What stars are there in space? Stars. Guiding thread for sailors

The question of how many stars there are in the sky worried the minds of people as soon as the first star was noticed by them in the sky (and they are still solving this problem). Astronomers did make some calculations, establishing that with the naked eye, about 4.5 thousand celestial bodies can be seen in the sky, and our galaxy includes about 150 billion stars. Given that the Universe contains several trillion galaxies, the total number of stars and constellations whose light reaches earth's surface, equals septillion - and this estimate is only approximate.

Explosions in the Universe

In virtually every city across the United States—and increasingly around the developing world—street lights, outdoor signs and car headlights glow 24 hours a day, drowning out the stars above in a dim orange glow. Light contamination is not exactly news. But by its nature it is a problem that hides its seriousness. "We're losing the night sky so gradually that people don't realize we're giving up," says Tyler Nordgren, an astronomer and dark-sky advocate. He's concerned that older generations of people who grew up watching the Milky Way disappear - and children today - have no idea what our ancestors watched every night when they went to bed.

A star is a huge ball of gas that emits light and heat (this is its main difference from the planets, which, being completely dark bodies, can only reflect the light rays falling on them). Energy generates light and heat, resulting from thermonuclear reactions occurring inside the core: unlike planets, which contain both solid and light elements, celestial bodies contain light particles with a slight admixture of solids (for example, the Sun consists of almost 74% hydrogen and 25% helium).

How we drowned out the night sky

This sky is an amazing sight. It was once common and banal, as inevitable as the weather. But despite the efforts of a small community of passionate astronomers, it is now disappearing faster than ever.


Light pollution is essentially a modern environmental problem. For most of human history, nighttime lighting—in the form of fires, candles, and oil lamps—was precious and rare.

Guiding thread for sailors

This led to the birth of what is now called the dark sky movement, with astronomers initially organizing to combat light pollution in the areas surrounding their observatories. Of course, that would be one thing if it were an unavoidable cost of doing business. It would be difficult to argue that we should give up the safety of night travel and the comfort of indoor lighting to see the stars.

The temperature of the celestial bodies is extremely hot: as a result of a large number of thermonuclear reactions, the temperature indicators of stellar surfaces range from 2 to 22 thousand degrees Celsius.

Since the weight of even the smallest star significantly exceeds the mass of the largest major planets, celestial bodies have sufficient gravity to hold all smaller objects around them, which begin to revolve around them, forming a planetary system (in our case, the Solar system).

But by and large, this is not the case. This may be because excessive light makes it harder for us to see possible dangers lurking in the shadows - and because, as Nordgren bluntly says, "The bad guys need to be able to see what they're doing too." Most of them come from poorly designed fixtures that shoot light into the sky rather than focusing it on the ground. Lights that are left for times and places where they are not needed also help.

What do we lose when we lose stars?

Simply cutting out this waste could save a ton of energy and money - and we could see the stars again.


Fixtures pointing upward to illuminate the surface of a building are among the worst offenders of light pollution. Of course, Mars never looks as big as the moon. But the part of the meme that really overwhelmed me was that we can actually see Mars if we know where to look—and if our skies are too polluted with excess light.

Flashing luminaries

It is interesting that in astronomy there is such a thing as “new stars” - and we are not talking about the appearance of new celestial bodies: throughout their existence, hot celestial bodies Moderate luminosity periodically flare brightly, and they begin to stand out so strongly in the sky that people in former times believed that new stars were being born.

For most of the year, it appears as a dot, an unusually bright and large star touched with a red hue. This rumor shows again and again how we have been divorced from our night skies. There are other factors contributing to this shutdown besides light pollution. Acknowledging the night sky is a slow, meditative process. Even if you're somewhere in the dark, you need to wait 20 minutes or so without looking at your phone for your eyes to adjust. And even something as dramatic as a meteor shower reveals its wonders slowly—you have to patiently take in the entire sky for a few minutes or hours to get a brief glimpse of the shooting star.

In fact, data analysis showed that these celestial bodies existed before, but due to the swelling of the surface (the gaseous photosphere), they suddenly became especially bright, increasing their glow tens of thousands of times, resulting in the impression that new stars had appeared in the sky. Returning to their original level of brightness, new stars can change their brightness up to 400 thousand times (at the same time, if the outbreak itself lasts only a few days, their return to the previous state often lasts for years).

