APOD: Betelgeuse Imagined (2020 Jan 01)

[Astronymus]

Does this decade discussion help us with Betelgeuse in any way?

[Tara_Li]

Could it be this confluence of cycles that triggers Betelguese?

[BDanielMayfield]

Damn, and I was thinking Orion looked odd this year... or the last. Something felt "wrong" in the constellation.

As there've only at most been less than 2 full days this year I'll assume it was late last year. About 10 days or so ago I had read a news article about the fading of Betelgeuse. Later when we had a clear night I looked and sure enough, the famous Red Super Giant did look dimmer than usual. It was noticeably dimmer than the three other main stars of Orion. It was about as bright as the belt stars.

Bruce

[TheOtherBruce]

Any ideas how accurate the artist's impression might be? That thing's too non-round IMHO to be a star, unless one just on the verge of popping its cork. I know the Wiki page mentions the possibility of massive convection cells on the outer photosphere, but this seems a bit much.

Also intriguing about the gas plumes, I didn't know they were so widely spread. Could Betelgeuse be close to casting off a planetary nebula as part of some pre-supernova process?

[neufer]

Does this decade discussion help us with Betelgeuse in any way?

Celestia depiction of Orion when Betelgeuse explodes

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<<Betelgeuse's time spent as a red supergiant can be estimated by comparing mass loss rates to the observed circumstellar material, as well as the abundances of heavy elements at the surface. Estimates range from 20,000 years to a maximum of 140,000 years. Betelgeuse appears to undergo short periods of heavy mass loss and is a runaway star moving rapidly through space, so comparisons of its current mass loss to the total lost mass are difficult. The surface of Betelgeuse shows enhancement of nitrogen, relatively low levels of carbon, and a high proportion of ¹³C relative to ¹²C, all indicative of a star that has experienced the first dredge-up. However, the first dredge-up occurs soon after a star reaches the red supergiant phase and so this only means that Betelgeuse has been a red supergiant for at least a few thousand years. The best prediction is that Betelgeuse has already spent around 40,000 years as a red supergiant, having left the main sequence perhaps one million years ago.

The current mass can be estimated from evolutionary models from the initial mass and the expected mass lost so far. For Betelgeuse, the total mass lost is predicted to be no more than about one M_☉, giving a current mass of 19.4–19.7 M_☉, considerably higher than estimated by other means such as pulsational properties or limb-darkening models.

All stars more massive than about 10 M_☉ are expected to end their lives when their core collapses, typically producing a supernova explosion. Up to about 15 M_☉, a type II-P supernova is always produced from the red supergiant stage. More massive stars can lose mass quickly enough that they evolve towards higher temperatures before their cores can collapse, particularly for rotating stars and models with especially high mass loss rates. These stars can produce type II-L or type IIb supernovae from yellow or blue supergiants, or type Ib/c supernovae from Wolf-Rayet stars. Models of rotating 20 M_☉ stars predict a peculiar type II supernova similar to SN 1987A from a blue supergiant progenitor. On the other hand, non-rotating 20 M_☉ models predict a type II-P supernova from a red supergiant progenitor.

The time until Betelgeuse explodes depends on the predicted initial conditions and on the estimate of the time already spent as a red supergiant. The total lifetime from the start of the red supergiant phase to core collapse varies from about 300,000 years for a rotating 25 M_☉ star, 550,000 years for a rotating 20 M_☉ star, and up to a million years for a non-rotating 15 M_☉ star. Given the estimated time since Betelgeuse became a red supergiant, estimates of its remaining lifetime range from a "best guess" of under 100,000 years for a non-rotating 20 M_☉ model to far longer for rotating models or lower-mass stars. Betelgeuse's suspected birthplace in the Orion OB1 Association is the location of several previous supernovae. It is believed that runaway stars may be caused by supernovae, and there is strong evidence that OB stars μ Columbae, AE Aurigae and 53 Arietis all originated from such explosions in Ori OB1 2.2, 2.7 and 4.9 million years ago.

A typical type II-P supernova emits 2×10⁴⁶ J of neutrinos and produces an explosion with a kinetic energy of 2×10⁴⁴ J. As seen from Earth, it would have a peak apparent magnitude of about −12.4. It may outshine the full moon and would be easily visible in daylight. This type of supernova would remain at roughly constant brightness for 2–3 months before rapidly dimming. The visible light is produced mainly by the radioactive decay of cobalt, and maintains its brightness due to the increasing transparency of the cooling hydrogen ejected by the supernova.

