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Betelgeuse- the second brightest star of the Orion constellation and a red supergiant: description and characteristics with photos, facts, color, coordinates, latitude, supernova.

Betelgeuse(Alpha Oriioni) is the second brightest star in Orion and the 9th in the sky. It is a red supergiant, 643 light years distant. Ends its existence and will explode as a supernova in the near future.

Here is a large, bright and massive star that is easy to spot in winter. Lives in the shoulder of the constellation Orion opposite Bellatrix. You will know where the star Betelgeuse is if you use our online star map.

Betelgeuse is considered a variable star and can periodically eclipse Rigel. The name comes from the Arabic translation “hand of Orion”. The modern Arabic "al-Jabbar" means "giant". The translators mistook Y for B and the name "Betelgeuse" appeared merely as a mistake. Next you will learn about the distance to the star Betelgeuse, its latitude, coordinates, class, declination, color and luminosity level with photos and diagrams.

Betelgeuse is located in the right shoulder of Orion (top left). If you place it in our system, it will go beyond the asteroid belt and touch the orbital path of Jupiter.

It belongs to the spectral class M2Iab, where “lab” indicates that we are dealing with a supergiant with intermediate luminosity. The absolute value reaches -6.02. The mass ranges between 7.7-20 times that of the Sun. It is 10 million years old and has an average luminosity 120,000 times that of the Sun.

The apparent value varies from 0.2-1.2 over 400 days. Because of this, it periodically bypasses Procyon and takes the 7th position in brightness. At its peak luminosity it eclipses Rigel, and during its dim period it drops below Deneb and becomes 20th.

The absolute magnitude of Betelgeuse varies from -5.27 to -6.27. The outer layers expand and contract, causing temperatures to rise and fall. The pulsation occurs due to an unstable atmospheric layer. When absorbed, it absorbs more energy.

There are several pulsation cycles with short-term differences of 150-300 days, and long-term ones cover 5.7 years. The star is rapidly losing mass, so it is covered by a huge shell of material, making observation difficult.

In 1985, two satellites were noticed in orbit around the star, but they could not be confirmed at that time. Betelgeuse is easy to find because it is located in Orion. From September to March it is visible from any point on Earth except 82°S. For residents northern hemisphere the star will rise in the east after sunset in January. In summer, it hides behind the Sun, so it cannot be seen.

Supernova and star Betelgeuse

Betelgeuse has reached the end of its evolutionary development and will explode as a Type II supernova in the next million years. This will result in a visual magnitude of -12 and last for a couple of weeks. The last supernova, SN 1987A, could be seen without instruments, although it occurred in the Large Magellanic Cloud, 168,000 light-years away. Betelgeuse will not harm the system, but will provide an unforgettable celestial spectacle.

Although the star is young, it has already practically used up its fuel supply. Now it contracts and increases internal heating. This caused helium to fuse into carbon and oxygen. As a result, an explosion will occur and a 20-kilometer neutron star.

The ending of a star always depends on its mass. The exact figure remains vague, but many believe it is 10 times larger than the Sun.

Facts about the star Betelgeuse

let's consider Interesting Facts about the star Betelgeuse with a photo and a view of its stellar neighbors in the constellation Orion. If you want more details, then use our 3D models, which allow you to independently navigate among the stars of the galaxy.

Part of two winter asterisms. Occupies the upper corner of the Winter Triangle.

The remaining angles are assigned to Procyon and Sirius. Betelgeuse is also part of the Winter Hexagon along with Sirius, Procyon, Pollux, Capella, Aldebaran and Rigel.

In 2013, Betelgeuse was thought to crash into a “cosmic wall” of interstellar dust in 12,500 years.

Betelgeuse is part of the Orion OB1 Association, whose stars share regular motion and uniform speed in space. The red supergiant is believed to have changed its motion because its path does not intersect with star formation sites. May be a runaway member that appeared approximately 10-12 million years ago in the Orion molecular cloud.

The star moves through space with an acceleration of 30 km/s. As a result, a shock wave with a length of 4 light years was formed. The wind pushes out huge volumes of gas at a speed of 17 km/s. They managed to display it in 1997, and its formation is approximately 30,000 years old.

