Astronomers discover unusual giant exoplanet with extremely strange orbit – 2024-07-19 02:02:00 – 2024-07-19 02:04:07 – 2024-07-19 02:06:36 – 2024-07-19 02:08:12 – 2024-07-19 02:09:58 – 2024-07-19 02:10:14

Using the 3.5-meter WIYN telescope located on Kitt Peak, Arizona, astronomers have managed to discover the extreme orbit of an exoplanet that is on its way to becoming a hot Jupiter. In addition to following one of the most elongated orbits of all exoplanets, the celestial body orbits its star backwards, which gives clues about the mystery of the evolution of hot Jupiters, NoirLab reported.

Among the more than 5,600 confirmed exoplanets in about 4,000 star systems, there are between 300 and 500 exoplanets that belong to a curious class known as hot Jupiters. These are very large, Jupiter-like exoplanets that orbit very close to their star — some as close as Mercury. While it’s a mystery how hot Jupiters end up in such close orbits, astronomers believe they start out in orbits far from their star and then migrate to inner orbits over time. The early stages of this process have rarely been observed, but with this analysis of an exoplanet with an unusual orbit, astronomers are one step closer to cracking the mystery of hot Jupiters.

The discovery of this exoplanet, named TIC 241249530 b, was made by NASA’s Transiting Exoplanet Survey Satellite (TESS) in January 2020 due to a dip in the brightness of a star as a Jupiter-sized planet passed in front of, or transited, it. To confirm the nature of these fluctuations and rule out other possible causes, a team of astronomers used two instruments on the 3.5-meter WIYN telescope at the National Science Foundation’s Kitt Peak National Observatory (KPNO), an NSF NOIRLab Program.

The team first used the NASA-funded NN-EXPLORE Exoplanet and Stellar Speckle Imager (NESSI), a technique that helps “freeze” atmospheric scintillation and eliminate any extraneous sources that might confuse the signal’s origin. Next, using the NASA-funded NEID spectrograph, the team measured the radial velocity of TIC 241249530 b by carefully observing how its host star’s spectrum, or the wavelengths of its emitted light, were shifted by the orbiting exoplanet.

Arvind Gupta, a postdoctoral researcher at NOIRLab and lead author of the research paper published in Nature, praised NESSI and NEID for being instrumental in the team’s efforts to characterize and confirm the exoplanet’s signal: “NESSI gave us a sharper view of the star than would have been possible otherwise, and NEID accurately measured the star’s spectrum to detect shifts in response to the orbiting planet,” Gupta explained. Gupta also highlighted the particular flexibility of NEID’s observing schedule, which allows the team to quickly adapt its observing plan based on new data.

NSF NOIRLab Program Director Chris Davis said, “The WIYN telescope is playing a crucial role in helping us understand why planets in other solar systems can be so different from system to system. The collaboration between NSF and NASA on the NN-EXPLORE program continues to yield impressive results in exoplanet research.”

Detailed analysis of the spectrum confirmed that the exoplanet is about five times more massive than Jupiter. The spectrum also revealed that the exoplanet is orbiting along an extremely eccentric, or elongated, path. The eccentricity of a planet’s orbit is measured on a scale of 0 to 1, where 0 is a perfect circular orbit and 1 is a highly elliptical orbit. This exoplanet has an orbital eccentricity of 0.94, making it more eccentric than the orbit of any other exoplanet discovered using the transit method. [1]By comparison, Pluto’s highly elliptical orbit around the Sun has an eccentricity of 0.25, while Earth’s eccentricity is 0.02.

If this planet were part of our Solar System, its orbit would extend from a position 10 times closer to the Sun than Mercury (at its closest approach to the star), to another point similar to the distance from the Earth to the Sun (at its greatest extension). This extreme orbit would cause temperatures on the planet that would range from those of a summer day to temperatures hot enough to melt titanium.

In addition to the unusual nature of the exoplanet’s orbit, the team also discovered that it orbits backwards, that is, in the opposite direction to the rotation of its host star. This is not something astronomers observe in most exoplanets, or in our own Solar System, and it helps the team interpret the exoplanet’s formation history.

The exoplanet’s unique orbital characteristics also provide clues about its future trajectory. Its exaggerated eccentric orbit and its close proximity to its host star are expected to eventually make the planet’s orbit more circular, as tidal forces on the planet sap energy from the orbit and cause it to gradually shrink and become more circular. Discovering this planet before this migration occurs is invaluable, as it provides crucial information about how hot Jupiters form, stabilize, and evolve over time.

Gupta said, “While we can’t rewind a video to watch the planetary migration process in real time, this exoplanet serves as a snapshot of the migration process. Planets like this are extremely rare and difficult to find, so I hope it can help us unravel the formation history of hot Jupiters.”

“We’re quite interested in what we can learn about the dynamics of this planet’s atmosphere after it makes one of its scorching close approaches to its star,” said Jason Wright, a professor of astronomy and astrophysics at Penn State who oversaw the project while Gupta was a doctoral student at the university. “Telescopes like NASA’s James Webb Space Telescope have the sensitivity to probe changes in the newly discovered exoplanet’s atmosphere as it undergoes rapid warming, so the team can still learn a lot more about the exoplanet.”

TIC 241249530 b is the second exoplanet discovered to display the pre-migration phase of a hot Jupiter. Together, these two observational examples confirm the idea that gas giants evolve to become hot Jupiters as they migrate from highly eccentric orbits to more closed and circular orbits.

“Astronomers have been searching for exoplanets that could be precursors to hot Jupiters or intermediate products of the migration process for more than two decades, so I was very surprised — and excited — to find one. It’s exactly what I was hoping to find,” Gupta said.