Two Stars Too Close For Comfort!


All stars, from the largest to the smallest, are enormous roiling balls of seething hot, mostly hydrogen gas. Hydrogen is the most abundant atomic element in the Cosmos, as well as the lightest. Most of the billions of stars, that have set our large barred-spiral Milky Way Galaxy on fabulous fire, do not live alone, but instead formed in binary or multiple star systems close to one or more sparkling stellar siblings. In December 2014, astronomers announced that they have observed a duo of sister stars that are so close together that they will wind up merging into a single supermassive star. In fact, this study suggests that the most massive stars are born as a result of the merging of smaller stars, as predicted by certain theoretical models.

Some of the binary or multiple star systems in our Galaxy are eclipsing. Such a system is composed of two or more sister stars which, when observed from our own planet, undergo eclipses and mutual transits. This is because their orbital plane faces the Earth. One such system is the eclipsing binary dubbed MY Camelopardalis (MY Cam), the subject of a recent study appearing in the journal Astronomy & Astrophysics. The observations of MY Cam were conducted by astronomers using the Calar Alto Observatory (Almeria). The researchers were from the University of Alicante, the Astrobiology Centre of the Spanish National Research Council (CAB-CSIC) and the Canaries’ Astrophysics Institute (IAC)–with additional, and extremely valuable help, coming from amateur astronomers!

The article suggests that MY CAM — the most massive binary stellar system known — is composed of an enchanting duo of sparkling sibling stars of spectral type O. Spectral type O stars are very hot, bright, and blue. The two glittering sibling stars are 38 and 32 times our Sun’s mass, and are still on the hydrogen-burning main sequence. The massive stars are also extremely close to each other–indeed, they may be too close for comfort, with an orbital period of less than 1.2 days! This is the shortest orbital period known for this particular type of stellar system, indicating that the stars were born as they are seen now. In other words, the stars were almost in contact with each other from the time they were both born!

The predicted upshot of this very close sibling relationship is the merger of both stars into a single stellar object of more than 60 solar-masses. This will likely occur before either one of them has had sufficient time to significantly evolve. Therefore, these results add credibility to certain theoretical models suggesting that most massive stars are born as the result of merging less massive stars.

Stellar Matters

Stars are enormous, glaring, roiling balls of hot nuclear-fusing gas. The billions upon billions of glittering stars dancing around the Cosmos transform their hydrogen into heavier and heavier atomic elements in their seething-hot cores, in a process that is termed stellar nucleosynthesis.

The first stars to light up the Cosmos were unlike the stars we wish upon today: they were born directly from the lightest of all primordial gasses–primarily hydrogen. Both hydrogen and helium (the second-lightest atomic element) were born in the hot Big Bang birth of the Universe about 13.8 billion years ago (Big Bang nucleosynthesis). Indeed, the only atomic elements born in the Big Bang fireball are hydrogen, helium, and small quantities of lithium. All of the rest of the atomic elements listed in the familiar Periodic Table were manufactured deep in the nuclear-fusing hearts of stars, their incredibly hot cores progressively fusing the nuclei of atoms to form increasingly heavier atomic elements. Without these heavier elements fused in the searing-hot hearts of our Universe’s stars, there would be no life. The oxygen we breathe, 바카라사이트 the elements composing the dirt, stones, and sand beneath our feet, the water that we drink, the iron in our blood, the carbon that is the basis for life on our planet, were all manufactured by the stars–or else in the explosive supernovae that marked their deaths. We are star dust. When very massive stars perish, they do not go peacefully–they blast themselves to pieces in the raging, fiery tantrum of a supernova explosion. When these heavy stars go supernova they throw their batch of freshly fused heavy atomic elements out into the space between stars. The first generation of stars were probably enormous–weighing-in at, perhaps, hundreds of times more than our Sun. They lived fast and died young. The heavier the star, the briefer its stellar existence. When the first stars blew themselves up in supernova fireworks, they hurled out the very first newly fused batch of heavy atomic elements into the Cosmos. These heavy atomic elements, or “metals” in the jargon of astronomers, are those that are heavier than hydrogen and helium.

Stars of all masses live out their lives on the hydrogen-burning main-sequence, whereby they manage to keep a necessary, and very delicate, balance between two constantly warring opponents–radiation pressure and gravity. The radiation pressure of a star tries to push everything out and away from the star. Basically, this pushing pressure keeps the immense seething sphere of roiling gas bouncy against the merciless, relentless pull of its own squeezing, crushing gravity–that tries to pull everything in towards the star. The star’s radiation pressure is the result of nuclear fusion, which begins with the burning of hydrogen into helium. This process of stellar nucleosynthesis progressively fuses lighter atomic elements into heavier ones.

 


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