Astronomers find two exoplanets around HD 114082

Astronomers in Spain have reported two giant exoplanets orbiting the young star HD 114082, adding a rare system of long-period worlds to the catalog of planets seen crossing in front of their stars. The finding was announced on May 18 by the University of La Laguna and the Instituto de Astrofísica de Canarias, which led the international collaboration behind the work. (ull.es) The team said the planets are unusual because they are both large, low-density and orbit a star only about 15 million years old. The study was published in *Astrophysical Journal Letters*. ### Why are astronomers paying attention to this particular star system? HD 114082 is an F-type star about 15 million years old, far younger than the Sun’s 4.6 billion years, and the researchers said that youth makes the system useful for studying how giant planets form and evolve. (ull.es) The ULL and IAC release said the star spins 15 times faster than the Sun, has 28% more mass, is about 1,000 degrees hotter and is nearly four times more luminous. Carlos del Burgo Díaz, the study leader at ULL and IAC, said the pair stands out among the youngest transiting planets because they take unusually long to complete an orbit. The paper identifies them as the longest-period young transiting exoplanets known, according to the journal abstract. (ull.es) ### What do the two planets look like? The inner planet, HD 114082 b, is about the size of Jupiter and orbits 20% closer to its star than Earth does to the Sun, the researchers said. The outer planet, HD 114082 c, sits at roughly Earth’s orbital distance from its star and has a radius 36% larger than Jupiter’s. (ull.es) The outer world drew the most attention because of its density. ULL and IAC said its mean density is more than 7.5 times lower than water’s, leading the team to say it would float in water. El Mundo and ABC Color highlighted that measurement in early coverage of the result. ### How were the planets detected if one of them transited only once? (ull.es) The study used data from NASA’s TESS and ESA’s CHEOPS space telescopes, along with ground-based observations from NGTS in Chile, ASTEP+ in Antarctica and Las Cumbres Observatory, according to the ULL and IAC releases. Those observations produced light curves showing dips in the star’s brightness when a planet passed in front of it. (ull.es) For HD 114082 b, the team said it recorded four non-consecutive transits, allowing the inner planet’s orbital period to be pinned down precisely. For HD 114082 c, the period was estimated from a single transit confirmed with two instruments and supplementary measurements, yielding an orbital period of about 314 days with a 9% margin of error. (ull.es) ### What else does the system tell researchers about planetary architecture? Alejandro Suárez Mascareño, a co-author affiliated with ULL and IAC, said the two planets move in nearly circular orbits in the same plane and may be in or near orbital resonance. That means their orbital periods could be related by a simple ratio, a clue that can help researchers reconstruct how the system formed inside its protoplanetary disk. (ull.es) The journal paper and institutional releases also place the planets inside a debris-disk system around HD 114082. That combination — young star, debris disk and two puffed-up giant planets — gives observers a target for follow-up work on dynamics, masses and atmospheric properties. (iac.es) ### What happens next for HD 114082? Carlos del Burgo said the next step is to catch a second transit of HD 114082 c so astronomers can measure its orbital period more accurately. After that, he said, refining the masses of both planets will require timing multiple transits of each world, a method that could also reveal additional members of the system. The ULL release said the system is likely to draw more follow-up observations in coming years, including with facilities such as the James Webb Space Telescope. (ull.es) The paper is published under the title *The Longest-period Young Transiting Exoplanets—A Duo of Puffy Giants inside a Debris Disk* in *Astrophysical Journal Letters*. (abc.com.py) (iopscience.iop.org)