Astronomy – Page 78 – A Darker View

Hot Jupiter-esque Discovery Hints at Planet Formation

A team of astronomers discovered a Jupiter-like planet within a young system that could serve as a decoder ring for understanding how planets formed around our sun. The W. M. Keck Observatory on Maunakea, Hawaii confirmed the discovery. The findings were headed by Bruce Macintosh, a professor of physics at Stanford University, and show the new planet, 51 Eridani b, is one million times fainter than its parent star and shows the strongest methane signature ever detected on an alien planet, which should yield additional clues as to how the planet formed. The results are published in the current issue of Science.

51Eri b — Image of 51 Eri b as seen by the NIRC2 instrument on Keck Observatory’s Keck II telescope. Credit: W. M. Keck Observatory, Christian Marois, NRC Canada

“This is the first exoplanet discovered with the Gemini Planet Imager, one of the new generation instruments designed specifically for discovering and analyzing faint, young planets orbiting bright stars,” said Franck Marchis, Senior Planetary Astronomer at the SETI Institute and member of the team that built the instrument and now conducts the survey.

While NASA’s Kepler space observatory has discovered thousands of planets, it does so indirectly by detecting a loss of starlight as a planet passes in front of its star, the Gemini Planet Imager was designed specifically for discovering and analyzing faint, young planets orbiting bright stars.

“To detect planets, Kepler sees their shadow,” said Macintosh, who is also a member of the Kavli Institute for Particle Astrophysics and Cosmology. “The Gemini Planet Imager instead sees their glow, which we refer to as direct imaging.”

Akin to trying to detect a firefly in front of a lighthouse, the team analyzed the light from the star, then blocked it out. The remaining incoming light was analyzed, with the brightest spots indicating a possible planet.

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Perseid Meteor Shower

Over the next few days the Perseid meteor shower will peak. As the most reliable shower each year this is also the most viewed meteor shower. Plentiful shooting stars combined with warm summer evenings makes this shower the easiest and most comfortable to view across much of the northern hemisphere. Quite a difference from the other reliable showers such as the Leonids and Quadrantids, that occur in November and January. Consider a warm summer night under a dark sky full of stars, a picnic blanket, relaxing while shooting stars streak across the sky. What could be better?

Leonids in Orion — A pair of Leonid meteors streak through Orion

The Perseid meteor shower occurs when the Earth passes through a stream of debris along the orbit of Comet Swift-Tuttle. This shower has been consistent throughout recorded history, mentioned in Chinese, Japanese and Korean records as early as the 1st century. Active from July 17th to August 24th, the shower will build slowly for weeks before the peak. A week before or after peak the shower can still be seen with around 20 meteors each hour. The shower is a northern hemisphere event, for southern observers the radiant never rises above the horizon.

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Hawaiian Heavens

You might recall a post from back in May describing a night spent on the summit with Jason Chu. He has been accumulating time lapse material for a significant project, capturing the telescopes of Mauna Kea under the beauty of the night sky.

Jason has published a preview of the work. Nice to see it come to life with a decent soundtrack and good editing…

New Record: Keck Observatory Measures Most Distant Galaxy

W. M. Keck Observatory press release…

A team of astrophysicists using the W. M. Keck Observatory in Hawaii has successfully measured the farthest galaxy ever recorded and more interestingly, captured its hydrogen emission as seen when the Universe was less than 600 million years old. Additionally, the method in which the galaxy called EGSY8p7 was detected gives important insight into how the very first stars in the Universe lit-up after the Big Bang. The paper will be published shortly in the Astrophysical Journal Letters.

Galaxy EGSY8p7 — EGSY8p7 is the most distant confirmed galaxy whose spectrum obtained with the W. M. Keck Observatory places it at a redshift of 8.68 at a time when the Universe was less than 600 million years old. Credit: Adi Zitrin, California Institute of Technology

Using Keck Observatory’s powerful infrared spectrograph called MOSFIRE, the team dated the galaxy by detecting its Lyman-alpha emission line – a signature of hot hydrogen gas heated by strong ultraviolet emission from newly born stars. Although this is a frequently detected signature in galaxies close to Earth, the detection of Lyman-alpha emission at such a great distance is unexpected as it is easily absorbed by the numerous hydrogen atoms thought to pervade the space between galaxies at the dawn of the Universe. The result gives new insight into

cosmic reionization’, the process by which dark clouds of hydrogen were split into their constituent protons and electrons by the first generation of galaxies.
“We frequently see the Lyman-alpha emission line of hydrogen in nearby objects as it is one of most reliable tracers of star-formation,” said California Institute of Technology (Caltech) astronomer, Adi Zitrin, lead author of the discovery paper. “However, as we penetrate deeper into the Universe, and hence back to earlier times, the space between galaxies contains an increasing number of dark clouds of hydrogen which absorb this signal.”
Recent work has found the fraction of galaxies showing this prominent line declines markedly after when the Universe was about a billion years old, which is equivalent to a redshift of about 6. Redshift is a measure of how much the Universe has expanded since the light left a distant source and can only be determined for faint objects with a spectrograph on a powerful large telescope such as the Keck Observatory’s twin 10-meter telescopes, the largest on Earth.

