Subscribe free to our newsletters via your
. 24/7 Space News .




STELLAR CHEMISTRY
A Sheep in Wolf-Rayet's Clothing
by Staff Writers
Washington DC (SPX) Feb 20, 2012


For a larger version of this image please go here.

It's well known that the universe is changeable: even the stars that appear static and predictable every night are subject to change. This image from the NASA Hubble Space Telescope shows planetary nebula Hen 3-1333. Planetary nebulae have nothing to do with planets - they actually represent the death throes of mid-sized stars like the sun.

As they puff out their outer layers, large, irregular globes of glowing gas expand around them, which appeared planet-like through the small telescopes that were used by their first discoverers.

The star at the heart of Hen 3-1333 is thought to have a mass of around 60% that of the sun, but unlike the sun, its apparent brightness varies substantially over time.

Astronomers believe this variability is caused by a disc of dust which lies almost edge-on when viewed from Earth, which periodically obscures the star.

It is a Wolf-Rayet-type star - a late stage in the evolution of sun-sized stars. These are named after (and share many observational characteristics with) Wolf-Rayet stars, which are much larger.

Why the similarity? Both Wolf-Rayet and Wolf-Rayet type stars are hot and bright because their helium cores are exposed: the former because of the strong stellar winds characteristic of these stars; the latter because the outer layers of the stars have been puffed away as the star runs low on fuel.

The exposed helium core, rich with heavier elements, means that the surfaces of these stars are far hotter than the sun, typically 25,000 to 50,000 degrees Celsius (45,030 to 90,030 Fahrenheit). The sun has a comparatively chilly surface temperature of just 5,500 degrees Celsius (9,932 Fahrenheit).

So while they are dramatically smaller in size, the Wolf-Rayet type stars such as the one at the core of Hen 3-1333 effectively mimic the appearance of their much bigger and more energetic namesakes: they are sheep in Wolf-Rayet clothing.

This visible-light image was taken by the high resolution channel of Hubble's Advanced Camera for Surveys. The field of view is approximately 26 by 26 arcseconds.

.


Related Links
-
Stellar Chemistry, The Universe And All Within It






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





STELLAR CHEMISTRY
Astronomers Watch Instant Replay of Powerful Stellar Eruption
Santa Barbara, CA (SPX) Feb 20, 2012
Astronomers are watching the astronomical equivalent of an instant replay of a spectacular outburst from the unstable, behemoth double-star system Eta Carinae, which was initially seen on Earth nearly 170 years ago. Astrophysicists affiliated with UC Santa Barbara and Las Cumbres Observatory Global Telescope Network (LCOGT) contributed to the study. Dubbed the "Great Eruption," the outburs ... read more


STELLAR CHEMISTRY
Back to the Moon A Modern Redux

X-rays illuminate the interior of the Moon

NASA Spacecraft Reveals Recent Geological Activity on the Moon

China publishes high-resolution full moon map

STELLAR CHEMISTRY
Rock Studies Continue for Opportunity

ISS may become Martian flight simulator

Honeycombs and Hexacopters Help Tell Story of Mars

Martian Carbon Dioxide Clouds Tied To Atmospheric Gravity Waves

STELLAR CHEMISTRY
Stark warning emerges from science summit

Glenn: I don't think of myself as a hero

ASU professor uses Star Trek themes to communicate science

50th anniversary of first US space flight is bittersweet

STELLAR CHEMISTRY
Launch of China's manned spacecraft Shenzhou-9 scheduled

Shenzhou 9 To Carry 3 Astronauts To Tiangong-1 Space Station

China to launch spacecraft in June: report

Is Shenzhou Unsafe?

STELLAR CHEMISTRY
Fifth ATV named after Georges Lemaitre

Space station panel installation delayed

Russian cosmonauts begin ISS spacewalk

Advanced Communications Testbed for Space Station

STELLAR CHEMISTRY
NuSTAR Mated to its Rocket

Rocket to be launched from Poker Flat Research Range

UA Huntsville scientific team helping Japanese space program launch safely

Iran mulls base to launch bigger satellites

STELLAR CHEMISTRY
Scattered Light Could Reveal Alien Atmospheres

Searching for Planets in Clouds of Dust

Elements of ExoPlanets

New super-Earth detected within the habitable zone of a nearby star

STELLAR CHEMISTRY
Virtual ghost imaging: New technique enables imaging even through highly adverse conditions

China firm preparing for Apple iPad talks: lawyer

BlackBerry PlayBook gets new engine in tablet race

Chinese firm in iPad row threatens to sue Apple in US




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement