This is a photo released by the James Webb Telescope on December 13, 2023, in which astronomers have discovered three special objects, a very, very small one"Stars"--Brown dwarfs
In the last issue, we talked about Weber's filmingHerbig-Harrow Object:hh797。
HH797 I don't know if you still have an impression, HH797 is located near a star cluster known as IC348, and it is a coincidence that the brown dwarf discovered by astronomers this time is in this star cluster.
IC348 is located in the constellation Perseus, about 1000 light-years away.
IC 348 This is a very young star clusterIt consists of a nebula and about 400 starsThe age of these 400 stars is generally around five million years.
Webb photographed IC 348 This is too young compared to the 4.6 billion years of the sun's history, basically in its infancy, and it is still in the growth stage.
So if you look at this cluster with a telescope, you will see that most of the stars here are still sucking on the gaseous material around them.
In 2013, Hubble observed the growth of stars as they sucked up food.
That flashing light, like fireworks, flashed for a period of 25For 3 days, this is a flicker that occurs when two stars are entangled and dragging the surrounding gaseous material with each other, which is very dreamy.
This is the charm of the IC348 star cluster, which is full of itThe magic of creation
It is precisely because of this (young) characteristic that astronomers have been able to find traces of brown dwarfs here.
Brown dwarfs are a special type of celestial body, which was only confirmed to exist in 1995, and it is the product of the failure of the evolution of stars, as it is calledFailed stars
Stars are now known to have evolved from nebulae.
Stellar formation schematic and nebulae first evolved into stars, first it will form a name calledProtostarof celestial bodies.
The protostar indicates that this is the most critical step in the formation of stars, and when the protostar is formed, it will be wrapped in nebulae, and these nebulae will be its food, and it will continue to absorb these substances to grow.
Then there are two outcomes in the process of growth.
The first outcome: the protostar absorbs enough matter that the inner core can produce the temperature and pressure at which hydrogen can fuse, i.e., the mass is reachedThe fusion reaction of the inner core hydrogen can be initiatedAt this time, the protostar has successfully evolved into a real star, a star that can continue to shine and heat.
The second situation of the star is: the protostar absorbs the substance, but the amount of the absorption is not enough to start the fusion reaction of hydrogen in the inner core, although it still shines at this time, its energy ** mainly depends on the heat accumulated by the initial gravitational energy, or the fusion reaction of a small part of deuterium in the inner core, and this part of the heat will dissipate after a long time, and it will gradually dim until it is finally dark to the point that there is no visible light radiation.
Then it is also no longer bright, so even initially it was like a star, it evolved from the original star, butIt doesn't shine like a real star all the time, and then it evolves into a brown dwarfA class of stars that have not successfully initiated a nuclear fusion reaction
Brown dwarf indicates that at this time, strictly speaking, it no longer belongs to the category of stars, but like a class of super-large gas giants, but there are also certain differences from planets, it is different from the origin of planets, planets are originated in the planetary disk around the star, that is, around the original dust disk of the original star, so the planet generally does not appear alone, it will surround the star, and the brown dwarf is evolved by the center of the protostar, it can exist alone.
Submillimeter telescopes photographed protoplanetary disks, so when astronomers found 3 independent and much smaller points of light than stars in IC348, they suspected that they might be brown dwarfs, of course, there were also suspicions that they might be wandering planets, that is, planets that escaped the gravitational pull of stars and existed independently, but thinking that IC348 is only about 5 million years old, the planets are only forming at this time, so it is impossible for them to escape the shackles of stars, so these 3 small dots are most likely brown dwarfs.
So according to the analysis of the data, the maximum mass of these three brown dwarfs is not more than 8 times the mass of Jupiter, and the smallest one is only 3-4 times the mass of Jupiter, which is a very unexpected data, such a small mass, challenging the current theoretical limit, the theoretical **, the minimum mass of brown dwarfs should be 13 times the mass of Jupiter, obviously these three brown dwarfs are smaller than the theoretical mass, especially the 3-4 times the mass of Jupiter.
The surface temperature of the three brown dwarfs is estimated to be between 800 and 1,500 degrees Celsius, which is about the same as a class of planets known as hot wood planets.
Brown dwarfs are the product of the failure of evolutionary stars, then their existence suggests that there is a mass limit to the formation of stars, that is, the formation of stars has a minimum mass, this mass astronomerIt is estimated to be 008 solar massesLess than this mass, the star will not be able to initiate the fusion reaction of hydrogen in the inner core, so it will not be able to form a star.
Of course this 008 The mass of the sun is only a theoretical speculation, and it may not be the case in practice, so observing a brown dwarf can help astronomers study the minimum limit of a star, what mass is a brown dwarf and what mass is a star, which is a question about the boundaries of the star.
Sun (yellow dwarf), brown dwarf, Jupiter comparison astronomers really confirmed the existence of brown dwarfs in 1995, when a brown dwarf star was discovered in the constellation Lepus, 19 light-years from Earthgl229b, which is a binary star system consisting of the red dwarf 229a and the brown dwarf 229b.
This brown dwarf star is about 60 times the mass of Jupiter.
The middle dot is 229b, so since it was first discovered in 1995, astronomers have identified thousands of such objects, and through the study of these thousands of samples, astronomers have found that although it is not really a star, it has some characteristics like a star.
For example, there are companion stars, such as the two brown dwarfs orbiting each other as captured by Hubble.
Hubble photographed two brown dwarfs, for example, they can also have planets like stars, such as this 2m1207.
The red dot in the lower left is planet 2m1207b, which is the first brown dwarf to be found to exist on a planet, so even if the brown dwarf is a failed star, it still has some properties like a star.
Okay, this is a little introduction to Webb's shooting and the brown dwarf, so that's all for this issue.
I am Tengbao, a popular science creator who loves astronomy, and I hope you will pay more attention and support.
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