Classification certificate for object 2018dyk
TNS Classification Report No. 2515 [ 2018TNSCR1182....1H ]

Date Received (UTC): 2018-08-15 01:01:20
Sender: Dr. Iair Arcavi
Group: None

I Arcavi J Burke D Hiramatsu C McCully A Howell G Hosseinzadeh (LCO) D French (Carnegie) A Zabludoff (Arizona) S Valenti (Davis) report/s a classification of object: AT 2018dyk

Type: TDE
Redshift: 0.037

Remarks: We obtained a spectrum of the nuclear transient AT 2018dyk/ZTF18aajupnt on 2018 August 12.3 UT with the robotic FLOYDS instrument mounted on the Las Cumbres Observatory 2-meter telescope on Haleakala, Hawai'i, under the "Transients in Galaxy Centers" program (PI: Arcavi). Using Superfit (Howell et al. 2005, ApJ, 634, 1190), we find a reasonable fit to the tidal disruption event (TDE) ASASSN-14ae (Holoien et al. 2014, MNRAS, 445, 3263; Arcavi et al. 2014, ApJ, 793, 38) at the redshift of the host galaxy (z=0.037; SDSS). The spectrum displays possible broad H-alpha, H-beta and He II emission lines, similar to those seen in other TDEs. Unlike other TDEs, however, it displays narrow H-beta and He II emission lines not seen in the SDSS host spectrum, stronger narrow H-alpha compared to the SDSS host spectrum, and it does not display a blue continuum. The ZTF light curve retrieved from the ZTF public alert stream via MARS (https://mars.lco.global/7014426/) peaks at an apparent magnitude of about 18.6, which at the deduced redshift corresponds to an absolute magnitude of -17.4, several magnitudes fainter than most TDEs but similar to the TDE iPTF16fnl (Blagorodnova et al. 2017, ApJ, 844, 46). The SDSS spectrum of the host galaxy shows weak H-alpha emission indicative of only weak current star formation, and does not show strong Balmer absorption which would be indicative of a recent strong starburst. The recent star formation history of the host galaxy appears similar to that of the TDE PTF09ge (Arcavi et al. 2014, ApJ, 793, 38), which formed less than 1% of it's current stellar mass in the last Gyr (French et al. 2016, ApJL, 818, 21; French et al. 2017, ApJ, 835, 176).

The following Classification spectrum was provided:

Obsdate: 2018-08-12 07:00:56
Instrument: FLOYDS-N
Telescope: Faulkes Telescope North

Details of the object and its spectra can be viewed here: https://wis-tns.weizmann.ac.il/object/2018dyk