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May 2017 night sky

—Charlie Christmann

Spring has sprung and more people will be outside looking up at the stars. This month we will take a look at the constellations of the Zodiac visible in the May night sky. Assuming most people will be out in the early evening, the locations in the night sky will be for 9:30 p.m., mid-month.

First, let’s say good bye to Orion, probably the second most recognized star grouping after the Big Dipper, as it will be setting before the sun soon. We won’t see Orion again until next fall.

The Zodiac includes the constellations along the path traced by the sun. This month, starting in the southeast (130 degrees), you will find Libra near the horizon, then Virgo in the east southeast (140 degrees) 45 degrees above the horizon, Leo in the southeast (220 degrees) 60 degrees up, Cancer in the west (270 degrees) 60 degrees up, and Gemini in the west northwest (280 degrees) near the horizon.

Libra:

The brightest star in Libra is called Zubeneschamali, Arabic for “the northern claw.” This is a blue-white dwarf star about 185 light-years away from the sun. There is some indication that this may be a binary star system, but so far, telescopes are not able to confirm it.

Zubenelgenubi, the second brightest star, meaning “the southern claw,” is a multiple star system with five stars. The two brightest components are a binary star system that is moving together.

Libra also contains the star Methuselah that confounds astronomers because it appears to be older than the age of the universe. Astronomers have been watching this star for at least one hundred years as it is merely an interloper in our neighborhood. It is traveling at 800,000 mph as it loops through the galaxy.

Virgo:

Spica (“Virgo’s ear of grain”) resides in Virgo. At 9:30 p.m., look 160 degrees from north and 40 degrees above the horizon to find this first magnitude star. This is one of the nearest massive binary stars to our solar system at a distance of 262 light-years. The primary star is one of the nearest stars sufficiently evolved and massive enough to explode as a Type II supernova.

Virgo also has twenty stars with known planets, more than any other constellation. It also contains The Virgo Cluster consisting of between 1300 and 2000 galaxies centered about 53 million light-years from us. The Local Group of galaxies is a part of the Virgo Cluster and both the Milky Way and Andromeda reside in the Local Group.

Leo:

The Leo constellation is home to the bright stars Regulus and Denebola and the nearby star Wolf 359. Regulus, Little King in Latin, is the twelfth brightest star in the night sky and consists of four actual stars. Regulus A and B can be seen using binoculars. Regulus C requires a larger telescope to be found. Regulus A is a binary system; the smaller companion is a low mass star and has not been seen directly.

Denebola is a relatively young star with an age estimated at less than four hundred million years. It has a strong infrared signature meaning it likely has a dusty disk and is a candidate to have, or be forming, planets.

Wolf 359 is a red dwarf that can only be seen with a good telescope despite it being only 7.8 light-years from Earth. It is the forth-nearest known star to us. Wolf 359 is one of the faintest and lowest-mass stars known and is subject to frequent flares that emit strong bursts of X-ray and gamma ray radiation.

Cancer:

The constellation of Cancer is difficult to find. Its brightest star, Al Tarf, only has a magnitude of 3.5. This dim star, 290 light-years away is actually a binary. Meaning “the eye,” it consists of an orange giant and a small fourteenth magnitude companion.

The Beehive Cluster, an open star cluster about 577 light years from Earth, can be found in Cancer. The Greek astronomer Ptolemy first described the Beehive and called it “the nebulous mass in the breast of Cancer.” This mass of stars has at least a thousand stars. Sixty-three percent of those stars are red dwarfs, and about a third of them are similar to our sun.

Gemini:

The two brightest stars are the hallmark of the Twins: Castor and Pollux. The second brightest neutron star pulsar is also found in Gemini.

Pollux is the brightest star in Gemini and the 17th brightest star in the night sky. It lives 33.78 light-years from Earth and weights about twice what our sun does. In 2006, Pollux b was found in a 590 day orbit. The planet weights more than two Jupiters.

Castor is the second brightest star in Gemini and is a visual binary. Each of those stars are also binary stars, making this a four star system. A fifth binary star is also thought to be a part of Castor, but is well separated from the other four.

Geminga was found by NASA’s Compton Gamma Ray Observatory in 1974. This pulsar is unusual because it is not seen in the radio spectrum. Astronomers believe a star more than three hundred light-years away went supernova about 300,000 years ago. They also think this nearby explosion may have cleared out the dust and gas in the vicinity of the Solar System resulting in a low density bubble.


 
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