APOD: The Deep Sky Toward Andromeda (2021 Sep 08)

[APOD Robot]

The Deep Sky Toward Andromeda

Explanation: What surrounds the Andromeda galaxy? Out in space, Andromeda (M31) is closely surrounded by several small satellite galaxies, and further out it is part of the Local Group of Galaxies -- of which our Milky Way galaxy is also a member. On the sky, however, gas clouds local to our Milky Way appear to surround M31 -- not unlike how water clouds in Earth's atmosphere may appear to encompass our Moon. The gas clouds toward Andromeda, however, are usually too faint to see. Enter the featured 45-degree long image -- one of the deeper images yet taken of the broader Andromeda region. This image, sensitive to light specifically emitted by hydrogen gas, shows these faint and unfamiliar clouds in tremendous detail. But the image captures more. At the image top is the Triangulum galaxy (M33), the third largest galaxy in the Local Group and the furthest object that can be seen with the unaided eye. Below M33 is the bright Milky-Way star Mirach. The image is the digital accumulation of several long exposures taken from 2018 to 2021 from Pulsnitz, Germany.

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[Ann]

Very interesting APOD! Can't resist comparing Stefan Ziegenbalg's very deep and wide field image with a similar, but less wide field, image by Rogelio Bernal Andreo:

Andromeda wide and deep. Photo: Stefan Ziegenbalg.

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Andromeda deep. Photo: Rogelio Bernal Andreo.

I apologize for posting today's APOD as an image rather than as an attachment, even though it's a bit too big. It's because I need to post two other attachments, and I'm only allowed three in all!

Anyway, let's look at the pictures, and let's start with Rogelio Bernal Andreo's at right. Note the red clouds of Hα near the Andromeda galaxy. The wisps of Hα have nothing to do with Andromeda itself, but belong to our own galaxy. Note that while Stefan Ziegenbalg's picture is upside down compared with Rogelio Bernal Andreo's, you can see the same wisps of red in Ziegenbalg's image.

Note, too, that although there is a lot of red fluff in Stefan Ziegenbalg's image, there is certainly a lot of green stuff there, too. The green stuff can't be Hα, so what is it? Is it normal unionized galactic cirrus in the Milky Way?

Okay, time for my next two attachments!

Sharpless-2 126. The blue arrow points at star 10 Lac,
ionizing star of Sharpless 2-126. Photo: Stefan Ziegenbalg.

10 Lac and Sharpless 2-126. Photo: Thomas Henne.

Note that in Stefan Ziegenbalg's image, the ionizing star of the Sharpless 2-126 nebula complex, 10 Lac, looks yellow. In reality, 10 Lac is a star of spectral class O9V, and it is not only intrinsically very blue, but the light that reaches us from this star is really blue, too. The fact that it looks yellow (and very faint) in Stefan Ziegenbalg's image must have to do with the filters he used for his image, and his heavy use of red Hα.

Also look at the star Mirach in Ziegenbalg's annotated image. This intrinsically orange star looks reddish-pink. This, too, must be a consequence of the filters used and the heavy use of red Hα.

In any case, it is certainly a most interesting image!

Ann

[Eclectic Man]

@ Ann. Fascinating and informative as ever. Thanks very much.

However, I am confused. I thought that the Andromeda galaxy was the most distant object visible to the unaided eye, but the description states that the Triangulum Galaxy is:

"the image top is the Triangulum galaxy (M33), the third largest galaxy in the Local Group and the furthest object that can be seen with the unaided eye."

[JohnD]

Thank you, Ann, for your labelled version of this picture! Without it I was confused.

But what a strange image! That red network seems to lie behind the galaxies, and that we are seeing the Energy Grid that lies between this and the next Universe, as in the Culture series of stories, by Sun-Earther Iain El-Bonko Banks of North Queensferry.

[orin stepanek]

What can be confusing is that most of the stuff is in the Milky way; rather than between the milky way and Andromeda and Triangulum! Mirach Star also in the Milky way! IMO!

I love that APOD puts These little animals in their stories!

[Chris Peterson]

@ Ann. Fascinating and informative as ever. Thanks very much.