It's the opposite of a news feed: a barely changing field hides just a few great pieces of information. This sky had depth: it was not a two-dimensional surface, like a planetarium, but a three-dimensional field.


Milky Way, from Cherry Springs State Park.

Every little point of light was truly a gigantic, burning sphere of hydrogen, billions of miles away. The rich, cloudy ribbon of white cut diagonally across the sky was a cross-section of the disk that is our galaxy, made up of hundreds of billions of stars, many of which orbit their own planets. For hours the stars seemed to migrate across the sky, but in reality the Earth was moving below me. Like famous photograph Carl Sagan's Pale Blue Dot, a brief glimpse allowed me to understand our true, unlikely position in the universe.

Life of heavenly bodies

Astronomers claim that stars and constellations are still being formed: according to the latest scientific data, about forty new celestial bodies appear annually in our galaxy alone.

At the initial stage of its formation, a new star is a cold, rarefied cloud of interstellar gas that rotates around its galaxy. The impetus for reactions to begin to occur in the cloud, stimulating the formation of a celestial body, can be a supernova that explodes nearby (an explosion of a celestial body as a result of which it is completely destroyed after some time).

Each of us, wherever we went, was pinned to the surface of a tiny spinning sphere, surrounded by an unimaginably vast collection of stars. “Increasingly, our concept of the universe simply stops in the atmosphere,” says astronomer Nordgren. We are raising a generation that believes this is nothing like what was seen in the past. So why bother looking at all?

We could still restore the stars - or drown them completely

The constellation Orion as seen at a dark sky location in Provo, Utah. As bright as the sky already is in many places, we're at a particularly crucial time for light pollution for several reasons. These lights cast light up and down, contributing to light pollution, while newer "full cut" models focus light downward. Dark Skies International and other advocates have tried to persuade cities to require these types of lights, but they are "far from universal."

Also quite likely reasons may be its collision with another cloud, or the process may be influenced by galaxies colliding with each other, in a word, everything that can influence the gas interstellar cloud and cause it to shrink into a ball under the influence of its own gravity.

During compression, gravitational energy is transformed into heat, causing the gas ball to become extremely hot. When the temperature inside the ball rises to 15-20 K, thermonuclear reactions begin to occur as a result of which the compression stops. The ball turns into a full-fledged celestial body, and over a long period of time, hydrogen is converted into helium inside its core.




But some experts say they may have the opposite effect. First, they are more efficient, allowing cities to produce more light while using less electricity, which could lead to brighter streets overall, something some residents have complained about in New York City.

Municipal codes that limit the amount of lung people and businesses can emit can also make a huge difference. Around the world, 49 municipalities and parks have officially designated themselves as “International Dark Places,” strictly limiting light pollution. For example, in Flagstaff, property owners are allowed to provide a certain amount of light based on the size of their property, and most must be shielded fixtures that only cast light downward.





Life of heavenly bodies

However, in the vast majority of countries, light pollution appears to be getting worse - and doing so faster than population growth. One reason is that increasingly efficient light fixtures allow us to produce more light at a lower cost, which economists call the Jevons Paradox. And the transition to bright skies at night appears to be happening even faster in the developing world, with many cities gaining more reliable access to electricity and quickly adopting Western-style street closures.

When the hydrogen supply runs out, the reactions stop, a helium core is formed and the structure of the celestial body gradually begins to change: it becomes brighter, and its outer layers expand. After the weight of the helium core reaches its maximum, the celestial body begins to decrease and the temperature rises.

While many today find it hard to believe that our grandparents and grandparents grew up constantly before our eyes, I had to venture far from small towns to get a general idea of ​​them. If nothing changes, it's very possible that our current city night skies - with a handful of stars here and there peeking through a blanket of orange glow - will also end up seeming like a quaint relic of pre-times, an era before we completely drowned out the night sky.

When a star like the Sun dies, it casts its outer layers into space, leaving its hot, dense core to cool for eons. But some other types of stars explode in titanic explosions called supernovae. A supernova can shine as brightly as a whole galaxy of billions of “normal” stars. Some of these explosions completely destroy the star, while others leave behind either a super-dense neutron star or a black hole—an object with such strong gravity that not even light can escape it.

