Category: Astronomy

Exploring the cosmos

Scientists Accurately Quantify Dust Around Planets in Search for Life

W. M. Keck Observatory press release…

A new study from the Keck Interferometer, a former NASA project that combined the power of the twin W. M. Keck Observatory telescopes atop Mauna Kea, Hawaii, has brought exciting news to planet hunters. After surveying nearly 50 stars from 2008 to 2011, scientists have been able to determine with remarkable precision how much dust is around distant stars – a big step closer into finding planets than might harbor life. The discovery is being published in the Astrophysical Journal online, on December 8th.

A dusty planetary system (left) is compared to another system with little dust in this artist's conception. Credit NASA/JPL-Caltech
A dusty planetary system (left) is compared to another system with little dust in this artist’s conception. Credit NASA/JPL-Caltech
“This was really a mathematical tour de force,” said Peter Wizinowich, Interferometer Project Manager for Keck Observatory. “This team did something that we seldom see in terms of using all the available statistical techniques to evaluate the combined data set. They were able to dramatically reduce all the error bars, by a factor of 10, to really understand the amount of dust around these systems.”

The Keck Interferometer was built to seek out this dust, and to ultimately help select targets for future NASA Earth-like planet-finding missions.

Like planets, dust near a star is hard to see. Interferometry is a high-resolution imaging technique that can be used to block out a star’s light, making the region easier to observe. Light waves from the precise location of a star, collected separately by the twin 10-meter Keck Observatory telescopes, are combined and canceled out in a process called nulling.

“If you don’t turn off the star, you are blinded and can’t see dust or planets,” said co-author Rafael Millan-Gabet of NASA’s exoplanet Science Institute at the California Institute of Technology in Pasadena, California, who led the Keck Interferometer’s science operations system.

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Venus Appears in the Sunset

Crescent Venus
Venus approaching inferior conjunction, 24Dec2013
This week will see the appearance of Venus in the sunset to become the evening star. Look for a brilliant object rising a little higher each night. This evening the planet is 9° above the Sun, by the 10th the planet will be over 11°. Even low in the sunset Venus is easy to spot, shining brightly at -3.9 magnitude.

On the 22nd Venus will joined by a thin crescent Moon. Only 1.8% illuminated the Moon will be a beautiful pair with the planet, only 6° away.

Evicted? Possible Black Hole Found 2,600 Light Years from Home

W. M. Keck Observatory press release…

Markarian 177 and SDSS1133
Using the Keck II telescope in Hawaii, researchers obtained high-resolution images of Markarian 177 and SDSS1133 using a near-infrared filter. Credit: W. M. Keck Observatory/M. Koss Et Al.
An international team of researchers analyzing decades of observations from many facilities — including the W. M. Keck Observatory on Mauna Kea, the Pan-STARRS1 telescope on Haleakala and NASA’s Swift satellite — has discovered what appears to be a black hole booted from its host galaxy. The team was led by Michael Koss, who was a postdoctoral fellow at the Institute for Astronomy (IfA) at the University of Hawaii at Manoa during most of the time the study was ongoing. The study will be published in the Nov. 21 edition of Monthly Notices of the Royal Astronomical Society.

The mystery object is part of the dwarf galaxy Markarian 177, located in the bowl of the Big Dipper, a well-known star pattern within the constellation Ursa Major. Although supermassive black holes usually occupy galactic centers, SDSS1133 is located at least 2,600 light-years from its host galaxy’s core. The team was able to detect it in astronomical surveys dating back more than 60 years.

In June 2013, the researchers obtained high-resolution near-infrared images of the object using the 10-meter Keck II telescope at Keck Observatory. “When we analyzed the Keck data, we found the emitting region of SDSS1133 is less than 40 light-years across, and that the center of Markarian 177 shows evidence of intense star formation and other features indicating a recent disturbance that matched what we expected for a recoiling black hole,” said Chao-Ling Hung, a UH Manoa graduate student performing the analysis of the Keck Observatory imaging in the study.

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The Sky Is Falling

Yes… The sky is falling… Literally.

Anyone who spends a good amount of time observing the night sky is well aware of how common meteors are. On any given night you will see five to ten meteors an hour is you observe carefully from a dark site. This rate goes up dramatically during a meteor shower. Most of the meteors you will see are quite small, ranging from dust grains to smallish sand sized bits. Anything large can be quite spectacular. Something the size of a pebble will create a bright meteor, a bright fireball that streaks across the sky.

Bolide Events from 1994 to 2013
The graphic shows atmospheric impact events from 1994 to 2013, credit NASA’s Near Earth Object (NEO) Program
I have personally witnessed many bright fireballs, it is just a function of how much time you spend outside at night. Meteors that are bright enough to light up the landscape, that leave glowing trains of vapor behind, clouds that last for many minutes, that twist and drift in the high atmospheric winds.

Estimates vary widely, but something like 50,000 tons of meteoric material rains down on the Earth every year. The process that allowed our planet to form continues to this day.

Occasionally a larger object enters the atmosphere. Something big enough to reach the ground intact. Or even something big enough to cause damage from the impact. How often this occurs would be a surprise to most of our fellow citizens who pay little attention to the the natural world around them.

