Starship Asterisk*

For anyone wondering, the W stands for Westerhout, a catalogue of radio sources.

I love all the different supernova remnants in Cygnus, there's more than the Veil Nebula especially G65.3+5.7.

[quote=BDanielMayfield post_id=286995 time=1541163150 user_id=139536]
[quote="APOD Robot" post_id=286988 time=1541131830 user_id=128559]
So far no source has been identified as with [url=http://chandra.harvard.edu/photo/2018/kes75/]the remains[/url] of W63's original star.[/quote]

So, no smoking gun, just smoke. This suggests that either (a) a black hole was formed, or (b) the progenitor star was totally disrupted. What are the odds between these two possibilities?
[/quote]

Not the latter... that doesn't happen. We either got a stellar mass black hole (which we would be unable to detect) or a neutron star (which could be very difficult to find around a remnant this old, which no longer has enough structure to define a center).

[quote="APOD Robot" post_id=286988 time=1541131830 user_id=128559]
So far no source has been identified as with [url=http://chandra.harvard.edu/photo/2018/kes75/]the remains[/url] of W63's original star.[/quote]

So, no smoking gun, just smoke. This suggests that either (a) a black hole was formed, or (b) the progenitor star was totally disrupted. What are the odds between these two possibilities?

[quote=RoyHoward post_id=286989 time=1541136494]
The remnant cannot be 150 light years in diameter, if it is 5000 light years away and exploded 15,000 years ago.
[/quote]
Sure it can. I don't recall whether astronomers have calculated the speed of particles expelled in a supernova explosion, but it can't be at the speed of light or the particles would have to be mass-less. For example the Sun is about 8.2 light minutes away, i.e. light from the Sun takes that long to reach Earth. However the ionized particles from a solar flare take around 24 hours, give or take a couple hours, to get here and make the Northern or Southern Lights. That is how satellite owners know when to prepare for solar flares. So figure out the speed by dividing the speed of light by the difference between 8 minutes and 24 hours. (It is early, I am still having breakfast.)

[quote=RoyHoward post_id=286989 time=1541136494]
The remnant cannot be 150 light years in diameter, if it is 5000 light years away and exploded 15,000 years ago.
[/quote]

It is not that it exploded 15,000 years ago...it is that it exploded around 20,000 years ago...and the light from it reached Earth...15,000 years ago.... see?

It is an OLD supernova...

Re-read it...

:---[===] *

[quote=RoyHoward post_id=286989 time=1541136494]
The remnant cannot be 150 light years in diameter, if it is 5000 light years away and exploded 15,000 years ago.
[/quote]

The fact that the supernova remnant is likely about 5,000 light years away has no bearing on the fact that the supernova progenitor exploded about 15,000 years ago and the remnant has grown to a size of about 150 light years.

Ann

The remnant cannot be 150 light years in diameter, if it is 5000 light years away and exploded 15,000 years ago.

[url=https://apod.nasa.gov/apod/ap181102.html] [img]https://apod.nasa.gov/apod/calendar/S_181102.jpg[/img] [size=150]Cygnus Shell Supernova Remnant W63[/size][/url]

[b] Explanation: [/b] The ghost of [url=https://www.nasa.gov/feature/jpl/the-fading-ghost-of-a-long-dead-star]a long-dead star[/url], the W63 supernova remnant shines like a faint cosmic smoke-ring along the plane of the Milky Way galaxy toward the northern [url=https://apod.nasa.gov/apod/ap070920.html]constellation Cygnus[/url] the swan. Its wraithlike appearance is traced against the [url=http://aspmonographs.org/a/volumes/article_details?paper_id=3]region's[/url] rich complex of interstellar clouds and dust by an eerie blue glow. Spanning over four full moons on the sky, [url=https://astroanarchy.blogspot.com/2018/10/a-very-rare-photo-cygnus-shell.html]the beautiful image[/url] is a telescopic mosaic in twelve panels that combines 100 hours of exposure time using narrow band filters. It shows characteristic light from ionized atoms of sulfur, hydrogen and oxygen in red, green, and blue hues. Likely over 5,000 light-years away, the visible part of the [url=https://arxiv.org/abs/astro-ph/0311530]still expanding[/url] shell supernova remnant is around 150 light-years in diameter. So far no source has been identified as with [url=http://chandra.harvard.edu/photo/2018/kes75/]the remains[/url] of W63's original star. Light from the star's [url=http://chandra.harvard.edu/xray_sources/supernovas.html]supernova explosion[/url] would have reached Earth over 15,000 years [url=https://ui.adsabs.harvard.edu/?#abs/1977A%26A....55...11A]ago[/url].


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