APOD: Antares and Clouds (2012 Apr 17)

[henrystar]

It is so nice that the globular cluster happens to be offset from the other things. What a help for studying it clearly! Just another blessing from God.

[Guest]

Antares will certainly end in a supernova, sometime in the next million years or so (and possibly in a few minutes).

If it happened in the next few minutes would we still see the same view of Antares for 550 years? This shouldn't confuse me, but it does.

[rstevenson]

Yes, the view would remain pretty much the same. But we wouldn't know it had gone nova in the next few minutes for about 550 years.

Less confused now?

Rob

[Chris Peterson]

Antares will certainly end in a supernova, sometime in the next million years or so (and possibly in a few minutes).

If it happened in the next few minutes would we still see the same view of Antares for 550 years? This shouldn't confuse me, but it does. :oops:

"Now" usually refers to when we observe something; in astronomy, it is seldom necessary to correct for light time. Unless it is stated otherwise, you should assume that something happens when we observe it.

[eder]

I'm going to paste my comment from a Recent Submissions thread here:

Ivan Eder, you've done full justice to this colorful region of the sky. You really bring out how the emission and reflection nebulosity is unevenly distributed around Sigma Orionis. (It's a double star, and I think that only one of the components is hot enough to produce a lot of Ha emission.) But please not how the nebulosity around both Sigma Orionis and Antares seems "thicker" on the right side of the star, as if some strong "wind" had blown the gas and dust to one side of the stars.

Let me add that this is a glorious image of a fantastically colorful region of the sky. We see the trademark blue reflection nebulosity here, but the Antares region is also one of the few regions of the sky where we can see yellow reflection nebulosity, as the light from the red supergiant Antares is reflected in dust clouds. What a coincidence that photogenic globular cluster M4, a background object, is seen among the sparkling colors of the Antares region.

Ann,
Do you mean sigma Scorpii instead of sigma Orionis?
Thank you for your nice comment, appreciate it.

Ivan

[Ann]

Ivan wrote:

Ann,
Do you mean sigma Scorpii instead of sigma Orionis?

Ooops! Yes, of course!

Ann

[sage]

OH, thank you both, Chris and Rob.

Less confused now?

haha! Yes!

[Guest]

I looked up some sky maps, it seems the brighter globular cluster towards the bottom of the picture should be M80, while the smaller one near the top should be M4. does anyone else think so?

There is a mistake in the APOD description. The cluster described as being 'far behind Antares'
is actually NGC 6144 while the bright cluster to the lower right of the pic is the cluster M4.

The description was indeed unclear. Which globular cluster is M4 is now better described. I apologize for the oversight.

- RJN

[eder]

I looked up some sky maps, it seems the brighter globular cluster towards the bottom of the picture should be M80, while the smaller one near the top should be M4. does anyone else think so?

The smaller globular is NGC 6144 closer to Antares, the larger and brighter one is Messier 4 towards the bottom. M80 is not shown on this image.

Ivan