Due to misunderstandings caused by the 2009 publication of the star's 15% contraction, apparently of its outer atmosphere, Betelgeuse has frequently been the subject of scare stories and rumors suggesting that it will explode within a year, leading to exaggerated claims about the consequences of such an event. The timing and prevalence of these rumors have been linked to broader misconceptions of astronomy, particularly to doomsday predictions relating to the Mayan calendar. Betelgeuse is not likely to produce a gamma-ray burst and is not close enough for its x-rays, ultraviolet radiation, or ejected material to cause significant effects on Earth. Following the dimming of Betelgeuse in December 2019,reports appeared in the science and mainstream media that again included speculation that the star might be about to go supernova – even in the face of scientific research that a supernova is not expected for perhaps 100,000 years. Some outlets reported the magnitude as faint as +1.3 as an unusual and interesting phenomenon, like Astronomy magazine, the National Geographic, and the Smithsonian magazine. Some mainstream media, like The Washington Post, ABC News in Australia, and Popular Science, reported that a supernova was possible but unlikely, whilst other outlets portrayed a supernova as a realisitic possibility. CNN, for example, chose the headline "A giant red star is acting weird and scientists think it may be about to explode," while The New York Post declared Betelgeuse as "due for explosive supernova." Phil Plait has again written to correct what he calls "Bad Astronomy," noting that Betelgeuse's recent behaviour "[w]hile unusual ... isn't unprecedented. Also, it probably won't go bang for a long, long time."

Following Betelgeuse's supernova, a small dense remnant will be left behind, either a neutron star or black hole. Betelguese does not have a core massive enough for a black hole so the remnant is predicted to be a neutron star of approximately 1.5 M_☉.>>

[geckzilla]

Any ideas how accurate the artist's impression might be? That thing's too non-round IMHO to be a star, unless one just on the verge of popping its cork. I know the Wiki page mentions the possibility of massive convection cells on the outer photosphere, but this seems a bit much.

Also intriguing about the gas plumes, I didn't know they were so widely spread. Could Betelgeuse be close to casting off a planetary nebula as part of some pre-supernova process?

It is my understanding that lumpy and non-round is a reasonable depiction of the star. The atmosphere is so tenuous that it doesn't take much force to push it around. Luís Calçada is an astronomer himself, and I've noted him to be a careful illustrator of astronomical phenomena. I really like his work.

[BDanielMayfield]

Any ideas how accurate the artist's impression might be? That thing's too non-round IMHO to be a star, unless one just on the verge of popping its cork. I know the Wiki page mentions the possibility of massive convection cells on the outer photosphere, but this seems a bit much.

Also intriguing about the gas plumes, I didn't know they were so widely spread. Could Betelgeuse be close to casting off a planetary nebula as part of some pre-supernova process?

It is my understanding that lumpy and non-round is a reasonable depiction of the star. The atmosphere is so tenuous that it doesn't take much force to push it around. Luís Calçada is an astronomer himself, and I've noted him to be a careful illustrator of astronomical phenomena. I really like his work.

Geck is right. Even though Betelgeuse has 20 times the mass of Sol we need to remember that surface gravity is inversely proportional to a body’s radius squared. I haven’t done the math yet, but it could be that Betelgeuse’s surface gravity is even less than Earth’s! Maybe even a lot less.

The Sun’s surface gravity is 28 G (28 times what we feel here on Earth), and yet look at how turbulent the Sun’s photosphere can be. Bloated stars will likely have extremely turbulent photospheres.

Bruce

[neufer]

Any ideas how accurate the artist's impression might be? That thing's too non-round IMHO to be a star, unless one just on the verge of popping its cork. I know the Wiki page mentions the possibility of massive convection cells on the outer photosphere, but this seems a bit much.

Also intriguing about the gas plumes, I didn't know they were so widely spread. Could Betelgeuse be close to casting off a planetary nebula as part of some pre-supernova process?

It is my understanding that lumpy and non-round is a reasonable depiction of the star. The atmosphere is so tenuous that it doesn't take much force to push it around. Luís Calçada is an astronomer himself, and I've noted him to be a careful illustrator of astronomical phenomena. I really like his work.

---

Geck is right. Even though Betelgeuse has 20 times the mass of Sol we need to remember that surface gravity is inversely proportional to a body’s radius squared. I haven’t done the math yet, but it could be that Betelgeuse’s surface gravity is even less than Earth’s! Maybe even a lot less.

