It's called “HD 65907” and it has many astronomers scratching their heads. That is to say that this good star in all respects is not what it seems to be. At first glance, she appears relatively young, but upon studying her more closely, researchers realized that she was much older. HD 65907 would have lied about its age and would in fact be a so-called “resurrected” star… But what is it, exactly?
To fully understand this, we must first look at the different methods used to measure the age of a star. One of these methods consists of studying the brightness and temperature of the star. Stars generally all follow the same pattern of life, a journey punctuated by key stages throughout what we call the main sequence. “As soon as they start to fuse hydrogen in their core, they maintain a strict relationship between their luminosity and their temperature”explains the specialized online media Universe Today. A study of these two parameters therefore makes it possible to determine its age.
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Another way to do this is to observe the heavy elements in its atmosphere. That of old stars is less loaded with them, because they would have formed at a time when the galaxy did not contain as many of them. If we rely on the first method, HD 65907 would be rather young, barely 5 billion years old.
But if we look at the heavy elements of her atmosphere, something is wrong since she has very few of them, which would make her much older. “Moreover, its trajectory in the galaxy does not correspond to that of other young stars, which tend to orbit quietly around the center. HD 65907 is much more erratic, suggesting that it recently moved here from another location.indicates Universe Today.
“You blue straggler”
An international team of astronomers decided to clarify this and shared a study to be published in the journal Astronomy & Astrophysics. By analyzing archival data, they put forward the following hypothesis: HD 65907 would be a blue straggler, a very particular type of star, but which would have the particularity of having been resurrected. We'll explain it to you.
Blue stragglers are stars that shine weakly (often in bluish tones) and which are behind in their evolution compared to other stars in their group. Typically, they are found in stellar clusters, groups of stars all the same age, in which they stand out because of their greater luminosity and heat. This particularity would come from the fact that they “stole” matter from another star, or even that they merged with it.
Ultimately, this “boost” offers a second youth to the stars and researchers think that this is what happened in this specific case… Except that it does not explain everything and a mystery remains. HD 65907 is not part of a cluster like other blue stragglers: instead, it wanders the cosmos on its own. How to rejuvenate without prey to devour? How then can we explain his apparent youth?
According to scientists, it may well have cannibalized the only star that was traveling with it at the time, 5 billion years ago. The dramaturgy of the cosmos is truly unparalleled.
