Unexpected Classification of Exoplanets Discovered

W. M. Keck Observatory press release

Since the mid-1990s, when the first planet around another sun-like star was discovered, astronomers have amassed an ever-expanding collection of nearly 3,500 confirmed exoplanets.

Exoplanet Formation
Assembly Line of Planets: This diagram illustrates how planets are assembled and sorted into two distinct size classes. Image credit: NASA/Kepler/Caltech (R. Hurt)
In a new Caltech-led study, researchers have classified these exoplanets in much the same way that biologists identify new animal species and found the majority of exoplanets fall into two distinct groups: rocky Earth-like planets and larger mini-Neptunes. The team used data from W. M. Keck Observatory and NASA’s Kepler mission.

“This is a major new division in the family tree of planets, analogous to discovering that mammals and lizards are distinct branches on the tree of life,” says Andrew Howard, professor of astronomy at Caltech and a principal investigator of the new research.

The lead author of the new study, to be published in The Astronomical Journal, is Benjamin J. (B. J.) Fulton, a graduate student in Howard’s group.

In essence, their research shows that our galaxy has a strong preference for either rocky planets up to 1.75 times the size of Earth or gas-enshrouded mini-Neptune worlds, which are from 2 to 3.5 times the size of Earth (or somewhat smaller than Neptune). Our galaxy rarely makes planets with sizes in between these two groups.

“Astronomers like to put things in buckets,” says Fulton. “In this case, we have found two very distinct buckets for the majority of the Kepler planets.”

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Astronomers Prove What Separates True Stars from Wannabes

W. M. Keck Observatory press release

Astronomers have shown what separates real stars from the wannabes. Not in Hollywood, but out in the universe.

“When we look up and see the stars shining at night, we are seeing only part of the story,” said Trent Dupuy of the University of Texas at Austin and a graduate of the Institute for Astronomy at the University of Hawaii at Manoa. “Not everything that could be a star ‘makes it,’ and figuring out why this process sometimes fails is just as important as understanding when it succeeds.”

Dupuy is the lead author of the study and is presenting his research today in a news conference at the semi-annual meeting of the American Astronomical Society in Austin.

He and co-author Michael Liu of the University of Hawaii have found that an object must weigh at least 70 times the mass of Jupiter in order to start hydrogen fusion and achieve star-status. If it weighs less, the star does not ignite and becomes a brown dwarf instead.

How did they reach that conclusion? The two studied 31 faint brown dwarf binaries (pairs of these objects that orbit each other) using W. M. Keck Observatory’s laser guide star adaptive optics system (LGS AO) to collect ultra-sharp images of them, and track their orbital motions using high-precision observations.

“We have been working on this since Keck Observatory’s LGS AO first revolutionized ground-based astronomy a decade ago,” said Dupuy. “Keck is the only observatory that has been doing this consistently for over 10 years. That long-running, high-quality data from the laser system is at the core of this project.”

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Segments!!

Fun at AstroDay

In the ten years I have lived on island I have never missed an AstroDay. This year was no change to that streak, I volunteered to do the last shift on the Keck Observatory table, 2-4pm. Show up at lunchtime, enjoy the activities myself for a while, say hi to everyone I know there, then do my shift on the table… Good plan.

Thermal image of a young guest at AstroDay
Thermal image of a young guest at AstroDay
We were using a thermal camera for our primary activity. Instead of borrowing the fancy, and very expensive, FLIR camera from the summit, our outreach group has bought one of the little iPad thermal cameras from Seek Thermal.

I was pleasantly surprised with this little thermal camera, it does a nice job costing only a few hundred dollars. Using the iPad linked to a large display using AirPlay the setup worked quite well in practice. I could handle the camera with no wires to tether me to one place.

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PPT in the News… Again

It was a last minute request. OK, not actually the last minute, but two days is not much lead time to plan a public outreach event.

Fortunately there was not much to arrange, a single solar telescope and the standard table setup we keep packed and ready to go, all we had to do was show up. Drive up to the Pōhakuloa Training Area to join in their Earth Day events. There would be several hundred students from local schools, tables and displays from other organizations, a good outreach opportunity.

Pōhakuloa Solar Telescope
A solar telescope set up at Pōhakuloa Training Area for Earth Day.
In ten years of driving past the front gates of PTA, I had never been inside. Why not, just an easy drive from Waikoloa, and I have a telescope that will do the job perfectly.

It seems odd that a military base would celebrate Earth Day. What do attack helicopters, live munitions, and troops have to do with the environment? The answer should not be that surprising… Military bases are often large effective nature reserves.

