Starship Asterisk*

thanks!

[quote=VictorBorun post_id=341385 time=1727086182 user_id=145500]
the link won't open
[/quote]

Try this one: https://inspirehep.net/literature/2765684 (I googled for the pdf from Chris' link, which was "stad3921.pdf")

the link won't open

[quote=VictorBorun post_id=341378 time=1727040722 user_id=145500]
[quote="Chris Peterson" post_id=341369 time=1727025925 user_id=117706]
[quote=VictorBorun post_id=341368 time=1727025571 user_id=145500]


If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

How come?
[/quote]
What does the speed of light have to do with this? Its expansion rate is just its size (determined by angular size and distance) divided by its age.
[/quote]

I mean why the range is so wide? can the shock front be so slow?

As for the speed of light I just used kilo light years of distance and kilo years of age which made me use c factor

then again
angular diameter is about 45 arc seconds = 0.0002 radians
(the estimated expansion's velocity) = (0.00008 to 0.00037)*c = 24 to 111 km/s
I think at as slow mean speed as 24 km/s and probably just 10 km/s currently the shock wave still totally ionizes its oxygen and all
[/quote]

I think it's very difficult to confidently assess the distance of an object like this. A [url=https://watermark.silverchair.com/stad3921.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAA1kwggNVBgkqhkiG9w0BBwagggNGMIIDQgIBADCCAzsGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMCjrL_ZTF-Mdjai_4AgEQgIIDDMgLW3W8FLKzQHRWAh7EfeNk3sJNFzb7LR87gRqot21PtfBtt13j1NdWwL3Ei2B4A3Mef3ZuFB7Xl-oA2xHqzqf6D4v11QCcJFzunK5QBDc4H4nuDbLBIVw_2A14UEkdm9Nn_ln1feVYoz3ppU7OYSy3Cq149pAdkLr9KT986P-kzobnYY-rkIH5pJYMN9X7uppE0TxH9CcT7VTUsHusRq9M04-5x9VSgq_kGMowQwseaexdyc1lbHSHa77ra0Vnza_ziJpLmepip7WRLIQrvqmYxsoCm7gDCtGw4uvkvE_uZ4gBs3u1UleK3Fmrv4F5CSG1b_o2F9IeKkhPrDaoKxVQquVPP-TmuWeMdo-DgLj8ZHACBCO5bc2mbXr5-wSLJ7MAcv2QmpArOrkG0ipr2_GCKqum9EVIEZrwG6RgbmMZaTSNSld-5VXqM-F1OowRcWuokCE1TMCo18VBbatb2Ei4N5eV0EwznHwDw-b9n6tmb5Xx5bK3moKxhi6g450__rH9FS5mPT5hbdJ0j1olCZtVqwpJXd5acrAnYhGqE2P91_kWIlyN87_bsOVSeUrLdJ806PXEvMhuCOI41xouJyP6Z-YTPwT2vsSjr5PGAV_1C5AIzXn5MKHb0lKQC71_7PxZJDJiyy8FqfNiXK96jCx5ilG4rp54oG_XfX7U_rX4sM9ZTepvPmmtofLQg-Pe-eSBjoGusHp5hfB6FVximW6uicrAxqvcmDMZ-Jtzaofvs1FdjJrXEIApx1XbNIsVBToRc4G5i9UwQCG4Z72riLNslehB-Xe_XTVRXkDPybZsRxKrWXWZlpBhYlqE82TS-NIbdaVTBNfhEJg5Ak6OwB_qU8kQbHdFed-Dfc635cPKBjLv1tob9XQGRQCkbtL9E-vsfiQ__WWsdPYU5gAUen96Dah3zqE1RqPxPieGdgt6Y2jj2rmOuPoAGOTfsLEHhTZ1HyiT4QYzKIedpJVjAwoSgIaWatYChCePDztwTmOOEp-_D-ABttMaPhpLdvHBPe4dxPJaMQ-Wd8vO5g]very recent paper[/url] (see the discussion in section 4) estimates a distance of 1.4 kpc and an age of 14 kyr.

