English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

ASASSN-14ko is a nuclear transient at the center of the AGN ESO 253-G003 thatundergoes periodic flares. Optical flares were first observed in 2014 by theAll-Sky Automated Survey for Supernovae (ASAS-SN) and their peak times arewell-modeled with a period of $115.2^{+1.3}_{-1.2}$ days and period derivativeof $-0.0026 \pm 0.0006$. Here we present ASAS-SN, Chandra, HST/STIS, NICER,Swift, and TESS data for the flares that occurred in December 2020, April 2021,July 2021, and November 2021. The HST/STIS UV spectra evolve from blue shiftedbroad absorption features to red shifted broad emission features over $\sim$10days. The Swift UV/optical light curves peaked as predicted by the timingmodel, but the peak UV luminosities varied between flares and the UV flux inJuly 2021 was roughly half the brightness of all other peaks. The X-rayluminosities consistently decreased and the spectra became harder during theUV/optical rise but apparently without changes in absorption. Finally, twohigh-cadence TESS light curves from December 2020 and November 2018 showed thatthe slopes during the rising and declining phases changed over time, whichindicates some stochasticity in the flare's driving mechanism. ASASSN-14koremains observationally consistent with a repeating partial tidal disruptionevent, but, these rich multi-wavelength data are in need of a detailedtheoretical model.

Chandra, HST/STIS, NICER, Swift, and TESS Detail the Flare Evolution of the Repeating Nuclear Transient ASASSN-14ko