Featured Mauna Kea Observatory discovery
Astronomers using telescopes on Mauna Kea have found a planet that defied the odds and escaped being engulfed by its star.
Located 160 light-years away, the Jupiter-like planet dubbed Halla orbits a red giant star, Baekdu, that previously inflated as it ran low on hydrogen in its core before shrinking back to its current size. This initial expansion should have consumed Halla, which orbits its star much closer than Earth orbits the sun, yet Halla surprisingly persists in its orbit.
Astronomers using the Canada-France-Hawaii Telescope and the W.M. Keck Observatory, both on Mauna Kea, observed the oscillations of Baekdu to track Halla and created a timeline of the star’s evolution.
“Planetary engulfment has catastrophic consequences for either the planet or the star itself — or both. The fact that Halla has managed to persist in the immediate vicinity of a giant star that would have otherwise engulfed it highlights the planet as an extraordinary survivor,” said Marc Hon, lead author of the study.
Astronomers will continue to study this intriguing system to better understand the many different ways that stars and planetary systems evolve over time, and how that evolution may be different than what we might expect. Learn more about this research through CFHT’s news release: cfht.hawaii.edu/en/news/Halla.
Special events
August will be excellent for moon-gazing as there will be two supermoons, with the first occurring Tuesday and the second on Aug. 30.
Supermoons occur when a full moon coincides with the moon being at its closest position to Earth, making it appear slightly brighter in the night sky. Additionally, when two full moons occur in the same month, the second one is often called a blue moon.
The rarity of this event led to the idiom “once in a blue moon.”
On the evening of Aug. 26, Saturn will be at a unique position in its orbit known as opposition. Opposition occurs when an outer planet (Mars, Jupiter, Saturn, Uranus or Neptune) is on the opposite side of Earth from the sun. At opposition the planet is at its closest position to Earth and will look somewhat brighter in the sky, rising at the same time as the sun sets and remaining in the sky the entire night.
Aug. 26 will be the best night to view Saturn in the sky, although it will be clearly visible in the early evening sky throughout August.
Through a very good pair of binoculars or a telescope, observers will be able to see Saturn’s famous system of rings as well as the planet’s largest moon, Titan.
Every summer, our sky is decorated with the beautiful Perseids meteor shower. This shower will be active from late July through August, with peak activity occurring the evening of Aug. 12.
The shooting stars in this meteor shower are the remnants of material left from the comet Swift-Tuttle. When the comet last passed through the inner solar system in 1992, it left behind a cloud of dust and ice in Earth’s orbit. Every year when Earth passes through this debris cloud, the dust and ice fall through our atmosphere and burn up, creating the shooting stars of the Perseids meteor shower.
At its peak we can expect 60-150 shooting stars per hour for this shower. The shooting stars will mostly travel across the sky from east to west, roughly originating from the constellation of Perseus rising in the east.
Evening observations
As we near the end of summer, the spectacular band of the Milky Way will stretch across the sky. Summer months in Hawaii are the best times to see the center region of the Milky Way sitting behind the constellations of Kamakaunuiamaui (Maui’s Fishhook) and Pimoe, an ulua swimming away from the fishhook.
On clear nights in areas with low-light pollution, the band of the Milky Way will be bright enough to illuminate the landscape. The glow of the Milky Way band appears fuzzy and cloudlike because we are looking at the combined light of countless stars that are all so far away that we cannot see their individual points with our naked eyes.
As we look at the band of the Milky Way, we are looking along the edge of our galaxy at all of the material that comprises our space in the universe.
Within this great band stretching across the sky, particularly in the area tucked between Pimoe and Kamakaunuiamaui, astronomers are able to look through the Milky Way and observe the central regions of our galaxy itself. It is in this very section of the sky that the observatories on Mauna Kea discovered and continue to observe the black hole at the center of our galaxy.
The gravity of this supermassive singularity plays an important role in our galaxy, and it’s possible that without this black hole, the Milky Way might not have formed at all. Astronomers across Hawaii continue to study this black hole to better understand its role in our cosmic history.
Stretching along the Milky Way band will be the navigational star family of Manaiakalani. Manaiakalani is made up of three main components: Kamakaunuiamaui, Pimoe and the Navigator’s Triangle.
Morning observations
Throughout August the sun will rise just after 6 a.m.; dawn will begin to color the sky at about 5:15 p.m.
Early-morning observers will have a very different view of the sky. The shape of Kaheiheionakeiki, Orion, will rise in the eastern sky along with the other stars that form the navigational star family of Kekaomakali‘i. Against the backdrop of these stars, observers will be able to find Jupiter, high in the southern sky.
August 2023 Skywatch by Honolulu Star-Advertiser
The ‘Imiloa Astronomy Center of Hawaii is a center for informal science education at the University of Hawaii at Hilo showcasing astronomy and Hawaiian culture as parallel journeys of human exploration.