[quote="Chris Peterson" post_id=341369 time=1727025925 user_id=117706]
[quote=VictorBorun post_id=341368 time=1727025571 user_id=145500]
[quote=AVAO post_id=341292 time=1726640376 user_id=144694]
The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).
[img2]https://live.staticflickr.com/65535/54003923134_eaa8397349_b.jpg[/img2]
[size=65]jac berne (flickr) eROSITA, XXM-Newton and more[/size]
[/quote]

If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

How come?
[/quote]
What does the speed of light have to do with this? Its expansion rate is just its size (determined by angular size and distance) divided by its age.
[/quote]

I mean why the range is so wide? can the shock front be so slow?

As for the speed of light I just used kilo light years of distance and kilo years of age which made me use c factor

then again
angular diameter is about 45 arc seconds = 0.0002 radians
(the estimated expansion's velocity) = (0.00008 to 0.00037)*c = 24 to 111 km/s
I think at as slow mean speed as 24 km/s and probably just 10 km/s currently the shock wave still totally ionizes its oxygen and all

[quote=VictorBorun post_id=341368 time=1727025571 user_id=145500]
[quote=AVAO post_id=341292 time=1726640376 user_id=144694]
The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).
[img2]https://live.staticflickr.com/65535/54003923134_eaa8397349_b.jpg[/img2]
[size=65]jac berne (flickr) eROSITA, XXM-Newton and more[/size]
[/quote]

If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

How come?
[/quote]
What does the speed of light have to do with this? Its expansion rate is just its size (determined by angular size and distance) divided by its age.

[quote=AVAO post_id=341292 time=1726640376 user_id=144694]
The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).
[img2]https://live.staticflickr.com/65535/54003923134_eaa8397349_b.jpg[/img2]
[size=65]jac berne (flickr) eROSITA, XXM-Newton and more[/size]
[/quote]

If the distance's estimation is 4 to 13 kly and the age's estimation is 7 to 10 ky then the expansion's velocity is estimated
((4/10) to (13/7))*(angular size in radians)*(the speed of light)

angular diameter is about 45 arc seconds = 0.0002 radians
(the estimated expansion's velocity) = (0.00008 to 0.00037)*c = 24 to 111 km/s

How come?

Yes, I can see the mermaid! :D


[float=left][img3="The Mermaid Nebula Supernova Remnant.
Image Credit & Copyright: Neil Corke; Text: Natalia Lewandowska (SUNY Oswego)"]https://apod.nasa.gov/apod/image/2409/Mermaid_Corke_1080.jpg[/img3][/float][float=right][attachment=1]APOD 18 September 2024 annotated.png[/attachment][/float]
[clear][/clear]


[quote]APOD Robot wrote:

(T)he Mermaid Nebula makes up part of an unusual subclass of supernova remnants that are two-sided and nearly circular.[/quote]

Like the Veil Nebula, you mean?


[float=left][img3="The Betta Fish Nebula. The Mermaid Nebula is at right. Credit: Marco Lorenzi."]https://cdn.astrobin.com/thumbs/S4Yg7nZ3nkXV_1824x0_esdlMP5Y.jpg[/img3][/float][float=right][img3="The Veil Nebula complex. Credit: Achint Thomas."]https://images.squarespace-cdn.com/content/v1/54011460e4b0e522f5da76b1/1698681551015-OMJP0AO4LADM5UOJ0BFN/veil_nebula-full.jpg?format=1500w[/img3][/float]
[clear][/clear]


Both the Betta Fish Nebula and the Veil Nebula are blue-green from OIII emission and red from Hydrogen alpha. The difference is that the Betta Fish (and Mermaid Nabula) is almost all blue-green, whereas the Veil Nebula contains a lot of red Hα.


[img3="There is a lot of red hydrogen in the Veil Nebula. Credit: Trevor Jones."]https://astrobackyard.com/wp-content/uploads/2023/10/veill-nebula-768x840.jpg[/img3]


A tentative guess on my part is that the Betta Fish Nebula may be older, and the lightweight hydrogen may have dispersed before the oxygen did. Of course it's also possible that the supernova progenitor that created the Betta Fish and Mermaid Nebula was in itself pretty hydrogen-poor, more so than the progenitor that created the Veil Nebula.

