A ‘guest star’ suddenly appears

T

he ancient Chinese skywatchers called them “Guest Stars.” Modern science calls them supernovas.

There are two kinds, Type 1 and 2. Type 1 supernovas are more complicated but are also more common. The process is inevitable when a binary star system forms with one star being more massive than the other. More massive stars use up their nuclear fuel faster than their lighter companions. As its core fuel runs out, the more massive star swells into a red giant and then “gives up the ghost.” It belches its outer atmosphere into space, forming an exotic and colorful death shroud called a planetary nebula. Meanwhile, the remaining core collapses into a dense ball of exotic carbon called electron degenerate matter. The remnant is a white dwarf ember about the size of our Earth but almost as dense as 1.4 solar masses. I call it a carbon time bomb. The white dwarf turns into a cosmic Dracula as its companion star’s orbit slowly decays to drift deeper into the gravity well of the dense white dwarf. The white dwarf “sucks” the gas off of the atmosphere of its still living companion. Over time, the dwarf sucks in enough gas to reach a critical density of 1.4 solar masses. This is called the Chandrasekhar limit, named after India-American astrophysicist Subrahmanyan Chandrasekhar. This causes the dwarf to suddenly implode then rebound with such force that it violently explodes.

Although it’s too early to know for sure, that’s what appears to be happening in the far away galaxy shown in this image.

Supernova SN 2022 hrs is in the intermediate spiral galaxy NGC 4647 located in the Virgo Super Cluster of galaxies. Our Milky Way galaxy is located on the outskirts of this supercluster. Look for the bright blue dot near the right outer edge of the smaller galaxy in the center of this image. It looks like a close by, foreground star in our Milky Way galaxy, but

it’s not. Rather, it’s embedded in NGC 4647, which is about 63 million light years from Earth.

It amazed me how blue SN 2022 hrs got during color processing in the PixInsight astrophotography program. It’s definitely brighter than the galactic core of NGC 4647. Recent estimates put the larger galaxy (M60) and NGC 4647 roughly 6 million light years (lyrs) apart. This is equivalent to double the separation between our Milky Way galaxy and its local group companion, the Pinwheel galaxy (M33). M60 and NGC 4647 are vastly different in size and type. NGC 4647 is an intermediate

spiral 90,000 lyrs in diameter while M60 is a massive elliptical 120,000 lyrs in diameter.

Even though it looks like they’re interacting, there is no proof that this is so. Something massive has caused intense star formation to occur on the right side of NGC 4647, giving it the blue color common in high-mass newborn stars. The opposite side contains older more red stars along with some prominent thick dust lanes. Could it be that dark matter around the halos of both galaxies is causing this anomaly? We can only speculate until we get more data.

MOUNT SANGRE OBSERVATORY SN 2022 hrs is a single star (bright blue dot in smaller galaxy near image center) that has catastrophically imploded immediately followed by an obliterating rebound explosion. It is currently outshining all of the hundreds of millions of stars in its host galaxy. SN 2022 hrs was discovered in mid April by Japanese amateur astronomer Koichi Itakagi. As of April 29, this supernova was still brightening.

SKY GUIDE APP Supernova SN 2022 hrs is high above the southeast horizon during prime viewing hours in May. I selected the M 60 galaxy as this will be the largest object visible in the eyepiece. If your telescope is able to resolve M 60, you should easily be able to see the supernova next to it.