Friday, July 19, 2013

Master Guide Secrets - The Stars Part 4



Checking Out Scorpio


It's midsummer and Orion is pretty much invisible because it's on the daylight side of the Earth right now. But halfway around the sky you'll find Orion's nemesis a striking constellation visible in the south along the ecliptic (the sun's path through the sky) where all the other constellations of the zodiac are found.

Use this chart to find objects discussed below.

Scorpio.


Scorpio is one of the few constellations like the Big Dipper, the Little Dipper and the Southern Cross that actually looks a lot like its namesake. The long sweeping curved tail of the scorpion is clearly visible against the night sky throughout the summer. It looks like this:
Scorpio is Latin for scorpion, but not everyone sees a scorpion, probably because not every country has the nasty little critters. The Javanese people of Indonesia see a "brooded swan" (Banyakangrem) probably because Scorpio is higher in the sky and less "upside down.  In the islands of the South Pacific, which are also scorpion fee, it is also called Kalapa Doyong, meaning the "leaning coconut tree." In China the curved "tail" is part of a larger constellation called the "Azure Dragon".  In Hawaii, the distinctive hook-shaped arrangement of stars is known as Maui's fishhook after one of their demigods who was apparently partial to fresh-caught tuna.

Here's how Scorpio looks in mid-summer (without the red lines, of course)

It's easiest to see Scorpio in the summer.  In July you'll find it low in the southern sky at around 9 or 10 pm.  The constellation used to be bigger, but the Romans needed a sign of the zodiac for September, so they borrowed the "claws" of the Scorpion and designated the new constellation Libra. Most people still see the whole scorpion complete with claws, not realizing the Romans declawed it a couple of millennia ago.

The brightest stars in Scorpius include:

Antares & its companion
  • Antares (α Sco) - Antares is a red supergiant, the 15th or 16th brightest star in the sky depending on who you talk to.  It's magnitude is somewhere between 0.96 and 1.8. Antares is part of a binary system.  It has a faint supergiant companion star.  Antares is 883 times larger than our own sun. If you put Antares where the sun is, the surface would like somewhere in our asteroid belt.  Antares is 550 light years or 170 parsecs from the Earth.  It is 10,000 times brighter than the sun as well, so wear your shades if you plan to visit.
  • β1 Sco (Graffias) - Beta Scorpii (β Sco, β Scorpii) is a multiple star system.  The Arabs called the star several names including Acrab, Akrab or Elacrab from the Arabic (العقرب‎) al-'Aqrab. In China it was known as 房宿四 (the Fourth Star of the Room).  Even with a small telescope you can see it as a binary star. This pair of stars (β1 and β2) are the most visible orbiting components in this system. β1 Scorpii, the brighter one is made up of β Sco A and β Sco B.  β Sco A is also a binary that can only be detected with a spectroscope.  β2 Scorpii meanwhile has two stars within it (β Sco C and β Sco E). β Sco E is also a binary that can only be detected with a spectroscope. There are six stars in the system. There used to be a D component, but the astronomers were wrong and they took it out, which is why there is no β Sco D and the names jump for β Sco C to β Sco E.  
  • δ Sco (Dschubba) - It's name is from the Arabic jabhat, "forehead" (of the scorpion). It's also called Iclarcrau or Iclarkrav.  Whatever you call it, the star is at the forehead of the "scorpion" outline.  Dschubba or Delta Scorpii is unusual because it's near the ecliptic, so it is occasionally occulted (covered up) by the Moon and on rare occasions, by the planets. The sun covers it up as well, but you can't see that from here on Earth.  Delta Scorpii (δ Sco) is part of one of the closes "associations" of massive stars to the sun called the Upper Scorpius Subgroup (astronomers come up with such romantic names for things).  The USS contains thousands of young stars, kind of like Woodstock in the sky. It's magnitude changes because δ Sco has irregular outbursts that throw off luminous gases from its equatorial region. Like other stars in the region, it also has a companion that causes the star to flare up. Dschubba (δ Sco) has a second class B companion star that comes as close to it as Mercury does to our Sun. This companion star orbits δ Sco every 20 days in a wildly eccentric orbit that takes it close in about once in ten years. It also has a possible third and fourth companion star ranging out to about twice the distance from the main star
  • θ Sco (Sargas) - Theta Scorpii (θ Sco, θ Scorpii) was named Sargas by the ancient Sumerians and more prosaically by the Chinese as 尾宿五 (Mandarin: wěi xiù wǔ) or the Fifth Star of the Tail.  Sargas is one of the brightest stars in the night sky, located about 300 light years (90 parsecs) from our sun.  Sargas is a bright yellow giant star, about 5.7 times larger than the Sun and 1834 times as bright. An F-type star, Sargas is yellow-white and rotates so rapidly it is thicker at the equator than at the poles. Sargas has the distinction of being one of the stars on the flag of Brazil.
  • λ Sco (Shaula) - Lambda Scorpii (λ Sco, λ Scorpii) comes it at number 2 (after Antares) as the second brightest star in Scorpius.  It's name, Shaula, comes from the Arabic الشولاء al-šawlā´ meaning the raised tail.  Again the pragmatic Chinese just call it 尾宿八 meaning "the Eighth Star of the Tail".  Located 702.1 light years from Earth, Shaula is actually a triple system.  It has two B-type stars and a pre–main sequence star.  The primary star is a beta Cephei variable star meaning its brightness changes.  All three stars lie in the same orbital plane so they were probably all created at the same time. Shaula is also on the flag of Brazil.
  • ν Sco (Jabbah) – If you live on a planet in the Jabbah system, you probably wouldn't get much sleep.  Nu Scorpii (ν Sco, 14 Scorpii) is at least a quintuple, if not a sextuple star system. Nu Scorpii A and B are the brightest pair, being both spectral type B2 subgiants. Nu Scorpii C and D are fainter spectral type B8 and B9 main sequence dwarf stars. Nu Scorpii A is a spectroscopic binary with faint B-type companion star. Like  Since it is near the ecliptic, Nu Scorpii, like Dschubba, can be occulted by the Moon and rarely by the odd planet. Mercury occulted it in 1821 and will again on December 2, 2031. Venus clipped Jabba in December 1852 and will do so again on December 30, 2095. Neptune occulted it in 1808.  Nu Scorpii also bounces light of a nearby nebula - IC 4592 giving it a nice blue color.  Jabbah or ν Sco is called 鍵閉 by the Chinese or Jiànbì, meaning Door Bolt – something to do with Chinese asterism.  
  • π Sco (Iclil) - Pi Scorpii is a triple star located some 590 light-years (180 parsecs) from the Earth. German astronomer Johann Bayer gave it the name Pi Scorpii in 1603. No one is sure, but he may have been hungry at the time.  It was first discovered to be a spectroscopic binary with two hot blue-white B-type main sequence stars rotating around each other. These two ahve a third smaller star orbiting around them at a distance.  Pi Scorpii is also part of the USS (Upper Scorpius subgroup) of the Scorpius-Centaurus Association. Whether it is a voting member or not is unknown.
  • σ Sco (Alniyat) Sigma Scorpii (σ Sco, σ Scorpii) - Al Niyat, one of the brighter members of Scorpio, is roughly 696 light years (214 parsecs) from earth.  The brightest component of the system is a spectroscopic binary, σ Scorpii A, an evolved giant star.  The binary has never been successfully resolved with a telescope, but has been identified with a spectroscope through changes in their combined spectrum. A is 18 times larger than the sun and radiates 20,000 times the luminosity. It's a variable star whose temperature and brightness varies significantly. The other member of the Al Niyat pair, σ Scorpii B, is a main sequence star that orbits at about four times the distance from the sun to Neptune.  A third member of the system, σ Scorpii C orbits even farther out taking a hundred years to complete an orbit. The final member, σ Scorpii D is a B9 dwarf star orbiting even farther out. The Al Niyat is also liley a part of the Upper Scorpius Subgroup. 
  • U Scorpii (U Sco) -  U Sco is one of only 10 known stars that are recurring novae.  U Sco is located near the northern edge of Scorpio and normally has a relatively faint magnitude of 18.  In successive outbursts in 1863, 1906, 1936, 1979, 1987, 1999, and 2010, U Sco reached a magnitude of 8.  Scientist haven't been successful at predicting U Sco outbursts yet, but expect the next one to happen between 2018 and 2022.

