Scholars from the University of Sydney recently identified a stellar body that decreases its mass. The star's 'weight loss' activity is already established in astronomical studies, but the observation of its occurrence is rare.
According to the study, the decrease of mass in this particular star was an effect of a greedy neighbor hovering nearby. The investigation is considered critical for our understanding of the origin and life of stars in the Milky Way galaxy.
What Are Slimmer Red Giants?
To seventeenth-century astronomers, Omicron Ceti or Mira was known as a wonderful star - a star whose brightness could change dramatically in about 11 months. Modern astronomers now recognize an entire class of long period Mira-type variables as cool, pulsating, red giant stars, 700 or so times the diameter of the Sun. Only 420 light-years away, red giant Mira (Mira A, right) itself co-orbits with a companion star, a small white dwarf (Mira B). Mira B is surrounded by a disk of material drawn from the pulsating giant, and in such a double star system, the white dwarf star's hot accretion disk is expected to produce some x-rays. But this sharp, false-color image from the Chandra Observatory also captures the cool giant star strongly flaring at x-ray energies, clearly separated from the x-ray emission of its companion's accretion disk. Placing your cursor over the Chandra x-ray image of Mira will reveal an artist's vision of this still wonderful interacting binary star system.
Like the subject of this study, there are other red giants scattered across our galaxy. At the moment, the population of these gigantic stellar bodies sums up to millions. Despite its warm name, red giants are colder than the stars at their peak. They also tend to become brighter as their life flushes away in their final phases.
The sun of our planetary system will eventually become among these red giants, but not anytime soon. According to numerous studies, the sun will turn into this type of star approximately four billion years from today.
Alongside the research about red giants, investigations revolve around the existence of the same type of stars but with a significantly slimmer mass.
Slimmer red giants are known as a normal part of the Milky Way neighborhood, but finding one is a highly-rare opportunity. With that said, University of Sydney scientists began to search for a red giant that falls under the 'slim' category.
Sydney Institute for Astronomy (SIfA) specialist and lead author of the study Yaguang Li explained that looking for a slimmer red giant is as hard as 'finding Waldo.'
In a report by EurekAlert, Li said that their team successfully identified at least 40 slimmer red giants, and most of the bodies are hidden in a constellation of normal stars.
Slimmer red giants have definitive features that separate them from normal red giants. Basic categories state that these stars are either smaller or have a smaller mass than their normal counterparts, Li continued.
Kepler Space Telescope Captures Slimmer Red Giants
The binary star system is the most common scenario that gives birth to a slimmer red giant. In this setup, two stars are near each other due to the gravitational pull they share with each other.
When these binary systems get old, each of them can get ahold of the gravitational sphere of the other. This imbalance usually results in the extraction of the lesser star's mass.
The latest study on red giant stars was made possible through the help of archival data collected by NASA's Kepler space telescope. The instrument gathered more than thousands of red giant bodies from 2009 to 2013.
The enormous dataset allowed the authors of this research to consolidate a list of stellar populations and single out stars that are possibly slimmer red giants. From the analysis, experts found that two features were prominent.
Underluminous red giants have dimmer brightness and measure around 0.8 to 2.0 solar mass. On the other hand, very low-mass red giants scale from 0.5 to 0.7 solar mass.
The study was published in the journal Nature Astronomy, titled "Discovery of post-mass-transfer helium-burning red giants using asteroseismology."
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