Talk:G299.2-2.9

4500 years old contradiction?

The lead says the remnant is 4500 years old and that it is 16,000 light years away. If that were literally true, we would not be able to see it for another 11,500 years, no? Nicolas Perrault (talk) 02:48, 29 April 2024 (UTC)

You are correct. I was jarred by the same time inconsistency. Your calculations are correct, given the figures in this article. They're wrong. 173.21.38.106 (talk) 03:47, 29 April 2024 (UTC)

The supernova could have happened 4,500 years ago from our perspective, and the object be 16,000 light years away. That just means that the actual supernova event occurred approximately 20,500 years ago. 132.160.77.184 (talk) 03:55, 29 April 2024 (UTC)

Perhaps the values are transposed 75.115.129.168 (talk) 13:19, 29 April 2024 (UTC)

The ref says the age is 4500 years:

• "Because it is older than most supernova remnants caused by these explosions, at an age of about 4500 years, G299.2-2.9 provides astronomers with an excellent opportunity to study how these objects evolve over time."
• https://chandra.harvard.edu/blog/taxonomy/term/5?page=7

Johnjbarton (talk) 17:43, 29 April 2024 (UTC)

We can only meaningfully talk about a distant object's apparent age based on what we see now. See One-way_speed_of_light. Holy (talk) 23:43, 29 April 2024 (UTC)

Then shouldn't we specify that it is ~20500 years old or so and then say it first appeared roughly 4500 years ago? Joecompan (talk) 00:14, 30 April 2024 (UTC)

No. We should say what the ref says. The ref says that analysis based on the radius of the remnant shell gives an age of 4500 years. That is the age of the shell blast wave structure.

The age of the nova is irrelevant. Astronomers will look around for other nova remnants and collect a bunch of these with different ages, then compare the structure they observe to nova explosion models. Over the history of the universe the explosion model does not change, so the date of the nova does not matter.

To reiterate, 20,500 years is not relevant to anything. Johnjbarton (talk) 00:33, 30 April 2024 (UTC)

I reworded the intro again, is this better? Johnjbarton (talk) 02:32, 30 April 2024 (UTC)

That's really good, thanks! It was fine as it was, but you've really improved it. Holy (talk) 03:13, 30 April 2024 (UTC)

Did you know nomination

The following is an archived discussion of the DYK nomination of the article below. Please do not modify this page. Subsequent comments should be made on the appropriate discussion page (such as this nomination's talk page, the article's talk page or Wikipedia talk:Did you know), unless there is consensus to re-open the discussion at this page. No further edits should be made to this page.

The result was: promoted by AirshipJungleman29 talk 16:11, 19 April 2024 (UTC)

(

• Comment or view
• Article history

)

Shell structure of G299.2-2.9

• ... that G299.2-2.9 (pictured) was the result of a natural thermonuclear explosion? Source: https://chandra.harvard.edu/photo/2011/g299/ https://iopscience.iop.org/article/10.1086/520105
  • Reviewed:
  • Comment: This is my first nomination :P

Created by MemeGod27 (talk).

Number of QPQs required: 0. Nominator has less than 5 past nominations.

Post-promotion hook changes will be logged on the talk page; consider watching the nomination until the hook appears on the Main Page.

( ͡°( ͡° ͜ʖ( ͡° ͜ʖ ͡°)ʖ ͡°)͡°) (talk) 16:37, 21 March 2024 (UTC).

• Um, that's just cutesy way of saying it was a supernova. Abductive (reasoning) 06:51, 23 March 2024 (UTC)

A couple of issues here. For one, what is "Source:" at the bottom? For another, the lede is far too long compared to the article's body. Generally, the lede should summarize the text in the article below, but in this case, it is the majority of the article. That does not seem difficult to fix, simply splitting it up. Perhaps the statement "and so provides astronomers..." could be sectionized out, leaving the lede as a summary. And while I'm here:

ALT1: ... that G299.2-2.9 (pictured) is one of the oldest known supernova remnants found in the Milky Way?

Maury Markowitz (talk) 16:25, 3 April 2024 (UTC)

(Thanks for the above, Maury, just jumping in here, to get things moving). I have split the article's leader, and moved part of it into the article body, as requested above. I have also moved the source link from below the images, and attached it to the image captions. I approve ALT1, and have struck ALT0. The article is new enough, long enough and neutral. The image is free and clear, and no QPQ is needed. That's the positive bit. On the negative side, Earwig finds enough plagiarised phrases to force a need to rephrase them. @MemeGod27: Please look at the Earwig link I have given you, and rephrase the words that are highlighted. We also need citations at the end of two of the article's paragraphs. When the copyvio and the citation issues are resolved, this should be good to go. Storye book (talk) 10:20, 9 April 2024 (UTC)

• That actually went quicker than expected. Everything should be good now, although some of the phrases cannot be reworded. I changed as much as I can, however. Thanks @Storye book:! :P MemeGod ._. (talk) 15:25, 18 April 2024 (UTC)
• Okay, got it. Sorry, it's taken me so long to respond, I guess I forgot about this. I should be able to get everything done in 1-2 hours, and I'll get back then. Thanks! :D MemeGod ._. (talk) 15:07, 18 April 2024 (UTC)

• Thank you, MemeGod27.
• Good to go. Storye book (talk) 17:05, 18 April 2024 (UTC)

Also, I forgot to add ALT1, what about "...that the supernova remnant G299.2-2.9 is the result of a natural thermonuclear explosion?" ( ͡°( ͡° ͜ʖ( ͡° ͜ʖ ͡°)ʖ ͡°)͡°) (talk) 16:48, 21 March 2024 (UTC)