Total Pageviews

Wednesday, March 9, 2011

CONSTELLATION

Andromeda, the Chained Princess

Lepus, the Hare

Aquarius, the Water Bearer

Libra, the Scales

Aquila, the Eagle

Lyra, the Lyre

Ara, the Altar

Boötes, the Bear Driver

Aries, the Ram

Microscopium, the Microscope

Auriga, the Charioteer

Monoceros, the Unicorn

Camelopardalis, the Giraffe

Orion, the Hunter

Canes Venatici, the Hunting Dogs

Pegasus, the Winged Horse

Canis Major, the Great Dog

Perseus, the Hero

Carina, The Keel

Pisces, the Fishes

Cancer, the Crab

Canis Minor, the Lesser Dog

Caelum, the Sculptor’s Cheasel

Pisces, the Fish

Capricornus, the Sea Goat

Piscis Austrinus, the Southern Fish

Cassiopeia, the Queen

Puppis, the Stern

Cepheus, the King

Pyxis, the Compass

Cetus, the Whale or Sea Monster

Sagitta, the Arrow

Columba, the Dove

Sagittarius, the Archer

Corona Borealis, the Crown

Scorpius, the Scorpion

Cygnus, the Swan

Sculptor, the Sculptor

Delphinus, the Dolphin

Scutum, the Shield

Draco, the Dragon

Serpens Caput, the Serpent's Head

Equuleus, the Little Horse

Taurus, the Bull

Gemini, the Twins

Triangulum, the Triangle

Hercules

Ursa Major, the Great Bear

Lacerta, the Lizard

Ursa Minor, the Little Bear

Leo Minor, the Little Lion

Vulpecula, the Fox


Thursday, February 17, 2011

JUPITER'S MOON EUROPA HELPS SOLVE STRIPEY MYSTERY

Jupiter-keck-seb
Last year, something strange happened to Jupiter.
Not only was the gas giant recovering from an asteroid smash, it also underwent a... changeJupiter lost one of its trademark stripes -- a.k.a. the South Equatorial Belt (SEB) -- for no apparent reason.
Although astronomers at the time theorized that there were perhaps some high-altitude clouds blocking our view of the SEB, it wasn't until the keen infrared eyes of Keck Observatory on Mauna Kea, Hawaii, zoomed in on the planet that the SEB came into focus again.
What's more, Jupiter's moon Europa helped astronomers unravel the mystery as to where the belt has been hiding.
Using the Keck II telescope’s Adaptive Optics system, astronomers would normally point a powerful laser above the observatory to create a "guide star." This artificial point of light can then be used to detect turbulence in the Earth's atmosphere; the shimmering laser signal feeds back into the adaptive optics, allowing the telescope to slightly deform its mirror (in real-time) to compensate for the distortion.
The result is a sharper image of an astronomical target, as atmospheric distortions can be removed from observations. It's these same distortions that can cause stars to "twinkle" at night.
So, with a little help from a little moon, an amazing infrared picture of Jupiter's inner turmoil came into focus.But there was a problem when observing Jupiter. As the planet is so bright, the laser guide star was overwhelmed and couldn't be used for Jovian observations. But all was not lost, Europa was there to lend a hand and on Nov. 30, 2010, it was very bright, right next to Jupiter in the sky. Europa became the "guide star" for the adaptive optics to sense atmospheric distortions.
Thermal infrared radiation (with a wavelength of 5 microns) was detected by Keck leaking from Jupiter's interior. When combining the thermal radiation data with near-infrared solar radiation being reflected by the upper clouds in the Jovian atmosphere, the churning detail in the cloaked SEB was revealed (pictured top).
As the SEB slowly begins to reveal itself once more, icy clouds in the upper atmosphere gradually dissipating, only the Keck infrared telescope could cut through the Jovian atmosphere to reveal the hidden trademark stripe we've been missing out on for these last few months.

VY Canis Majoris

About Stars: Wolf-Rayet Stars

A Wolf-Rayet StarSpectral class: WN, WC

These are very hot and blue stars with surface temperatures of 25 000 - 50 000 kelvin and a mass in the beginning of 25 times solar. Only a few hundred are known in our galaxy. WR stars cast away quickly large parts of their hull into space. Therefore in very big telecsopes they look similar to planetary nebulae.
Before the Wolf-Rayet phase they have been red supergiants or LBV which now expose their core. Supposably every star with enough mass goes through the Wolf-Rayet stadium. These stars are short before an explosion as supernova (astronomically that is. Those stars can as well still live for another several thousand years).

The very strong stellar wind is caused by a heightened accumulation of heavy elements on the surface. These block the light on its way out and therefore heat up the star, which powers the wind. The stellar wind can blow away up to one solar mass every 10 000 years.

Example: WR 124

Red Supergiant Stars

They are the largest stars in the universe in terms of volume, although they are not the most massive. 


Red Supergiant StarsRed supergiants (RSGs) are supergiant stars (luminosity class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive. Betelgeuse and Antares are the best known examples of a red supergiant.

Stars with more than about 10 solar masses after burning their hydrogen become red supergiants during their helium-burning phase. These stars have very cool surface temperatures (3500–4500 K), and enormous radii. The five largest known red supergiants in the Galaxy are VY Canis Majoris, Mu Cephei, KW Sagitarii, V354 Cephei, and KY Cygni, which all have radii about 1500 times that of the sun (about 7 astronomical units, or 7 times as far as the Earth is from the sun). The radius of most red giants is between 200 and 800 times that of the sun, which is still enough to reach from the sun to Earth and beyond.

These massively large stars are little more than "hot vacuums", having no distinct photosphere and simply "tailing off" into interstellar space. They have a slow, dense, stellar wind and if their core's nuclear reactions slow for any reason (such as transitioning between shell fuels) they may shrink into a blue supergiant. A blue supergiant has a fast but sparse stellar wind and causes the material already expelled from the red supergiant phase to compress into an expanding shell.

The mass of many red supergiants allow them to eventually fuse elements up to iron. Near the end of their lifetimes, they will develop layers of heavier and heavier elements with the heaviest at the core.

The red supergiant phase is relatively short, lasting only a few hundred thousand to a million or so years. The most massive of the red supergiants are thought to evolve to Wolf-Rayet stars, while lower mass red supergiants will likely end their lives as a type II supernova.

The red sun around which the fictitious planet Krypton orbits in both Superman and Superman Returns is also a red supergiant (as opposed to that of a red dwarf star in the comics) that undergoes a supernova explosion, causing Krypton's destruction by means of the shockwaves emitted by the dying star (in the comic series, Krypton was destroyed by the planet's unstable cores).