Strange New 'Twin' Worlds Found 239
toomanyairmiles writes "The BBC reports on the the discovery of 'twin worlds' which orbit each other, successfully blurring the line between planets and stars. 'Their existence challenges current theories about the formation of planets and stars.' according to the Journal of Science article which reports their existence. 'The pair belongs to what some astronomers believe is a new class of planet-like objects floating through space; so-called planetary mass objects, or "planemos", which are not bound to stars.'"
Not dark matter (Score:5, Informative)
Re:Challenging views? (Score:5, Informative)
What i think you meen is that a nebula of the right size can form a stelar object that doesnt have the mass for fusion.
Re:Makes me wonder about some things. (Score:5, Informative)
Re:Not dark matter (Score:1, Informative)
In cosmology, dark matter refers to matter particles, of unknown composition, that do not emit or reflect enough electromagnetic radiation (light) to be detected directly, but whose presence may be inferred from gravitational effects on visible matter such as stars and galaxies. Dark matter explains several anomalous astronomical observations, such as anomalies in the rotational speed of galaxies (the galaxy rotation problem). Estimates of the amount of matter present in galaxies, based on gravitational effects, consistently suggest that there is far more matter than is directly observable. The existence of dark matter also resolves a number of seeming inconsistencies in the Big Bang theory, and is crucial for structure formation.
We as people are pretty easy to detect directly, and are great reflectors of light. While alive we even manage to produce alot (infrared, that is).
The search for dark matter stems from the uncomfortable facts that:
1. Observationaly the universe appears to be expanding at an increasing rate. This leads to an open universe in which everything keeps expanding for ever. Closed loops seem more in line with the law of thermodynamics, simply because the net energy/mass/matter of the universe would be 0 over the (very) long run, and all the energy of the universe could be treated as a vaccum flucuation.
2. The bits of the observable universe dont' move anything like they should given what we can see.
3. It really requires a significant rehash of the creation and evolution of the universe to abandon it.
4. It works out soooo well on paper.
5. No one to my knowledge has simply tweaked with extra-dimensional strings to create energy/matter/mass that exists out side of the observable dimensions, but still affecting them indirectly. Then again, stings are a conveniant mathamatical method with no direct method of detection yet.
Re:Makes me wonder about some things. (Score:5, Informative)
http://www.nineplanets.org/origin.html [nineplanets.org]
#3 on that page is the step which explains why the solar system is on the same plane. Pluto being outside that plane is most likely it is actually a kupier belt object and was far enough out from the formation of our sun to not have fully fallen into the accretion disc.
More information is available at http://en.wikipedia.org/wiki/Accretion_disc [wikipedia.org]
http://en.wikipedia.org/wiki/Protoplanetary_disc [wikipedia.org]
The reason your explanation doesn't work for why the planetary bodies are on the same plane is because they are all in stable orbits. To plane out into a disc they would need to still be falling towards the sun.
Planetary rings are in the ring pattern because they follow the orbit of the object from which they were created, they are not collected and built up from smaller particles but probably the result of the destruction of a large object.
http://en.wikipedia.org/wiki/Planetary_rings [wikipedia.org]
Re:How did they discover them? (Score:2, Informative)
The researchers discovered the companion candidate in an optical image taken with ESO's 3.5-m New Technology Telescope at La Silla, Chile. They decided to take optical spectra and infrared images of the pair with ESO's 8.2-m Very Large Telescope to make sure that it is a true companion, instead of a foreground or background star that happens to be in the same line of sight. These follow up observations indeed confirmed that both objects are young, at the same distance, and much too cool to be stars. This suggests the two are physically associated.
Re:How did they discover them? (Score:2, Informative)
KFG
Re:Makes me wonder about some things. (Score:3, Informative)
The reason your explanation doesn't work for why the planetary bodies are on the same plane is because they are all in stable orbits. To plane out into a disc they would need to still be falling towards the sun.
But aren't they getting close to the sun all the time? In effect still falling towards it? Seems like it would be perpetual motion were they not?
TLF
RTFA? (Score:3, Informative)
Six times the distance from the Sun to Pluto. If you're on one planet you might be lucky to see the tiny dot of the other planet in the night's sky... I don't recall if it said they were orbiting a star (for light) or not. So even the picture is misleading.
Re:Circle each other???? (Score:5, Informative)
Re:Just goes to show... (Score:3, Informative)
Re:Makes me wonder about some things. (Score:3, Informative)
Also, tidal distortions have an effect which slows the rotation of planets down, especially if they have a relatively big moon orbitting them, until the rotational period and the orbital period match. For example, the moon always presents the same side towards the Earth because of tidal locking, and the Earth probably had about an 18-hour day some billion years ago, and will probably have a 30+ hour day in another billion years