- Pan-Starrs
- Asas-Sn
- Atlas
- Holoien, TWS
- Huber, ME
- Shappee, BJ
- Eracleous, M
- Auchettl, K
- Brown, JS
- Tucker, MA
- Chambers, KC
- Kochanek, CS
- Stanek, KZ
- Rest, A
- Bersier, D
- Post, RS
- Aldering, G
- Ponder, KA
- Simon, JD
- Kankare, E
- Dong, D
- Hallinan, G
- Reddy, NA
- Sanders, RL
- Topping, MW
- Bulger, J
- Lowe, TB
- Magnier, EA
- Schultz, ASB
- Waters, CZ
- Willman, M
- Wright, D
- Young, DR
- Dong, S
- Prieto, JL
- Thompson, TA
- Denneau, L
- Flewelling, H
- Heinze, AN
- Smartt, SJ
- Smith, KW
- Stalder, B
- Tonry, JL
- Weiland, H
- et al.
© 2019. The American Astronomical Society. All rights reserved.. We present the discovery of PS18kh, a tidal disruption event discovered at the center of SDSS J075654.53+341543.6 (d ≃ 322 Mpc) by the Pan-STARRS Survey for Transients. Our data set includes pre-discovery survey data from Pan-STARRS, the All-sky Automated Survey for Supernovae, and the Asteroid Terrestrial-impact Last Alert System as well as high-cadence, multiwavelength follow-up data from ground-based telescopes and Swift, spanning from 56 days before peak light until 75 days after. The optical/UV emission from PS18kh is well-fit as a blackbody with temperatures ranging from T ≃ 12,000 K to T ≃ 25,000 K and it peaked at a luminosity of L ≃ 8.8 × 1043 erg s-1. PS18kh radiated E = (3.45 ± 0.22) × 1050 erg over the period of observation, with (1.42 ± 0.20) × 1050 erg being released during the rise to peak. Spectra of PS18kh show a changing, boxy/double-peaked Hα emission feature, which becomes more prominent over time. We use models of non-axisymmetric accretion disks to describe the profile of the Hα line and its evolution. We find that at early times the high accretion rate leads the disk to emit a wind which modifies the shape of the line profile and makes it bell-shaped. At late times, the wind becomes optically thin, allowing the non-axisymmetric perturbations to show up in the line profile. The line-emitting portion of the disk extends from r in ∼ 60r g to an outer radius of r out ∼ 1400r g and the perturbations can be represented either as an eccentricity in the outer rings of the disk or as a spiral arm in the inner disk.