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First Image Of Planet-Like Body Orbiting A Star
deglr6328 writes "The Gemini North Telescope has, for the first time, directly imaged a planet like body orbiting a star. The object is a brown dwarf, 55 to 78 times the mass of planet Jupiter and 14 AU distant from its parent star 15 Sge. It was imaged using adaptive optics(see also here) that correct for the blurring effect of the atmosphere using deformable mirrors. Cool!"
Is that a Starbuck's I can see on the high-res JPEG?
What ever happene dto Gliese 229?
That was imaged back quite a while ago by a caltech team.
I found papers about it at Jean Schnieder's webpage, but not a listing...
Do you know why the road less traveled by is littered with the bones of the unwary?
Someone needs to mod the above up; it's important. I would have rephrased the post to reflect that this was NOT the first image of a brown dwarf orbiting a star if I knew about it before I submitted the comment.
On closer examination, the Gemini North press release does not claim to be the first to image a brown dwarf; from the site:"The faint companion is separated from its parent star by less than the distance between the Sun and the planet Uranus and is the smallest separation brown dwarf companion seen with direct imaging". It is only the CNN story that incorrectly claims this.....Hmmmm perhaps a notification is in order.
- "Hear that?! The percolations are imminent! Cease your ingress!"
The Law of Hydrostatic Equilibrium: Within every layer [of a star], the outward force of pressure equals the inward force of gravity.
Stars must have M 0.08 Msun to fuse hydrogen.
There exists a high-mass cutoff because very high mass stars cannot attain hydrostatic equilibrium. Very high mass stars produce enormous numbers of high-energy photons (L and T are both large). Photons exert pressure on gas (an effect called radiation pressure.) Ordinarily, the effects of radiation pressure are small, but for stars with M > 60 Msun, models indicate the radiation pressure is large enough to blow the star apart.
When a star exhausts the supply of H (hydrogen) in its core, it becomes a giant or supergiant, depending on its mass.
Once a star has used up all the H in its core, fusion of H into He (helium) stops. The core starts to contract just as it contracted as a protostar before H fusion began. As the core contracts, it releases energy. This energy heats up the layer immediately above the contracting He core. The layer immediately above the core becomes hot enough to initiate the fusion of hydrogen into helium.
The star now has three main layers:
(1) Helium core (inner layer): Releases energy as it shrinks in radius.
(2) Fusion shell: Releases energy as it fuses hydrogen into helium.
(3) Hydrogen envelope (outer layer): Absorbs energy, and swells greatly in size.
These swollen stars are now giants (if M 8 Msun).
Supergiants and giants with M > 0.4 Msun become hot enough to fuse He into C by the "triple alpha process", making primarily C (carbon), sometimes overshooting and making O (oxygen), and making Be (beryllium) as an intermediary product (and lots of gamma rays, too).
Once a giant or supergiant begins to fuse He in its core, it has four main layers.
Supergiants and giants with M > 3 Msun become hot enough to fuse C into heavier elements.
There is a limit to fusion: Iron (Fe).
The stages in the life of a 25 Msun star:
Hydrogen fusion lasts 7 million years
Helium fusion lasts 500,000 years
Carbon fusion lasts 600 years
Oxygen fusion lasts 6 months
Silicon fusion lasts 1 day
The star's core is now solid iron: end of the line as far as fusion is concerned.
Two choices:
(1) The star finds an alternative pressure source to maintain hydrostatic equilibrium which doesn't rely on the random thermal motions of atoms and ions; or
(2) The star collapses giving you:
a) black hole
or
b) nova/supernova
All clear now?
woof.
citations/references:8 starrfield.html
4 /n otes16.html
e r2 1.html
http://www.sciam.com/specialissues/0398cosmos/039
www-astronomy.mps.ohio-state.edu/~ryden/ast162_
cse.psc.sc.edu/hses/StarEvol/pages/reds.htm
blueox.uoregon.edu/~jimbrau/astr122/Notes/Chapt
www.imsa.edu/edu/astrophys/studentwork/inquiry/ (not as good)