Nearly 300 variable stars detected with Kepler spacecraft

Utilizing knowledge from NASA’s Kepler spacecraft, astronomers from the Pedagogical College of Cracow, Poland, and elsewhere have detected 278 variable stars within the open cluster NGC 6791 and its environment. The discovering was reported in a paper revealed March 13 on the arXiv pre-print repository.

Variable stars may supply vital hints into features of stellar construction and evolution. They may be useful for higher understanding the gap scale of the universe. Particularly, research of variable stars in star clusters are of particular curiosity for astronomers as they’ve the potential to assist determine systematic errors that have an effect on stellar distance indicators.

Positioned about 13,300 light years from the Earth within the Lyra constellation, NGC 6791 is among the most studied open clusters (OCs). It has an estimated age of roughly 8 billion years and an iron to hydrogen abundance ratio that’s greater than twice that of our sun. This makes it one of many oldest and most metal-rich clusters within the Milky Way galaxy. With a mass of roughly 4,000 solar masses, it is usually one of the crucial huge OCs recognized thus far.

Earlier observations of NGC 6791 have discovered that it hosts a number of stellar populations and detected lots of of variable stars within the cluster. Not too long ago, a staff of astronomers led by Sachu Sanjayan has analyzed the information obtained by Kepler’s extended mission generally known as K2, hoping to find extra variables in NGC 6791.

“We introduced a seek for variable stars within the Kepler superstamp knowledge. All out there pixels had been searched, via a Fourier amplitude spectrum, and a contiguous optimum aperture for every object that exhibits a major flux variation had been outlined,” the researchers defined.

All in all, the staff recognized 278 variable stars, out of which 119 turned out to be newly detected variables. Among the many complete pattern, 17 binaries, 45 pulsators, 62 rotational and 5 unclassified variables had been discovered to be members of NGC 6791. The remaining 28 binaries, 25 pulsators, 83 rotational, 4 unclassified and 9 unidentified variables are both not cluster members or their membership is but to be decided.

The colour-magnitude diagrams (CMDs) present {that a} majority of the recognized variable stars in NGC 6791 are situated in the principle sequence. Photo voltaic-like pulsators are largely situated within the crimson large department (RGB) and crimson clump (RC), whereas semi-regular variables are situated within the RGB and asymptotic giant branch (AGB). As well as there are 5 blue straggler (BS) and three excessive horizontal department (EHB) stars.

The examine discovered that the metallicity isn’t constant among the many recognized variable cluster members. The astronomers assume that this may very well be as a result of presence of a number of stellar populations inside NGC 6791, nevertheless a uniform spectroscopic survey is critical with a view to verify this assumption.

Based mostly on the newly collected knowledge, the researchers managed to derive elementary parameters for NGC 6791. The outcomes point out that the cluster is 8.9 billion years outdated, has a metallicity at a degree of 0.26–0.28, and is situated some 13,500 mild years away.

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