When temperatures reach 100 million K, thermonuclear processes resume inside the core, during which helium is converted into solid metals: helium - carbon - oxygen - silicon - iron (when the core becomes iron, all reactions completely stop). As a result, the bright star, having increased by a hundred times, turns into a Red Giant.

However, as more supernovae are discovered, the line dividing the two categories blurs. Stars that live for a long time may not be particularly massive, adding credence to the white dwarf theory. Instead, they show a lot of carbon and oxygen, which is the composition of a white dwarf. The maximum mass of a white dwarf is 4 times that of the Sun, a value known as the Chandrasekhar limit. White dwarfs of nearly Chandrasekhar masses are essentially identical, so they undergo almost identical explosions.

The most popular theory for a white dwarf star going supernova is an act of stellar cannibalism. If a white dwarf has a nearby companion star, it can steal gas from the companion. If the amount of material accumulated by a white dwarf pushes its mass toward the Chandrasekhar limit, the white dwarf could explode without leaving anything behind.

Exactly how long a particular star will live largely depends on its size: small celestial bodies burn hydrogen reserves very slowly and are quite capable of existing for billions of years. Due to their insufficient mass, reactions involving helium do not occur in them, and after cooling, they continue to emit a small amount of the electromagnetic spectrum.

Because they are short-lived, such stars must also be massive. It then suddenly drops and then intensifies over the next few months. The pattern of light emission over time is consistent with the explosion of a "supergiant" star. The supergiant progressed through a sequence of stages that produced increasingly heavier elements in its core - from hydrogen to helium, carbon, oxygen, etc. but this sequence comes to a violent end when the core is turned to iron. Iron can only absorb nuclear energy, not produce it.


The life of luminaries of medium parameters, including the Sun, is about 10 billion. After this period, their surface layers usually turn into a nebula with an absolutely lifeless core inside. This core some time later transforms into a helium white dwarf, with a diameter not much larger than the Earth, then darkens and becomes invisible.

Since it can no longer produce energy, the star loses its source of internal pressure and collapses. When the collapse reaches a critical density, it stops. At this point, the matter at the star's core is packed so tightly that a block of its material the size of a sugar cube would weigh millions of tons. The core became a neutron star - an object more massive than the Sun, but only a few miles in diameter.

The collapse process releases enough energy to rip the outer layers of the star into bits and blast them into space at a few percent of the speed of light. These fragments carry helium, calcium, oxygen, carbon and other elements into space, where they may someday be incorporated into new stars and planets.

If a medium-sized celestial body was quite large, it first turns into a black hole, and then a supernova breaks out in its place.

But the lifespan of supermassive luminaries (for example, the North Star) lasts only a few million years: in hot and large celestial bodies, hydrogen burns extremely quickly. After a huge celestial body ends its existence, an extremely powerful explosion occurs in its place - and a supernova appears.

Explosions in the Universe

Astronomers call a supernova an explosion of a star during which an object is almost completely destroyed. After a few years, the volume of the supernova increases so much that it becomes translucent and very rarefied - and these remnants can be seen for several thousand more years, after which it darkens and transforms into a body consisting entirely of neutrons. Interestingly, this phenomenon is not uncommon and occurs in the galaxy once every thirty years.


Classification

Most of the celestial bodies visible to us are classified as main sequence stars, that is, celestial bodies within which thermonuclear processes occur, causing the conversion of hydrogen into helium. Astronomers divide them, depending on their color and temperature indicators, into the following classes of stars:

  • Blue, temperature: 22 thousand degrees Celsius (class O);
  • White-blue, temperature: 14 thousand degrees Celsius (class B);
  • White, temperature: 10 thousand degrees Celsius (class A);
  • White-yellow, temperature: 6.7 thousand degrees Celsius (class F);
  • Yellow, temperature: 5.5 thousand degrees Celsius (class G);
  • Yellow-orange, temperature: 3.8 thousand degrees Celsius (class K);
  • Red, temperature: 1.8 thousand degrees Celsius (class M).