And I must say that the eastern Veil Nebula is the only nebula in the sky that gives me the creeps! It's the Grinning Joker Nebula!


[float=left][img3="The Eastern Veil Nebula. Credit: Achint Thomas."]https://images.squarespace-cdn.com/content/v1/54011460e4b0e522f5da76b1/b7876cb3-e21b-4dd3-aae5-3acd7b6f771d/vn-wv.jpg[/img3][/float][float=right][attachment=0]Grinning Joker in the Veil Nebula Brian Ventrudo.png[/attachment][c][size=85][color=#0040FF]The Grinning Joker Nebula. Credit: Brian Ventrudo.[/color][/size][/c][/float]
[clear][/clear]


Oh shudder!!! 😲 We need to call Batman and Robin!!


[img3="No, boys, you are not wanted back on Earth, you are wanted in constellation Cygnus to fight the evil Joker Nebula!"]https://1.bp.blogspot.com/-QtL1U9Rqxng/X-ab9bhJsUI/AAAAAAAAUhI/kvLaA83vxMEoUe20M3Uis0M_b0I6SRyAgCLcBGAsYHQ/s564/1.jpg[/img3]


Ann

[quote="APOD Robot" post_id=341291 time=1726632352 user_id=128559]
[url=https://apod.nasa.gov/apod/ap240918.html] [img]https://apod.nasa.gov/apod/calendar/S_240918.jpg[/img] [size=150]The Mermaid Nebula Supernova Remnant[/size][/url]

[b] Explanation: [/b] New [url=https://science.nasa.gov/universe/stars/]stars[/url] are [url=https://webbtelescope.org/contents/media/images/4190-Image]born[/url] from the [url=https://science.nasa.gov/missions/webb/investigating-the-origins-of-the-crab-nebula-with-nasas-webb/]remnants[/url] of [url=https://science.nasa.gov/universe/the-lives-times-and-deaths-of-stars/]dead[/url] [url=https://en.wikipedia.org/wiki/Star]star[/url]s. The gaseous remnant of the [url=https://en.wikipedia.org/wiki/Gravitational_collapse]gravitational collapse[/url] and subsequent death of a very [url=https://apod.nasa.gov/apod/ap200830.html]massive star[/url] in our [url=https://science.nasa.gov/resource/the-milky-way-galaxy/]Milky Way[/url] created the [url=https://www.astrobin.com/kpl1kc/?q=Betta%20fish]G296.5+10.0[/url] [url=https://apod.nasa.gov/apod/ap230115.html]supernova remnant[/url], of which the [url=https://www.astrobin.com/84ogxw/]featured[/url] Mermaid Nebula is part. Also known as the [url=https://www.astrobin.com/gcl2j7/C/]Betta Fish Nebula[/url], the Mermaid Nebula makes up part of an unusual [url=https://heasarc.gsfc.nasa.gov/docs/objects/snrs/snrstext.html]subclass of supernova remnants[/url] that are [url=https://ui.adsabs.harvard.edu/abs/1992A%26A...265..752S/abstract]two-sided[/url] and nearly circular. Originally [url=https://ui.adsabs.harvard.edu/abs/1979ApJ...230L..27T/abstract]discovered[/url] in [url=https://science.nasa.gov/ems/11_xrays/]X-rays[/url], the filamentary nebula is a frequently studied source also in [url=https://science.nasa.gov/ems/05_radiowaves/]radio[/url] and [url=https://science.nasa.gov/ems/12_gammarays/]gamma-ray[/url] light. The blue color visible here originates from [url=https://en.wikipedia.org/wiki/Doubly_ionized_oxygen]doubly ionized oxygen[/url] (OIII), while the deep red is emitted by [url=https://en.wikipedia.org/wiki/Hydrogen-alpha]hydrogen gas[/url]. The nebula's [url=https://www.mewcats.com/cdn/shop/files/MermaidCatCostumeFunnyPhotoPropClothes_1.jpg]mermaid-like[/url] shape has proven to be [url=https://ui.adsabs.harvard.edu/abs/2024MNRAS.528.2095E/abstract]useful[/url] for measurements of the [url=https://apod.nasa.gov/apod/ap210120.html]interstellar magnetic field[/url].


