Observation of the planetary transit TIC 393818343 c using different photometric filters (Zero-Point on ip Filter), different telescopes and different locations. Credit: Conzo et al., 2024
Astronomers report the detection of a second exoplanet orbiting a G-type star known as TIC 393818343, located about 300 light years away. The new alien world is about three times less massive than Jupiter. The discovery was detailed in a research paper published October 9 on the preprint server. arXiv.
TIC 393818343 is an ancient G-type star estimated to be 3.8 billion years old. The star is about 8% larger and more massive than the sun, has an effective temperature of 5,756 K, and its metallicity is about 0.32 dex.
In May 2024, the first exoplanet orbiting TIC 393818343 was detected. The planet, which received the designation TIC 393818343 b, orbits its host every 16.25 days in an eccentric orbit. Since TIC 393818343 b is slightly larger and more than four times as massive as Jupiter, and its equilibrium temperature is around 805 K, it has been classified as a hot Jupiter.
Today, a team of astronomers led by Italian amateur astronomer Giuseppe Conzo confirmed the presence of another planet in this system: TIC 393818343 c. The discovery is based on ground-based observations made using several telescopes around the world, including the Nastro Verde Observatory in Italy.
“The second planet was initially spotted by the Las Cumbres Observatory (LCOGT) and amateur astronomers. (…) By studying variations in the transit time of the first planet, the researchers noticed discrepancies in the period predicted orbital of TIC 393818343 b. The shift in transit times was greater than one hour, leading to the suspicion and confirmation of TIC 393818343 c,” the authors of the paper explained.
According to the study, TIC 393818343 c is about 30% smaller than Jupiter and its mass is estimated to be about 0.36 Jupiter masses, giving a density of 0.96 g/cm.3. The planet has an orbital period of 7.84 days, so it is an internal companion of TIC 393818343 b, and its equilibrium temperature is expected to be around 1,027 K.
Based on the derived parameters, astronomers classified TIC 393818343 c as a super-Neptunian gas giant exoplanet, ruling out the possibility that it is a terrestrial world. The so-called super-Neptunes are alien worlds larger than Neptune with masses up to 0.47 Jupiter masses. The scientists added that super-Neptunian planets like TIC 393818343 are generally rarely found around solar-type stars.
In their concluding remarks, the researchers noted that in order to better uncover the properties of TIC 393818343 c, atmospheric spectroscopy of this planet should be carried out along with radial velocity measurements to reveal its true mass.
More information:
G. Conzo et al, TIC 393818343 c: Discovery and characterization of a Neptune-type planet in the constellation of Delphinus, arXiv (2024). DOI: 10.48550/arxiv.2410.07425
Journal information:
arXiv
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