Alpha Orionis is the brightest source in the near-infrared region of the sky. Only 13% of the energy is displayed in visible light. In 1836, John Herschel noted stellar variability. In 1837, the star eclipsed Rigel and repeated this in 1839. It was because of this that in 1603 Johann Bayer mistakenly gave Betelgeuse the designation “alpha” (as the brightest).

The star Betelgeuse is believed to have begun life 10 million years ago as a hot blue O-type star. And the initial mass exceeded the solar mass by 18-19 times. Until the 20th century, the name was written as "Betelge" and "Betelgeuse".

Betelgeuse has been recorded in different cultures under different names. In Sanskrit it is written as “bahu” because the Hindus saw a deer or antelope in the constellation. In China, Shenxia is the “fourth star,” as a reference to Orion’s belt. In Japan - Heike-boshi as a tribute to the Heike clan, which took the star as a symbol of their clan.

In Brazil, the star was called Zhilkavai - the hero whose leg was torn apart by his wife. In northern Australia it was nicknamed "Owl Eyes", and in south africa- a lion hunting three zebras.

Betelgeuse also appears in various feature films and books. So the hero of Beetlejuice shares a name with the star. Betelgeuse was the home system of Zaford Beeblebrox from The Hitchhiker's Guide to the Galaxy. Kurt Vonnegut starred in Sirens of Titan, as did Pierre Boulle in Planet of the Apes.

Betelgeuse star size

It is difficult to determine the parameters, but the diameter covers approximately 550-920 solar. The star is so huge that it shows a disk in telescopic observations.

The radius was measured using an infrared spatial interferometer, which showed a mark of 3.6 AU. In 2009, Charles Townes announced that the star had shrunk by 15% since 1993, but had not lost any brightness. This is most likely caused by shell activity in the expanded atmospheric layer. Scientists have found at least 6 shells around the star. In 2009, a gas emission was recorded at a distance of 30 AU.

Alpha Orionis became the second star after the Sun where it was possible to calculate the angular size of the photosphere. This was done by A. Michelson and F. Paze in 1920. But the numbers were inaccurate due to attenuation and measurement errors.

The diameter is difficult to calculate due to the fact that we are dealing with a pulsating variable, which means the indicator will always change. In addition, it is difficult to determine the stellar edge and photosphere, since the object is surrounded by a shell of ejected material.

It was previously believed that Betelgeuse has the largest angular diameter. But later they carried out a calculation in R Doradus and now Betelgeuse is in 3rd place. The radius extends to 5.5 AU, but can be reduced to 4.5 AU.

Distance of the star Betelgeuse

Betelgeuse lives 643 light-years away in the constellation Orion. In 1997, the figure was thought to be 430 light years, and in 2007 it was put at 520. But the exact figure remains a mystery, because direct parallax measurements show 495 light years, and adding natural radio emission shows 640 light years. Data from 2008 obtained by the VLA suggested 643 light years.

Color index – (B-V) 1.85. That is, if you wanted to know what color Betelgeuse is, then this is a red star.

The photosphere has an extended atmosphere. The result is blue emission lines rather than absorption lines. Even ancient observers knew about the color red. So Ptolemy in the 2nd century gave a clear description of the color. But 3 centuries before him, Chinese astronomers described yellow. This does not indicate an error, because previously the star could have been a yellow supergiant.

Temperature of the star Betelgeuse

The surface of Betelgeuse warms up to 3140-4641 K. The atmospheric index is 3450 K. As the gas expands, it cools.

Physical characteristics and orbit of the star Betelgeuse

• Betelgeuse - Alpha Orionis.
• Constellation: Orion.
• Coordinates: 05h 55m 10.3053s (right ascension), + 07° 24" 25.426" (declination).
• Spectral class: M2Iab.
• Magnitude (visible spectrum): 0.42 (0.3-1.2).
• Magnitude: (J-band): -2.99.
• Absolute value: -6.02.
• Distance: 643 light years.
• Variable type: SR (semi-regular variable).
• Massiveness: 7.7-20 solar.
• Radius: 950-1200 solar.
• Luminosity: 120,000 solar.
• Temperature mark: 3140-3641 K.
• Rotation speed: 5 km/s.
• Age: 7.3 million years.
• Name: Betelgeuse, Alpha Orionis, α Orionis, 58 Oroni, HR 2061, BD + 7° 1055, HD 39801, FK5 224, HIP 27989, SAO 113271, GC 7451, CCDM J05552+0724AP, AAVSO 0549+07.

