Astronomers working with the Hubble telescope have published a new image of it. It captures the galaxy UGC 5460, home to two recent supernovae. One of them may be an “imposter”.
UGC 5460 is located 60 million light-years from Earth toward the constellation Ursa Major. Like our Milky Way, it is classified as a spiral galaxy. Hubble photos show its bar and winding spiral arms densely studded with bright blue star clusters. A much closer object can also be seen in the left corner of the image. It is a Milky Way star that is only 577 light years away from us.
The galaxy UGC 5460 became a target for Hubble observations because of two supernovae outbreaks there in recent years, designated SN 2011ht and SN 2015as. The telescope collects data for three different programs aimed at studying different types of supernovae.
SN 2015as is a so-called core-collapse supernova. They occur when a massive star exhausts its thermonuclear fuel supply and then collapses under its own gravity. Hubble’s observations of SN 2015as will help researchers understand what happens when a supernova’s expanding shockwave collides with the surrounding gas clouds.
As for SN 2011ht, astronomers have doubts about its nature. It can be either a supernova with core collapse or an “imposter” — a luminous blue variable. This is the name given to a rare variety of stars that are pulsating hypergiants. Their luminosity can exceed that of the sun by millions of times. Luminous blue variables can produce such powerful ejections of matter that they could be mistaken for supernovae — but unlike them, the luminosity survives such events. Hubble will search for a surviving star at the location of SN 2011ht, which will help solve the mystery of the outburst.
Earlier we reported on how the Hubble and Chandra telescopes put together a stellar Valentine’s Day bouquet.
According to Esahubble.org
