Starship Asterisk*

eegriff wrote: ↑Mon Apr 05, 2021 6:58 pm Veil Nebula fragment located. Watch the video. https://www.youtube.com/watch?v=hlx-6FVyT8o

neufer wrote: ↑Mon Apr 05, 2021 9:56 pm

johnnydeep wrote: ↑Mon Apr 05, 2021 9:30 pm
Does the progenitor star (20 times the mass of the Sun per WikiPedia) still exists, and if so, has it been located? Is it a white dwarf or a neutron star?

https://en.wikipedia.org/wiki/Cygnus_Loop#Searches_for_a_compact_stellar_remnant wrote:

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<<Most stars that produce supernovae leave behind compact stellar remnants- a neutron star or black hole, typically depending on the mass of the original star. Various techniques based on the features of the supernova remnant estimate the Cygnus Loop progenitor star's mass at 12 to 15 Solar masses, a value that puts the expected remnant firmly within neutron star boundaries. However, despite many searches, no compact stellar remnant had been confidently identified since the identification of the supernova remnant.

A noted anomaly is that in X-rays, the nebula appears perfectly spherical aside from a "blowout region" to the south. Searches for a compact stellar remnant have been largely concentrated here, as the hole may have been caused by the violent ejection of a neutron star. A detailed 2012 study of the blowout region identified a possible pulsar wind nebula, as well as a point-like source within it. Although at almost exactly the same position as a known Seyfert galaxy, the slight offset combined with a lack of a radio counterpart makes the point-like source probably unrelated to the galaxy. Whether or not the feature is a pulsar wind nebula or not, and if so whether or not it is related to the Cygnus Loop, is still unknown for certain. If it is indeed the compact stellar remnant of the supernova, the neutron star would have to have been ejected from the center of the nebula at a speed of roughly 1,850 km/s, depending on the precise age and distance of the remnant.>>

johnnydeep wrote: ↑Mon Apr 05, 2021 9:30 pm
Does the progenitor star (20 times the mass of the Sun per WikiPedia) still exists, and if so, has it been located? Is it a white dwarf or a neutron star?

https://en.wikipedia.org/wiki/Cygnus_Loop#Searches_for_a_compact_stellar_remnant wrote:

?

---

<<Most stars that produce supernovae leave behind compact stellar remnants- a neutron star or black hole, typically depending on the mass of the original star. Various techniques based on the features of the supernova remnant estimate the Cygnus Loop progenitor star's mass at 12 to 15 Solar masses, a value that puts the expected remnant firmly within neutron star boundaries. However, despite many searches, no compact stellar remnant had been confidently identified since the identification of the supernova remnant.

A noted anomaly is that in X-rays, the nebula appears perfectly spherical aside from a "blowout region" to the south. Searches for a compact stellar remnant have been largely concentrated here, as the hole may have been caused by the violent ejection of a neutron star. A detailed 2012 study of the blowout region identified a possible pulsar wind nebula, as well as a point-like source within it. Although at almost exactly the same position as a known Seyfert galaxy, the slight offset combined with a lack of a radio counterpart makes the point-like source probably unrelated to the galaxy. Whether or not the feature is a pulsar wind nebula or not, and if so whether or not it is related to the Cygnus Loop, is still unknown for certain. If it is indeed the compact stellar remnant of the supernova, the neutron star would have to have been ejected from the center of the nebula at a speed of roughly 1,850 km/s, depending on the precise age and distance of the remnant.>>

APOD Robot wrote: ↑Mon Apr 05, 2021 4:06 am Veil Nebula: Wisps of an Exploded Star

Explanation: Wisps like this are all that remain visible of a Milky Way star. About 7,000 years ago that star exploded in a supernova leaving the Veil Nebula. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history. Today, the resulting supernova remnant, also known as the Cygnus Loop, has faded and is now visible only through a small telescope directed toward the constellation of the Swan (Cygnus). The remaining Veil Nebula is physically huge, however, and even though it lies about 1,400 light-years distant, it covers over five times the size of the full Moon. The featured picture is a Hubble Space Telescope mosaic of six images together covering a span of only about two light years, a small part of the expansive supernova remnant. In images of the complete Veil Nebula, even studious readers might not be able to identify the featured filaments.

VictorBorun wrote: ↑Mon Apr 05, 2021 8:35 pm

eegriff wrote: ↑Mon Apr 05, 2021 6:58 pm Veil Nebula fragment located. Watch the video. https://www.youtube.com/watch?v=hlx-6FVyT8o

yes!

eegriff wrote: ↑Mon Apr 05, 2021 6:58 pm Veil Nebula fragment located. Watch the video. https://www.youtube.com/watch?v=hlx-6FVyT8o

MarkBour wrote: ↑Mon Apr 05, 2021 6:16 am

In images of the complete Veil Nebula, even studious readers might not be able to identify the featured filaments.

Okay, that sounds like a veiled challenge to locate today's APOD in the APOD from 2019-10-31 (https://apod.nasa.gov/apod/ap191031.html).

Capture.png

And it does seem rather challenging. The lighting may be different, and by
a crudely estimated 1/35 field of view, the scales are vastly different.
Here's my guess, the tiny red rectangle in the image at the right.
But my confidence is low.

MarkBour wrote: ↑Mon Apr 05, 2021 6:16 am

In images of the complete Veil Nebula, even studious readers might not be able to identify the featured filaments.

Okay, that sounds like a veiled challenge to locate today's APOD in the APOD from 2019-10-31 (https://apod.nasa.gov/apod/ap191031.html).

Capture.png

And it does seem rather challenging. The lighting may be different, and by
a crudely estimated 1/35 field of view, the scales are vastly different.

Here's my guess, the tiny red rectangle in the image at the right.

But my confidence is low.

APOD Robot wrote: ↑Mon Apr 05, 2021 4:06 am In images of the complete Veil Nebula, even studious readers might not be able to identify the featured filaments.

SpaceCadet wrote: ↑Mon Apr 05, 2021 7:34 am @MarkBour - thanks for the info. That last bit is especially great bc I have always wondered if astronomers could actually see and watch the expansion of the galaxies they study considering their size and speed.

Ifikratis wrote: ↑Mon Apr 05, 2021 5:16 am Incredible image.

If not a camera artifact, at the upper part of the image (more easily seen on the middle left) there are parallel blue lines which seem to be interstellar magnetic field lines.

In images of the complete Veil Nebula, even studious readers might not be able to identify the featured filaments.

SpaceCadet wrote: ↑Mon Apr 05, 2021 5:57 am How large is the nebula in total? What does 5 times the size of the full moon at 1400 light year's distance mean? Thanks

The Veil Nebula is expanding at a velocity of about 1.5 million kilometers per hour. Using images taken by the Hubble Space Telescope between 1997 and 2015, the expansion of the Veil Nebula has been directly observed.