APOD: Behind Betelgeuse (2020 May 11)

[APOD Robot]

Behind Betelgeuse

Explanation: What's behind Betelgeuse? One of the brighter and more unusual stars in the sky, the red supergiant star Betelgeuse can be found in the direction of famous constellation Orion. Betelgeuse, however, is actually well in front of many of the constellation's other bright stars, and also in front of the greater Orion Molecular Cloud Complex. Numerically, light takes about 700 years to reach us from Betelgeuse, but about 1,300 years to reach us from the Orion Nebula and its surrounding dust and gas. All but the largest telescopes see Betelgeuse as only a point of light, but a point so bright that the inherent blurriness created by the telescope and Earth's atmosphere make it seem extended. In the featured long-exposure image, thousands of stars in our Milky Way Galaxy can be seen in the background behind Betelgeuse, as well as dark dust from the Orion Molecular Cloud, and some red-glowing emission from hydrogen gas on the outskirts of the more distant Lambda Orionis Ring. Betelgeuse has recovered from appearing unusually dim over the past six months, but is still expected to explode in a spectacular supernova sometime in the next (about) 100,000 years.

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[Ann]

The truly great thing about an image like this one is the amazing starry and nebular background.

Betelgeuse Adam Block.png

Betelgeuse and friends. Photo: Adam Block.

212 hour Orion Constellation with arrow.png

A 212-hour exposure of Orion. Photo: Stanislav Volskiy.

So what is the red nebulosity that we can see in Adam Block's image? The caption said it is part of the Lambda Orionis Nebula.

I'd say not. If we look at a deep exposure of constellation Orion where north is up, we can see a stubby little red "arm" reaching for Betelgeuse. You can see this "arm" quite clearly in Stanislav Volskiy's image. I've marked it with an arrow.

Betelgeuse with 52 Orionis Stanislav Volskiy.png

A crop of Stanislav Volskiy's image.

I'd say it is the tip of this "arm" that we see in Adam Block's image. The "red arm" doesn't reach all the way to Betelgeuse, which is exactly what we see in both Adam Block's and Stanislav Volskiy's images.

So in my opinion, south is up in Adam Block's image, and east is to the right. The blue star close to the top left corner in Adam Block's image is probably 52 Orionis, an A5V-type star (but suspiciously bright for its class according to Hipparcos, oh well). The same star can be seen, faintly, to the lower right of Betelgeuse in Stanislav Volskiy's image. I have added an enlarged crop of this part of Volskiy's image, which corresponds to the general area seen in Adam Block's image.

Ann

[orin stepanek]

betelgeuse_block_960.jpg

A lot of stars around Betelgeuse!

[neufer]

The shape of the Orion Spur

---

Click to play embedded YouTube video.

<<The Orion Arm is a minor spiral arm of the Milky Way Galaxy that is 3,500 light-years across and approximately 10,000 light-years in length, containing the Solar System, including Earth. It is also referred to by its full name, the Orion–Cygnus Arm, as well as Local Arm, Orion Bridge, and formerly, the Local Spur and Orion Spur.

The arm is named for the Orion Constellation, which is one of the most prominent constellations of Northern Hemisphere winter (Southern Hemisphere summer). Some of the brightest stars and most famous celestial objects of the constellation (e.g. Betelgeuse, Rigel, the three stars of Orion's Belt, the Orion Nebula) are within it as shown on the interactive map below.

The arm is between the Carina–Sagittarius Arm (the local portions of which are toward the Galactic Center) and the Perseus Arm (the local portion of which is the main outer-most arm and one of two major arms of the galaxy).

Long thought to be a minor structure, namely a "spur" between the two arms mentioned, evidence was presented in mid 2013 that the Orion Arm might be a branch of the Perseus Arm, or possibly an independent arm segment.

Within the arm, the Solar System is close to its inner rim, in a relative cavity in the arm's Interstellar Medium known as the Local Bubble, about halfway along the arm's length, approximately 26,000 light-years from the Galactic Center.>>

[smitty]

Is there evidence -- pro or con -- of any planets orbiting Betelgeuse? Thanks.

[Mountainjim62]

So what part of the Milky Way do I see in the sky on dark nights?

[neufer]

Is there evidence -- pro or con -- of any planets orbiting Betelgeuse? Thanks.

