A Jupiter-like exoplanet so close to its parent star has long been thought to have no friends in its cosmic neighborhood. A new study now reveals that many of them may have friends on planets.
Astronomers think that hot Jupiter, an exoplanet that is at least as large as Jupiter but orbits its star in 10 days or less, and its cousin, warm Jupiter, which orbits its star in 10 days are the sole occupants of its star system. Astronomers think that the enormous gravity of these gas giants threw other planets out of the star system after these giants formed and migrated towards their stars. To date, observations support this theory.
But the new study, which analyzed data from NASA’s Kepler Space Telescope, found that 12% of known Hot Jupiters and up to 70% of hot Jupiters, may have nearby planets.
Related: The James Webb Space Telescope discovered an unexpected ‘hot Jupiter’ exoplanet
“Hot Jupiter is not as lonely as we thought,” Songhu Wang, a professor of astronomy at Indiana University Bloomington and author of the new study, said last week at the 242nd meeting of the American Astronomical Society held in Albuquerque, New Mexico, and online. “The presence or absence of additional close friends within the same system provides the most fundamental properties that will shed light on the history of their formation.”
Scientists have been searching for a companion planet near hot, warm Jupiter for the past three decades. They used data from the now-defunct Kepler spacecraft and NASA’s other exoplanet hunter, the Transiting Exoplanet Survey Satellite (TESS), to look for the dip in stellar brightness that results when a planet “transits” in front of the star’s disk and briefly blocks part of it. its light, as seen from the spacecraft’s perspective.
While this method is excellent for planet hunting, it can’t reveal much about smaller exoplanets and isn’t aligned enough for spacecraft to observe their transits. This may be the reason why previous studies have largely not detected companion planets near hot Jupiters. Wang said.
So to spot these invisible neighbors, Wang and his team, instead of focusing on transits, studied how the gravity of nearby planets affects the orbital speed of hot and warm Jupiters. This method — known as transit time variation or TTV — does not require a companion planet to transit its star in front of the telescope and allows astronomers to detect worlds close to hot Jupiters that cannot be detected by the transit method, according to Wang.
In the Kepler data, Wang’s team studied 101 Jupiter-sized planets and detected TTV signals originating from nearby planets for 16 of them. Two signals came from worlds near hot Jupiter known as Kepler-412b and Kepler-1976b.
Kepler-412 b is a gas giant exoplanet discovered in 2014 approximately 3,500 light years from Earth on the border of the Lyra constellation within the Milky Way galaxy. It weighs the same as Jupiter and takes 1.7 days to orbit its parent star at a distance of 2.7 million miles (4.3 million km). In contrast, Kepler-1976 b, discovered this year, orbits its star every five days at a distance of about 5.2 million miles (8.3 million km). In comparison, Mercury circles our sun at an average distance of 36 million miles (58 million kilometers).
The remaining 14 of the 16 TTV signals detected hinted at a planet near warm Jupiter, but none of the signals detected in this study could reveal specifics of the orbiting planet such as its size or mass, the researchers wrote in the new study.
How exactly hot, warm Jupiter evolves into its short-lived orbit around its parent star has been an open question for more than 25 years. One leading theory states that hot Jupiters formed far from their parent stars in highly elliptical orbits, which over time contracted into narrow circular paths. During this process, the gas giant migrates towards its host star. Along the way, these giants interacted gravitationally with other planets and nearly drove them out of their star systems. In this way, they soon became the worlds of their own that are visible today.
A second, less cited theory states that hot Jupiters formed in the outer regions of the stellar disk, but migrated inward in a more peaceful manner, allowing them to coexist with other nearby planets. So far, astronomers have only discovered a handful of such systems to support this theory.
In the new study, Wang and his co-authors propose a “unified framework” that combines both theories. About 12% of these gas giant planets formed in star systems together with other planets, but did not experience strong gravitational interactions with their neighboring planets. This explains why there are a handful of hot Jupiters detected near other planets, while the remaining 88% of planets will be stripped away. their systems on other planets, supporting observations from Kepler and TESS, according to the study.
Although scientists still don’t fully understand how hot Jupiters migrate inward, the presence of neighboring worlds around them is strong evidence that not all hot Jupiters have violent histories as previously thought, Wang said at a press conference last week.
The new research is described in a paper published in March in The Astronomical Journal.
2023-10-23 19:08:35
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