However, I am confused. I thought that the Andromeda galaxy was the most distant object visible to the unaided eye, but the description states that the Triangulum Galaxy is:

"the image top is the Triangulum galaxy (M33), the third largest galaxy in the Local Group and the furthest object that can be seen with the unaided eye."

Indeed, M33 may not be the farthest, either. It really comes down to the vision and experience of the observer. There are probably a number of bright, nearby galaxies that can be seen by the right person under the right conditions. So saying with certainty which is farthest is going to be tricky.

What's pretty certain is that M31 is the only galaxy that is easily seen by most people when it's pointed out.

[orin stepanek]

I have never seen either M1 or M33 Looking into the sky (to my recollection; or didn't know what I was looking at the time). I have however spotted Andromeda on several photographer's posted scenic pictures! I haven't spotted Triangulum on pictures though I haven't really looked for it!

[johnnydeep]

Thank you, Ann, for your labelled version of this picture! Without it I was confused.

But what a strange image! That red network seems to lie behind the galaxies, and that we are seeing the Energy Grid that lies between this and the next Universe, as in the Culture series of stories, by Sun-Earther Iain El-Bonko Banks of North Queensferry.

On a PC at least, mousing over the APOD image reveals the annotations. But I think this doesn't work right - or at all - on an iPad, for example.

[neufer]

I am confused. I thought that the Andromeda galaxy was the most distant object visible to the unaided eye, but the description states that the Triangulum Galaxy is: "the image top is the Triangulum galaxy (M33), the third largest galaxy in the Local Group and the furthest object that can be seen with the unaided eye."

Indeed, M33 may not be the farthest, either. It really comes down to the vision and experience of the observer. There are probably a number of bright, nearby galaxies that can be seen by the right person under the right conditions. So saying with certainty which is farthest is going to be tricky. What's pretty certain is that M31 is the only galaxy that is easily seen by most people when it's pointed out.

• http://www.uitti.net/stephen/astro/essa ... ject.shtml

https://en.wikipedia.org/wiki/GRB_080319B

The extremely luminous afterglow of GRB 080319B was imaged by Swift's X-ray Telescope (left) and Optical/Ultraviolet Telescope (right). This was by far the brightest gamma-ray burst afterglow ever seen.

---

<<GRB 080319B was a gamma-ray burst (GRB) detected [in the Constellation Boötes] by the Swift satellite at 06:12 UTC on March 19, 2008. The burst set a new record for the farthest object that was observable with the naked eye: it had a peak visual apparent magnitude of 5.7 and remained visible to human eyes for approximately 30 seconds. The magnitude was brighter than 9.0 for approximately 60 seconds. If viewed from 1 AU away, it would have had a peak apparent magnitude of −67.57 (21 quadrillion times brighter than the Sun seen from Earth). Until this gamma-ray burst event, the Triangulum Galaxy, at a distance of about 2.9 million light years, was the most distant object visible to the naked eye. The Triangulum galaxy remains the most distant permanent object viewable without aid.

The GRB's redshift was measured to be 0.937, which means that the explosion occurred about 7.5 billion years ago, and it took the light that long to reach Earth. This is roughly half the time since the Big Bang. The first scientific paper submitted on the event suggested that the GRB could have easily been seen to a redshift of 16 (essentially to the time in the universe when stars were just being formed, well into the age of reionization) from a sub-meter sized telescope equipped with near-infrared filters.

The afterglow of the burst set a new record for the "most intrinsically bright object ever observed by humans in the universe", 2.5 million times brighter than the brightest supernova to date, SN 2005ap. Evidence suggests that the afterglow was particularly bright due to the gamma jet focusing exactly at the line of sight to Earth. This allowed an unprecedented examination of the jet structure, which appears to have consisted of a narrowly focused cone and a secondary wider one. If this is the norm for GRB jets, it follows that most GRB detections only capture the fainter wide cone, which means that most distant GRBs are too faint to detect with current telescopes. This would imply that GRBs are a far more common phenomenon than so far assumed.