Betelgeuse's surface gravity is 1/32,600 of Earth’s.

This orange blob shows the star Betelgeuse, as seen by the Atacama Large Millimeter/submillimeter Array (ALMA). This is the first time that ALMA has ever observed the surface of a star and this first attempt has resulted in the highest-resolution image of Betelgeuse available

The Sun’s surface gravity is 28 G (28 times what we feel here on Earth), and yet look at how turbulent the Sun’s photosphere can be.

Bloated stars will likely have extremely turbulent photospheres.

[BDanielMayfield]

Any ideas how accurate the artist's impression might be? That thing's too non-round IMHO to be a star, unless one just on the verge of popping its cork. I know the Wiki page mentions the possibility of massive convection cells on the outer photosphere, but this seems a bit much.

Also intriguing about the gas plumes, I didn't know they were so widely spread. Could Betelgeuse be close to casting off a planetary nebula as part of some pre-supernova process?

It is my understanding that lumpy and non-round is a reasonable depiction of the star. The atmosphere is so tenuous that it doesn't take much force to push it around. Luís Calçada is an astronomer himself, and I've noted him to be a careful illustrator of astronomical phenomena. I really like his work.

---

Geck is right. Even though Betelgeuse has 20 times the mass of Sol we need to remember that surface gravity is inversely proportional to a body’s radius squared. I haven’t done the math yet, but it could be that Betelgeuse’s surface gravity is even less than Earth’s! Maybe even a lot less.

Betelgeuse's surface gravity is 1/32,600 of Earth’s.

This orange blob shows the star Betelgeuse, as seen by the Atacama Large Millimeter/submillimeter Array (ALMA). This is the first time that ALMA has ever observed the surface of a star and this first attempt has resulted in the highest-resolution image of Betelgeuse available

The Sun’s surface gravity is 28 G (28 times what we feel here on Earth), and yet look at how turbulent the Sun’s photosphere can be.

Bloated stars will likely have extremely turbulent photospheres.

Thanks for the confirmation Art. I should have been much more definitive in my comment.

[Ann]

Any ideas how accurate the artist's impression might be? That thing's too non-round IMHO to be a star, unless one just on the verge of popping its cork. I know the Wiki page mentions the possibility of massive convection cells on the outer photosphere, but this seems a bit much.

Also intriguing about the gas plumes, I didn't know they were so widely spread. Could Betelgeuse be close to casting off a planetary nebula as part of some pre-supernova process?

Click to view full size image

A huge nebula surrounding Betelgeuse (inset). The nebula is made of
material previously cast off by Betelgeuse. Photo: ESO/VLT.

Phys.org wrote:

Betelgeuse, a red supergiant in the constellation of Orion, is one of the brightest stars in the night sky. It is also one of the biggest, being almost the size of the orbit of Jupiter — about four and half times the diameter of the Earth's orbit. The VLT image shows the surrounding nebula, which is much bigger than the supergiant itself, stretching 60 billion kilometres away from the star's surface — about 400 times the distance of the Earth from the Sun...

The process by which material is shed from a star like Betelgeuse involves two phenomena. The first is the formation of huge plumes of gas (although much smaller than the nebula now imaged) extending into space from the star's surface, previously detected using the NACO instrument on the VLT. The other, which is behind the ejection of the plumes, is the vigorous up and down movement of giant bubbles in Betelgeuse's atmosphere — like boiling water circulating in a pot...

The material visible in the new image is most likely made of silicate and alumina dust. This is the same material that forms most of the crust of the Earth and other rocky planets. At some time in the distant past, the silicates of the Earth were formed by a massive (and now extinct) star similar to Betelgeuse.

Ann

[BDanielMayfield]

Phys.org wrote:

Betelgeuse, a red supergiant in the constellation of Orion, is [usually, but not right now] one of the brightest stars in the night sky.

That article also reports the star as being one of the largest. But now, during this dimming phase, has it also contracted in size?

[Ann]

Phys.org wrote:

Betelgeuse, a red supergiant in the constellation of Orion, is [usually, but not right now] one of the brightest stars in the night sky.

That article also reports the star as being one of the largest. But now, during this dimming phase, has it also contracted in size?

My amateur guess is that, yes, Betelgeuse has probably contracted in size.

Ann

[BDanielMayfield]

Interesting to note that 2 suns have been found to orbit BETELGEUSE.Thank you links!

