A group of astronomers has announced the discovery of two new exoplanets, around HIP 104045. Although this news is interesting because it leads us to think about possible inhabited worlds, neither of the two exoplanets is rocky. They are, in fact, quite a bit more massive…
HIP 104045 is a star similar to the Sun. It is 175 light-years from the Solar System. The two new worlds are designated HIP 104045 b and HIP 104045 c. It must be remembered that, when naming exoplanets, what is done is to resort to the name of the star and assign it a letter according to the order of its discovery. The letter is always expressed in lower case (capital letters are reserved for stars) and the a is not used. So HIP 104045 b and c are, respectively, the first and second planets discovered around it.
This implies, therefore, that if a third exoplanet is discovered at some point around the star, it will be called HIP 104045 d, and it could well be closer than those discovered so far. Anyway, back to the present, HIP 104045 b is a planet similar to Jupiter. HIP 104045 c, meanwhile, is similar to Neptune, though more massive. The discovery was published on March 2 on the arXiv platform (and is linked at the end of this article). The method used for detection has been radial velocity. Although it is no longer the most successful method, radial velocity detection consists of observing the variation in the speed of the star. From our perspective, it can be observed how it approaches and moves away from the Solar System, due to the effect of gravitational interaction with the planets in its environment. Thanks to this technique, more than 600 exoplanets have been discovered so far. The transit method (consisting in observing the fall of light from a star when a planet passes in front of it) has been much more fruitful.
Some details about exoplanets are already known The team of researchers has observed the star HIP 104045 with the HARPS spectrograph (for High Accuracy Radial Velocity Planet Searcher). The instrument is installed on the 3.6-meter telescope at the European Southern Observatory in La Silla, Chile. The observations are part of the Solar Twin Planet Search (STPS) program, which, as its name suggests, searches for planets around stars similar to ours. In addition to announcing detection, some features are shared.
Both planets have been discovered thanks to HARPS observations and 13 years of observations from other campaigns. The closest to the star, of both, is HIP 104045 c. It is a superneptune with about 14% of the mass of Jupiter. Its orbital period is 316 days and it is approximately 0.92 astronomical units from the star. That is, it is somewhat closer to its star than Earth is to the Sun. For its part, HIP 104045 b is a planet somewhat less massive than Jupiter. Its mass is estimated to be at least half that of the Jovian giant. It takes 2315 days (just over 6 years) to complete one orbit around its star. It is at a distance of 3.46 astronomical units. As a comparison, Jupiter orbits 5.2 astronomical units from the Sun. Regarding the star, it must be added that it is very similar to ours. HIP 104045 is, in fact, of the same spectral type. It is of type G5V (the Sun is G2V), with a mass and size slightly greater than that of our star. Its surface temperature is 5826 K (5552 ºC) and it is estimated to be about 4.5 billion years old.
HIP 104045 is similar to the Sun The authors of the study emphasize that HIP 104045 is very similar to the Sun. Its composition is similar, although it has a lower amount of volatile elements, compared to other stars that are considered twins of the Sun. Despite this, it is not among the which have a lower abundance. Hence, they suggest that the star could have gobbled up material from a rocky planet. Thus, they place HIP 104045 halfway between the Sun-like stars that are most metal-rich and those with the lowest abundance.
At first, they explain, they suggested that the planetary system of HIP 104045 could resemble that of our Solar System. That is, the gas giants and ice giants would be in the outer regions. More than 3 astronomical units. The interior regions, for their part, would be populated by rocky planets. The presence of HIP 104045 c at a shorter distance may cast doubt on this assumption. In any case, the finding does not present us with potentially habitable planets. It is still interesting because, in any case, we are dealing with a star similar to ours, with a planetary system that differs from ours. Its study, and that of other similar star systems, will allow us to better understand to what extent the Solar System could be a unique system. It is something that has been raised in recent times and that could also be a factor in explaining why the Earth has life…