Featured Mauna Kea discovery
A team of researchers utilizing the Canada-France- Hawaii Telescope on Mauna Kea, led by Tomer Shenar at the University of Amsterdam, found a highly unusual star that has the most powerful magnetic field ever found in a massive star.
The star, HD 45166, might one day become one of the most magnetic objects in the universe: a type of neutron star known as a magnetar.
This finding marks the discovery of a new type of astronomical object — a massive magnetic helium star — and sheds light on the origin of mysterious magnetars.
Having studied similar helium-rich stars before, Shenar was intrigued by the unique characteristics of HD 45166, which is 3,000 light-years away. He suspected that magnetic fields could explain what he was seeing.
“This star became a bit of an obsession of mine,” Shenar said. “I remember having a eureka moment while reading the literature: ‘What if the star is magnetic?’”
Shenar and his collaborators set out to test this hypothesis by taking new observations of the star system with the instrument ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) installed at CFHT. These observations revealed that HD 45166 has a phenomenally powerful magnetic field, about 43,000 gauss. For comparison, the magnetic field of the sun is 1-2 gauss, and its sunspots reach up to 3,000 gauss.
In a few million years, HD 45166 will explode as a very bright but not particularly energetic supernova. During this explosion its core will contract, trapping and concentrating the star’s already daunting magnetic field lines.
The result will be a neutron star with a magnetic field of around 100 trillion gauss — the most powerful type of magnet in the universe.
Prior to the team’s discovery, astronomers thought the most likely magnetar formation scenarios involved stars much more massive than HD 45166.
“Magnetars are rare and mysterious objects, so the team’s discovery of the first massive magnetic helium star that will later become a magnetar enhances our understanding of their formation,” said Nadine Manset, CFHT’s director of science operations and ESPaDOnS instrument scientist. “ESPaDOnS is an ideal instrument for measuring the magnetic fields of stars and it is always rewarding to see it unveil new magnetic secrets of stars.”
Special events
From mid- to late October, the night skies will be decorated with the Orionid meteor shower. This meteor shower will produce about 20 shooting stars an hour, one every three minutes, when it peaks on Oct. 21.
The shooting stars from the Orionid shower were left from the tail of Halley’s comet, which came through the inner solar system in 1986.
Evening observations
In the early evening, stargazers will be able to find two of the navigational star families established by the Polynesian Voyaging Society. These “super constellations” are important tools that are utilized by the Hokule‘a and Hikianalia.
Setting in the west will be the “summer” star family of Manaiakalani. This starline is made up of three main pieces: the Navigator’s Triangle, Pimoe (a mischievous ulua fish) and Kamakaunuiamaui, the fishhook of Maui. Rising in the east will be Kalupeakawelo, also known as “the Kite of Kawelo.”
Kalupeakawelo is set up to take on a sort of 3D effect in the sky. To properly picture the kite in the sky, imagine that you are lying down and holding the strings that attach to ‘Iwakeli‘i and Kamo‘i (Cassiopeia and Cepheus) with one hand, and holding the strings that attach to Nalani and Kaikilani (Canopus and Ankaa) with the other hand.
The square body of the kite, marked by Manokalanipo, Kakuhihewa, Pi‘ilani and Keawe (Alpheratz, Scheat, Algenib and Markab), is flying high up above your head.
The gas giant planets Jupiter and Saturn will stand out among the southern kite strings of Kalupeakawelo.
Saturn will be the fainter of the two planets but will still be visible against the backdrop of the stars as the planets will not usually twinkle in the sky. Through a telescope, observers will be able to see the beautiful rings of Saturn that make the planet famous.
Jupiter lies to the east of Saturn. As the fourth- brightest object humans can see in the sky, Jupiter will stand out along the western horizon.
By using a pair of binoculars or a telescope, sky observers will be able to spot four bright dots that accompany the gas giant planet. These are Jupiter’s four largest moons: Io, Europa, Ganymede and Callisto.
The moons are often referred to as the “Galilean moons,” as they were first recorded by Galileo Galilei in 1610.
Morning observations
Throughout October the sun will rise just before 6:30 a.m., meaning that the sky will still be dark enough for stargazing until just after 5:30 a.m.
Early morning stargazers will see a very different perspective of the sky. Rising in the eastern sky will be the incredibly bright planet Venus, which will stand out as the brightest object in the sky at this time.
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.
