Mass Difference Between Brown Dwarfs and Full-Fledged Stars Finally Determined

Posted Aug 17, 2006 at 7:51AM EST by QJ Staff

Listed in: Tags: fusion, Hydrogen, Jupiter, Texas

Like so many things in the cosmos, some stars practically die a-borning. These "failed stars" are known as "brown dwarfs," and are simply not large enough to sustain a long-term hydrogen fusion reaction.

Before now, scientists believed the minimum mass required to sustain a long-term hydrogen reaction is equal to that of 75 times that of Jupiter. Although Jupiter's chemical makeup is almost identical to that of a star, it's mass is far too small to even begin a hydrogen reaction. As far as brown dwarfs are concerned, it has been difficult to confirm theories because brown dwarfs look a lot like red dwarfs - which are able to sustain the reaction required for full "starhood."

Harvey Richer of the University of British Columbia has used Hubble to observe the faintest red dwarf stars yet observed. These are located in a very old cluster identified as NGC 6397, about 8500 light years away. At 13.5 billion years, this cluster dates back to the beginning of the universe. According to another team member, Jay Anderson of Rice University in Texas, "...the brown dwarfs have by now faded off into obscurity so there is a very stark contrast between the stars that could burn hydrogen and the ones that couldn't."

Theories predict that the low-end mass for true stars should be determined by how many metals are present. Stellar objects with a metal content similar our own sun would need a minimum mass no less than 7.5% that of Sol. The NGC 6397 cluster has a metallic content that is less than 1% of the Sun's, so this dividing line is expected to be slightly greater - 8.3% that of Sol, or 83 times the mass of Jupiter.

The new Hubble observations are able to identify starts 10 to 20 times fainter than earlier ones. "This kind of observation is probably the best kind of constraint one can get," says Gibor Basri of UC Berkeley. He added that the hydrogen burning limits observed so far are in line with current theory.

Via New Scientist

This story sucks? This story rocks!

Vote Now!

(0)

(0)

QJ.NET Categories
• Apple • E3 • Featured Articles • Gadgets • Games for Windows • iPad • iPhone • MMORPG • Mobile • News • Nintendo 3DS • Nintendo DS • Opinions & Analysis	• Photography • PlayStation 3 • PoV • PS Vita • PSP • Rumors • Science • Site News • Tabula Rasa • Wii • Wii U • World of Warcraft • Xbox 360

Sitemap

Newest Downloads

05/22/2012 - 05/29/2012

RGLoader 0v290 Beta	05/27/2012
WiiMod 3.2	05/27/2012
WiiMC v1.2.7	05/25/2012
True Blue Firmeware v2.7	05/24/2012
3DS Video Converter v2.3	05/24/2012
Mobile Assault 1.8.2	05/24/2012
PSP Tools Alpha 0.1	05/22/2012
Newton War	05/22/2012
DaedalusX64 r766	05/22/2012
PSPMarble	05/22/2012
The Undead 4 - Nazi Zombies	05/21/2012
3DSExplorer v1.2.1	05/21/2012
J-Runner v0.2 Beta 275	05/19/2012
Priiloader 0.8 Beta 3	05/19/2012
Quake Rev PAK release 4	05/19/2012

Most Comments this Month
Sound Off: On Game Expirat..	(57)
Say Goodbye to the Xbox 36..	(30)
EA Blames iOS Rock Band Ex..	(28)
Flash0 Contents Of Vita's..	(27)
Sony Had a Rough Year; Vit..	(26)
PlayStation 3: Now Featuri..	(22)
Sound Off: Toughest Game C..	(20)
Apparently You Can Pre-Ord..	(19)
Love It or Hate It, It's A..	(16)
Pre-Order Generic Shooter..	(15)
PoV: This Collectors Editi..	(15)
You've Been Up in Arms Abo..	(15)
Metal Gear Solid For Vita..	(14)
PoV: Paid MMOs are Dead	(14)
PoV: You Are Wrong about C..	(14)
Get Off Xbox Live, You Ped..	(14)
This is Next Gen?	(14)
Stop Your Whining, Start C..	(13)
Diablo III Getting Mauled..	(12)
Pokemon Liquid Crystal! K..	(12)
OK, So Maybe Microsoft Can..	(12)
Does Microsoft Ever Have a..	(12)
Operation Raccoon City Pro..	(12)
Update: EA Drops Free BF3..	(11)
Max Payne 3 Will Eat Your..	(11)

Top Jumps this Month
Naruto Shippuden: Ul..	(161)
neur0n Knocks Out An..	(97)
Pokemon Liquid Cryst..	(90)
Bust Out Your PSP Fo..	(86)
PSP homebrew - LameC..	(65)
Wii homebrew - WAD M..	(50)
PSP Comics Reader v2..	(50)
PSP Homebrew: 6.xx P..	(43)
PSP Homebrew - PSPDi..	(41)
Hellcat Working On R..	(40)
PSP homebrew - DSonP..	(38)
neur0n Gives You Mor..	(37)
Sound Off: On Game E..	(34)
PSP GBA v1.2: Gamebo..	(33)
Latest Left 4 Dead 2..	(31)
Another CFW Goodie F..	(30)
GTA IV patch 1.0.6.0..	(29)
Download full Sid Me..	(28)
Soywiz Releases PSP..	(27)
Sound Off: Should Ap..	(27)
Homebrew - PSP/PS3 P..	(24)
Metal Gear Solid For..	(21)
DS homebrew game - S..	(21)
PSP homebrew - Mario..	(20)
Brian Lara Internati..	(20)

Quick Jump Daily Digest

Mass Difference Between Brown Dwarfs and Full-Fledged Stars Finally Determined

Related Stories: