number of analyses of similar systems.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record T. R. Marsh, S. G. Parsons, M. C. P. Bours, S. P. Littlefair, C. M. Copperwheat, V. S. Dhillon, E. Breedt, C. Caceres, M. R. Schreiber, The planets around NN Serpentis: still there, Monthly Notices of the Royal Astronomical Society, Volume 437, Issue 1, 01 January 2014, Pages 475–488, is available online at: http://dx.doi.org/10.1093/mnras/stt1903
Uncontrolled Keywords: astro-ph.SR; astro-ph.SR; astro-ph.EP
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Oxford University Press
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Date Deposited: 25 Jul 2019 13:07
Last Modified: 04 Sep 2021 09:09
DOI or ID number: 10.1093/mnras/stt1903
URI: https://researchonline.ljmu.ac.uk/id/eprint/11037
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