Who among you would not dream of witnessing the epochal departure from the earth's horizon of one of the most prominent stars?

According to some sources, the right shoulder of the sky hunter can at any moment emit its last breath in the form of a long and bright supernova explosion, leaving behind an empty space invisible to the naked eye.

This will completely change the appearance of the sky that so beautifully enlivens the winter sky of our latitudes. Should we expect this event in our lifetime, and does it pose a threat to our planet?

According to a number of news reports, a huge supernova explosion could ignite at any second. Betelgeuse will increase its brightness thousands of times and will illuminate the sky for several months until it gradually goes out and leaves behind an expanding one with an invisible neutron star or black hole at its center. Such a cosmic catastrophe does not threaten us with anything serious, unless one of the poles of the exploding star is directed towards the Earth. The flow of gamma rays and charged particles will create some problems with the magnetic environment and ozone layer planets and their atmospheres. Is there any reason to trust such information, or is this just another media horror story?

Probability of explosion

Scientists do not deny the likelihood of such an outcome. However, it is not known for certain whether the star will explode tomorrow, or in a million years, and it is also unknown whether it will explode at all. Despite all the power modern astronomy, knowledge concerning the life of stars seems to be reliving its infancy. The paradox of the existence of giants and the problems of modeling star formation in close systems cast doubt on the existing scientific paradigms about the life of stars. The discovery of objects that do not fit into the framework of existing theories rather creates more questions than answers. An example of this is even the well-known Betelgeuse, about which, it would seem, we should know everything.

Unknown Betelgeuse

What do we know about Betelgeuse? An amateur astronomer, pointing his finger at the reddish light, will tell about its colossal size, variability and other publicly available facts. And, in order to excite the listener’s imagination, he will add that if you place it in the place of the Sun, then all the planets would be in the depths of the supergiant terrestrial group, and perhaps even . In this he will be right, but no matter how strange it may be, a professional astronomer will operate with almost the same set of knowledge about the red giant. For example, the exact size, mass and distance to Betelgeuse have not yet been established.

The distance to the star is estimated at such rough limits as 420-650, some sources give even terrifying boundaries from 180 to 1300 light years. Estimates of the mass and radius are also not accurate and vary within 13-17 solar masses and 950-1200 solar radii, respectively. Such large discrepancies are explained by the fact that, due to its remoteness, the distance to Betelgeuse cannot be measured using the annual parallax method. In addition, Betelgeuse is neither a double star nor part of any close cluster. This feature does not allow us to correctly estimate the mass and other characteristics of the star, including absolute luminosity.

Even the fact that Betelgeuse became the first star (naturally, after the Sun) whose angular size was measured and a detailed image of its disk was obtained, in fact, does not give us any significant data regarding its parameters and nature.

The situation is similar with the entire “stellar” section of astronomy. Scientists not only have to develop new models that describe the mechanisms of formation, evolution and death of stars, but also radically reshape the old ones. For example, how to explain the existence of recently discovered stars with a mass of 200-250 solar masses, if the upper theoretical limit until recently was estimated at 150 solar masses? How can we explain the nature of gamma-ray bursts? Other discoveries are just around the corner that will continue to baffle astronomers.

Will there be an explosion?

Returning to Betelgeuse, we can give a unique verdict to those sources that declare the imminent appearance of the brightest “farewell fireworks” in our sky. Astronomers make it clear that although such an event has a very real probability of happening before our eyes, this probability is extremely small, and it is not possible to evaluate it. Naturally, the means mass media, trying to revive the public, remake these cautious statements in their own way.

