APOD: Sharpless 249 and the Jellyfish Nebula (2014 Dec 03)

[APOD Robot]

Sharpless 249 and the Jellyfish Nebula

Explanation: Normally faint and elusive, the Jellyfish Nebula is caught in this alluring telescopic mosaic. The scene is anchored right and left by two bright stars, Mu and Eta Geminorum, at the foot of the celestial twin while the Jellyfish Nebula is the brighter arcing ridge of emission with dangling tentacles below and right of center. In fact, the cosmic jellyfish is part of bubble-shaped supernova remnant IC 443, the expanding debris cloud from a massive star that exploded. Light from the explosion first reached planet Earth over 30,000 years ago. Like its cousin in astrophysical waters the Crab Nebula supernova remnant, the Jellyfish Nebula is known to harbor a neutron star, the remnant of the collapsed stellar core. An emission nebula cataloged as Sharpless 249 fills the field at the upper left. The Jellyfish Nebula is about 5,000 light-years away. At that distance, this narrowband composite image would be about 300 light-years across.

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[Ann]

There is some information about how this image was obtained and what filters were used, but I wish it was clearer and in English.

Ann

[Boomer12k]

So.....the first episode of Star Trek Next Generation wasn't so far off???? Space fairing jelly fish???

Any who...

Fine image....

:---[===] *

[molechaser]

I'm not an astronomer or astrophysicist, but something doesn't sound right about the distances mentioned in todays description. If the light of the supernova reached earth 30,000 years ago then it must have been 30,000 light years away. Now it is only 5000 light years away? It has moved a distance of 25,000 light years in the time span of 30,000 years, which means the nebula/neutron star remnant has been moving toward earth at 83% of the speed of light! Am I in left field on this one?

[Ann]

I'm not an astronomer or astrophysicist, but something doesn't sound right about the distances mentioned in todays description. If the light of the supernova reached earth 30,000 years ago then it must have been 30,000 light years away. Now it is only 5000 light years away? It has moved a distance of 25,000 light years in the time span of 30,000 years, which means the nebula/neutron star remnant has been moving toward earth at 83% of the speed of light! Am I in left field on this one?

The fact that the light of the supernova that created the Jellyfish Nebula reached the Earth 30,000 years ago doesn't mean that the supernova had to be 30,000 light-years away at the time when it exploded.

Consider Supernova 1987A in the Large Magellanic Cloud. This supernova was discovered on February 24, 1987, almost 28 years ago. The fact that it was discovered almost 28 years ago doesn't mean it was 28 light-years away when it exploded. In fact, it was about 160,000 light-years away, since it was located in the Large Magellanic Cloud.

A supernova that was relatively nearby when it was discovered on the Earth 30,000 years ago can be much closer than 30,000 light-years away - or rather, its remnants can be much closer than 30,000 light-years.

Ann

[bactame]

This apod title is dated Dec 3 in the archive BUT is dated Dec 2 onscreen.!!

[owlice]

Thanks! The editors have been alerted.

[Guest]

I'm not an astronomer or astrophysicist, but something doesn't sound right about the distances mentioned in todays description. If the light of the supernova reached earth 30,000 years ago then it must have been 30,000 light years away. Now it is only 5000 light years away? It has moved a distance of 25,000 light years in the time span of 30,000 years, which means the nebula/neutron star remnant has been moving toward earth at 83% of the speed of light! Am I in left field on this one?

Not sure I like the 'slow light' explanation that Anna provided. I would suspect that the numbers in the APOD post are in error, and should be verified against other sources. Esp the 30K years ago number. That is probably where the error is.

[Nitpicker]

I'm not an astronomer or astrophysicist, but something doesn't sound right about the distances mentioned in todays description. If the light of the supernova reached earth 30,000 years ago then it must have been 30,000 light years away. Now it is only 5000 light years away? It has moved a distance of 25,000 light years in the time span of 30,000 years, which means the nebula/neutron star remnant has been moving toward earth at 83% of the speed of light! Am I in left field on this one?

Not sure I like the 'slow light' explanation that Anna provided. I would suspect that the numbers in the APOD post are in error, and should be verified against other sources. Esp the 30K years ago number. That is probably where the error is.

I'm sure Ann was not suggesting 'slow light'.

IC 443 is estimated to be about 5,000 light years away, and the explosion which caused it is estimated to have been first observable from Earth more than 30,000 years ago. That means that the explosion happened more than 35,000 years ago and it took 5,000 years for the light to reach Earth. What we see today is what remains ~30,000 years after the explosion.

[Chris Peterson]

Not sure I like the 'slow light' explanation that Anna provided. I would suspect that the numbers in the APOD post are in error, and should be verified against other sources. Esp the 30K years ago number. That is probably where the error is.

The numbers are just fine. Read Ann's comment again. There was no "slow light" explanation.

[starsurfer]

The figure in light years is a measurement of distance whereas the figure in just years is a measurement of time. The two aren't connected together.

[Tszabeau]

The female face, on the left of frame, is uncanny.

[bactame]

This is an interesting apod with a handsome set of notes among the underlined words. When you go to the link at Supernova Remnant IC 443 it is the apod of June 2, 2006. The image for that apod shows a trail IC 443 produces in radio, x-ray & visible lights. So we see a star trail from which we can estimate its motion....however not said is which way the object is moving. I would think it was left to right. Now today's apod shows 2 dark nebula...which one is IC 443? Furthermore it seems to have traveled left to right and has the same shaped trajectory as the 2006 apod. At any rate, amazing that this SN produced so much debris.

[Chris Peterson]

Now today's apod shows 2 dark nebula...which one is IC 443?

Both of these objects are a part of IC 443.

At any rate, amazing that this SN produced so much debris.

It's not as much debris as it looks like, though. It's still just the remnants of a single star (well, actually there is another supernova remnant mixed in, but most of the material is from a single event). That star probably massed 10 or 20 times that of the Sun, but we're still only looking at a few solar masses worth of material. It's extremely tenuous, and spread out over a large volume. If you were hanging in space in this region, you would not even know these nebulas were there. You'd see nothing but a simple starfield.

[Ron-Astro Pharmacist]

And possibly in around 5,000 years+ a

starbucks.jpg (5.14 KiB) Viewed 28702 times

Wonder how much coffee will be then? We better start a trust fund for our great x 10 (to the fiftith) grandchildren so they can enjoy a morning cup too.