NGC1555Sometimes known as Hind's Variable Nebula, Sh2-238 or HH 155 (in a strange numerical coincidence), is a variable nebula 4 light years across, illuminated by the protoypal star T Tauri. It is 400 light years away from Earth. It was was discovered in 1852, by John Russell Hind.
T Tauri Variable StarIt is a variable star in the constellation Taurus, the prototype of the T Tauri stars. T Tauri appears from Earth amongst the Hyades cluster, not far from ε Tauri, but, being 470 ly away, it is actually 320 light-years behind and not a member of the cluster.
NGC1554Struve's Lost Nebula, was discovered by Struve and confirmed by d'Arrest. Despite this, at NGC 1554's coordinates, (epoch J2000) 04h 22m 00.0s +19° 36′ 00″ there is no nebula. However, there is a 14th magnitude star, 4' west-southwest of T Tauri, so there is a possibility that the nebula Struve discovered was surrounding a variable star and it only flares up every now and then (perhaps even on a centuries long cycle). Alternatively it may have been an error caused by a pair of faint stars.
There are two clearly visible nebulous objects (the middle left of the large image) that look like galaxies or possibly stars embedded in a reflection nebula, yet not reported in Simbad.
Animated Picure: Timelapse of variable nebula activity of NGC 1555 from October 2022 to March 2023 compiled from contributions from bigamateurtelescope.com
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