Scorpio also has four deep space objects that were included in Charles Messier's early catalog of nebula and galaxies.  They were:

M4 (NGC 6121)
  • M4 (NGC6121) – NGC 6121 is the nearest known globular cluster to the Sun.  Discovered by Philippe Loys de Chéseaux in 1746, M4 lies in Scorpio about 1.3° west of Antares.  If the sky is dark it can just barely be seen the naked eye if you have good eyesight.  Partially obscured by dust in the galactic plane it looks slightly red as a result.  It looks like a ball of stars with a unique central bar. The Hubble recently detected a planetary system within the cluster.



  • M6 (NGC6405) – Called the Butterfly Cluster this open cluster of stars vaguely resembles a
    The Butterfly Cluster
    butterfly in shape. First officially observed by Giovanni Battista Hodierna in 1654, the Butterfly cluster may have been seen by 1st century astronomer Ptolemy with his unusually acute eyesight while he was busy discovering its neighbour, the Ptolemy Cluster. The cluster was cataloged #6 by Charles Messier and contains hot, blue B type stars and a notable K type orange giant star that's a semi-regular variable.  Astronomers estimate its distance as somewhere around 1,600 light years from Earth.  With a magnitude 4.2, the star should be easy to spot just  above and slightly to the left of the "stinger" of Scorpio's tail.
The Ptolemy Cluster
  • M7 (NGC 6475) -  The Ptolemy Cluster, as it has been known since it was first observed by Roman astronomer Ptolemy in 130 AD, is an open cluster of stars, located just below M6 and to the left of the Stinger in Scorpio's tail.  Astronomers with telescopes have counted some 80 stars in the cluster.  M7 is 980 light years from Earth.






 
M80
  • M80 (NGC6093) --  M80 is a globular cluster located midway between Antares and Graffias. Even with an a amateur telescope, you can see M80 as a mottled ball of light.  It contains several hundred thousand stars and is one of the denser globular clusters in the Milky Way Galaxy.  In 1860, a nova within the cluster briefly outshined the entire cluster. 
You'll notice that Scorpio is located near the center of that bright hazy band of stars that cuts across the night sky in summer. Those stars are closer in toward the center of our galaxy which is why the look all packed together. When you look toward Scorpio you are looking toward the hub of the galaxy. Earth sits about 2/3 of the way out from the center of the galaxy (28,000 light years to be sort of precise) and 20 light years above the galaxy's equatorial plane within the "Orion" spiral arm. It is called that because the stars that make up the Orion constellation are all within that arm of the Milky Way Galaxy.

Scorpio is one of the easiest of constellations to spot.  Along with The Big Dipper, Orion, Cassiopeia, The Little Dipper, Canis Major and Minor and Taurus the Bull, they are among the easiest constellations to identify.  Ahead in our series we'll share some tips on viewing the moon and we'll talk a little about some other standout astronomical objects you can find with a telescope or binoculars.  Also coming up we'll give you instructions on how to build a ginormous telescope of your own. 

Meanwhile, keep looking up!  Jesus is coming.



Tom King, Master Guide

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