Libra the scales

Breaking News - M106 now sports a faint supernova. The Type II supernova designated 2014bc was first picked up in April by the Katzman Automatic Imaging Telescope (KAIT) as part of the Lick Observatory Supernova Search. The exploded star was estimated to only be 15th magnitude at the time it was first imaged but has brightened a bit to magnitude 13.5. M106 is a 9th magnitude galaxy located 23.5 million light-years away in the constellation Canes Venatici. This particular supernova might be a bit of a challenge to see due to its close proximity to the galaxy’s bright nucleus. In general, supernovae are usually found in the galactic arms, a nice contrast with a dark background.

This month we look at Libra the scales. Located in the southern part of the sky and positioned on the ecliptic, Libra owns 538 square degrees of sky making it 29th in size. Mythology has the scales related to Virgo located to the upper right. Even though it possesses a moderate area, it bears two of the longest star names in the entire sky. First, we have the alpha star named Zubenelgenubi which turns out to be the second brightest in Libra. Located some 76 light-years from our Sun, alpha Librae appears as a double star system. The brighter of the two called Alpha-2 shines at magnitude 2.7 and is a spectroscopic binary to which we cannot split visually. Alpha-1 has a magnitude of 5.2 and is also a spectroscopic binary of which the two are only separated by a mere 10 astronomical units (AU) or roughly the distance between the Sun to Saturn. Alpha 1 and 2 are separated by 5,870 AU.

The other tongue twister is Zubeneschamali or the beta star is burning twice as hot as the Sun and about 130 times more luminous. Because of its B8 spectral class, this hot main-sequence star appears blue-white but people have described it as simply green. Located 160 light-years from us, Zubeneschamali is rotating at 250 km/sec or 100 times faster than our Sun. One mystery still looms on one particular star. Methuselah is designated as the oldest star in the entire universe but the numbers simply do not add up. Although the Known universe is estimated (by today’s values) as 13.77 billion years old, Methuselah is estimated at 14.46 billion years old.

Now too far from Zubeneschamali is the face-on galaxy NGC 5885 located some 80 million light-years away. This magnitude 12.1 galaxy has a few pink star-forming regions which are evident in photos. NGC 5885 is about 1/10 of the way to Zubenelgenubi. Keep moving down that imaginary line till you come across the trio of NGC 5861, NGC 5858 and IC 1091. Them glow are magnitudes 11.6, 12.8 and 13.7n respectively. NGC 5061 made the news in April of 1996 as two independent observers reported discovering supernova 1996X. Yet another trio of distant galaxies farther south along the same line. They are numbered NGC 5809, NGC 5809 and PGC 53595. However, these might pose a challenge as their magnitudes are 13.6, 14.2, and 14.1.


We are starting to move into globular cluster territory which is evident in Scorpius and Sagittarius. But for now, we have a small globular cluster under the catalogue number NGC 5897. It measures 11 arc minutes round and is a faint magnitude 8.4. There does not seem to be a central concentration like M13 and the stars seem tiny thanks to its 46,000 light-year distance. NGC 5897 can be found almost halfway up the line from Sigma to Gamma Librae.

More and more stars are now found to harbour planets. In the case of Gliese 581, a red dwarf located 20.4 light-years away that is about one-third as massive as the Sun and is home to a few worlds. Gliese 581 C is believed to be a rocky planet, about 50 percent bigger than Earth and about five times more massive. The "super-Earth" orbits 15 times closer to its star than Earth is to the Sun, but because red dwarfs are about 50 times dimmer than the Sun and much cooler, this means that Gliese 581 C is well within the star's habitable zone! The habitable zone is the space around a star where liquid water and life can exist on a planet's surface.


Well, the anticipated first-time meteor shower on May 23/24 never held up to predictions. Instead of the publicized 200 meteors per hour, the May Camelopardalids only yielded up to 10 per hour. The professions did warn us that this was a new shower with no past history. But we do have an annual show coming up on the 24th. The June Bootids is a variety show with a rate from 0-100 meteor per hour. And when/if we see any, they will be only moving at 18 km/sec opposed to the Perseid meteor shower seen in August that blaze about four times that speed. Here is hoping for some better numbers.

Libra is also home to the planet Saturn. The planet is still easy to spot at magnitude 0.2 and takes on a yellowish tint. As always consult the RASC Observer’s Handbook 2014 for more information and timing of satellites. Jupiter is sinking in the western sky and is out of sight at 10 p.m. locally by the middle of the month. Mars is still a bright object high in the night sky, showing off its lighter tinge of orange.

Have you ever spotted the planet Venus during the day? It could be quite challenging for the first time. The best marker to help in your quest is the moon. Since Venus and the moon are close to the ecliptic, it sounds logical to use the brighter of the two. Your next opportunity comes on June 24 Once you have found the thin crescent, Venus will be three moon widths to the 11 o’clock position.

C/2014 E2 (Jacques) will reach perihelion in early July. In late August this comet will pass within 0.6 AU of the earth. It is predicted to reach a maximum brightness of magnitude 5 in early July. In fact, Comet Jacques will come within 13 million km of Venus around July 12. Let’s hope the predictions hold for this comet.

Summer solstice officially begins on June 21 10:51 UT in the northern hemisphere and winter in the southern hemisphere. The Full Strawberry Moon occurs on the 13th at 4:11 UT and the New Moon (lunation 1132) on the 27th at 8:08 UT.

Until next month, clear skies everyone.

Gary Boyle

eNews date: 
Sunday, June 1, 2014