Periodicities in the K2 light curve of HP Librae

Solanki, Siddhant; Kupfer, Thomas; Blaes, Omer; Breedt, Elmé; Scaringi, Simone

Abstract

We analyse Kepler/K2 light-curve data of the AM CVn system HP Librae (HP Lib). We detect with confidence four photometric periodicities in the system: the orbital frequency, both positive and negative superhumps, and the positive apsidal precession frequency of the accretion disc. This is only the second time that the apsidal precession frequency has ever been directly detected in the photometry of a helium accreting system, after SDSS J135154.46-064309.0. We present phase-folded light curves and sliding power spectra of each of the four periodicities. We measure rates of change of the positive superhump period of ∼10−7 d. We also redetect a quasi-periodic oscillation (QPO) at ∼300 cyc d–1, a feature that has been stable over decades, and show that it is harmonically related to two other QPOs, the lowest of which is centred on the superhump/orbital frequency. The continuum power spectrum is consistent with a single power law with no evidence of any breaks within our observed frequency range.

Citation

Solanki, S., Kupfer, T., Blaes, O., Breedt, E., & Scaringi, S. (2021). Periodicities in the K2 light curve of HP Librae. Monthly Notices of the Royal Astronomical Society, 500(1), 1222-1230. https://doi.org/10.1093/mnras/staa3240

• Journal Article Type: Article
• Acceptance Date: Oct 15, 2020
• Online Publication Date: Oct 20, 2020
• Publication Date: 2021-01
• Deposit Date: Dec 31, 2020
• Publicly Available Date: Jun 29, 2021
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Royal Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 500
• Issue: 1
• Pages: 1222-1230
• DOI: https://doi.org/10.1093/mnras/staa3240
• Public URL: https://durham-repository.worktribe.com/output/1255123