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Mercury Appears in the Evening Sky

The planet Mercury is starting an evening apparition. The planet should become visible this week just above the fading glow of the setting Sun as a magnitude -1 object. The planet is moving about 1° further from the Sun and higher in the sunset each day, reaching a maximum elongation of 27° on September 4th. This will be the best evening apparition for Mercury in 2015.

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Keck Observatory Astronomer Wins Major Prize

W. M. Keck Observatory press release…

UCLA professor and longtime W. M. Keck Observatory astronomer, Andrea Ghez will be awarded the 2015 Bakerian Medal, the Royal Society’s premiere prize lecture in the physical sciences, the organization announced this week.

“I’m thrilled to receive the Bakerian Medal from the Royal Society,” said Ghez, who is UCLA’s Lauren B. Leichtman and Arthur E. Levine Professor of Astrophysics. “The research that is being recognized is the product of a wonderful collaboration among the scientists in the UCLA Galactic Center Group and the University of California’s tremendous investment in the W. M. Keck Observatory. Having cutting-edge tools and a great team makes discovery easy.”

The medal is accompanied by a cash prize of 10,000 pounds (approximately $15,500), and Ghez will deliver the Bakerian Lecture in London in November. The organization, the oldest scientific academy in continuous existence, cited Ghez’s “acclaimed discoveries using the techniques of optical astronomy, especially her sustained work on the motions and nature of the stars orbiting the black hole in the centre of our Galaxy.”

“All the data for this project came from Keck Observatory,” Ghez said. “We were able to launch this project 20 years ago because of the unique way that Keck Observatory works. We were able to modify instrumentation and try new approaches to data collection in a way that simply isn’t possible at other observatories. Working at Keck Observatory and with the staff there has been an amazing experience.”

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Telescopes Team Up to Find Distant Uranus-Sized Planet Through Microlensing

W. M. Keck Observatory press release…

The W. M. Keck Observatory in Hawaii and NASA’s Hubble Space Telescope have made independent confirmations of an exoplanet orbiting far from its central star. The planet was discovered through a technique called gravitational microlensing. This finding opens a new piece of discovery space in the extrasolar planet hunt: to uncover planets as far from their central stars as Jupiter and Saturn are from our sun. The Hubble and Keck Observatory results will appear in two papers in the July 30 edition of The Astrophysical Journal.

OGLE-2005-BLG-169 Microlensing — A graphic explanation of the microlensing study of OGLE-2005-BLG-169. Credit: NASA, ESA, and A. Feild (STSCI)

The large majority of exoplanets cataloged so far are very close to their host stars because several current planet-hunting techniques favor finding planets in short-period orbits. But this is not the case with the microlensing technique, which can find more distant and colder planets in long-period orbits that other methods cannot detect.

Microlensing occurs when a foreground star amplifies the light of a background star that momentarily aligns with it. If the foreground star has planets, then the planets may also amplify the light of the background star, but for a much shorter period of time than their host star. The exact timing and amount of light amplification can reveal clues to the nature of the foreground star and its accompanying planets.

“Microlensing is currently the only method to detect the planets close to their birth place,” said team member, Jean-Philippe Beaulieu, Institut d’Astrophysique de Paris. “Indeed, planets are being mostly formed at a certain distance from the central star where it is cold enough for volatile compounds to condense into solid ice grains. These grains will then aggregate and will ultimately evolve into planets.”

The system, cataloged as OGLE-2005-BLG-169, was discovered in 2005 by the Optical Gravitational Lensing Experiment (OGLE), the Microlensing Follow-Up Network (MicroFUN), and members of the Microlensing Observations in Astrophysics (MOA) collaborations—groups that search for extrasolar planets through gravitational microlensing.

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Full Moon

Full Moon will occur today at 00:43HST.

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Fossil Star Clusters Reveal Their Age

W. M. Keck Observatory press release…

Using a new age-dating method and the W. M. Keck Observatory on Maunakea, an international team of astronomers have determined that ancient star clusters formed in two distinct epochs – the first 12.5 billion years ago and the second 11.5 billion years ago. These results are being published in Monthly Notices of the Royal Astronomical Society.

Cosmic Timeline of Globular Clusters — A cosmic timeline showing the birth of the Universe in a Big Bang 13.7 billion years ago to the present day. Credit: NASA/CXC/SAO and A. Romanowsky

Although the clusters are almost as old as the Universe itself, these age measurements show the star clusters – called globular clusters – are actually slightly younger than previously thought.

“We now think that globular clusters formed alongside galaxies rather than significantly before them,” research team leader, Professor Duncan Forbes of Swinburne University of Technology said.

The new estimates of the star cluster average ages were made possible using data obtained from the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, which was carried out on Keck Observatory’s 10-meter, Keck II telescope. Observations were carried out over years using the powerful DEIMOS multi-object spectrograph fitted on Keck II, which is capable of obtaining spectra of one hundred globular clusters in a single exposure.

DEIMOS breaks the visible wavelengths of objects into spectra, which the team used to reverse-engineer the ages of the globular clusters by comparing the chemical composition of the globular clusters with the chemical composition of the Universe as it changes with time.

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Venus Disappears into the Sunset

The 2015 evening apparition of Venus is drawing to a close. Already quite low in the sky at sunset the planet will disappear into the bright glow over the next couple weeks. Venus will pass through inferior conjunction on August 15th and reappear in the dawn during the first weeks of September.

Accompanying Venus into solar conjuntion is the bright planet Jupiter, continuing their dance in the sunset.

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