Supernova explosions are classified as cosmic events that are observed de facto. There has never been a case in science where a supernova explosion was recorded, which was predicted and expected in advance. For this reason, astronomers can only indirectly judge the processes preceding the explosion.

With regards to Betelgeuse, scientists confidently state that the star is in its final life stage, when the current percentage of carbon and subsequent heavy elements can no longer support stable thermonuclear processes. According to existing models, this will most likely lead to the termination of the hydrodynamic equilibrium of the star, in other words, to a supernova explosion. There is also the possibility that Betelgeuse will end its life not so brightly, but will simply gradually shed its shell, turning into an oxygen-neon white dwarf.

Anyway modern science unable to set an exact date for the explosion or deny the very fact that it will happen. The resulting media frenzy about the appearance of a “second Sun” erupted after controversy arose in the global astronomical community over the rapid decline in the average brightness and size of Betelgeuse. Many astronomers confidently stated that this phenomenon is explained by an imminent supernova explosion, which, by cosmic standards, is about to occur within the next two millennia. Others are more restrained in their predictions, and explain the fading of the star by certain temporary or periodic processes. This unannounced astronomical dispute shows how much new and unknown scientists have to learn.

A dream on a galactic scale

Undoubtedly, a bright light in the sky would inspire people to forget about how insignificant they are in the Universe. One has only to think for a moment that this same explosion could be observed by possible inhabitants of other distant systems of our vast galaxy. Such stellar news will bring real, invaluable benefits to astronomers. If such a close and expected supernova explosion occurs in our lifetime, curious glances of all types of telescopes and other equipment will be directed in its direction. In frantic delight, scientists will fill their databases with tons of valuable information coming from the light of the explosion. Every day, information about the next sensational discovery will be heard from all corners of the world. But these are just vague dreams.

Reality dictates its own rules. The explosion of Betelgeuse is not only something to be afraid of or even expected to see, in fact, one can only dream about it. Moreover, a brighter light, if it lit up before our eyes, would hardly be comparable in brightness to the full moon and would not bring us any significant harm. In the meantime, we have the opportunity to continue to observe the red star of Orion and hope that astronomers will expand their knowledge without such rare and amazing events.

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List of the brightest stars

Orion constellation - one of the most beautiful and richest cosmic wonders. There is a whole range of different cosmic objects here, from nebulae to unique stars. Among these wonders there is a real giant among the stars - Betelgeuse , also called Alpha Orionis . The generally accepted version is that the name Betelgeuse comes from the distorted Yad al-Jawza - “hand of the Twin” (Arabic). This star has other names: “Al-Manqib” (“shoulder”), “Ardra”, “Nakshatra” (Hindi), “Bahu” (Sanskrit), “Claria” (Coptic, “bandage”).
This is indeed a very interesting star, one of the brightest stars in the night sky, and one of the largest stars in the observable Universe, also one of the possible candidates for a supernova explosion in the next few centuries, or even earlier in the Milky Way.

Betelgeuse in the constellation Orion is marked with a red circle

To see Betelgeuse in the sky, find the constellation Orion and look at the red star in the upper triangle. Betelgeuse is a reddish star located in the right shoulder (left side) of the constellation Orion, and is the second brightest star in this constellation. She is a red supergiant, and her size is truly impressive. If we place this star in the place of the Sun, then it would fill all space up to the orbit of Jupiter at its maximum size, and at its minimum - up to the orbit of Mars. Betelgeuse is brighter than the Sun in 80 000 - 100 000 once. In this case, the mass of the star is only 13 — 17 solar, since its atmosphere is more rarefied and the density is much lower than the solar one. The distance to the star is estimated to be approximately 500-640 light years from Earth. It is a semi-regular variable star, that is, its luminosity and size change with different periods. With modern instruments, it is possible to view the star's disk, and in some cases spots on the surface, using interferometry in infrared light. The spots could be giant convective cells rising from beneath the supergiant's surface. Their increased brightness is due to the fact that they are hotter than the surrounding surface.
Betelgeuse is the first star for which the angular diameter visible from Earth was measured (December 13, 1920), and it is approximately 0,047-0,055 arcsec and varies depending on the luminosity of the star.

