Full published link with images:
https://www.washington.edu/news/2021/01/14/hs-hydra/
Newswise – The sun is the only star in our system. But many of the light points in our night sky are not so lonely. According to some estimates, more than three-quarters of the stars exist as binaries – with one partner – or in even more complex relationships. Stars in close quarters can have a profound effect on their neighbors. They can tear material apart, come together or twist each other’s movements through the cosmos.
And sometimes these changes occur over a few generations.
That is what a team of astronomers from the University of Washington, the University of Western Washington and the University of California, Irvine discovered when they analyzed more than 125 years of astronomical observation of a nearby stellar binary called HS Hydrae. This system is called binary eclipsing: From Earth, the two stars appear to pass each other – or orbit each other – as they orbit a center of gravity. shared. The eclipses cause the light emitted by the binary to decrease from time to time.
On January 11 at the 237th meeting of the Astronomical Society of America, the team outlined the value of more than a century of changes to the eclipses with the stars in HS Hydrae. Both stars began to decline in small amounts starting around a hundred years ago, going up to almost full eclipses by the 1960s. The rate of eclipsing then fell over just half a century, and stopped around February 2021.
“There is a historical record of observation of HS Hydrae that largely spans modern astronomy – beginning with late 19th century photographic plates through satellite imagery taken in 2019. By diving into these charts, we recorded the total rise and fall of this rare type of binary eclipsing, ”said team leader James Davenport, professor of astronomical research at UW and deputy director of the UIRAC DIRAC Institute.
The eclipses of the two stars that make up HS Hydrae change as another body – possibly the third star of an unserved companion – turns the baking side toward Earth. Such systems, known as eclipsing binaries that are growing, are rare, with only about a dozen known to date, according to Davenport. Identifying this type of binary requires multiple perspectives to look for long-term changes in the rate of discount, which would indicate that the interior of the binary changes over time.
HS Hydrae has such an observation record because, at 342 light-years away, it is a very close and clear system and the two stars orbit each other every 1.5 days. Scientists first described HS Hydrae as a binary eclipsing in 1965. In a 2012 paper, astronomers based in Switzerland and the Czech Republic reported that the rate of discounting from HS had decreased. Hydrae from 1975 through 2008, showing that the two stars dipped less and had smaller proportions of each other over time. That team also predicted that the eclipses would end around 2022.
Davenport and his team took a look at HS Hydrae using observations on the system in 2019 with NASA’s Satellite Survey Transiting Exoplanet, or TESS. They only saw a 0.0075 magnitude drop in light from HS Hydrae, a sign that the two stars were only covering each other at the time of eclipses. For comparison, eclipses in 1975 saw a fall of more than 0.5 magnitude.
“Fifty years ago, these two stars were almost completely intertwined. In the early 21st century, the rate of eclipse was around 10%, and in the latest observations from 2019, they barely exceeded it, ”said Davenport.
With this new data, the team is now predicting that HS Hydrae eclipses will stop around February 2021.
The views from the 1960s through 2019 catalog the decline of HS Hydrae as a binary eclipsing evolution. But Davenport and his team also found evidence of a resurgence. Harvard’s Digital Access to a Sky Century, or DASCH, is a digital catalog of photometric data taken from more than a century’s worth of Harvard University astronomical plates. The team shook this record and found ideas from HS Hydrae from 1893 to 1955 that they could examine to find signs of mitigation.
The researchers broke DASCH’s views on HS Hydrae by a decade. From the late 19th century through the 20s, HS Hydrae showed no measurable discount. But things began to change in the 1930s, where they measured a small drop of 0.1 magnitude in brightness. The level of discount rose through the 1940s and peaked in the 1950s with a 0.5 decrease in brightness.
Based on this 126-year history of HS Hydrae studies, the team predicts that the system will start rolling out again around the year 2195. However, that assumes it is a star The third companion is a small, dim M – dwarf – which other teams have said. – continues to behave as it has so far.
“We certainly don’t know if we keep watching,” Davenport said. “The best we can say right now is that HS Hydrae has been constantly changing across today’s astronomy.”
Missions like TESS are likely to identify eclipsing binaries that are growing in the coming years. This should open up new opportunities for astronauts to understand how star systems are built, as well as how they change over time – whether they are busy, dynamic systems such as HS Hydrae, or more complex systems. quiet, like ours.
Co-authors of the paper are UW graduate students Diana Windemuth and Jessica Birky; UW researcher Karen Warmbein; Erin Howard at Western Washington University; and Courtney Klein at UC Irvine. The research was funded by NASA, the National Science Foundation, the Heising-Simons Foundation, the Research Association for the Advancement of Science, the DIRAC Institute, the UW Department of Astronomy, the Charles and Lisa Simonyi Fund for Arts and Sciences and the Washington Research Foundation.
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References:
- “The Rise and Fall of a Remarkable Eclipsing Binary Star,” presented by James Davenport (University of Washington), AAS 237, January 11, 2021, Session 133.06 (Stellar Binary Systems I)
- AAS press conference “Evolution Stars & Nebulae I,” Thursday, January 14, 2021 at 4:30 pm Eastern US Time (1:30 pm US Pacific Time)
Donation Numbers: NSF BPC-A # 1246649, NSF DGE-1839285, NSF DGE-1762114, NSF AST-0407380, NSF AST-0909073, NSF AST-1313370.