We present and analyse a new tidal disruption event ( TDE ) , AT2017eqx at redshift z = 0.1089 , discovered by Pan-STARRS and ATLAS .
The position of the transient is consistent with the nucleus of its host galaxy ; the spectrum shows a persistent blackbody temperature T \gtrsim 20 , 000 K with broad H I and He II emission ; and it peaks at a blackbody luminosity of L \approx 10 ^ { 44 } erg s ^ { -1 } .
The lines are initially centered at zero velocity , but by 100 days the H I lines disappear while the He II develops a blueshift of \gtrsim 5 , 000 km s ^ { -1 } .
Both the early- and late-time morphologies have been seen in other TDEs , but the complete transition between them is unprecedented .
The evolution can be explained by combining an extended atmosphere , undergoing slow contraction , with a wind in the polar direction becoming visible at late times .
Our observations confirm that a lack of hydrogen a TDE spectrum does not indicate a stripped star , while the proposed model implies that much of the diversity in TDEs may be due to the observer viewing angle .
Modelling the light curve suggests AT2017eqx resulted from the complete disruption of a solar-mass star by a black hole of \sim 10 ^ { 6.3 } M _ { \odot } .
The host is another Balmer-strong absorption galaxy , though fainter and less centrally concentrated than most TDE hosts .
Radio limits rule out a relativistic jet , while X-ray limits at 500 days are among the deepest for a TDE at this phase .