Astronomers Discover Third-Closest Star System To Earth

The Bad Astronomer writes "Astronomers have found the third-closest star system to the Earth: called WISE 1049-5319, it's a binary brown dwarf system just 6.5 light years away. Brown dwarfs are faint, low mass objects 13 — 75 times the mass of Jupiter, and are so dim they are very difficult to detect. These newly-found nearby objects were seen in observations from 1978 but went unnoticed at the time, but since that date the large apparent motion of the binary made their proximity obvious. Only two star systems are closer: Alpha Centauri (4.3 light years) and Barnard's star (6 light years)."

Comments

These are the starts that are closest to me

[Anonymous Coward]

Sheldon's going to have to fix his song.

Re:These are the starts that are closest to me

[Dr. Sheldon Cooper]

I most certainly shall not. I don't consider a brown dwarf to be a real star. I generally don't spend time considering topics related to astronomy at all, as it is widely known that astronomy is a field for children or H1B imports with selective mutism and a penchant for broadway musicals.

To put it in terms you would be more likely to understand, if stars were thespians, a brown dwarf would be on par with Jean Claude Van Damme.

And before you ask, a thespian is what you normies call an actor.

If brown dwarfs can't sustain fusion

[mozumder]

then why are they considered stars?

Re:If brown dwarfs can't sustain fusion

[skade88]

According to the Brown Dwarf Wiki article "However, for some years now there has been debate concerning what criterion to use for defining the separation between a brown dwarf and a giant planet at very low brown dwarf masses (~13 Jupiter masses).[3] One school of thought is based on formation, and another on interior physics.[3] Dwarfs are categorized by spectral classification, with the major types being M, L, T, and Y.[3] Despite their name, most brown dwarfs would appear magenta to the human eye.[3] Another debate is whether brown dwarfs are required to have experienced fusion at some point in their history. Some planets are known to orbit brown dwarfs: 2M1207b, MOA-2007-BLG-192Lb, and 2MASS J044144b. Brown dwarfs may have fully convective surfaces and interiors, with no chemical differentiation by depth.[4]" http://en.wikipedia.org/wiki/Brown_dwarf

Re:If brown dwarfs can't sustain fusion

[skade88]

Dwarf planets and stars are sensitive and preferred it if you called them little planets and little stars.

Re:If brown dwarfs can't sustain fusion

[jc42]

I think if it is the center of a planetary system, then it is a star.

This is a nice example of why you need to be careful in how you define things. With the above definition, our own sun isn't a "star" (most of the time).

Isaac Newton was one of the people who pointed this out. The objects in our solar system actually orbit the barycenter of the system, the technical name for what is often called the center of mass (or more weirdly, the center of gravity). Because most of the solar system's mass outside the sun is Jupiter, and because Jupiter is far enough away from the sun, the barycenter of the solar system is usually outside the sun. Not far outside, true, but outside the visible "surface" of the sun. It's only inside the sun when most of the other big planets are on the other side from Jupiter.

So, technically speaking, Earth and the other planets don't actually orbit the sun; they orbit the barycenter, which is (usually) outside the sun. The sun itself also orbits the same barycenter, in a very close orbit. And a few humorous remarks have been made based on the fact that Newton actually demonstrated that the Earth doesn't revolve around the sun.

We probably need a better definition of the term "star" than "has planets". That also causes a different problem: It's a circular definition, since the common definition of a "planet" includes orbiting a star. So one might decide that Jupiter is a star, and at least its four major moons instantly become planets, which then is used in the definition of "star" to prove that Jupiter is indeed a star.

There's a lot of humor in the way such terms are being defined by various (mostly non-astronomical) parties. Maybe we should go back to the definition that a star is an astronomical thing that undergoes sustained nuclear fusion. Ya think that'd work?

(We do have to carefully word it so that the experimental fusion projects in Earthly labs don't qualify as stars. ;-)

And where's the mass of the universe?

[sshambar]

Can someone explain to me how discovering the THIRD closes system to ours in 2013 doesn't suggest that all the Dark Matter(tm) that's out there just isn't a mass of brown dwarfs that we can't see, and not a whole new class of matter?

Re:And where's the mass of the universe?

[Waffle Iron]

As I recall, it's because the orbital velocities of regular stars in disk-shaped galaxies suggest that dark matter is distributed spherically around the galactic center rather than concentrated in the disk. That implies that unlike brown dwarfs, dark matter interacts neither with normal matter nor itself by any force other than gravity.

Re:And where's the mass of the universe?

[Baloroth]

Can someone explain to me how discovering the THIRD closes system to ours in 2013 doesn't suggest that all the Dark Matter(tm) that's out there just isn't a mass of brown dwarfs that we can't see, and not a whole new class of matter?

Because of Big Bang nucleosynthesis. We can know how much baryonic matter ("normal" matter) there is in the universe by certain cosmological observations. Other cosmological observations show there is more matter out there than that (about 5 times more) and therefore it cannot all be brown dwarfs, black holes, or other dark but non-exotic forms of matter.

Re:And where's the mass of the universe?

[myrikhan]

IIRC there aren't enough of them and they're too low mass to make up the dark matter. After a bit of searching I found this thesis. It looks like a good introduction to the area.

http://arxiv.org/pdf/1110.2757

Re:And where's the mass of the universe?

[Waffle Iron]

No, it's the same gravity, which affects both normal matter and dark matter the same.

The difference is that if dark matter interacted by any force other than gravity (such as electromagnetism, etc.), then it would be deflected on encounters with other objects instead of passing right through them. This would eventually cause the dark matter to settle into a disk, like the rest of the stuff in the galaxy. However, it instead seems to remain in its initial spherical distribution to this day.

Re:Proxima Centauri

[skade88]

Mod this up or edit the wiki article so Proxima Centauri is 14 light years away...

Re:Can someone explain something to me?

[osu-neko]

The premise behind your question is the fallacy of the convertibility of human time and resources, as if we're all interchangeable and equally qualified to participate in any task. Let me put it this way: how much further would we get into understanding the Standard Model if the millions of people playing World of Warcraft would work on that instead?

Once you already have the world's theoretical physicists working on theoretical physics problems like like, what makes you think people in other fields would make a useful contribution?

Astronomers look for objects in the sky because they're astronomers. They aren't going to crack problems of theoretical high-energy physics, and they're not in the mood to play WoW 24/7...

Re:Third closest system?

[Anonymous Coward]

Debug your code. The index starts at zero.