APOD: Filaments of the Cygnus Loop (2020 Sep 28)

[APOD Robot]

Filaments of the Cygnus Loop

Explanation: What lies at the edge of an expanding supernova? Subtle and delicate in appearance, these ribbons of shocked interstellar gas are part of a blast wave at the expanding edge of a violent stellar explosion that would have been easily visible to humans during the late stone age, about 20,000 years ago. The featured image was recorded by the Hubble Space Telescope and is a closeup of the outer edge of a supernova remnant known as the Cygnus Loop or Veil Nebula. The filamentary shock front is moving toward the top of the frame at about 170 kilometers per second, while glowing in light emitted by atoms of excited hydrogen gas. The distances to stars thought to be interacting with the Cygnus Loop have recently been found by the Gaia mission to be about 2400 light years distant. The whole Cygnus Loop spans six full Moons across the sky, corresponding to about 130 light years, and parts can be seen with a small telescope toward the constellation of the Swan (Cygnus).

<< Previous APOD

This Day in APOD

Next APOD >>

[Ann]

I guess it's ringing like a bell.

Ann

[dpw711]

Just wondering. What would be the effects on our Solar System should our dear Sun become one of the stars "interacting" with such a shock wave?

[XgeoX]

these ribbons of shocked interstellar gas are part of a blast wave at the expanding edge of a violent stellar explosion that would have been easily visible to humans during the late stone age

Yes, they observed it with the Rubble telescope! Nyuk, nyuk, nyuk...

Eric

[orin stepanek]

Reminds me of a similar APOD a while back! Beautiful photo nevertheless!

[BDanielMayfield]

Just wondering. What would be the effects on our Solar System should our dear Sun become one of the stars "interacting" with such a shock wave?

Reasonable question. Since the Cygnus Loop's diameter is now "about 130 light years" that would put the SN at about 65 light years from the stars its shock wave is now encountering. Is that distance sufficient to be out of the danger zone from the type of SN that formed this remnant?

Of course radiation from the SN first hitting solar systems 65 years after the blast would be the principle hazard. Now, 20,000 years later the material in this shock wave will be very thin. Would the stellar winds from stars at that range be strong enough to shield any habitable zone planets from further ill effects?

[BDanielMayfield]

Glad to see that GAIA is now providing results that are clearing up distance questions. This is from the Wikipedia article Cygnus Loop:

Distance

Until 1999, the most often-quoted distance to the supernova remnant was a 1958 estimate made by R. Minkowski, combining his radial velocity measurements with E. Hubble's proper motion study of the remnant's optical filaments to calculate a distance of 770 parsecs or 2500 light-years.[13][14] However, in 1999, William Blair, assuming that the shock wave should be expanding at the same rate in all directions, compared the angular expansion along the sides of the bubble (visible in Hubble Space Telescope images) with direct line-of-sight measurements of the radial expansion towards the Earth and concluded that the actual size of the bubble was about 40% smaller than the conventional value, leading to a distance of about 1470 ly.[13][14]

A larger revised value of 540 pc (1760 ly) appeared to be corroborated by Blair's later discovery, via the Far Ultraviolet Spectroscopic Explorer (FUSE), of a star seemingly behind the Veil. A UV spectrum of this star, KPD 2055+3111 of spectral type sdOB, showed absorption lines in its spectrum indicate that its light is partially intercepted by the supernova remnant. With an estimated (but uncertain) distance of about 1860 ly away, this star seemed to support the revised estimate of 1760 ly.[14]

A more recent investigation of the Cygnus Loop's distance using Gaia parallax measurements of several stars seen toward the Cygnus Loop has led to a more accurate distance estimate.[15] One of these stars, a 9.6 magnitude B8 star (BD+31 4224) located near the remnant's northwestern rim shows evidence of interactions of its stellar wind with the Cygnus Loop's shock wave, thereby indicating it is located actually inside the remnant. This star's Gaia estimated distance of around 770 ± 30 pc, along with two other stars both at 735 ± 30 pc which exhibit spectral features indicating they must lie behind the remnant, leads to new distance of 735 ± 25 pc or around 2400 light-years. (Note: The Gaia estimated distance to the sdOB star KPD 2055+3111 is 793 pc (2600 ly). This new distance, surprisingly close to the value estimated some 60 yrs ago by Minkowski, means the Cygnus Loop is physically some 40 pc (130 ly) in diameter and has an age of around 21,000 years.[15]

[neufer]

---

Recent NASA photograph of the Cygnus Loop in ultraviolet light, with labels added to point out well known features: The Western Veil (NGC 6960) The Eastern Veil (NGC 6992, NGC 6995, IC 1340) NGC 6974 and NGC 6979 along the northern edge Pickering's Triangle The Southestern Knot, a prominent X-ray feature

---

[neufer]

Click to play embedded YouTube video.