A record for the number of observed bursts with the same satellite on one day, four, was also set. This burst was named with the suffix B since it was the second burst detected that day. In fact, there were five GRBs detected in a 24-hour period, including GRB 080320. It was soon suggested that this spectacle be named the Clarke Event, as it first reached Earth just hours before the death of Arthur C. Clarke, who was the 1956 Hugo Award winner for his 1955 science fiction short story "The Star".>>

[Joe Stieber]

On a PC at least, mousing over the APOD image reveals the annotations. But I think this doesn't work right - or at all - on an iPad, for example.

On my 12.9" iPad, a simple press on the picture takes you to the large version. However, if you press and hold on the picture, a couple of small boxes pop up which are linked to the large version. At that point, just press on the white area outside the picture and the boxes go away leaving the annotated main page image in view. To go back to the unannotated picture, you need to refresh the page (unless there's some other trick I don't know). It's a nuisance, but since the iPad doesn't really have a mouse, perhaps we shouldn't expect normal mouse functions.

BTW, I was in a friend's suburban backyard last night under an unusually clear (and moon-free) sky. It's in New Jersey, about 5 miles east of Philadelphia's city hall, so it's deep in suburban light pollution. It was impossible to see either M31 or M33 with unaided eyes (no surprise); however, M31 was prominent in my 15x56 binoculars, but no luck spotting M33 in the binos. I couldn't distinguish M31's satellites, M32 or M110, either.

[Bird_Man]

Thank you, Ann, for your labelled version of this picture! Without it I was confused.

On a PC at least, mousing over the APOD image reveals the annotations. But I think this doesn't work right - or at all - on an iPad, for example.

On my iPad, I was able to tap the image to reveal the annotations.

[VictorBorun]

I wish IT would make a protocol for jpeg+ images that makes an image gradually fade and change to its alternative version and back again regularily in 1 second + 1 second period.
Doing it in all upgraded browsers, viewers and editors, desktop or mobile, even during a pan or a zoom-in.

Then an astronomy pic can have
1) a simple version of true or enhanced colors and
2) an alternative with overlays of narrow-band things like Hα or invisible wavelengths like radio or ɣ.

A bright red hydrogen cloud might temporarily make a bluish star yellow but the user would get an impression of an ever-bluish star, part of the time seen in the clear and part of the time seen through a red haze.

[Joe Stieber]

Thank you, Ann, for your labelled version of this picture! Without it I was confused.

On a PC at least, mousing over the APOD image reveals the annotations. But I think this doesn't work right - or at all - on an iPad, for example.

On my iPad, I was able to tap the image to reveal the annotations.

I just tried tapping (rather than pressing) the image my iPad and the annotations show momentarily before it goes to the large version. However, using the back arrow to return to the main page then shows the annotated image. I'm running iPadOS 14.7.1.

[VictorBorun]

Andromeda wide and deep. Photo: Stefan Ziegenbalg.

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Some rings with their normals 59° away from our line of sight?

[johnnydeep]

On my iPad, I was able to tap the image to reveal the annotations.

I just tried tapping (rather than pressing) the image my iPad and the annotations show momentarily before it goes to the large version. However, using the back arrow to return to the main page then shows the annotated image. I'm running iPadOS 14.7.1.

Yeah, that works for me, but the behavior is still odd.

[Ann]

Click to view full size image

Click to view full size image

Some rings with their normals 59° away from our line of sight?

You're right, Victor, it sure looks like two humongous rings! The large upper one is very obvious. It's got a stem or a stalk, too. Doesn't it look like a giant mushroom to you? Even though the cap of the mushroom has only got its outline left.

Ann

[neufer]

You're right, Victor, it sure looks like two humongous rings! The large upper one is very obvious. It's got a stem or a stalk, too. Doesn't it look like a giant mushroom to you? Even though the cap of the mushroom has only got its outline left.

• It looks like a giant mushroom cloud to me.

The centre of the associated nebular complex N44 in the LMC.