The mottled surface of Betelgeuse obtained using infrared interferometry

The spectral class of the star is M2Iab, and the temperature of the upper layers of the atmosphere (or, as they say, the surface) is about 3600º K ( 3326.85ºС), which is much colder than the Sun's temperature of 5778º K ( 5504.85 ºС), this gives the star a reddish tint, as opposed to the yellow of the sun.

Photo of Betelgeuse taken by the Takahashi E-180 astrograph

The age of Betelgeuse is estimated at about 10 million years, which by astronomical standards is a very short period of time; for comparison, the age of the Sun is estimated at about 5 billion years (and the Sun has approximately the same amount of time left to “live”). However, Betelgeuse is in one of the last stages of its existence - the burning of carbon in the core of the star, and most scientists suggest that in the relatively near future (several hundred years, or maybe at any moment) it could explode in the form class II supernova. Such a supernova explosion would be a very spectacular event. It will be visible even during the day and will be the brightest object in the sky after the Sun, and will shine like this for several weeks, since in a short period of time it will release as much energy as the Sun releases in its entire life. After a few centuries, in the place of the star there will only be a nebula with a neutron star, or a black hole, inside. A similar nebula, for example, is the Crab Nebula.
It may have already exploded, but, alas, we will not see this for at least 500 years. At this distance, a supernova explosion does not pose any threat to earthly life.

Betelgeuse is losing its outer shell. Image from the Herschel telescope

Some scientists believe that there will be no explosion, the star will simply shed its outer layers of atmosphere, exposing a heavy dense core (presumably oxygen-neon), thus forming a white dwarf. The star is still constantly losing large amounts of its matter from the upper layers of the atmosphere, forming a huge cloud of gas and dust around itself. In the new photos, these gas nebulae around the star are clearly visible.
In the photo above you can see several condensed arcs of matter on the left side of the image. Some scientists suggest that these arcs are completely unrelated to the star and that it is not matter that the star is losing, but rather a dark cloud of gas and dust that lights up Betelgeuse. If this is true, then Betelgeuse will collide with it in the future. But this remains to be seen.

Photo of Betelgeuse obtained using the Very Large Telescope in Chile

But still, most astronomers believe that the gas plume belongs precisely to the substance that the star ejected from itself. A recent image from the Very Large Telescope in Chile resolves not only the star's disk, but also the huge plume of gas surrounding the star. This trail provides insight into how a massive star loses matter as it approaches the end of its life. The researchers discovered a strong flow of interstellar medium around the star, which originates in star-forming regions in Orion's Belt and has a speed of 11 km/s. Betelgeuse crosses this stream at 30 km/s, spewing sunny wind at a speed of 17 km/s. Previously obtained observational data indicate that over the past decade, Betelgeuse's surface has decreased significantly, but its luminosity has not changed. Scientists cannot yet explain this.

Betelgeuse photo from the orbital telescope. E. Hubble.

P.S. Admin . It is noteworthy that during the observation period from 1993 to 2009, the diameter of the star decreased by 15 % , With 5,5 to approximately 4.7, and by 2011 - to 4,5 astronomical unit, and astronomers cannot yet explain what this is connected with. However, the brightness of the star did not change any noticeably during this time.
The reasons for the observed decrease in the radius of Betelgeuse may also be associated with incorrect interpretation of the data obtained, for example:
differences in the brightness of different parts of the star's surface; Due to rotation, these irregularities change position, causing the apparent brightness to change. These changes can be mistaken for changes in diameter.
Modeling of supergiant stars suggests that such stars may be non-spherical, similar to a potato. irregular shape. It is assumed that Betelgeuse may have a rotation period 18 years, that is, while Betelgeuse was observed by orbital telescopes for less than one revolution around its axis.
It is possible that scientists are not observing the true diameter of the star, but a certain layer of dense molecular gas, the movements of which create the appearance of a change in the true size of the star.
There is a gas nebula around the star, which for a long time could not be seen due to the fact that it was eclipsed by the light of the star.

Light of Orion. A second sun may appear in the sky.

