Can anyone tell me where the Nemesis theory is at.Are we any closer to finding out the truth??????????????????:
Member
Can anyone tell me where the Nemesis theory is at.Are we any closer to finding out the truth??????????????????:
Established Member
I don't think we can say for sure that the Sun doesn't have a stellar partner, but it seems to be extremely unlikely. A very distant low-mass brown dwarf might be able to escape our detection, and a gas giant could be easily missed if located deep in the Oort Cloud. We can't detect smaller objects at these distances (thousands of AUs) yet.
The Nemesis theory was invented to explain the perceived regularity in mass extinctions. Since there is no clear periodicity, Nemesis is not needed.
Member
You wrote "Since there is no clear periodicity, Nemesis is not needed."
Isnt periodicity a topic of hot debate?
Order of Kilopi
It appears Muller himself published work as recently as '05 on the "Cycles of Fossil Diversity" which addresses the apparent periodicity.
His website.
Work relevant to Nemesis, from Muller's group, appears 5yrs old.
I am of the opinion that some sort of stellar companion will be discovered.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Member
That sounds like the right answer. Thank you
Established Member
Sounds more like what you were looking for, but I shouldn't speculate on your motives.
CJSF
"In the nightgown of the sullen moon, How the windows lean into the room, In the nightgown of the sullen moon."
-They Might Be Giants
Established Member
There was some work done trying to locate the position of a large planet at 25,000 AU's some years ago. They used changes in comets orbits to try and back track probable poistions and speed of orbit.
However they were unable to locate said planet once they had it's orbit and speed nailed down. So it was classified as 'doubtfull'.
Intresting enough I read something more recent that indicated that Sol's Oort cloud and Alpha Centari's Oort clouds, extend out far enough that they intersect each other at thier outer edges. This could pontetialy be a source for cometary orbit changes as well.
Order of Kilopi
Interesting indeed.
Cite?
John Matese, I think, is one of the scientists to whom you refer?
And coupling Matese's ideas and work with others like Levison, Brown, Murray... I can't help but consider it more likely than not.
IMHO, of course.
Where the telescope ends, the microscope begins. Which of the two has the greater view?
Established Member
Nemesis theory implies that mass extinctions are of cosmic origin. That may sound appealing to astronomers and to general public, but (literally) more earthly origins like massive volcanism should not be dismissed easily.
Member
One of the pros may be in a better position to comment, but it seems that the Tycho dataset provides a strong upper limit on the brightness of a solar companion star.I don't think we can say for sure that the Sun doesn't have a stellar partner, but it seems to be extremely unlikely.
Tycho is a catalog the HIPPARCOS satellite produced. It has less accurate astrometry than the main HIPPARCOS catalog, but the Tycho observations were still accurate enough (well under 1 arcsecond) to detect the parallax of any star close enough to fit the Nemesis hypothesis. They didn't turn up any stars close enough. Tycho is nearly complete down to around magnitude +11, so assuming Nemesis exists, and is not lurking in the small number of brighter stars Tycho missed, it has to have a visual magnitude dimmer than +11.
At the distances suggested for Nemesis, this corresponds to an absolute magnitude of +17 or dimmer. This is very dim, less than 0.01% the brightness of the Sun. Historically a star like this would be hard to find, but give it another decade or so, when GAIA should identify it without any trouble, if it exists.
Order of Kilopi
From what I understand, the Nemesis theory is in the dustbin of history.Originally Posted by normdowling
As for closer to the truth, we're pretty sure its not out there.
Order of Kilopi
FWIW, a gas giant more than 10,000 AU away would not be visible by even the Hubble (30 mag. limit). Perhaps Spitzer's greater IR sensitivity gives it an advantage here, but I don't know how much.
This distance is about 5% to 10% the radius of the Oort Cloud. This certainly doesn't make the giant likely, just unlikely to see.
Established Member
Cite's for the Oort Overlap.
From Wiki http://en.wikipedia.org/wiki/Oort_cloud
From NSS http://72.14.253.104/search?q=cache:...nk&cd=12&gl=us
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