Astronomers from the Subaru Telescope and W.M. Keck Observatory on Mauna Kea have made significant discoveries with the identification of a massive planet and a brown dwarf orbiting distant stars. These findings enhance our understanding of the formation and evolution of giant planets and substellar objects, marking the first results from the new Observing Accelerators with SCExAO Imaging Survey program (OASIS).
The OASIS initiative combines precision stellar motion data from space-based missions with advanced imaging capabilities provided by Mauna Kea’s observatories. According to Thayne Currie, a professor at the University of Texas at San Antonio and principal investigator of OASIS, “These discoveries may help advance our abilities to image another Earth with future space-based observatories such as NASA’s Roman Space Telescope.”
Details of the Discoveries
The first newly identified companion, designated HIP 71618 B, is a brown dwarf with a mass approximately 60 times that of Jupiter, situated about 169 light-years away in the constellation Bootes. Brown dwarfs are often referred to as “failed stars” because they form like stars but lack sufficient mass to initiate nuclear fusion. As a result, they are cooler and much fainter at visible wavelengths compared to longer infrared wavelengths, which can be captured by the observatories.
Data collected from both Keck/NIRC2 and Subaru/SCExAO within a few days revealed this companion. Further follow-up observations from both observatories over the subsequent year confirmed its orbital details.
The second companion discovered, HIP 54515 B, is an 18-Jupiter-mass planet located 271 light-years from Earth in the constellation Leo. This planet orbits its star at a distance similar to that of Neptune from the Sun, yet it appears exceptionally close to its host star when viewed from Earth—comparable to the apparent size of a football seen from over 200 miles away. The Subaru Telescope’s SCExAO system provided the ultra-sharp images necessary to detect this faint giant planet in proximity to its bright star.
Upcoming Celestial Events
In addition to these discoveries, the Quadrantids meteor shower will peak on the night of January 3 into January 4. This meteor shower, which originates from the asteroid 2003 EH1, can produce up to 40 meteors per hour at its peak. Observers in Hawaii can expect favorable viewing conditions this year, especially after midnight when the radiant rises higher in the sky.
Throughout January, the star family Kekaomakali‘i, or the “Bailer of Makali‘i,” will be prominent in the night sky. This constellation, essential for traditional Hawaiian navigation, includes notable stars such as Hokulei (Capella), Na Mahoe (Gemini), and Kapuahi (Aldebaran). These celestial bodies serve as guides for Pacific voyagers.
In the southern sky, the four chiefs—Manokalanipo (Alpheratz), Kakuhihewa (Scheat), Keawe (Markab), and Pi‘ilani (Algenib)—can be observed, along with the bright Makali‘i (Pleiades) star cluster, which continues to shine brightly. This cluster signifies the ongoing makahiki season, a period of rest, reflection, and renewal in Hawaiian culture.
For stargazers, Jupiter (Ka‘awela) will be visible shortly after sunset, while Hokuloa (Venus) can be seen radiantly in the southwestern sky. These planets present excellent opportunities for observation, particularly with the aid of binoculars or telescopes.
Early risers can also catch a glimpse of Jupiter in the pre-dawn western sky throughout January, serving as a brilliant beacon before sunrise. Observers should look towards Hokupa‘a in the northern sky to spot the Big Dipper, leading them to Hokule‘a (Arcturus), which plays a crucial role in navigation.
To learn more about the OASIS program and its findings, visit the websites of the W.M. Keck Observatory and the Subaru Telescope.
The ‘Imiloa Astronomy Center of Hawaii provides informal science education focused on astronomy and Hawaiian culture, highlighting the shared journey of human exploration.