According to sources at the Mauna Kea Observatory in Hawaii, the red giant Betelgeuse, located in the constellation Orion, is rapidly changing its shape.
Only over the past 16 years has the star ceased to be round, it has shrunk at the poles. Such symptoms may indicate that very soon ( we're talking about months, perhaps even weeks) the star will go supernova.
Earthlings will be able to observe this event with the naked eye. A very bright star will flash in the sky. Scientists disagree on the degree of brightness, some say that it will be equal to the Moon, others promise the appearance of a second Sun.
The entire transformation will take about six weeks. In some parts of the Earth they will learn what white nights are; for others, the unusual phenomenon will add two to three hours to the length of daylight.
Then, the star will finally cool down and will be visible to earthlings in the form of a nebula.
For people, such events in space are not dangerous.
Waves of charged particles - a consequence of the explosion, will, of course, reach our planet, but this will happen in several centuries. Our distant descendants will receive a small dose of ionizing radiation.
IN last time a similar event was visible to earthlings in 1054.

Betelgeuse (alpha).

The biggest visible star
On the right shoulder of Orion, in the crown of the Winter Hexagon, the beautiful Betelgeuse shines in the winter skies.

Orion constellation. Betelgeuse is a reddish-orange star in the upper left corner of the constellation.

This star is not called Alpha Orionis for nothing, although dazzling bluish Rigel - in the photo in the lower right corner - is brighter most of the time. Betelgeuse is a unique star in many respects, which astronomers have been studying for many years and discovering more and more interesting facts.
First, Betelgeuse is one of the largest stars in the Universe. Its diameter is about a thousand times greater than the diameter of the Sun. Even the largest known star, VY Canis Major, exceeds Betelgeuse in diameter only twice (and, accordingly, eight times in volume). So it’s not for nothing that this star bears the proud title of a red supergiant.
If it were in the place of the Sun, it would almost fill the orbit of Saturn:

Only eight known stars (all red hypergiants) are larger than Betelgeuse in volume, but all of them appear very dim in Earth's sky. The reason is simple: Betelgeuse is much closer than all of them.

Betelgeuse is 640 light years away, and on a galactic scale this is very small. Betelgeuse is the closest supergiant to us.
An interesting conclusion follows from this: Betelgeuse in the earth's sky has the largest apparent diameter of all stars (of course, after the Sun.)
It is clear that everything that is smaller in diameter than a minute of arc is perceived by the human eye as a point. The angular diameters of absolutely all stars (except the Sun) are less than an arc minute, so they all look like points. In fact, of course, all their angular diameters are different. Betelgeuse's angular diameter was first determined in 1920 to be 0.047 arcseconds, which was the largest angular diameter of a star then known. Since then, however, the star R Dorado, invisible in the northern hemisphere, was discovered, the angular diameter of which turned out to be 0.057 arcseconds. But even in the southern hemisphere it is almost invisible: at maximum brightness it is hardly visible to the naked eye, and at minimum it cannot be seen in every telescope. R Dorado is so cold that it emits mostly infrared radiation. But since then, the angular measurements have been refined, and for Betelgeuse the apparent diameter is determined to be from 0.056 to 0.059 arcseconds, which restores its lost position as the largest visible star. It's not so easy to oust the queen of the winter skies!
Not surprisingly, Betelgeuse was the first star for which photographs of its disk were obtained. That is, in which the star looked not like a point, but like a disk. (What bright stars look like disks in the above photograph - a convention of an image that can convey a difference in brightness only by a difference in size). The photograph was taken by the Hubble Orbital Telescope in 1995.
Here is this historical image in ultraviolet light (NASA/ESA credit):

It is clear that the colors in the photograph are relative: the redder, the colder. A bright spot near the center of the star is considered one of its poles, that is, Betelgeuse’s rotation axis is directed almost towards us, but slightly to the side.
More recently, namely in July last year (2009), new photographs of Betelgeuse were taken at the ground-based Very Large Telescope (VLT) in Chile. Here is one of them:

