Secrets Of The Strange Stars That Circle Our Supermassive Black Hole


Stellar Masquerade

One attainable clarification is that S2 and its companions could also be previous stars masquerading as younger ones — “a phenomenon we understand quite well in Los Angeles,” Ghez as soon as quipped to a science reporter.

In this case, what appear to be younger stars are literally the cores of older suns that collided and merged. The collisions may have stripped away the suns’ cool outer layers, exposing their sizzling interiors. The consequence can be a cluster of large stars that seem a lot youthful than they are surely.

But there’s an issue with this state of affairs. A collision violent sufficient to strip away the outer layers must also annihilate each stars and go away solely a path of sizzling fuel. And so astronomers have proposed options. For instance, maybe the celebs shaped elsewhere and migrated inward underneath the black gap’s gravitational pull.

The downside with this clarification is that the majority energetic star formation within the Milky Way happens removed from the core, in its spiral arms. It would take the celebs too lengthy emigrate as near the middle as S2.

Dense mud clouds do lie nearer to Sgr A* than the spiral arms, to inside a number of dozen light-years. Stars are most likely forming inside them. It’s conceivable {that a} cluster of younger stars may spiral all the way down to inside a number of light-years of the middle — and achieve this in lower than 10 million years.

The downside right here is that to get nearer to the black gap, the celebs must shed angular momentum — the amount that retains planets in good protected orbits round stars as a substitute of “falling” straight into them.

One method to lose angular momentum is to stumble upon different stars. But it’s troublesome to think about how stars may endure this course of and migrate to inside light-hours of Sgr A* with out being destroyed. Besides, the method ought to go away behind a path of stars towards Sgr A* for a protracted distance, one thing astronomers haven’t but seen. Instead, the shell of stars orbiting near Sgr A* has a particular periphery.

Star Birth in a Disk

Another chance is that Sgr A*’s central cluster stars shaped inside a rotating disk of fuel and dirt instantly surrounding the black gap. In truth, some observations recommend most stars within the central cluster orbit roughly in the identical airplane — an association harking back to the most important planets in our photo voltaic system. The planets shaped in a disk of fuel and dirt, so maybe S2 and its fellow vacationers did, too.

However, not all astronomers agree the central cluster has a disklike construction. Another caveat: To spawn stars, the disk would should be dense sufficient to face up to the black gap’s tidal forces.

It’s additionally conceivable that Sgr A*’s companion stars shaped in mud clouds circling at excessive velocity inside a number of light-years of the galactic heart. Collisions between the clouds may have spawned shock waves, triggering star formation. As the results of collisions between the clouds, they and the brand new stars embedded inside them may have shed sufficient momentum to settle into orbits across the black gap. The galactic core’s sturdy magnetic discipline would have step by step swept the leftover interstellar mud and fuel away from the black gap. What would stay is a disk of younger stars in shut orbit to Sgr A*.

This state of affairs explains a lot of what astronomers see within the galactic core, though not all. UCLA astronomer Brad Hansen thinks he has a viable different: Hot younger stars now orbit the Milky Way’s central black gap as a result of a second smaller black gap dragged them there.

The course of begins in a crowded younger star cluster, dozens of light-years from the galactic heart. Collisions between large stars within the cluster’s core kind an intermediate-sized black gap within the vary of 1,000 to 10,000 photo voltaic lots. Gradually, the black gap would migrate towards the galactic heart, dragging its cargo of “hostage stars” together with it. Hansen argues that is the one method to shortly transport large younger stars into the galactic heart from an out of doors star-birth location.

All the black-hole ferry state of affairs lacks is tough proof to help it. If a second black gap orbits the first black gap within the galactic core, its presence is perhaps detectable. Its tug on Sgr A* may trigger a detectable wiggle. Clearly, astronomers nonetheless have quite a lot of work left to totally perceive the processes at work within the galactic core.



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