The small constellation of Lyra is not only very beautiful in the configuration of the stars that make up it, but also contains among them absolutely unique universal diamonds. The star Sheliak - Beta Lyrae is one of such jewels.
Translated from Arabic, Sheliak means a turtle shell (or even the turtle itself), but the same word is used to name an ancient musical instrument similar to a harp or, in fact, a Lyre, because a resonator body was made from a turtle shell, which was necessary for a more melodious sound of the strings. A musical culture on Earth was born somewhat cruelly, singing, among other things, the heavenly distances in which man saw the Worlds of his future - incomparably happier than the one in which he lived then. But man evolved, and at some point, wood began to be used more and more often for making musical instruments - Kifaras and Lyras with a wooden body sounded even better than turtle ones. But the dim star in the constellation Lyra remained called the Turtle.
What exactly this star attracted the attention of ancient astronomers is unknown now, but it was clearly not deprived of attention. It is simply that much of the scientific information from that historical period was lost. And in the 18th century it was discovered that about once a week the star slightly "winks" - fading for a short time, becoming dimmer by about two times. This could easily have been noticed in ancient times, and certainly was noticed (as astronomers of all developed countries of the ancient era noticed similar behavior of the star Algol in the constellation Perseus), but they just could not explain it.
The variability of Beta Lyrae (as well as the variability of Algol) was explained by a young amateur astronomer, John Goodricke. He had no special education, and was also deaf and dumb, but a very keen-sighted and insightful person. John's passion was observing stars, and by the age of 20 he had already examined many of them for brightness variations - simply with the naked eye, since there were no other methods at the end of the 18th century.
Only intuition can explain John Goodricke's guess that the apparent brightness of some stars most likely changes because in reality it is not one star, but two, which, rotating around the center of mass of the system, periodically obscure each other for an observer on Earth. This bold assumption was confirmed a hundred years after the death of the amazing seer.
John Goodricke died very young - at 22, succumbing to pneumonia - two years after discovering and explaining the variability of Beta Lyrae, and just four days after being elected a Fellow of the Royal Society of London.
At the turn of the 19th and 20th centuries, astronomers learned to perform detailed spectral analysis of stars and track the behavior of absorption lines in their spectrograms. In the spectra of Sheliak (Beta Lyrae) and Beta Persei (Algol), the lines behaved similarly - slightly swaying around the places assigned to them by the chemistry of the star - synchronously with the dynamics of brightness changes. This clearly indicated the presence of two luminaries in the system and their orbital motion. This was irrefutable evidence, but indirect. A century later - already in our days - a direct image of the Beta Lyrae system was obtained using the CHARA infrared interferometer. And astronomers saw with their own eyes two stars orbiting the center of mass of the system, alternately eclipsing each other.
It was also discovered that the shapes of these stars are distorted by tidal interactions and resemble oblong melons. It was even discovered that matter flows from one star to another, which changes the proportion of masses in the system and slows down the rotation, increasing the period by 19 seconds per year. At the same time, part of the matter forms an extended accretion disk around the system, which partially dissipates into interstellar space. And in addition to the exchange of mass in this system, there is a significant loss of it.
The period of brightness variation in the Beta Lyrae system is 13 days. But since eclipses occur twice during the entire period (the stars eclipse each other in turn, as if changing places), brightness minima occur approximately once a week. But they are slightly different in depth - 0.9 and 0.5 stellar magnitudes.
Nowadays, the horizons of astronomy have expanded somewhat, thanks to advanced technologies for studying the Universe. And it is already believed that Beta Lyrae is a relatively close system to us. But still, 900 light years is not that close. To see separately stars that are twice as close to each other as the Sun and Mercury is a great achievement for optical interferometry.
The distance separating the components of this system is estimated at 40 million km. Somewhere at this distance from the Sun, in the era of the famous Le Verrier, astronomers were looking for the planet Vulcan. And they found nothing. But now they see a system of two giant stars with similar orbits.
Both components of this system are quite massive — 3 and 13 times the mass of the Sun. And in luminosity — 26 thousand and 6 thousand times, respectively. It is interesting that during the existence of the system — about 20 million years — these stars seemed to have swapped roles. The one that is now massive was skinny, developed more slowly, and the neighboring star — having quickly swelled to the size of a giant — began to share matter with the smaller star. The neighbor was not modest, and took over as much as was given. And now the star that had less mass has gained it in excess. And continues to do so.
Somewhat removed from this close and amazing pair of stars, another component of the system, the so-called Beta Lyrae B, slowly drifts along a huge orbit. What we talked about before was Beta Lyrae A. But there are many more stars in this system.
Beta Lyrae B is clearly visible even in binoculars - it is a 7th magnitude star, separated from the eclipsing variable pair by 46 arc seconds (this is the apparent size of Jupiter). In a small telescope, this double star looks very nice and is an easy object for beginner astronomy enthusiasts. Now it is known that it is also a double system, though a spectral one - not divisible into components in any telescope (they are very close to each other, or maybe it just has not deserve such close attention, and some super-powerful interferometer has not yet been deployed on it).
Another star was found 64 arc seconds away from the main pair of stars, though rather faint for amateur optics - Beta Lyrae C - 13th stellar magnitude. And further away from the aforementioned luminaries, astronomers are now checking for involvement in the system of several more stars - D, E and F. Moreover, in relation to Beta Lyrae F, even convincing evidence of a gravitational connection has been found.
Once again, we started with one star and ended up with a whole star cluster. However, this situation is not uncommon in our Universe. A rare type of star in it are stars like our Sun - stable and completely alone. But maybe that is why we now have the opportunity to study the entire diversity of other cosmic luminaries.
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