Brown dwarfs are often referred to as ‘stars’ on a stranded ‘because they were born with insufficient mass to ignite their star-studded nuclear fusion lights – even though they formed as their more massive ‘real’, fiery, attractive and scorching. Hydrogen. Star parents. Because of their small size, astronomers found it difficult to distinguish brown dwarfs from giant planets, such as the bright striped colossus of our solar system Jupiter. Indeed, gas giants such as Jupiter and the “falling stars” have some similar characteristics. In June 2019, based on preliminary results from a new study of 531 stars by the Gemini Observatory, a team of astronomers published their findings that brown dwarfs and large planets are becoming increasingly susceptible to very different origins. Consequently, gas giants and brown dwarfs are too far away to be “kissing cousins.”
The GPI Exoplanet Survey is one of the most sensitive and important to date in direct filming of exoplanets using direct imaging and is still being conducted at the Gemini Southern Telescope in Chile. “Our analysis of the first 300 observed stars already shows strong trends,” Dr. Eric L. Nielsen said in a press release from the Gemini Observatory on June 11, 2019. Nielsen, of Stanford University in Palo Alto, California, is the lead author of the new study.
In November 2014, GPI principal investigator Dr. Bruce McIntosh, who is also from Stanford University, and his international team observed about 600 nearby stars using a newly commissioned tool. GPI is funded by the Gemini Observatory partnership, most of which comes from the National Science Foundation (NSF) in the United States. NSF and the National Research Council of Canada funded scientists who participated in GPIES.
To imagine a distant alien planet orbiting a star behind our Sun is a huge challenge. Indeed, a difficult task becomes possible only with the use of a handful of tools. The problem is that these distant worlds are small and fuzzy and live next to the overwhelming light of their whirling dark star. Indeed, the task of observing a weak and distant exoplanet can be compared to the detection of a butterfly flying in front of a street lamp, when the observer is at a distance of 16 km. Even the brightest planets are illuminated by the radiance of its parent star. Although the brightest planets emit a gentle glow, they are still about ten thousand times paler than their star. The good news is that GPI can observe planets a million times weaker – it’s much more sensitive than previous planet image-building tools. “GPI is a great tool for planet study, and the Gemini Observatory has given us time for a thorough and systematic study,” Dr. McIntosh said in a press release from the Gemini Observatory on June 11, 2019.
GPIES is now completing its mission. Of the first batch of 300 stars, GPIES has discovered half a dozen giant planets and three brown dwarfs. “This analysis of the first 300 stars observed by GPIES is the largest and most sensitive study with a direct representation of giant planets published to date,” Dr. McIntosh added. Although brown dwarfs are more massive than planets, they still make up the rest of the stellar nest because they haven’t accumulated enough mass to turn hydrogen into heavier atomic elements – like real stars. “Our analysis of this Gemini study suggests that distant giant planets may have a shape different from their brown dwarf counterparts,” Dr. Nielson said in the same Gemini press release.
Giant planets vs. star shorts
Brown dwarf stars are eccentrics. Indeed, their very existence invites astronomers to solve a tantalizing riddle. This is because they defy any attempt to clearly distinguish between “failed stars” and giant planets.
For example, sparkling and shimmering young stars (protostars) are located in a dense compressed drop, consisting mainly of gas with a small amount of dust. When a star is born, the temperature in the center of the dense drop rises to the red point, causing hydrogen atoms to merge with the formation of helium atoms. Hydrogen is the most common and lightest atomic element in the universe, and helium is the second lightest. All stars, regardless of their mass, consist mainly of hydrogen, and hydrogen and helium formed during wild exponential inflation as a result of the birth of the Great Bang Universe about 13 years ago, 8 billion years ago.
On the contrary, giant gas planets similar to Jupiter are an obscure matter. At the heavier end of the mass range, which is 60 to 90 times the mass of Jupiter, the volume of the brown dwarf is primarily determined by the pressure of electronic degeneration – as in the case of white dwarfs. White dwarfs are the remnants of nuclei left behind by tiny stars similar to the Sun, after they burned the necessary supply of thermonuclear fuel and entered “this quiet night” with relative calm and softness. On the contrary, at the lighter end of the mass range – which is about 10 times the mass of Jupiter – the volume of the brown dwarf is regulated in the same way as for the planet. Complicating factor is that the radii of brown dwarfs are only 10-15% higher than the mass range of their fellows on the planet. This presents astronomers with the difficult task of distinguishing giant planets from brown dwarfs.
Since small brown dwarfs never gain enough weight to participate in the nuclear fusion process, those that are at the lighter end of the mass range (less than 13 Jupiter masses) cannot heat up enough to even do so – melt deuterium. Meanwhile, these brown dwarfs, occupying a heavier part of the mass range (more than 60 masses of Jupiter), cool so quickly – only after about 10 million years – that they can no longer tolerate thermonuclear fusion. Ten million years is a very short period in the strange “life” of the “failed star.”