Large areas of land, much of which sits unused and undisturbed, are closed to public access. An active range needs huge safety and buffer zones around the firing ranges. Of the 133,000 acres that makes up PTA, only a small percentage is directly impacted by the training activities. The rest is home to a endemic and endangered species, closed to any activity that can disturb the land.

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Primordial Galaxy Discovered, First of Its Kind

MACS1423-z7p64 galaxy
Graphic illustration of how MACS1423-z7p64 was detected via gravitational lensing with NASA’s Hubble Space Telescope and confirmed by W. M. Keck Observatory’s MOSFIRE. Credit: NASA/W. M. Keck Observatory/A. Hoag/M. Bradac
W. M. Keck Observatory press release

Seven years of meticulous observing have resulted in a cosmic discovery that comes from an era dating back 13.1 billion years, giving scientists a detailed glimpse of what may have happened just after the Big Bang.

Using the world-class W. M. Keck Observatory on Maunakea, Hawaii, an international team of astronomers from the United States, Australia, and Europe has confirmed the existence of one of the most distant galaxies in the universe.

To characterize the faint galaxy, the discovery team, led by Austin Hoag, a University of California, Davis physics graduate student, used MOSFIRE, the most in-demand instrument on the 10-meter Keck I telescope.

What makes this galaxy extraordinary is that it is ordinary. It is thought to be a common galaxy at that distance and age of the universe. However, such galaxies would normally be too faint to detect. The astronomers used a method called gravitational lensing to magnify the galaxy so they could study it.

“Most objects that we’ve seen at that distance are extremely bright, and probably rare compared to other galaxies,” said Hoag. “We think this galaxy is much more representative of other galaxies of its time.”

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W. M. Keck Observatory Achieves First Light with New Instrument

W. M. Keck Observatory press release

W. M. Keck Observatory overnight captured the very first successful science data from its newest, cutting-edge instrument, the Keck Cosmic Web Imager (KCWI).

KCWI First Light Image
KCWI’s first look at the cosmos involved a spectral image of an exquisitely dense core of an ancient astronomical relic, showcasing the highest spectral resolving power and spatial resolution of the instrument. Credit W. M. Keck Observatory
KCWI captures three-dimensional data, as opposed to the traditional two-dimensional image or spectrum of conventional instruments. In a single observation, it records an image of the object at multiple wavelengths allowing scientists to explore both the spatial dimension (as in an image) and the spectral dimension (or color) of an object.

“I’m thrilled to see this new instrument,” said Keck Observatory Director Hilton Lewis. “It takes years to design and build these very sophisticated instruments. KCWI is a superb example of the application of the most advanced technology to enable the hardest science. I believe it has the potential to transform the science that we do, and continue to keep Keck Observatory right at the forefront of astronomical research.”

KCWI is extremely sensitive, specifically designed to capture high-resolution spectra of ultra-faint celestial bodies with unprecedented detail. It is able to differentiate even the slightest changes in spectral color with a great degree of accuracy.

This powerful capability is key for astronomers because a highly-detailed spectral image allows them to identify a cosmic object’s characteristics, including its temperature, motion, density, mass, distance, chemical composition, and more.

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Ancient Dead Galaxy Sets New Record

W. M. Keck Observatory press release

Galaxy ZF-COSMOS-20115
Artist’s impression of galaxy ZF-COSMOS-20115. The galaxy has likely blown off all the gas that caused its rapid star formation and mass growth, and rapidly turned into a compact red galaxy. Credit: CREDIT: Leonard Doublet/Swinburne University of Technology.
An international team of astronomers has, for the first time, spotted a massive, inactive galaxy from a time when the Universe was only 1.65 billion years old. This rare discovery, made using the world-class W. M. Keck Observatory on Maunakea, Hawaii, could change the way scientists think about the evolution of galaxies.

This research publishes today in the journal Nature, with Professor Karl Glazebrook, director of Swinburne’s Centre for Astrophysics and Supercomputing , as the lead author. To characterize the faint galaxy, the discovery team used MOSFIRE, the most in-demand instrument on the 10-meter Keck I telescope.

“This observation was only possible due to the extreme sensitivity of the new MOSFIRE spectrograph,” said Glazebrook. “It is the absolute best in the world for faint near-IR spectra by a wide margin. Our team is indebted to the accomplishment of Chuck Steidel, Ian McClean, and all the Keck Observatory staff for building and delivering this remarkable instrument.”

Astronomers expect most galaxies from this epoch to be low-mass minnows, busily forming stars. However, this galaxy is ‘a monster’ and inactive.

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Observatory Still Life Gallery

Often you just need to take note of the small scenes that make up daily life. Over the years I have made an effort to photograph these scenes, there is so much richness in our everyday existence that too many do not notice…