APOD: Cetus Galaxies and Supernova (2018 Dec 06)

[APOD Robot]

Cetus Galaxies and Supernova

Explanation: Large spiral galaxy NGC 1055 at top left joins spiral Messier 77 (bottom right) in this cosmic view toward the aquatic constellation Cetus. The narrowed, dusty appearance of edge-on spiral NGC 1055 contrasts nicely with the face-on view of M77's bright nucleus and spiral arms. Both over 100,000 light-years across, the pair are dominant members of a small galaxy group about 60 million light-years away. At that estimated distance, M77 is one of the most remote objects in Charles Messier's catalog, and is separated from fellow island universe NGC 1055 by at least 500,000 light-years. The field of view is about the size of the full Moon on the sky and includes colorful foreground Milky Way stars along with more distant background galaxies. Taken on November 28, the sharp image also includes newly discovered supernova SN2018ivc, its location indicated in the arms of M77. The light from the explosion of one of M77's massive stars was discovered by telescopes on planet Earth only a few days earlier on November 24.

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[Ann]

Very interesting!

As soon as I saw the picture of the supernova in M77, I guessed that it was a Type II supernova. Or at least, I guessed that it wasn't a Type Ia supernova. The new supernova in M77 frankly looked too faint to be a Type Ia one. Type Ia supernovas are made by exploding white dwarfs, and while they release less energy overall than most Type II supernovas, they are very bold and bright in visual light.

Type II supernovas are made by massive stars undergoing core collapse. They release most of their energy as neutrinos, if my memory serves me right. Optically they are usually fainter than their Type Ia cousins.

I thought that SN 2018ivc looked kind of puny compared with the overall brightness of M77. Then again, M77 is a big and bright galaxy, a lot brighter than the Milky Way. According to my software Guide, M77 is about three times brighter than our own galaxy. A lot of the light of M77 may be emitted by the galaxy's active core, however.

I really appreciate this APOD!

Ann

[Boomer12k]

I would try to get my own image of it, but it is too bloody cold!!!!!
Very clear...but near freezing...

Great image, and SN... Maybe someone "over there" got a really good shot of it...of course that would be about 60 million years ago...our time. And the SN Remnant is probably long dispersed... but we get to see the flash...

:---[===] *

[Chris Peterson]

I would try to get my own image of it, but it is too bloody cold!!!!!
Very clear...but near freezing...

Ah... what we call a balmy evening here! It's very far from freezing at the moment... it would have to rise by a good 30° to get close.

[MarkBour]

I would try to get my own image of it, but it is too bloody cold!!!!!
Very clear...but near freezing...

Great image, and SN... Maybe someone "over there" got a really good shot of it...of course that would be about 60 million years ago...our time. And the SN Remnant is probably long dispersed... but we get to see the flash...

:---[===] *

I was just thinking, that at a distance of 60MLyr, if someone in M77 was looking at us with a really, really strong telescope today, they might see our little Earth struck by a meteor, creating a tiny light, the Chicxulub crater, and wiping out much of the life on our planet. It would be a far less impressive event compared to what we're seeing today from M77.

Of course in M77 today, nobody is looking at that supernova. As you pointed out, Boomer, it already happened and got over with 60 million years ago. Maybe we should send them a photograph.

[Ann]

I would try to get my own image of it, but it is too bloody cold!!!!!
Very clear...but near freezing...

Great image, and SN... Maybe someone "over there" got a really good shot of it...of course that would be about 60 million years ago...our time. And the SN Remnant is probably long dispersed... but we get to see the flash...

:---[===] *

I was just thinking, that at a distance of 60MLyr, if someone in M77 was looking at us with a really, really strong telescope today, they might see our little Earth struck by a meteor, creating a tiny light, the Chicxulub crater, and wiping out much of the life on our planet. It would be a far less impressive event compared to what we're seeing today from M77.

Of course in M77 today, nobody is looking at that supernova. As you pointed out, Boomer, it already happened and got over with 60 million years ago. Maybe we should send them a photograph.

Click to view full size image

Well, if we think of the supernova as happening "now" (and we should), then we must also accept the possibility that someone inside M77 might be looking at M77 "now". The problem is the postal service, if we want to send the M77ans the message that we, too, have seen their supernova.

If we were to send them a speed-of-light photograph, showing them our view of their supernova, the problem for them would be that our photograph would arrive at their home some 60 million years too late. Or wait, wouldn't that be 120 million years too late for them?

Click to view full size image

There it is!! Amateur astronomer Annmarie Geniusz of Duluth, Minnesota,
examines M31, the Andromeda Galaxy (upper left corner),
through 7x50 binoculars on a recent clear night. Photo: Bob King.

When I was 15 years old, I had just read about the Andromeda galaxy and realized that I could see it myself in the sky. Long story short, I grabbed my parents' binoculars and found Andromeda. I felt, extremely strongly, that there was someone inside that fuzzy yellowish splotch in the sky looking back at me, and I almost had to resist the urge to wave at them.

But then I started to work out the math. If I waved at them, the light (or whatever) from my arm and hand movement would take two million years to reach Andromeda. And then, if someone in Andromeda were to catch my wave and wave back, their wave would reach the Earth four million years after I had originally waved at them.

The postal service in space is lousy.

Ann

[De58te]

As we are on flights of fancy. Since the dinosaur extinction event happened 65 million years ago, the people on M77 would see the Earth 5 million years after the dinosaurs died. But lets think about people with telescopes in NGC 1055. In a spiral arm facing us so they won't have too many stars in the way. Since the Milky Way and Andromeda Galaxy are some 2.3 million light years apart, and NGC 1055 and M77 are just 500,000 light years apart, they are over 4 times closer together than Andromeda and us. The galaxies being all about the same size 100,000 light years, and Ann said M77 is some 3 times brighter than us, then I figure that M77 must be quite a sight in the night sky to the people with telescopes in NGC 1055. We should send a picture of supernova SN2018ivc to NGC 1055 for their amusement and they can send their pictures of M77 back to us.

[Fred the Cat]

The postal service in space is lousy.

Ann

You need a quantum telescope. The cats may find themselves out of the box but not out of the bag.

[MarkBour]

The postal service in space is lousy.

Ann

True. Still, we just can't stop looking at all of the cool messages.