That would indeed be interesting if it where true, considering that Betelgeuse itself is a runaway star, thought to have once been in a system in which another star has already gone Supernova. However, this proposal has been refuted:

Betelgeuse is generally considered to be a single isolated star and a runaway star, not currently associated with any cluster or star-forming region, although its birthplace is unclear.[75]

Two spectroscopic companions have been proposed to the red supergiant star. Analysis of polarization data from 1968 through 1983 indicated a close companion with a periodic orbit of about 2.1 years. Using speckle interferometry, the team concluded that the closer of the two companions was located at 0.06″±0.01″ (~9 AU) from the main star with a position angle (PA) of 273 degrees, an orbit that would potentially place it within the star's chromosphere. The more distant companion was estimated at 0.51″±0.01″ (~77 AU) with a PA of 278 degrees.[76][77] Further studies have found no evidence for these companions or have actively refuted their existence,[78] but the possibility of a close companion contributing to the overall flux has never been fully ruled out.[79] High-resolution interferometry of Betelgeuse and its vicinity, far beyond the technology of the 1980s and '90s, have not detected any companions.[16][80]

[Ann]

That article also reports the star as being one of the largest. But now, during this dimming phase, has it also contracted in size?

My amateur guess is that, yes, Betelgeuse has probably contracted in size.

Ann

The APOD of January 2, 2020, provided a link to the following information about the light variations of Betelgeuse:

Click to view full size image

Betelgeuse, with the inner solar system overlaid.
Note the enormous bright spot at upper left. Photo: ESO/ALMA.

The Astronomer's Telegram wrote:

The light variations are complicated and arise from pulsations as well from the waxing and waning of large super-granules on the star's convective surface. Measures of Wing TiO-band (705 nm) and near-IR colors indicate that currently Betelgeuse has relatively strong TiO-bands and has a corresponding lower photospheric temperature of T~3580 K (relative to T~ 3660 K near maximum brightness- typically V ~ 0.2-0.3 mag).

So Betelgeuse pulsates, so that it grows larger or smaller, but it also has "super-granules" on its surface. My guess is that these "super-granules" are often hotter than the rest of the surface of Betelgeuse, so that the absence of these might make Betelgeuse fainter.

TiO is titanium oxide, which is a very common ingredient in sun screen lotions. In other words, titanium oxide in the atmosphere of Betelgeuse blocks some of the light from Betelgeuse. Apparently the TiO bands of Betelgeuse are stronger than usual.

Ann

[Astronymus]

Damn, and I was thinking Orion looked odd this year... or the last. Something felt "wrong" in the constellation.

As there've only at most been less than 2 full days this year I'll assume it was late last year. About 10 days or so ago I had read a news article about the fading of Betelgeuse. Later when we had a clear night I looked and sure enough, the famous Red Super Giant did look dimmer than usual. It was noticeably dimmer than the three other main stars of Orion. It was about as bright as the belt stars.

Bruce

I noticed it when I drove home from last year's (yeah, last year...) company christmas party. As I was driving on the Autobahn and no alcohol was involved (I'm very strict with this.), I looked out the side window and it didn't represent the familiar sight.

[neufer]

Click to play embedded YouTube video.

Damn, and I was thinking Orion looked odd this year... or the last. Something felt "wrong" in the constellation.

... when we had a clear night I looked and sure enough, the famous Red Super Giant did look dimmer than usual. It was noticeably dimmer than the three other main stars of Orion.

... when I drove home from last year's company christmas party... I looked out the side window and it didn't represent the familiar sight.

[Chris Peterson]

TiO is titanium oxide, which is a very common ingredient in sun screen lotions. In other words, titanium oxide in the atmosphere of Betelgeuse blocks some of the light from Betelgeuse. Apparently the TiO bands of Betelgeuse are stronger than usual.

We observe the gas-phase absorption lines of TiO... which is quite different from TiO₂, titanium dioxide which is found in sunscreens.

[jajvj]

Surely, the sun is not to scale in the diagram? Mercury is practically grazing the surface.

[Chris Peterson]

Surely, the sun is not to scale in the diagram? Mercury is practically grazing the surface.

No. To be consistent with the sizes of the planets as shown, the Sun needs to be several times larger. That, of course, would result in it appearing larger than the orbits of the interior planets. And, of course, the scale of the planets themselves is completely different than the scale of the distance between them in this image.

Always a problem when you're trying to depict the Solar System. Make the orbits visible and the planets are mostly too small to see. Make the planets visible and you can't fit most of them in the image.

