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| The location of Alpha Centauri A and B, Proxima Centauri and the Sun in the Hertzsprung-Russell (HR) diagram. (Photo credit: Wikipedia) |
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| English: Apparent orbit of Alpha Centauri by professor see (Photo credit: Wikipedia) |
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| English: Alpha Centauri (Photo credit: Wikipedia) |
Centauri Dreams ☆
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Planet Discovery Through Disk Structure
As the number of confirmed planets and planet candidates has
grown, we’ve gone through a variety of techniques for exoplanet hunting,
as Michael Lemonick’s new book Mirror Earth: The Search for Our
Planet’s Twin (Walker & Co., 2012) makes clear. I’m only a third of
the way into the book but I bring it up because it’s germane to today’s
discussion in two ways. The first is purely administrative. Readers of
Centauri Dreams are used to seeing information about the book I’m
reading on the front page, but as many emails have reminded me, lately
it’s been absent.
What’s happening is this: The s
A New Year Awaits
I’ve gotten so used to thinking ‘maybe this will be the year when
the first Alpha Centauri planet is discovered’ that I almost said it
again about 2013. Fortunately, we already have a (still unconfirmed)
Centauri B b, and the latest I’ve heard is that it may take five years
or so before we can say something definitive about a planet in a
habitable zone orbit around our neighboring system. So the coming year
may not be the year of Alpha Centauri, but we can expect exoplanet news
in abundance as the various teams continue their work, and plenty of
activity from the organizations now working to a
Alpha Centauri in Perspective
In his new article on Alpha Centauri in Astronomy &
Geophysics, Martin Beech (Campion College, University of Regina) noted
that the Alpha Centauri stars seem to go through waves of scientific
interest. Beech used Google’s Ngram Viewer to look for references to the
system in both the scientific literature as well as general magazines
and newspapers, finding that there is a 30-year interval between peaks
of interest. The figure is suspiciously generational, and Beech wonders
whether it reflects an awakening of interest in this nearby system as
each generation of scientists and publishers ari
Dec 24 2012
Best Wishes for a Stellar Holiday
Martin Beech has written a superb summary of Alpha Centauri
studies for the Royal Astronomical Society’s journal Astronomy and
Geophysics, covering recent work up to and including the discovery of
planet candidate Centauri B b. A fine holiday gift! I had been hoping to
write it up this morning, but Christmas events, not least of which is
the need for some last minute shopping, have made that impos
Dec 21 2012
New Models of Galactic Expansion
Unexpectedly waking this morning despite Mayan prophecy, I
suddenly remembered the storms that had kept me up for an hour during
the night. There was little rain, but the winds were gusting and I could
hear trees branches slapping against the siding and dogs baying inside
nearby houses. When I got up to look out the window, city light under
the overcast created a dim bronze aura. You would think i
Dec 20 2012
Tightly Spaced Habitable Zone Candidates
We saw yesterday how a newly refined radial velocity technique
allowed researchers to identify five planet candidates around the nearby
star Tau Ceti. The latter has long held fascination for the exoplanet
minded because it’s a G-class star not all that different from the Sun,
and one of the planets around it — if confirmed — appears to be in its
habitable zone. But smaller stars remain much in th
Dec 19 2012
Tau Ceti’s Five Planet Candidates
I discovered while trying to get to my copy of Stephen Dole’s
Habitable Planets for Man that my office was so choked with stacks of
books mixing with Christmas gifts about to be wrapped that I couldn’t
reach the necessary shelf. Thus space studies end inevitably in office
cleaning, the only benefit of which is that there is now a clear path to
the most distant of the bookshelves and Dole’s book (t
Dec 18 2012
Solar System Origins: No Supernova?
How do we get from clouds of gas and dust in interstellar space
to stars like the Sun? It takes the right triggering event, which can
cause such a cloud to collapse under its own gravity, and we’ve
generally assumed that the trigger was a supernova. Indeed, one way to
check the theory is to look for the radioactive isotope iron 60 (60Fe),
which is considered a marker for a supernova as it can only
Dec 17 2012
An Early Nod to Beamed Propulsion
It’s always interesting how different strands of research can
come together at unexpected moments. The last couple of posts on
Centauri Dreams have involved new work on Titan, and early references in
science fiction to Saturn’s big moon. The science fiction treatments
show the appeal of a distant object with an atmosphere, with writers
speculating on its climate, its terrain, and the bizarre life-
Dec 14 2012
Titan: A Vast, Subsurface Ocean?