[table][tr][td=left][url=https://asterisk.apod.com/discuss_apod.php?date=240917][b]<< Previous APOD[/b][/url][/td] [td=center][url=https://asterisk.apod.com/view_retro.php?date=0918][b]This Day in APOD[/b][/url][/td] [td=right][url=https://asterisk.apod.com/discuss_apod.php?date=240919][b]Next APOD >>[/b][/url][/td][/tr][/table]
[/quote]


The APOD is a great SNR image... even if it is mirrored :wink:
Most of the SNR can only be seen in the X-ray.

The supernova remnant G295.5+09.7 is estimated to be between 7,000 and 10,000 years old.
The distance of this remnant is somewhere between 4,000 and 13,000 light years from Earth.
It contains the pulsar PSR J1210-5226 (yellow circle).



[img2]https://live.staticflickr.com/65535/54003923134_eaa8397349_b.jpg[/img2]
[size=65]jac berne (flickr) eROSITA, XXM-Newton and more[/size]

[url=https://apod.nasa.gov/apod/ap240918.html] [img]https://apod.nasa.gov/apod/calendar/S_240918.jpg[/img] [size=150]The Mermaid Nebula Supernova Remnant[/size][/url]

[b] Explanation: [/b] New [url=https://science.nasa.gov/universe/stars/]stars[/url] are [url=https://webbtelescope.org/contents/media/images/4190-Image]born[/url] from the [url=https://science.nasa.gov/missions/webb/investigating-the-origins-of-the-crab-nebula-with-nasas-webb/]remnants[/url] of [url=https://science.nasa.gov/universe/the-lives-times-and-deaths-of-stars/]dead[/url] [url=https://en.wikipedia.org/wiki/Star]star[/url]s. The gaseous remnant of the [url=https://en.wikipedia.org/wiki/Gravitational_collapse]gravitational collapse[/url] and subsequent death of a very [url=https://apod.nasa.gov/apod/ap200830.html]massive star[/url] in our [url=https://science.nasa.gov/resource/the-milky-way-galaxy/]Milky Way[/url] created the [url=https://www.astrobin.com/kpl1kc/?q=Betta%20fish]G296.5+10.0[/url] [url=https://apod.nasa.gov/apod/ap230115.html]supernova remnant[/url], of which the [url=https://www.astrobin.com/84ogxw/]featured[/url] Mermaid Nebula is part. Also known as the [url=https://www.astrobin.com/gcl2j7/C/]Betta Fish Nebula[/url], the Mermaid Nebula makes up part of an unusual [url=https://heasarc.gsfc.nasa.gov/docs/objects/snrs/snrstext.html]subclass of supernova remnants[/url] that are [url=https://ui.adsabs.harvard.edu/abs/1992A%26A...265..752S/abstract]two-sided[/url] and nearly circular. Originally [url=https://ui.adsabs.harvard.edu/abs/1979ApJ...230L..27T/abstract]discovered[/url] in [url=https://science.nasa.gov/ems/11_xrays/]X-rays[/url], the filamentary nebula is a frequently studied source also in [url=https://science.nasa.gov/ems/05_radiowaves/]radio[/url] and [url=https://science.nasa.gov/ems/12_gammarays/]gamma-ray[/url] light. The blue color visible here originates from [url=https://en.wikipedia.org/wiki/Doubly_ionized_oxygen]doubly ionized oxygen[/url] (OIII), while the deep red is emitted by [url=https://en.wikipedia.org/wiki/Hydrogen-alpha]hydrogen gas[/url]. The nebula's [url=https://www.mewcats.com/cdn/shop/files/MermaidCatCostumeFunnyPhotoPropClothes_1.jpg]mermaid-like[/url] shape has proven to be [url=https://ui.adsabs.harvard.edu/abs/2024MNRAS.528.2095E/abstract]useful[/url] for measurements of the [url=https://apod.nasa.gov/apod/ap210120.html]interstellar magnetic field[/url].


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