The Chelyabinsk event got the world’s attention. A medium sized object exploded in the atmosphere directly over a mid-sized city causing modest damage. Due to the prevalence of camera gear in modern Russia we were treated to an unprecedented view of this event. With historical events like Tunguska, all we have is eyewitness accounts and a few grainy black and white photographs of the damage taken years after the impact. Now we get dozens of videos of the event that detail how it occurred from dozens of viewpoints.

While this event is unusual, it was not unprecedented, objects of this size will continue to impact our planet. Meanwhile the event fades from public awareness, at least until it happens again… Which it will.

To drive home this point researchers at NASA’s Near Earth Object (NEO) Program have released a map of impacts over the last few years. Using atmospheric sensors that detect the pressure wave of the airburst they were able to locate and estimate the size of the larger events. For further details you can read the press release.

The Chelyabinsk meteor can be seen as a large dot over southern Russia. That event may be the largest dot on the map, but it is not alone. It is the number of other dots that may surprise some people. Our planet is impacted regularly.

Mikaelyan Meteor
A meteor breaking up over Groningen, Netherlands, 18:57, 13 Oct 2009, photo by Robert Mikaelyan, used with permission

Astronomers Thrilled by Extreme Storms on Uranus

W. M. Keck Observatory press release…

The normally bland face of Uranus has become increasingly stormy, with enormous cloud systems so bright that for the first time ever, amateur astronomers are able to see details in the planet’s hazy blue-green atmosphere.

“The weather on Uranus is incredibly active,” said Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, and leader of the team that first noticed the activity when observing the planet with adaptive optics on the W. M. Keck Observatory in Hawaii.

Uranus NIRC2
Infrared images of Uranus (1.6 and 2.2 microns) obtained on Aug. 6, 2014, with adaptive optics on the 10-meter Keck II telescope. Credit: Imke De Pater (UC Berkeley) & W. M. Keck Observatory
“This type of activity would have been expected in 2007, when Uranus’s once every 42-year equinox occurred and the sun shined directly on the equator,” noted co-investigator Heidi Hammel of the Association of Universities for Research in Astronomy. “But we predicted that such activity would have died down by now. Why we see these incredible storms now is beyond anybody’s guess.”

In all, de Pater, Hammel and their team detected eight large storms on Uranus’s northern hemisphere when observing the planet with the Keck Observatory on August 5 and 6. One was the brightest storm ever seen on Uranus at 2.2 microns, a wavelength that senses clouds just below the tropopause, where the pressure ranges from about 300 to 500 mbar, or half the pressure at Earth’s surface. The storm accounted for 30 percent of all light reflected by the rest of the planet at this wavelength.

When amateur astronomers heard about the activity, they turned their telescopes on the planet and were amazed to see a bright blotch on the surface of a normally boring blue dot.

‘I got it!’

French amateur astronomer Marc Delcroix processed the amateur images and confirmed the discovery of a bright spot on an image by French amateur Régis De-Bénedictis, then in others taken by fellow amateurs in September and October. He had his own chance on Oct. 3 and 4 to photograph it with the Pic du Midi one-meter telescope, where on the second night, “I caught the feature when it was transiting, and I thought, ‘Yes, I got it!’” said Delcroix.

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Leonid Meteor Shower

The Leonids are one of the better known annual meteor showers. Some years see high Leonid activity, with amazing numbers of meteors. This shower has occasionally created true meteor storms. Unfortunately 2014 is not predicted to be one of those years, with very modest numbers expected.

Leonids in Orion
A pair of Leonid meteors streak through Orion
The shower will peak on November 17 around 22:00UT, with an expected ZHR of around 15 meteors per hour. While this occurs in the middle of the day for the islands, the Leonids exhibit a broad peak allowing viewing for days before and after maximum. Moonlight should not be a problem with a thin waning crescent in the sky.

Due to the gravitational influence of Jupiter, the Leonids are not expected to produce any exceptional showers for some decades. We are unlikely to see any repeats of the early 21st century storms anytime soon.

All Pau

Living in Hawaiʻi you pick up a few additions to your vocabulary. For centuries the islands have been a stew of languages, each borrowing words from one another. Hawaiian, Portuguese, Chinese, Japanese, English, Spanish and more have all added to the flavor of these islands. Everyone uses a few words from other languages in everyday conversation. Then there are local folks who grew up speaking the full mixture, a pidgin unique to the islands.

Radio
A handheld radio used at Keck for daily communication.
Working with a bunch of island guys you need to learn a bit of pidgin simply to understand the conversations around you. To an English speaker, such as myself, the syntax seems mixed about. The words are mostly English and Hawaiian, with a clear context and a little exposure you begin to pick it up. After a while it seems natural to hear pidgin around you.

Some of the words that Hawaiian supplies seem much better than the English equivalents, it is understandable that they are used in preference to the English words. Some are simply more appropriate on an island… Mauka and Makai make perfect sense where everything is either towards the mountain or towards the sea. Puʻu us the perfect name for the numerous volcanic hills that dot the island. Puka, for small hole, just sounds right.

My favorite is Pau, meaning finished or done, a word that is commonly heard on the Keck radio channels. “How are you guys doing up there?” might go the radio chatter, “We all pau!” Something about the word just works, the sound and the meaning in agreement.

I expect these words will stay in my vocabulary, alongside British expressions I picked up living in England decades ago. Language is a fluid and dynamic thing, part of the richness of our lives.