The story of Haumea, as told by astronomer Mike Brown, is a space-based detective tale.
The story of Haumea, as told by astronomer Mike Brown, is a space-based detective tale.
Brown, a Caltech professor perhaps best known for being one of the astronomers who helped demote Pluto from planet to ice dwarf, described the discovery of dwarf planet Haumea, named for the Hawaiian goddess of childbirth, in the Kuiper belt to a crowd of astronomers and scientists at the Fairmont Orchid, Hawaii Thursday. Brown was one of a long slate of speakers for the W.M. Keck Observatory 20th Anniversary Science Meeting.
“The children of Haumea are pieces of her that broke off,” Brown said, expanding on the Hawaiian legend. That name, selected because of the significant amount of research and study of Haumea done using Keck’s telescopes, became even more appropriate, he added, when scientists eventually discovered two moons orbiting Haumea, itself an incredibly dense object with a rocky core and pure water ice mantle, were made of the same ice.
Brown said he initially theorized something large struck Haumea, causing pieces of mantle to break away. The first time he proposed that idea, theorists said no way, there was only a one in a billion chance that could have happened. Brown kept studying the objects, using more data from Keck, when he and other scientists had a bit of luck, showing Hiiaka, the first moon, and Haumea were made of the same ice. That brought down the odds of an impact to one in 100,000.
As Keck’s instruments improved, images became clearer, and a dot on a picture Brown initially disregarded showed up, more clearly, as a second moon, Namaka. Further study showed Namaka, too, was an icy object.
“It sounds like a giant impact” would have created those two moons, Brown said. This time, theorists dropped the odds to one in 1,000 for such a collision.
Then, Brown said, “we got lucky one more time. This whole thing wouldn’t have been discovered if (Keck) hadn’t been doing this other project to look at other small objects. It was a nice combination of everything coming together.”
The data Brown and others collected backed up the theoretical impact, one that brought an object about 1,000 kilometers across into contact with Haumea at about 3 kilometers per second, cracking the mantle and ejecting icy objects away from the dwarf planet. Two remained in orbit.
Throughout the day Thursday, scientists shared similar ways in which Keck’s instruments — including ones remarked upon nostalgically by scientists, even as they noted the significant improvements new instruments have made in creating quality images — had shaped understanding of what is in this solar system and farther outside it.
Claire Max, with the University of California, Santa Cruz’s Center for Adaptive Optics, showed how the next generation of adaptive optics — the technology that is used to cancel the distortion caused by observing outer space through the Earth’s atmosphere. Max described the measurement that grades adaptive optics, the Strehl ratio, and said that the images Keck’s adaptive optics instruments are now getting score between 5 percent and 40 percent on that scale. A perfect image would score 100 percent.
“The worst performance of next generation adaptive optics is better than the best today,” Max said.
Max was one of several speakers to note the observatory’s high performance rate, which includes having some of the highest numbers of discoveries and scientific papers published.
“We really are the leader in the field,” Max said.
Scientists are using Keck, in conjunction with images from the Kepler telescope, which takes images of bright objects from space, to identify Earth-sized and Earthlike planets, Geoff Marcy, an astronomer with the University of California Berkeley, said.
“Out of 200 billion stars in the Milky Way, we wonder how many harbor Earthlike planets?” Marcy said. “We still don’t know the answer.”
But Marcy offered a new insight on Thursday, a discovery that has not yet been released.
“Twenty-three percent of sunlike stars have a planet (the size of) one to three Earths within Mercury’s orbit,” Marcy said. “What about farther out? You get the feeling most stars have an Earth-size planet.”
Marcy said the figures were surprising, adding that with those numbers and with that many Earthlike planets in the habitable zone around their respective stars, it is likely some will have water and simple, single-cell organisms will have evolved.
The science meeting continues today. Keck’s Waimea headquarters will be open from 11 a.m. to 3 p.m. Saturday for an open house.