Yesterday’s look at a major river on Titan took on a decidedly
science fictional cast, but then Titan has always encouraged writers to
speculate. Asimov’s “First Law” (1956) tackles a storm on Titan as a way
of dealing with the Three Laws of Robotics. Arthur C. Clarke filled
Titan with a large human colony in Imperial Earth (1976), and Kim
Stanley Robinson used Titanian nitrogen in his books on th
Dec 13 2012
Titan’s Big River
One of the wonderful things about daily writing is that I so
often wind up in places I wouldn’t have anticipated. Today’s topic
includes the discovery of a long river valley on Titan that some are
comparing to the Nile, for reasons we’ll examine below. But the thought
of rivers on objects near Saturn invariably brought up the memory of a
Frank R. Paul illustration, one that ran as the cover of the
Dec 12 2012
Widening the Habitable Zone
Finding a way to extend the classical habitable zone, where
liquid water can exist on the surface of a planet, is a project of
obvious astrobiological significance. Now a team of astronomers and
geologists from Ohio State University is making the case that their
sample of eight stars shows evidence for just such an extension. The
stars in question, drawn from a dataset created by the High Accuracy
Dec 11 2012
Thoughts on Patrick Moore
Patrick Moore, the legendary figure of British astronomy who died
recently at his home in West Sussex, was deeply familiar with Ptolemy.
The latter, a 2nd Century AD mathematician and astronomer, was the
author of the Almagest, an astronomical treatise that presented the
universe as a set of nested spheres and assumed a geocentric cosmos.
Moore’s comprehensive knowledge of astronomy’s history woul
Dec 10 2012
Interstellar Flight: The View from Kansas
If Kansas may not be the first place that comes to mind when you
think about interstellar matters, be aware that its state motto is ‘Ad
Astra Per Aspera’ — to the stars through difficulties. That’s a familiar
phrase for anyone who has pondered the human future in space, appearing
in countless science fiction stories and often invoked by those with a
poetical streak. It turns out that the Kansas mo
Dec 07 2012
Brown Dwarf Results Promising for Planets
Do planets form easily around brown dwarf stars? Are they actually
common? We’re getting a glimpse of the possibilities in new work at the
Atacama Large Millimeter/submillimeter Array (ALMA), where a brown dwarf
known as ISO-Oph 102 (also called Rho-Oph 102) is under investigation.
In most respects it seems like a fairly run-of-the-mill brown dwarf,
about 60 times the mass of Jupiter and thus una
Dec 05 2012
Voyager: Dark Highway Ahead
One rainy night in the mid-1980s I found myself in a small motel
in the Cumberlands, having driven most of the day after a meeting and
reaching Newport, TN before I decided to land for the night. It’s funny
what you remember, but small details of that trip stick with me. I
remember the nicking of the wiper blades as I approached Newport, the
looming shapes of the mountains in the dark, and most of
Dec 04 2012
ASPW 2012: A Report from Huntsville
Richard Obousy, a familiar face on Centauri Dreams, is president
and primary propulsion senior scientist for Icarus Interstellar, whose
portfolio includes Project Icarus, the redesign of the Project Daedalus
starship. Dr. Obousy is just back from the latest Advanced Space
Propulsion Workshop and, as he did for the 2010 ASPW, he now offers his
take on the event. Although I missed this ASPW, I’ll be
Dec 03 2012
The news from Reaction Engines Ltd. about its air-breathing
rocket engine SABRE is interesting not only for its implications in
near-term space development, but also for its pedigree. Reaction Engines
grew out of British work on a single-stage-to-orbit concept called
HOTOL ((Horizontal Take-Off and Landing) that was being developed by
Rolls Royce and British Aerospace in the 1980s. Initially backe
by Paul Gilster
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29 days ago
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