Credit: Pixabay/CC0 public domainAstronomers have taken the first ever spin measurements of the planets that make up the HR8799 star system.The W. M. Keck Observatory in Hawaii and Gemini Observatory in Gemini both discovered the HR 8799 star constellation in 2008. It is located at 129 light years away. It has four super-Jupiter, each one more massive than Jupiter. HR 8799 was one of the first systems of planetary planets to be directly photographed by a telescope.However, none have been measured the rotation periods or spin rates of HR 8799 planets. In fact, spin rates (which translate into the length of one day on a planet) have been measured only for a few of the many exoplanets that have been discovered.This breakthrough was possible thanks to a Caltech and Keck Observatory science and engineering team who developed the Keck Planet Imager and Characterizer. The instrument was commissioned between 2018 and 2020. It can image exoplanets with a very high spectral resolution. KPIC has a resolution high enough to determine how fast the planets spin.The infrared infrared allows for artistic visualizations of the rotating HR 8799 planets. The bright patches are caused by holes in clouds that allow instruments to detect the deeper layers of the planets' atmospheres. The upper left shows the label for each planet. This is only one possible way to imagine how the planets may look from Earth, as the orientations of their spin-axes are not known. Credit: W. M. Keck Observatory/Adam MakarenkoThe Astronomical Journal has accepted a study on the findings for publication. This work is the first science result from KPIC.The minimum rotation speeds for two of the HR8799 planets, HR 8799, d and HR, 8799, e respectively, were 10.1 km/s and 15 km/s. This means that the day could last as little as 3 hours or as long as 24 hours. However, the tilts of planets are still unknown. Jupiter rotates at 12.7 km/s. A Jupiter day lasts almost 10 hours.The team also managed to limit the spin rate of a third planet (HR 8799 c), to less than 14 km/s. It was not possible to determine the rotation rate of HR 8799b, the fourth planet.This animation of HR-8799 is a time-lapse animation. It was created in 2017. It includes 7 images taken by W. M. Keck Observatory during a span of 7 years. It depicts the orbital motions of the four planets within the system. Credit: J. Wang Caltech/C. Marois, NRC-HIAThe spin rates of planets can provide important clues about how they formed.Jason Wang, 51 Pegasi B Postdoctoral Scholar Research Associate Astronomy at Caltech, and the lead author of this study, said that KPIC allowed us to make the most precise spectral resolution observations of the HR8799 exoplanets. This allows us to study the planets with a finer granularity that ever before. It unlocks the key to understanding not only how they formed, but also how gas giants develop in the universe.Continue exploring Direct image of recently discovered brown dwarf capturedMore information: Detection and Bulk Properties of the HR 8799 Planets with High Resolution Spectroscopy, arXiv:2107.06949v1 [astro-ph] Journal information: Astronomical Journal Detection and Bulk Properties of the HR 8799 Planets with High Resolution Spectroscopy, arXiv:2107.06949v1 [astro-ph] arxiv.org/abs/2107.06949v1