The resulting photos show that Betelgeuse has a tail. This tail extends six radii of Betelgeuse itself (comparable to the distance from the Sun to Neptune). What kind of tail this is, why it is there and what it means, scientists themselves do not yet know, although there are many assumptions.
Measuring Betelgeuse
It is interesting to give the main parameters of Betelgeuse. We will see that by almost all parameters, Betelgeuse turns out to be one of the “winners” of the known Universe.
In diameter, as already mentioned, Betelgeuse is about a thousand times larger than the Sun. It is very difficult to accurately determine the diameter and distance from the Sun of a single star, and no satellites have been discovered near Betelgeuse (although it is very possible that they exist, they simply cannot be seen next to such a giant). But Betelgeuse is so huge that its diameter was measured “directly”, i.e. using an interferometer - this operation could be applied to a very small number of stars, and Betelgeuse was the first.
Betelgeuse's mass exceeds the Sun by about 15 times (from 10 to 20 - measuring the mass of a single star is generally the aerobatics of astrometry, more precisely it has not yet been possible). How can it be that the diameter is a thousand times larger, which means that the volume is a billion times larger, but the mass is only 15 times larger, what is the density there? And here it is. And if we take into account that the core of the star is much denser than its outer layers, then the outer layers of Betelgeuse are much rarer than anything that we can imagine, except for interstellar space, into which Betelgeuse, like almost every star, transitions very gradually, i.e. It is impossible to determine exactly where a star ends and interstellar space begins. But nevertheless, fifteen solar masses is quite a lot for a star. Only 120 known stars are heavier than Betelgeuse.
How many times is Betelgeuse brighter than the Sun? One hundred thirty-five thousand times! True, this is taking into account infrared radiation, and in visible light it is about a hundred thousand times. That is, if you mentally placed Betelgeuse and the Sun at the same distance, Betelgeuse would be a hundred thousand times brighter than the Sun. On the list of the most powerful known stars, Betelgeuse ranks approximately twenty-fifth (roughly because the exact brightness of many hypergiants is not precisely known). If Betelgeuse were placed at the standard distance of ten parsecs from Earth (about 32 light years), it would be visible during the day, but at night objects would cast shadows in its light. But it’s better not to put it there, because the radiation of a supergiant is the kind of thing that it’s better for living beings to look at from afar. It seems that the absence of nearby supergiants (of any color) is one of the conditions for life on Earth.
The surface temperature of Betelgeuse is three and a half thousand kelvins (well, ordinary degrees are also close to that). This is not much for a star; Our Sun has a surface temperature of 5700 K, that is, twice as hot. That is, Betelgeuse is a “cold” star, one of the coldest known stars. The temperature of a star determines its color, or rather the shade of its glow. Those mysterious people who manage to see stars in color clearly define the color of Betelgeuse as distinctly reddish (see epigraph). That's why Betelgeuse is called a red supergiant. You shouldn’t think that it’s really bright red, like a poppy: rather, its surface is yellowish-orange.

Presumably, this is what the surface of Betelgeuse looks like.

