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The Question
(Submitted November 30, 1996)
Do you have any new information on the Nemesis Star,the so called
companion star to our Sun ?
The Answer
To recap the story of Nemesis (see, e.g., 1990 October issue of Scientific
American): in 1984, Raup & Sepkoski claimed that mass extinctions, like the
one that killed the dinosaurs 65 million years ago, occurred every 32 million
years. Since the favored theory for the demise of dinosaurs is an asteroid
or cometary impact, the periodicity would suggests some mechanism to disturb
the comets in the Oort cloud every 32 million years. Richard Muller and others
hypothesized that a faint companion star, nicknamed Nemesis, that orbits the
Sun every 32 million years, could explain this.
However, many geologists are not convinced that mass extinctions are periodic,
so they see no need for such a star. Nevertheless, Muller and colleagues have
embarked on the difficult search for a possible, dim companion to the Sun.
The most recent report I could find on this was a conference paper from 1994
(Carlson et al 1994 in "New Developments Regarding the KT Event and Other
Catastrophes in Earth History", Houston Univ., p19-20). Here are some
sentences off the abstract: "Unfortunately, standard four-color photometry
does not distinguish between red dwarfs and giants. ... Every star of the
correct spectral type and magnitude must be scrutinized. ... We are currently
scrutinizing 3098 fields, which we believe contain all possible red dwarf
candidates in the northern hemisphere. ... The software is now completed
and we are eliminating stars every clear night." I presume the search is
still on-going but have not yielded a positive detection.
A good description and more references can be found at:
http://www.nineplanets.org/hypo.html#nemesis
You may also want to check out the article in the 1990 October issue of
Scientific American
Koji Mukai and Eric Christian
with help from Drs. Chen, Loewenstein and Snowden
for Imagine the Universe!
Questions on this topic are no longer responded to by the "Ask an Astrophysicist" service. See http://imagine.gsfc.nasa.gov/docs/ask_astro/ask_an_astronomer.html
for help on other astronomy Q&A services.
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