---

Filaments of the Cygnus Loop

Explanation: What lies at the edge of an expanding supernova? Subtle and delicate in appearance, these ribbons of shocked interstellar gas are part of a blast wave at the expanding edge of a violent stellar explosion that would have been easily visible to humans during the late stone age, about 20,000 years ago.

Yes, they observed it with the Rubble telescope! Nyuk, nyuk, nyuk...

. A bit early to obtain a true color image, however:

<<Lascaux is a complex of caves near the village of Montignac, in the department of Dordogne in southwestern France. Over 600 parietal wall paintings cover the interior walls and ceilings of the cave. The paintings represent primarily large animals, typical local contemporary fauna that correspond with the fossil record of the Upper Paleolithic in the area. They are the combined effort of many generations and, with continued debate, the age of the paintings is now usually estimated at around 17,000 years (early Magdalenian).>>

[johnnydeep]

Filaments of the Cygnus Loop

Explanation: What lies at the edge of an expanding supernova? Subtle and delicate in appearance, these ribbons of shocked interstellar gas are part of a blast wave at the expanding edge of a violent stellar explosion that would have been easily visible to humans during the late stone age, about 20,000 years ago. The featured image was recorded by the Hubble Space Telescope and is a closeup of the outer edge of a supernova remnant known as the Cygnus Loop or Veil Nebula. The filamentary shock front is moving toward the top of the frame at about 170 kilometers per second, while glowing in light emitted by atoms of excited hydrogen gas. The distances to stars thought to be interacting with the Cygnus Loop have recently been found by the Gaia mission to be about 2400 light years distant. The whole Cygnus Loop spans six full Moons across the sky, corresponding to about 130 light years, and parts can be seen with a small telescope toward the constellation of the Swan (Cygnus).

So, does anyone have a guess as to where in the full Veil Nebula this close-up filament is? Not that it matters much, but I'm just curious. I suppose knowing the identities of some of the stars might help.

[WWW]

The Nexus ?

https://www.youtube.com/watch?v=fmIaHAtabSU

[alter-ego]

…

So, does anyone have a guess as to where in the full Veil Nebula this close-up filament is? Not that it matters much, but I'm just curious. I suppose knowing the identities of some of the stars might help.

The FoV is ~2.5' x 1.2', the location is marked by the white cursor. The narrow filament just visible in the narrow field.

[johnnydeep]

…

So, does anyone have a guess as to where in the full Veil Nebula this close-up filament is? Not that it matters much, but I'm just curious. I suppose knowing the identities of some of the stars might help.

The FoV is ~2.5' x 1.2', the location is marked by the white cursor. The narrow filament just visible in the narrow field.
APOD Location-Wide.png APOD Location-Narrow.png

Thanks! I've been trying to convince myself that your identification of the region was correct, and I can't. So how did you figure this out, oh "Serendipitous Sleuthhound"?

[alter-ego]

…

So, does anyone have a guess as to where in the full Veil Nebula this close-up filament is? Not that it matters much, but I'm just curious. I suppose knowing the identities of some of the stars might help.

The FoV is ~2.5' x 1.2', the location is marked by the white cursor. The narrow filament just visible in the narrow field.
APOD Location-Wide.png APOD Location-Narrow.png

Thanks! I've been trying to convince myself that your identification of the region was correct, and I can't. So how did you figure this out, oh "Serendipitous Sleuthhound"?

This was one of the easier finds I've had. Only a dash serendipity and splash sleuthing.
First, verifying the star field is straight forward. After extracting a zoomed in view and rotating it, I circled 19 stars readily identifiable in the apod:
 

Oriented to closely match APOD

Scaled to match comparison image

---

As far as how I found it, I'd like to say it was nothing but Zen and the Art of Star Field Identification. However, I must admit it was just coordinates. Not where I am now, but where the FoV is. Go to the "featured image" link and scroll down. Near the bottom you'll see the location coordinates and image orientation.
Thanks for asking.