In addition to the main sequence luminaries, scientists distinguish the following types of celestial bodies:

  • Brown dwarfs are too small celestial bodies for the process of converting hydrogen into helium to begin inside the core, so they are not full-fledged stars. They themselves are extremely dim, and scientists only learned of their existence from the infrared radiation they emit.
  • Red giants and supergiants - despite their low temperature (from 2.7 to 4.7 thousand degrees Celsius), this is an extremely bright star, the infrared radiation of which reaches its maximum.
  • Wolf-Rayet type radiation is distinguished by the fact that it contains ionized helium, hydrogen, carbon, oxygen and nitrogen. This is a very hot and bright star, which is the helium remnants of huge celestial bodies, which at a certain stage of development lost their mass.
  • Type T Tauri - belong to the class of variable stars, as well as to such classes as F, G, K, M, . They have a large radius and high brightness. You can see these luminaries near molecular clouds.
  • Bright blue variables (also known as S doradus variables) are extremely bright, pulsating hypergiants that can be up to a million times brighter than the Sun and 150 times heavier. It is believed that a celestial body of this type is the brightest star in the Universe (it is, however, very rare).
  • White dwarfs are dying celestial bodies into which medium-sized luminaries are transformed;
  • Neutron stars also refer to dying celestial bodies, which after death form larger luminaries than the Sun. The nucleus in them shrinks until it is converted into neutrons.


Guiding thread for sailors

One of the most famous celestial bodies in our sky is the North Star from the constellation Ursa Minor, which almost never changes its position in the sky relative to a certain latitude. At any time of the year, it points to the north, which is why it received its second name - the North Star.

Naturally, the legend that the North Star does not move is far from the truth: like any other celestial body, it rotates. The North Star is unique in that it is closest to the North Pole - at a distance of about one degree. Therefore, due to the angle of inclination, the North Star seems motionless, and for many millennia it has served as an excellent landmark for sailors, shepherds, and travelers.

It should be noted that the North Star will move if the observer changes his location, since the North Star changes its height depending on latitude. This feature made it possible for sailors to determine their location when measuring the angle of inclination between the horizon and the North Star.



In reality, the North Star consists of three objects: not far from it there are two satellite stars, which are connected to it by forces of mutual attraction. At the same time, the Polar Star itself is a giant: its radius is almost 50 times greater than the radius of the Sun, and its luminosity is 2.5 thousand times higher. This means that the North Star will have an extremely short life, and therefore, despite its relatively young age (no more than 70 million years), the North Star is considered old.

Interestingly, in the list of the brightest stars, the North Star is in 46th place - which is why in the city in the night sky, illuminated by street lamps, the North Star is almost never visible.

Falling luminaries

Sometimes, looking at the sky, you can see a fallen star, a bright luminous point, rushing across the sky - sometimes one, sometimes several. It looks as if a star has fallen, but the legend that immediately comes to mind is that when a fallen star catches your eye, you need to make a wish - and it will certainly come true.

Few people think that in reality these are meteorites flying towards our planet from space, which, having collided with the Earth’s atmosphere, turned out to be so hot that they began to burn and resemble a bright flying star, which received the concept of a “fallen star”. Oddly enough, this phenomenon is not uncommon: if you constantly monitor the sky, you can see a star falling almost every night - over the course of a day, about a hundred million meteors and about a hundred tons of very small dust particles burn up in the atmosphere of our planet.

In some years, a fallen star appears in the sky much more often than usual, and if it is not alone, earthlings have the opportunity to observe the meteor shower - despite the fact that it seems as if the star fell on the surface of our planet, almost all celestial bodies of the shower burn up in the atmosphere.

They appear in such numbers when the comet approaches the Sun, heats up and partially collapses, releasing a certain number of stones into space. If you trace the trajectory of meteorites, you get the misleading impression that they are all flying from one point: they move along parallel trajectories and each fallen star has its own.

Interestingly, many of these meteor showers arise at the same period of the year and earthlings have the opportunity to see the fall of a star for quite a long time - from several hours to several weeks.

And only large-sized meteorites with sufficient mass are capable of reaching the earth’s surface, and if at that time such a star fell not far from settlement, for example, this happened several years ago in Chelyabinsk, this can cause extremely destructive consequences. Sometimes there may be more than one fallen star, which is called.

