Astronomers can use a new tool to understand giant stars. It is a detailed study of the temperatures and sizes of giant stars. The work will serve as a standard reference on giant stars for a long time.
It will show us what the Sun will go through late in its life.
The study began in 1997 when a group of Astronomers started using the Testbed Interferometer. The testbed was built for the upcoming interferometer. Astronomers kept collecting data on giant planets after the PTI closed. Astronomers used telescopes at the observatory after that to keep collecting data.
The lead author is from the observatory. He is a member of the astronomer faculty at the school. He is the Chief Scientist for the Navy. The study was published in The Astrophysical Journal.
Giant stars are not the same as main-sequence stars or dwarf stars. They have left the main sequence because the hydrogen in their cores is no longer available. A giant star will be more Luminous and have a larger radius than a main-sequence star or dwarf star. They can be between tens and thousands of times more powerful than the Sun and have a much greater radii. Supergiants and hypergiants are stars that are more powerful than giant stars.
Pollux is a giant star in the constellation. It is the closest giant star to the Sun. Pollux is shown in relation to the Sun. The image is from Omnidoom. The public domain.
Astronomers have done surveys of giant stars before. The Mount Wilson Observatory has a Mark III Stellar Interferometer. This new one is noteworthy for its high precision and the number of stars measured. The PTI was very efficient. It was possible to collect large amounts of stellar fringe visibility data on any given night. Data was gathered between other observing tasks. In a press release Van Belle said, "At best, every other study is only half this size, in terms of the number of stars."
The temperature measurement is two to four times more accurate than previous studies. If you tell me what colour a star is or what type of star it is, I can tell you its temperature and be more confident in that.
CW Leonis, not a part of this study, glows from deep within a thick shroud of dust in an image from the NASA/ESA Hubble Space Telescope. CW Leonis is a red giant star with a carbon-rich atmosphere that is 400 light-years from Earth. As the outer layers of CW Leonis were thrown out into the void, the dense clouds of sooty gas and dust were created. The image is from the Hubble and NASA.
This study is useful for a number of reasons.
Astronomers can learn a lot about an exoplanet if it is related to the star it is in. The mass, luminosity, and size of the star are used to infer the characteristics of the planet. The more accurate star and planet measurements are.
The study can tell us what to expect.
The Sun will eventually become a red giant and will swell in size to the point that it will encompass Mercury and Venus. There is a lot we don't know about giant stars. Estimates range from 10 to 100 times its current size. The data in this study will help us understand what happens to the Sun when it swells, as well as explain some of our star's current processes.