---

https://www.gemini.edu/node/171

<<N44 is an emission nebula with superbubble structure located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way in the constellation Dorado. Originally catalogued in Karl Henize's "Catalogue of H-alpha emission stars and nebulae in the Magellanic Clouds" of 1956, it is approximately 1,000 light-years wide. N44 has a smaller bubble structure inside known as N44F. The superbubble structure of N44 itself is shaped by the radiation pressure of a 40-star group located near its center; the stars are blue-white, very luminous, and incredibly powerful. N44F has been shaped in a similar manner; it has a hot, massive central star with an unusually powerful stellar wind that moves at 7 million kilometers per hour. This is because it loses material at 100 million times the rate of the Sun. However, varying density in the N44 nebula has caused the formation of several dust pillars that may conceal star formation. This variable density is likely caused by previous supernovae in the vicinity of N44; many of the stars that have shaped it will eventually also end as supernovae. The past effects of supernovae are also confirmed by the fact that N44 emits x-rays.

N44 is classified as an emission nebula because it contains large regions of ionized hydrogen. However, the three strongest emission lines in the nebula are singly ionized oxygen atoms, which emit at an ultraviolet wavelength of 372.7 nm, doubly-ionized oxygen atoms, which emit at a blue-green wavelength of 500.7 nm, and neutral hydrogen atoms, which emit the hydrogen-alpha line at a red wavelength of 656.2 nm.>>

[johnnydeep]

Click to view full size image

Click to view full size image

Some rings with their normals 59° away from our line of sight?

You're right, Victor, it sure looks like two humongous rings! The large upper one is very obvious. It's got a stem or a stalk, too. Doesn't it look like a giant mushroom to you? Even though the cap of the mushroom has only got its outline left.

Ann

They look like rings, but are they? My eye can easily find other potential rings nearby those two.

[VictorBorun]

Doesn't it look like a giant mushroom to you? Even though the cap of the mushroom has only got its outline left.
Ann

They look like rings, but are they? My eye can easily find other potential rings nearby those two.

how giant are they? One expects a tube of bipolar planetary nebula generated by the magnetic tube of the plasma accretion disk in a close binary system no larger than a few light years. To be 1° wide it had to be 100 ly close to us. Is it plausible at all?

Now a cometary-type mushroom stem can be larger, but why such filament would reside on the axis of a ring?

[JohnD]

Galactic 'shrooms, man! Far out!

[johnnydeep]

Doesn't it look like a giant mushroom to you? Even though the cap of the mushroom has only got its outline left.
Ann

They look like rings, but are they? My eye can easily find other potential rings nearby those two.

how giant are they? One expects a tube of bipolar planetary nebula generated by the magnetic tube of the plasma accretion disk in a close binary system no larger than a few light years. To be 1° wide it had to be 100 ly close to us. Is it plausible at all?

Now a cometary-type mushroom stem can be larger, but why such filament would reside on the axis of a ring?

Here are two more possibilities:

Rings Near M31?

[starsurfer]

Galactic 'shrooms, man! Far out!

Sacred Mushroom Galaxy anyone?

[VictorBorun]

Here are two more possibilities:
rings near traingulum.JPG

You just went and deleted the largest mushroom stem in question!
Making it just an interface between two bubbles, a wall or a membrane visually thickening where it's edge-on for us.
A bubble can well have radius of 10 ly. No magnetic tube required

[johnnydeep]

Here are two more possibilities:
rings near traingulum.JPG

You just went and deleted the largest mushroom stem in question!
Making it just an interface between two bubbles, a wall or a membrane visually thickening where it's edge-on for us.
A bubble can well have radius of 10 ly. No magnetic tube required

Well, how do we really distinguish between the two? Sometimes I think we are too prone to see things that aren't really there.

[VictorBorun]

You just went and deleted the largest mushroom stem in question!
Making it just an interface between two bubbles, a wall or a membrane visually thickening where it's edge-on for us.
A bubble can well have radius of 10 ly. No magnetic tube required

Well, how do we really distinguish between the two? Sometimes I think we are too prone to see things that aren't really there.

I think
1) a jet in a magnetic tube has smooth cylinder walls while
2) a wall of a filament between 2 or 3 touching bubbles has a hazy surface of trailing matter all around and
3) a cometary trunk is smoothe at its head part and has a source of stellar wind in its vicinity blowing onto the head

Look at an edge-on disk galaxy. The dusty curls at the both surfaces of the disk look like parts of bubbles' shells visible where a bubble crushes into the dense bubble foam of the disk.

Click to view full size image

Those dusty lanes are hazy all over.
And look at a planetary nebula. The walls are glossy-smoothe:

Click to view full size image