Since ancient times, man has sought to comprehend the unknown, fixing his gaze on the night sky, on which millions of stars are literally scattered. Scientists have always paid serious attention to the study of space and now they have the opportunity, with the help of powerful scientific equipment, not only to examine it, but also to take unique photographs. I invite you to enjoy the amazing photographs of space that they took quite recently and learn some interesting facts.

Separate Nebula

The beautiful triple nebula NGC 6514 in the constellation Sagittarius. The nebula's name was suggested by William Herschel and means "divided into three petals." The exact distance to it is unknown, but according to various estimates it ranges from 2 to 9 thousand light years. NGC 6514 consists of three main types of nebulae - emission (pinkish), reflective (blue) and absorption (black). (Photo by Máximo Ruiz):

Space Elephant Trunk

The Elephant Trunk Nebula meanders around an emission nebula and a young star cluster in the IC 1396 complex in the constellation Cepheus. The length of the cosmic elephant trunk is more than 20 light years. These dark, whisker-like clouds contain material for the formation of new stars and hide protostars - stars in the final stages of their formation - behind layers of cosmic dust. (Photo by Juan Lozano de Haro):



Ringworld

Hoag's Object is a strange ring-shaped galaxy in the constellation Serpens, named after its discoverer. The distance to Earth is about 600 million light years. In the center of the galaxy there is a cluster of relatively old yellow stars. It is surrounded by an almost regular ring of younger stars with a blue tint. The diameter of the galaxy is about 100 thousand light years. Among the hypotheses about the origin, a collision of galaxies that occurred several billion years ago is being considered. (Photo by R. Lucas (STScI | AURA), Hubble Heritage Team, NASA):



Moon over Andromeda

The large spiral galaxy, the Andromeda Nebula, is located just 2.5 million light years away and is the closest spiral galaxy to our Milky Way. It can be seen with the naked eye as a small blurry speck in the sky. This composite photograph compares the angular size of the Andromeda Nebula and the Moon. (Photo by Adam Block and Tim Puckett):



Io's ever-changing surface

Jupiter's moon Io is the most volcanically active object in the world. solar system. Its surface is constantly changing due to new lava flows. This photo of the side of Io's moon facing Jupiter is a composite of images taken in 1996. spacecraft NASA Galileo. The absence of impact craters is explained by the fact that the entire surface of Io is covered with a layer of volcanic deposits much faster than craters appear. The likely cause of the volcanic activity is the changing gravitational tides caused by the huge Jupiter. (Photo by Galileo Project, JPL, NASA):



Cone Nebula

Strange formations can be observed near the Cone Nebula. They arise from the interaction of interstellar dust with light and gas emanating from young stars. The blue glow around the star S Mon is the reflection of the bright star's radiation from surrounding stardust. The star S Mon is located in the open star cluster NGC 2264, located 2,500 light-years from Earth. (Photo by Subaru Telescope (NAOJ) & DSS):



Spiral galaxy NGC 3370

Spiral galaxy NGC 3370 is located about 100 million light-years away in the constellation Leo. It is similar in size and structure to our Milky Way. (Photo by NASA, ESA, Hubble Heritage (STScI | AURA):



Spiral Galaxy M74

This spiral galaxy is one of the photogenic ones. It consists of approximately 100 billion stars and is located at a distance of about 32 million light years from us. Presumably, this galaxy contains a black hole of intermediate mass (that is, significantly larger than stellar masses, but smaller than the black holes at the center of galaxies). (Photo by NASA, ESA, and the Hubble Heritage (STScI | AURA) - ESA | Hubble Collaboration):



Lagoon Nebula

This is a giant interstellar cloud and H II region in the constellation Sagittarius. Located 5,200 light-years away, the Lagoon Nebula is one of only two star-forming nebulae faintly visible to the naked eye at mid-latitudes. Northern Hemisphere. Not far from the center of the Lagoon is a bright hourglass region - the result of the turbulent interaction of stellar winds and powerful radiation. (Photo by Ignacio Diaz Bobillo):



Luminous streak in the Pelican Nebula

Easily visible in the sky, the luminous streak of IC 5067 is part of the large Pelican emission nebula with a characteristic shape. The stripe is about 10 light years long and outlines the head and neck of the space pelican. It is located at a distance of about 2,000 light years from us. (Photo by César Blanco González):



thunder cloud

This beautiful photo was taken in southern Alberta, Canada. This is a receding rain cloud, with unusual protrusions characteristic of squamous clouds visible on its near edge, and rain falling from the far edge of the cloud. Also read the article “ Rare species clouds." (Photo by Alan Dyer):



