Discoveries of extrasolar planets are becoming so common they now pass with little fanfare With the tally of extrasolar planets hovering ambiguously around 100 and researchers scrambling to keep track of the rapidly growing the total, the International Astronomical Union (IAU) may soon embark on an official cataloguing effort, SPACE.com has learned.
The IAU is the recognized clearinghouse for information on all objects in our solar system, as well as general astronomical naming conventions. But it has yet to take up the task of counting planets around other stars, the first of which was found in 1995.
Last night Alan Boss, who chairs the IAU's Working Group on Extrasolar Planets, sent an e-mail to his colleagues asking them for feedback on how to approach creation of the first IAU extrasolar planet catalogue.
"I intend for us to begin this task this summer," Boss told SPACE.com. He expects the group to work on the problem over the next two months in advance of an October deadline for reporting to the IAU.
Symbolic 100th planet
There was a time when discoveries of extrasolar planets made big headlines. Now they are so common that they sometimes pass into the public domain with little fanfare.
Consider the case of HD 2039 b, a planet roughly four times as big as Jupiter whose existence -- and status as exoplanet No. 100 -- was quietly posted yesterday on a web site called the Extrasolar Planets Encyclopaedia. No press release, no cameras, no announcement.
The designation is only symbolic, says Jean Schneider, a French researcher who maintains the list. By some counts, the list is larger -- if one includes planet-like objects that float freely in space and don't orbit stars. By other counts, it is smaller -- if one excludes possible planets that have not been through peer review and published in a scientific journal.
That's not to say the field is in disarray. Science is proceeding as it always does: Things are found. Some are verified. Some are tossed out.
But lately the pace has gotten frenetic.
In recent weeks, two separate groups, one from the
United States and one from Switzerland, each announced the discovery of a dozen or so planets. Some of the objects were known to be duplicate findings. In an interview with SPACE.com last week, U.S. team member Debra Fischer, from the University of California, Berkeley, put the overall count of known extrasolar planets below 100. Also last week, Swiss planet-hunter Stephane Udry said the count of known (but not reviewed) planets was at 100, but that two of them had been called into question by follow-up observations.Boss, who is also a planet-formation theorist at the Carnegie Institution in Washington, said Schneider's list contains everything that's been announced (excepting the free-floating planets, which almost no one seems to want to deal with yet). But some of the planets on the list might need to be removed.
"Several of the objects that have been announced, including several from just two weeks ago, do not appear to exist, based on data taken by another group," Boss said. "Until these question marks are removed, even the total number of announced (vs. published) planets is not clear."
Nonetheless, Boss said, Schneider's list may be accepted as the de facto standard because it's hundredth entry was reported yesterday by the online web site of the BBC.
What is clear, Boss says, is that "we are very close to having 100 good candidates for extrasolar planets. If we are not at exactly 100 extrasolar planets right now, we probably will be in a month or two."
Fischer said her team has "planets coming down the data pipeline in a steady stream."
Udry said his colleagues at the Geneva Observatory will announce more planets "very probably before the end of the year" he said in an e-mail interview. He adds that between 2005 and 2008, when a handful of space-based telescopes are launched to search for planets, the tally will grow "up to several hundreds." Other research teams have other "possible planet candidates" scoped out.
An official counting agency may soon become imperative.
Boss said his IAU group should take responsibility for the task. First, though, he and his colleagues will have to decide how to assess and count these objects, none of which has ever been directly imaged. Boss has asked the other members of the working group to consider how to deal with observations that have indicated potential planets but that cannot be readily reproduced or verified.
One research team, the Optical Gravitational Lensing Experiment (OGLE), alone
announced dozens of these candidate planets in February.Boss also wonders how credit for discoveries ought to be handled in a world where planets are sometimes detected by more than one group working independently. Should a team that announces a claim have priority over one that instead submits their work to a scientific journal?
More Extrasolar Planet News
advertisement
