David Buckley, an astronomer from South Africa, told RIA Novosti about the rediscovery of the most amazing star of the Milky Way, discovered by Soviet scientists back in the 1970s and turned out to be a battleground for two "space dwarfs", one of which is a unique white dwarf pulsar.
“When we began to observe this object and understood what it was, our colleagues from the press service immediately suggested that our article about its discovery be called Star Wars: Revenge of the Dwarf. This is a truly unique object that has all the characteristics of a pulsar, but it is not one. Many people still do not believe that this system looks the way we imagine it,”said Buckley, who made a presentation on the discovery of this object at the Institute of Astronomy of the Russian Academy of Sciences in Moscow.
Episode 1: The Phantom Menace
As the South African astronomer emphasized, this star was originally discovered not by his scientific team, but by Soviet astronomers. In 1971, they discovered an unusual twinkling star in the constellation Scorpio and published a description of it in the journal Astronomical Circular.
Soviet scientists tracked the fluctuations in the brightness of the star and considered that it was one of the fairly common variable stars of the Delta Shield type, the brightness of which changes every few hours due to the expansion and contraction of the surface layers.
40 years later, Buckley says, this ordinary star suddenly became one of the most unusual, interesting and unique objects in the Milky Way thanks to two virtually random circumstances.
First, the star was noticed by amateur astronomers, who noticed unusual periodic pulsations in its radiation that their Soviet predecessors had not seen, and then Buckley himself began to follow it, checking the instruments of one of the recently built South African radio telescopes.
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“The discovery of this star's extraordinary properties was a product of coincidence. Randomness and intuition play a huge role in astronomy, they are one of the main ways to discover something really interesting. As a rule, when people write applications for grants and the construction of telescopes, they make very specific plans for the future, but it usually turns out that the most interesting and significant discoveries are made at these facilities in a completely random way and in a completely different area,”continues the astronomer.
According to Buckley, this role of accidents in science is extremely badly combined with the fact that “today, in the world in general, and in science in particular, people who are similar in mentality to accountants flourish. They decide what to spend the money on, what benefits can be derived from these spending, and what experimental results should be obtained. They need a guaranteed result, but science works in a completely different way - scientists are like seafarers who go to the unexplored ocean in search of new lands and continents."
Studying the "space ocean" two years ago, Buckley and his British colleagues, Tom Marsh and Boris Gaensicke, discovered that Scorpio's AR represents the very "new space earth" they were trying to find.
As Buckley noted, the very first observations of the flares and dimming of the star showed that in fact its brightness does not change every three and a half hours, as the measurements of Soviet scientists showed, but also every two minutes. At the same time, the brightness periodically grew to impossibly high values in all ranges, starting with radio waves and ending with ultraviolet light.
This inexplicable behavior of the star, the scientist recalls, attracted the attention of many other astronomers, and Buckley and his associates had the opportunity to observe AR Scorpio using the Hubble, the Swift X-ray telescope, the VLT ground observatory, the ATCA radio observatory in Australia and a number of other powerful astronomical instruments …
Episode 3: revenge of the midget
These observations helped scientists decipher a very unusual spectrum of flares and understand that the "Soviet" variable star actually consists of two halves: a white dwarf and a red dwarf, whose exotic interaction gave rise to flares. Moreover, as it turned out later, not one, but two series of flares of different nature.
How this binary system came about, Buckley says, is still a mystery to astronomers. It consists of a white dwarf, whose mass is about three times less than the mass of the Sun, and a large red dwarf, slightly smaller than the Sun. The red dwarf, despite the fact that it is the main source of those flares that have been noticed by amateur astronomers, is quite an ordinary star, in contrast to the white dwarf, which has unique properties.
In general, the "vengeful dwarf", as Buckley called this object, behaves more like pulsars (rotating neutron stars) than other white dwarfs, which are the cores of burnt-out stars. In particular, it rotates incredibly fast, completing one revolution on its axis in 117 seconds, and has a powerful magnetic field, whose strength is about 1.5 billion times stronger than that of the Earth's "magnetic shield".
This magnetic field, according to Buckley and his colleagues, periodically generates beams of radio waves and charged particles and emits them from the magnetic poles of the white dwarf into outer space. The axis of rotation of this star, by a happy coincidence, sometimes turns out to be directed towards its "big brother".
As a result, every two minutes - the turnover time of the white dwarf - the red dwarf momentarily falls under the "bombardment" of the white dwarf, participating in a kind of "star wars".
White dwarf volleys are absorbed by electrons in the red dwarf's atmosphere, causing them to accelerate to near-light speeds and then emit this energy in the form of light, heat, radio waves, and other forms of electromagnetic radiation. Due to this, the brightness of AR Scorpio grows to impossibly high values for stars of similar mass, exceeding the permissible levels by about an order of magnitude.
“Now we are most interested in whether there are other objects of this type in the Universe. We are now discussing how we can look for such 'white pulsars', and are analyzing the archives of previous observations of variable stars in the hope of finding other examples of such behavior of white dwarfs,”continues Buckley.
Not all astronomers agree with this explanation. Dmitry Bisikalo, director of the Institute of Astronomy of the Russian Academy of Sciences, explained to RIA Novosti that there are other explanations for how these flares are born, which do not require constant “bombardment” of the star with radio wave beams from a white dwarf or the interaction of its magnetic field with the matter of a red dwarf. Other scientists, he said, generally doubt that this system exists in the form in which Buckley and his associates imagine it.
Space polygon
Nevertheless, British and South African astronomers, as Buckley himself explained, continue to observe the AR of Scorpio, and they recently received new data that will help astrophysicists understand how this system came to be. Many other scientists who agree with Buckley's calculations, in turn, believe that it can serve as a unique testing ground for a variety of cosmological and astrophysical theories.
“The AR of Scorpio emits a large number of electrons moving at the speed of light, and observing their interactions with hydrogen clouds near this star can help us test some theories describing relativistic effects. In addition, my theoretical colleagues assure me that this star can be an interesting source of gravitational waves and that it will help us check if the photon has mass,”explains the scientist.
In addition, scientists do not yet know how this system arose - according to Buckley, for its existence in its current form, it is necessary for the white dwarf to somehow spin up to the speeds that it has today. This, in principle, would be possible if he "stole" matter from the red dwarf, but astronomers did not record any traces of this. Therefore, the history of the development of these "star wars", as well as how such stars can affect the appearance of the Galaxy, remains a mystery to scientists.
On the other hand, the South African astronomer is sure that such objects cannot serve as a source of mysterious fast radio flares, a kind of "signals from aliens", over the nature of which scientists have been guessing for almost ten years.
According to him, the newest MeerKAT radio telescope, now under construction in South Africa with the participation of Buckley, will begin to study them next year in tandem with the Russian network of MASTER telescopes, which will look for traces of these flares in the visible range. They, as the astronomer concludes, have an even more mysterious origin than white dwarf pulsars, and observations of them, the scientist hopes, will help fill another gap on the cosmic "map of the oceans."