Ford Prefect

---

Zaphod Beeblebrox

---

<<In a footnote in _The Hitchhiker's Guide to the Galaxy_, we are told that Ford Prefect's original name is "only pronounceable in an obscure Betelgeusian dialect" which was almost wiped out by the "Great Collapsing Hrung Disaster of Gal./Sid./Year 03758," a mysterious catastrophe which took place on the planet of Betelgeuse Seven and which Ford's father was the only man to survive. Ford never learned to pronounce his original name, which was a matter that caused his father to die of shame (which is still a terminal disease in some parts of the Universe). At school, he was nicknamed "Ix," which translates as "boy who is not able satisfactorily to explain what a Hrung is, nor why it should choose to collapse on Betelgeuse Seven". Despite all this, his semi-cousin Zaphod Beeblebrox calls him "Ford" the first time they are reunited in all versions of the story except for the film, where Zaphod addresses him as "Praxibetel Ix," then introduces him by saying "This is my semi-half brother, Ix... I'm sorry, sorry, Ford." Zaphod Beeblebrox is from a planet in the vicinity of Betelgeuse, and is a "semi-half-cousin" of Ford Prefect, with whom he "shares three of the same mothers". Because of "an accident with a contraceptive and a time machine", his direct ancestors from his father are also his direct descendants (see Zaphod Beeblebrox the Fourth).>>

[smitty]

So is it no longer possible to get a serious answer to a serious question here?

[johnnydeep]

The shape of the Orion Spur

---

This image is disturbingly unsatisfying: does the Orion Spur extend up through the Perseus Arm and thence connect to the Cygnus Arm? It sure looks like it from that pic. And what is the unlabeled "arm" between the Sagittarius Arm and the Perseus Arm, terminating in Turner 5, and containing all the objects with labels on the bottom, from which the Orion Spur looks to be an offshoot? Is that the actual Orion Arm? If so, why in Orion's name isn't it labeled as such, seeing as this widipedia article has "Orion Arm" as its title?!

[neufer]

Observed (normal lines) and extrapolated (dotted lines) structure of the spiral arms of the Milky Way, viewed from north of the galaxy – stars generally move clockwise in this view. The gray lines radiating from the Sun's position (upper center) list the three-letter abbreviations of the corresponding constellations

---

So what part of the Milky Way do I see in the sky on dark nights?

No one can easily observe the Milky Way behind the central Sagittarius center.

If you reside in the Northern Hemisphere, you will also have difficulty observing the Milky Way from between Sagittarius and Puppis.

[johnnydeep]

So in my opinion, south is up in Adam Block's image, and east is to the right. The blue star close to the top left corner in Adam Block's image is probably 52 Orionis, an A5V-type star (but suspiciously bright for its class according to Hipparcos, oh well). The same star can be seen, faintly, to the lower right of Betelgeuse in Stanislav Volskiy's image. I have added an enlarged crop of this part of Volskiy's image, which corresponds to the general area seen in Adam Block's image.

I believe you are exactly right. I have a hard time rotating star fields in my mind's eye, so I had to resort to pasting images into Libre Office Impress and rotating them to see what you determined. I'd insert my result here, but I don't know how to add a JPEG from my local drive. This didn't work:

[img]file:///C:/Users/g0177325/Documents/betelgeuse%20in%20orion%20inset.JPG[/img]

[Ann]

So is it no longer possible to get a serious answer to a serious question here?

I'll do my best to give you a serious answer to your question about possible planets around Betelgeuse. Mind you, planets are not my forte. I'm a blue star and star forming galaxies nerd.

Anyway, Betelgeuse. According to Jim Kaler, Betelgeuse started out as an O star, with a mass of (according to Kaler) 18 or 19 solar masses, and with a temperature (I would guess) of at least 30,000 K, and more likely perhaps 35,000 K. At that temperature, the young blue and blisteringly hot Betelgeuse would have emitted an absolute torrent of ultraviolet light, but, in comparison, much lower amounts of visible and infrared light. In short: If you want a star that will fry your retinas to a crisp and turn your body into one large tumour, an O-star like Betelgeuse would be the star for you. Don't expect to find any sort of distance from an O-star that will provide you with pleasant daylight and nice warmth while at the same time not giving you a continuous full body scan.

So that was what Betelgeuse was like in its first flush of youth. Betelgeuse is still young as stars go, but now it has swollen into monstrous proportions and cooled to a tenth of what its temperature used to be. Its "surface", if you can call it a surface (because Betelgeuse is bubbling and burping and swelling and shrinking and shedding body parts - I mean, shedding parts of its atmosphere - all over the place, so it would be really hard to say where Betelgeuse ends and where "empty space" begins), but whatever "surface" it has extends well beyond a distance corresponding to the orbit of Mars around the Sun, that much is certain.

Does this mean there can't be a planet orbiting Betelgeuse?