I mentioned above that the apparent diameter of Betelgeuse is from 0.056 to 0.059 arcseconds. This scatter is not due to measurement inaccuracy. And because the body of the star itself pulsates with an approximate period of several years, changing both size and brightness. It would be logical to assume that as the size of the star decreases, the brightness of the star will also decrease, but in fact, everything happens exactly the opposite: at its minimum size, Betelgeuse acquires maximum brightness. At its maximum brightness, Betelgeuse turns out to be brighter than Rigel, whose magnitude is 0.18, that is, the brightest star in the constellation. Therefore, in terms of its brilliance, Betelgeuse has the right to be designated Alpha Orion.
This in itself is not surprising: the heating of a star during compression is a commonplace in astrophysics (occurs due to the transition of gravitational potential energy to kinetic, who knows the wording more precisely, correct me). But why does Betelgeuse pulsate like that? What exactly are the processes going on inside her? Nobody knows this.
The brief youth of a giant star
Remember when we talked about how young Sirius is - only 250 million years old? So, Betelgeuse is a small child compared to Sirius: it is only 10 million years old! When it caught fire, dinosaurs had long since died out on Earth, mammals had already occupied the main position on land, the continents had almost taken their current shape, the youngest mountain systems(including the Himalayas). Realize that Ural Mountains much older than Betelgeuse!
But unlike Sirius, which is unclear where it came from, it is very clear where Betelgeuse came from.
Orion is a unique constellation: the stars in it are not only visible to our eyes, but in reality they are quite close to each other in space. And they are close in age too. The fact is that most of Orion is occupied by a giant nebula - the Molecular Cloud of Orion, in which intense star formation processes take place (that is, it is a “stellar cradle”, and almost the closest to Earth). Young stars fly away from this nebula in all directions. Of these young, hot blue stars, exemplary peers, who flew relatively close from the place of their birth, is Orion.
But if all the other stars in Orion are hot to the point of blue (which is typical for young stars), then why is Betelgeuse red?
Because it's very big.
The lifespan of a star is determined by how long it takes for hydrogen in the star’s core to completely transform into helium (people, should I write an educational program about why stars burn?) It would seem that the larger and heavier the star, the more hydrogen it contains, and the longer it should burn. But here again everything is the other way around: the larger and heavier the star, the higher the temperature in its core and the faster it goes there thermonuclear reaction. Since Betelgeuse was born heavier and larger than its peers Rigel, Bellatrix and other Orion stars, the hydrogen in its core burned faster and burned out in just a few million years. And after the hydrogen in the core burns out, the star enters its dying stage - transformation into a red giant. In the case of Betelgeuse, it turned into a red supergiant.
That is, despite the fact that Betelgeuse is one of the youngest stars in the Universe in terms of age, it is already on the verge of death. Alas, large hot stars live very short lives, ending their stormy lives in just a few million years. There are several other red hypergiants known that have entered the last phase of their development, but they are all very far from us. Therefore, Betelgeuse provides a unique, albeit sad, opportunity to study the last phase of a star's life from a relatively close distance.
It is known that over the past 15 years, Betelgeuse has shrunk in diameter by 15 percent. This is a constant contraction that is not associated with pulsations. Mathematical models of stars say that such a reduction in size is also a sign that the end of the star’s evolution is approaching.
What's next for Betelgeuse? This is not peaceful Sirius-Main, now Sirius B, which simply quietly shed its scarlet shells and turned into a white dwarf. Betelgeuse's mass is so great that it will shed its shells in one of the grandest explosions known to the Universe - in a Supernova explosion.
And this will be the closest Supernova to the Earth, possibly in the entire existence of the Earth. Precisely because there is not and never was a single supergiant: supergiants are doomed to end their evolution in Supernova explosions, the remnants of Supernovae are characteristic and easily identified, and so there is not a single one nearby.
When it will be? Betelgeuse will explode within the next millennium. Maybe tomorrow.
How will it look like? Instead of a shining point, a disk of dazzling brightness will appear in the sky, which will be visible during the day, and at night you can read by its light. This disk will slowly dim, and the night sky will likely return to normal within a few months. In place of Betelgeuse, an amazingly beautiful nebula will appear, which will be visible to the naked eye for several years. Then nothing will be visible.
What will remain of Betelgeuse? No, not a white dwarf - it's too heavy for that. What will remain is a neutron star (pulsar) or a black hole.
How will this affect life on Earth? Most likely not at all. Betelgeuse is far enough from Earth that the hard radiation from the Supernova explosion is scattered in space without reaching solar system, and what arrives will be reflected by the solar magnetosphere. Only if Betelgeuse’s rotation axis were directed directly towards the Earth, then hard gamma radiation would painfully hit the biosphere. But we know from Hubble photographs that Betelgeuse's rotation axis is away from the Earth. So it will be possible to admire the heavenly fireworks from Earth completely safely.
The same fate awaits Rigel, Bellatrix and the other bright stars of Orion over the next tens of millions of years. Before becoming a red supergiant, Betelgeuse was apparently a hot blue star like them. They will be replaced by young stars, still hidden from us in the depths of the Orion Molecular Cloud.
So go and see Betelgeuse while it's still shining. Heaven is not unchanging.