M87 likewise features a massive jet of plasma blasting out into deep space from the stellar core.
These phenomena: the jet and the novae, are unassociated astronomical events, or so scientists believed. Astronomers just recently found that the novae in M87 seem to be uncharacteristically aligned along the jet, rather of spread randomly throughout the galaxy. Is the jet in some way setting off nova surges?
Another idea is that the jet is triggering star formation: more stars implies more binaries, which implies more novae.
Astronomers have discovered a strange positioning of novae explosions along the course of an enormous jet in the galaxy M87. While the jet and novae were previously thought to be unrelated phenomena, this alignment suggests a connection.
Astronomers discovered a strange alignment of novae explosions with a massive jet in the M87 galaxy. In spite of different theories, the specific reason for this alignment stays a mystery.
Everyone enjoys a great mystery, and astronomers have simply revealed a brand-new one in a close-by supermassive galaxy called M87. Like the majority of galaxies, M87 frequently plays host to a smattering of excellent surges called novae, each the outcome of a star stealing product from a next-door neighbor. M87 likewise includes a huge jet of plasma blasting out into deep area from the stellar core.
These phenomena: the jet and the novae, are unassociated huge occurrences, approximately scientists thought. Astronomers just recently found that the novae in M87 appear to be uncharacteristically aligned along the jet, instead of spread randomly throughout the galaxy. Is the jet somehow triggering nova surges?
It might be, but the secret is: how?
The jet emerging from the galactic core of M87. Credit: The Hubble Heritage Team (STScI/AURA) and NASA/ESA
Recent Findings and Theories
Utilizing data from two separate surveys by the Hubble Space Telescope, a group of astronomers validated the presence of 135 novae within M87, and they appear to happen with unforeseen frequency in the path of the jet. “The probability that this circulation happened by opportunity is of order 0.3%,” the team wrote in a preprint release of their paper.
For the moment, it is uncertain if this scenario is special to M87, or if this is a typical effect of stellar jets.
” No other galaxy with jets has been observed with adequate level of sensitivity or frequency to yield samples of novae large sufficient to inspect if M87s putative nova-jet connection is ubiquitous, unusual, or spurious,” the scientists said.
Artists conception of a white dwarf, right, accreting hydrogen from its companion star. Credit: NASA/CXC/M. Weiss.
Understanding Novae and Galactic Jets.
Heres what we know so far. Novae are triggered by explosions from the surface area of white-dwarf stars. For a nova to take place, the white dwarf needs to be in a binary set, and be close enough to its partner star to accrete material from it. Unlike a supernova, a nova doesnt totally ruin the white dwarf, and the exact same star can have several novae occur in time as a growing number of material is taken from its partner.
M87s galactic jet is driven by the black hole at the center of the galaxy– which, by the way, was the first black hole ever imaged by astronomers in 2019. As product spirals in towards the back hole, an accretion disk types around it, and effective magnetic fields funnel extreme radiation outward, causing it to be expelled at relativistic speeds, taking a trip nearly 5000 lightyears out into deep area.
The great void at the center of M87. Credit: EHT.
Challenging Theories.
There are a number of theories as to how the jet may set off novae.
One simple explanation is that radiation from the jet is heating up donor stars in its path, increasing mass transfer to their white dwarf partners and activating a thermonuclear runaway. Such heating would make novae more regular.
Regrettably, the mathematics on this theory does not check out. As effective as the radiation from the jet is, the stars are too little and the ranges undue for it to have much impact. We can most likely rule this response out: the effect is “orders of magnitude” too weak.
Another recommendation is that the jet is triggering star formation: more stars suggests more binaries, which implies more novae. Theres a problem with this explanation too. In this scenario, you would likewise expect to see a comparable boost in star formation along the galaxys counterjet, which isnt borne out by the proof.
Astronomers are going back to the drawing board.
Emerging Hypotheses.
There are a couple of other ideas they are thinking about however have not yet correctly evaluated. Maybe, for example, the jets shock waves are shepherding gas and dust together as it moves through the galaxy, forming clouds of interstellar medium. As one of these clouds comes to a binary star system, it would increase the rate of product accretion, triggering a nova. Similarly, a shock wave might also heat up a star up (better than radiation could by itself), increasing the mass transfer rate.
These last 2 possibilities are as-of-yet just guesses: they havent yet been fully checked out.
For now, it stays a secret.
In the words of the authors, “the boosted rate of novae along M87s jet is now securely established, and unexplained.”.
Adjusted from a short article initially released on Universe Today.
Reference: “A 9-Month Hubble Space Telescope Near-UV Survey of M87. II. A Strongly Enhanced Nova Rate near the Jet of M87” by Alec M. Lessing, Michael M. Shara, Rebekah Hounsell, Shifra Mandel, Nava Feder and William Sparks, 28 September 2023, Astrophysics > > High Energy Astrophysical Phenomena.arXiv:2309.16856.