No, it absolutely doesn't mean that, and yes, there may certainly, certainly be planets in orbit around Betelgeuse! If you ask me, we have no reason whatsoever to believe that the whopping protoplanetary disks that give birth to massive stars can't also give rise to planets. If anything, I would guess that the massive disks that give birth to massive stars would be particularly good at making planets.

Of course, life on a planet orbiting Betelgeuse would be pure hell. I'd say it would be impossible.

A fascinating aspect about Betelgeuse, at least to me, is that it is a single star. Since I am so very interested in blue stars, I know that by far most really hot and massive blue stars are members of binary or multiple systems. So why is Betelgeuse single? Was it born as a hot, massive but single star? Maybe. But I wonder if it didn't have one or more stellar companions in its early youth, and then it lost those companions, one way or another. And if it lost its stellar companions, couldn't it have lost its planets as well?

Here's what I think. If Betelgeuse had planets at the distances of Mercury, Venus, Earth and Mars, it probably swallowed them when it grew to its present gigantic proportions. I guess the once-inner planets of Betelgeuse are no more.

As for any outer planets of Betelgeuse, I just don't know. Don't ask me. If Betelgeuse once had outer planets, then those planets might still be there, for all I know.

No planets have been discovered around Betelgeuse, but I guess it would be hard to look for planets around such a huge, bright, misshapen and variously-illuminated star as Betelgeuse.

Ann

[smitty]

Ann, thank you for your excellent answer! Just the sort of helpful answer I was looking/hoping for.

[Ann]

Ann, thank you for your excellent answer! Just the sort of helpful answer I was looking/hoping for.

Thanks, Smitty! Anyway, I'd better clarify something I said, or else I guess our astronomer-in-residence (Chris Peterson, whose presence I'm very grateful for) will set me straight.

There may, for all I know, actually be underground life on a planet or a moon of Betelgeuse. In our own solar system, Europa, moon of Jupiter, and Enceladus, moon of Saturn, are believed to host underground oceans, and who is to say there can't be life in them? And there are other possible abodes of life in our solar system, like Ganymede and Callisto, moons of Jupiter, Titan, moon of Saturn, and minor planet Pluto.

So yes, there might be life under the surface of a planet in orbit around Betelgeuse, or under the surface of a moon orbiting a planet in orbit around Betelgeuse. For all any of us knows, there might be.

But let me put it like this: We wouldn't want to travel to any planet or moon of Betelgeuse's to search for life there.

No way Jose!

Ann

[Ann]

I have to make one more post here.

Betelgeuse will in all probability go supernova. Astronomers are sure that it will.

When Betelgeuse has exploded, it will probably leave a neutron star behind. Betelgeuse is not the kind of supermassive behemoth that I, at least, expect will end up as a black hole.

This isn't a spherical version of New York, but it will do.

---

So Betelgeuse will almost certainly leave a neutron star behind. Neutron stars typically weigh a little less than 1.4 solar masses, and their diameters are the size of a big city. Think of New York as a perfectly spherical object, and it would be the size of a typical neutron star.

A supernova rendering. Source: https://www.supernovae.net.

---

But you won't get a city-sized neutron star if you don't get a supernova explosion first. So Betelgeuse has to blow itself to smithereens for its core to end up as a neutron star. The question is: Can any planets of Betelgeuse survive such a terrific explosion?

The answer seems to be: Maybe. Maybe they can. At least astronomers have indeed detected planets in orbits around four pulsars.

But are the planets that orbit a few pulsars really the surviving cinders of the original planets of the pre-supernova stars? That is not so certain. This is what Wikipedia says about it:

Wikipedia wrote:

There are three types of pulsar planets known so far. The PSR B1257+12 planets were formed out of the debris of a destroyed companion star that used to orbit the pulsar.[11] In PSR J1719-1438, the planet most likely is the companion, or what's left of it after being almost entirely blasted away by the extreme irradiation from the nearby pulsar. PSR B1620-26 b is most likely a captured planet.

So for now, it doesn't seem as if pulsar planets are the original planets that have survived the supernova explosion.

Ann

[smitty]

Thanks again, Ann, for your helpful, informative replies to my original question about planets. I'm glad I asked . . . I learned much from your replies.

[neufer]

Betelgeuse has to blow itself to smithereens for its core to end up as a neutron star.

The question is: Can any planets of Betelgeuse survive such a terrific explosion?

I think I know the answer to that...all right, all right ...don't rush me

Click to play embedded YouTube video.