Three bright nebulae in Sagittarius

The Lagoon Nebula M8 is to the left of the center of the picture, M20 is a colored nebula to the right. The third nebula, NGC 6559, lies just above M8 and is separated from it by a dark streak of stardust. All of them are located at a distance of about 5 thousand light years from us. (Photo by Tony Hallas):



Galaxy NGC 5195: question mark

The dwarf galaxy NGC 5195 in the constellation Canes Venatici is well known as a small satellite of the spiral galaxy M51, the Whirlpool Galaxy. Together they resemble a cosmic question mark, with NGC 5195 being the point. It is located at a distance of about 30 million light years from Earth. (Photo by Hubble Legacy Archive, NASA, ESA):



Amazing expanding crab

This crab nebula, located 6,500 light-years away in the constellation Taurus, is the remnant of a supernova explosion, an expanding cloud of material left after the explosion of a huge star. The nebula is currently about 10 light-years across and is expanding at a speed of approximately 1000 km/s. (Photo by Adam Block, Mt. Lemmon SkyCenter, U. Arizona):



Variable star RS Stern

This is one of the most important stars in the sky. One of the reasons is that she accidentally found herself surrounded by a dazzling reflection nebula. The brightest star in the center is the pulsating RS Puppis. It is nearly 10 times more massive than the Sun, 200 times larger, and has an average brightness of 15,000 times that of the Sun, with RS Puppis changing brightness nearly five times every 41.4 days. RS Puppis lies about a quarter of the way between the Sun and the center of the Milky Way, at a distance of 6,500 light years. years from Earth. (Photo by Hubble Legacy Archive, NASA, ESA):



Ocean planet Gliese 1214b

Exoplanet (super-Earth) in the constellation Ophiuchus. The first ocean planet discovered, it orbits the dim red dwarf star GJ 1214. The planet is close enough to Earth (13 parsecs, or about 40 light years), and because it transits the disk of its star, its atmosphere can be studied in detail using current technology . One year on the planet lasts 36 hours.

The planet's atmosphere consists of thick water vapor with a small admixture of helium and hydrogen. However, given the high temperature on the planet's surface (about 200 degrees Celsius), scientists believe that the water on the planet is in such exotic states as “hot ice” and “super-liquid water”, which are not found on Earth.

The age of the planetary system is estimated at several billion years. The mass of the planet is approximately 6.55 times the mass of the Earth, while at the same time the diameter of the planet is more than 2.5 times greater than that of the Earth. This picture shows how the artist imagines the passage of the super-Earth Gliese 1214b across the disk of its star. (ESO Photo, L. Calçada):



Stardust in the Southern Corona

Here you can see clouds of cosmic dust that are located in the star field near the border of the constellation Corona Southern. They are less than 500 light-years away and block light from more distant stars in the Milky Way galaxy. In the very center of the image are several reflection nebulae. (Photo by Ignacio Diaz Bobillo):



Galaxy cluster Abell 1689

Abell 1689 is a cluster of galaxies in the constellation Virgo. One of the largest and most massive galaxy clusters known, it acts as a gravitational lens, distorting the light of galaxies behind it. The cluster itself is located at a distance of 2.2 billion light years (670 megaparsecs) from Earth. (Photo by NASA, ESA, Hubble Heritage):



An open cluster in the constellation Taurus, sometimes called the Seven Sisters; one of the closest star clusters to Earth and one of the most visible to the naked eye. This is perhaps the most famous star cluster in the sky. The Pleiades star cluster is about 12 light-years in diameter and contains about 1,000 stars. The total mass of the stars in the cluster is estimated to be about 800 times the mass of our Sun. (Photo by Roberto Colombari):



Shrimp Nebula

Just south of Antares, in the tail of the nebula-rich constellation Scorpio, lies the emission nebula IC 4628. Hot, massive stars, only a few million years old, illuminate the nebula with invisible ultraviolet light. Astronomers call this cosmic cloud the Shrimp Nebula. (ESO Photo):