[neufer]

TiO is titanium oxide, which is a very common ingredient in sun screen lotions. In other words, titanium oxide in the atmosphere of Betelgeuse blocks some of the light from Betelgeuse. Apparently the TiO bands of Betelgeuse are stronger than usual.

We observe the gas-phase absorption lines of TiO... which is quite different from TiO₂, titanium dioxide which is found in sunscreens.

<<Titanium dioxide (TiO₂) occurs in nature as the minerals rutile and anatase. Additionally two high-pressure forms are known minerals: a monoclinic baddeleyite-like form known as akaogiite, and the other is an orthorhombic α-PbO2-like form known as brookite, both of which can be found at the Ries crater in Bavaria.

Rutile is the most common (and most stable) natural form of TiO₂. Rutile has one of the highest refractive indices at visible wavelengths of any known crystal [birefringence refractive indices: n_ω = 2.613, n_ε = 2.909 (vs. 2.45 for diamond)] and also exhibits a high (color) dispersion. Owing to these properties, it is useful for the manufacture of certain optical elements, especially polarization optics, for longer visible and infrared wavelengths up to about 4.5 μm. Rutile derives its name from the Latin rutilus, red, in reference to the deep red color observed in some specimens (when viewed by transmitted light).>>

Relief Map of Nördlinger Ries

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<<The Nördlinger Ries (most commonly referred to simply as Ries crater or the Ries) is a large circular depression in western Bavaria north of the Danube. The meteorite impact crater formed 14.808 ± 0.038 million years ago in the Miocene. The original crater rim had an estimated diameter of 24 km. The present floor of the depression is about 100 to 150 m below the eroded remains of the rim.

It was originally assumed that the Ries was of volcanic origin. In 1960 Eugene Shoemaker and Edward C. T. Chao showed that the depression was caused by meteorite impact. The key evidence was the presence of coesite, which, in unmetamorphosed rocks, can only be formed by the shock pressures associated with meteorite impact. Shoemaker was encouraged by the Nördlingen St. George's church built of locally derived suevite. The suevite was formed from mesozoic sediments shocked by the bolide impact. Stone buildings in Nördlingen contain millions of tiny diamonds, all less than 0.2 mm across. The impact that caused the Nördlinger Ries crater created an estimated 72,000 tonnes of them when it impacted a local graphite deposit. The Ries crater impact event is believed to be the source of moldavite tektites found in Bohemia and Moravia (Czech Republic). The tektite melt originated from a sand-rich surface layer that was ejected to distances up to 450 km downrange of the crater.

The Ries impact crater was a rampart crater, thus far a unique finding on Earth. Rampart craters are almost exclusively found on Mars. Rampart craters exhibit a fluidized ejecta flow after impact of the meteorite, most simply compared to a bullet fired into mud, with the ejecta resembling a mudflow. Another impact crater, the much smaller (3.8 km diameter) Steinheim crater, is located about 42 km west-southwest from the centre of Ries. The two craters are believed to have formed nearly simultaneously by the impact of a binary asteroid. Recent computer modeling of the impact event indicates that the impactors probably had diameters of about 1.5 km (Ries) and 150 m (Steinheim), had a pre-impact separation of some tens of kilometers, and impacted the target area at an angle around 30 to 50 degrees from the surface in a west-southwest to east-northeast direction. The impact velocity is thought to have been about 20 km/s.>>

[rstevenson]

I like the concept of named decades. Using that concept, I've now lived in nine decades -- 40s, 50s, 60s, 70s, 80s, 90s, 00s, 10s, and now 20s -- though in a few days I'll be only a relatively youthful 72. If I live as long as my parents I'll easily make it to 11 decades (or portions thereof.)

Rob

[neufer]

Click to play embedded YouTube video.

I like the concept of named decades. Using that concept, I've now lived in nine decades -- 40s, 50s, 60s, 70s, 80s, 90s, 00s, 10s, and now 20s -- though in a few days I'll be only a relatively youthful 72. If I live as long as my parents I'll easily make it to 11 decades (or portions thereof.)

decadence (n.) 1540s, "deteriorated condition, decay," from Middle French décadence (early 15c.), from Medieval Latin decadentia "decay," from decadentem (nominative decadens) "decaying," present participle of decadere "to decay," from Latin de- "apart, down" (see de-) + cadere "to fall". Meaning "process of falling away from a better or more vital state" is from 1620s. Used of periods in art since 1852, on French model.