<<Despite its American sound and its common use by the fiery animated cartoon character Yosemite Sam, smithereens did not originate in American slang. Although no one is entirely positive about its precise origins, scholars think that smithereens likely developed from the Irish word smidiríní, which means "little bits." That Irish word is the diminutive of smiodar, meaning "fragment." According to print evidence, the plural form smithereens first appears in English in the late 18th century; use of singular smithereen then follows.>>

[neufer]

So is it no longer possible to get a serious answer to a serious question here?

I'll do my best to give you a serious answer to your question about possible planets around Betelgeuse. Mind you, planets are not my forte. I'm a blue star and star forming galaxies nerd.

According to Jim Kaler, Betelgeuse started out as an O star, with a mass of (according to Kaler) 18 or 19 solar masses, and with a temperature (I would guess) of at least 30,000 K, and more likely perhaps 35,000 K. At that temperature, the young blue and blisteringly hot Betelgeuse would have emitted an absolute torrent of ultraviolet light, but, in comparison, much lower amounts of visible and infrared light. In short: If you want a star that will fry your retinas to a crisp and turn your body into one large tumour, an O-star like Betelgeuse would be the star for you. Don't expect to find any sort of distance from an O-star that will provide you with pleasant daylight and nice warmth while at the same time not giving you a continuous full body scan.

So that was what Betelgeuse was like in its first flush of youth. Betelgeuse is still young as stars go,...

Betelgeuse is just 8.0–8.5 Myr old
...a minimal age for planets to form under the best of circumstances::

<<[Protoplanetary disk] grains eventually stick together to form mountain-size (or larger) bodies called planetesimals. Collisions and gravitational interactions between planetesimals combine to produce Moon-size planetary embryos (protoplanets) over roughly 0.1–1 million years. Finally, the planetary embryos collide to form planets over 10–100 million years.>>

And starting as a bright massive [~15M_☉] O-star
strong radiation pressure and "an absolute torrent of ultraviolet light "
would have made it difficult for any small early protoplanetary disk grains
to not simply disperse/disintegrate:

<<Observations using the Spitzer Space Telescope indicate that extremely massive stars of spectral category O, which are much hotter than the Sun, produce a photo-evaporation effect that inhibits planetary formation.>>

[Ann]

So is it no longer possible to get a serious answer to a serious question here?

I'll do my best to give you a serious answer to your question about possible planets around Betelgeuse. Mind you, planets are not my forte. I'm a blue star and star forming galaxies nerd.

According to Jim Kaler, Betelgeuse started out as an O star, with a mass of (according to Kaler) 18 or 19 solar masses, and with a temperature (I would guess) of at least 30,000 K, and more likely perhaps 35,000 K. At that temperature, the young blue and blisteringly hot Betelgeuse would have emitted an absolute torrent of ultraviolet light, but, in comparison, much lower amounts of visible and infrared light. In short: If you want a star that will fry your retinas to a crisp and turn your body into one large tumour, an O-star like Betelgeuse would be the star for you. Don't expect to find any sort of distance from an O-star that will provide you with pleasant daylight and nice warmth while at the same time not giving you a continuous full body scan.

So that was what Betelgeuse was like in its first flush of youth. Betelgeuse is still young as stars go,...

Betelgeuse is just 8.0–8.5 Myr old
...a minimal age for planets to form under the best of circumstances::

<<[Protoplanetary disk] grains eventually stick together to form mountain-size (or larger) bodies called planetesimals. Collisions and gravitational interactions between planetesimals combine to produce Moon-size planetary embryos (protoplanets) over roughly 0.1–1 million years. Finally, the planetary embryos collide to form planets over 10–100 million years.>>

And starting as a bright massive [~15M_☉] O-star
strong radiation pressure and "an absolute torrent of ultraviolet light "
would have made it difficult for any small early protoplanetary disk grains
to not simply disperse/disintegrate:

<<Observations using the Spitzer Space Telescope indicate that extremely massive stars of spectral category O, which are much hotter than the Sun, produce a photo-evaporation effect that inhibits planetary formation.>>

So no planets for Betelgeuse, then?

10 Lacertae and its nebula complex by Thomas Henne.png

10 Lacertae and friends. 10 Lac is one of the extremely few
main sequence O-type stars in the solar neighbourhood.
I guess it lacks planets. Photo: Thomas Henne.

So what. O stars, the kind of star that Betelgeuse used to be, only make up 0.00003% of the main sequence stars in the solar neighbourhood.

For all we know, the other 99.99997% of the main sequence stars in the solar neighbourhood may have planets!

Ann

[neufer]

So no planets for Betelgeuse, then? So what.

So no Ford Prefect or Zaphod Beeblebrox
http://asterisk.apod.com/viewtopic.php? ... 85#p302107