Tag: Keck

New Hypervelocity Binary Star Challenges Dark Matter, Stellar Acceleration Models

W. M. Keck Observatory press release…

A team of astronomers at the Friedrich Alexander University led by Péter Németh has discovered a binary star moving nearly at the escape velocity of our galaxy. There are about two dozen so-called hypervelocity stars known to be escaping the galaxy. While all of them are single stars, PB3877 is the first wide binary star found to travel at such a high speed. Additionally, the results of the new study challenge the commonly accepted scenario that hypervelocity stars are accelerated by the supermassive black hole at the galactic center. The findings are being published in the Astrophysical Journal Letters today.

PB3877 Binary
PB3877 is a hyper-velocity wide binary star zooming through the outskirts of the Milky Way galaxy. This image shows its current location as well as our Sun.
The team, in collaboration with researchers from the California Institute of Technology, showed the binary cannot originate from the Galactic Center, and no other mechanism is known that is able to accelerate a wide binary to such a high velocity without disrupting it. They therefore hypothesized there must be a lot of dark matter to keep the star bound to the Milky Way galaxy; or the binary star, PB3877, could be an intruder that has been born in another galaxy and may or may not leave the Milky Way again.

PB3877 was first reported to be a hyper-velocity, hot compact star, when it was discovered form the Sloan Digital Sky-Survey (SDSS) data in 2011. New spectroscopic observations were done with the 10 meter Keck II telescope at W. M. Keck Observatory on Maunakea, Hawaii and with the 8.2 meter Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile.Caltech astronomers Thomas Kupfer and Felix Fürst observed PB3877 with the ESI Instrument fitted on the Keck II telescope.

“When we looked at the new data, much to our surprise, we found weak absorption lines that could not come from the hot star,” Kupfer said. “The cool companion, just like the hot primary, shows a high radial velocity. Hence, the two stars form a binary system, which is the first hyper-velocity wide binary candidate.”

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Dear Keck Staff

We have a lot of fun when the kids come to visit. We regularly offer tours of Keck to local school groups. When they come we lay in a schedule of activities… Solar telescopes, an IR camera demonstration, tours of our remote operations, the activities can vary depending on the grade level.

After the last tour we got a packet of thank you letters from one of the classes. These are just fun to read, it is great to see what the kids remember from their visit. A drawing of telescopes set up in the lawn caught my eye, I was responsible for running the solar telescope activity!

Dear Keck Staff
A thank you letter from a student after a tour of Keck Observatory

Solved! 40 Year-old Mystery on the Size of Shadowy Galaxies

W. M. Keck Observatory press release…

Using the world’s largest telescopes, researchers discovered ancient cold gas clouds larger than galaxies in the early Universe. The discovery was announced today at a press conference at the 227th meeting of the American Astronomical Society in Orlando, Florida.

Gas Cloud Measurement
Artists impression of the power of background galaxies to measure the size of gas clouds as compared to the conventional method of using quasars. Credit: Adrian Malec (Swinburne University) and Marie Martig (Max Plank Institute)
The discovery, led by Associate Professor Jeff Cooke, Swinburne University of Technology, and Associate Professor John O’Meara, St. Michael’s College, has helped solve a decades-old puzzle on the nature of gas clouds, known as damped Lyman alpha systems, or DLAs.

Cooke and O’Meara realized that finding DLA gas clouds in the line of sight to background galaxies would enable measurements of their size by determining how much of the galaxy they cover.

“Our new method first identifies galaxies that are more likely to have intervening DLA gas clouds and then searches for them using long, deep exposures on the powerful Keck Observatory 10m telescopes on Maunakea and deep data from the VLT 8m telescopes in Chile,” Cooke said. “The technique is timely as the next generation of giant 30m telescopes will be online in several years and are ideal to take advantage of this method to routinely gather large numbers of DLAs for study.”

DLA clouds contain most of the cool gas in the Universe and are predicted to contain enough gas to form most of the stars we see in galaxies around us today, like the Milky Way. However, this prediction has yet to be confirmed.

DLAs currently have little ongoing star formation, making them too dim to observe directly from their emitted light alone. Instead, they are detected when they happen to fall in the line of sight to a more distant bright object and leave an unmistakeable absorption signature in the background object’s light.

Previously, researchers used quasars as the background objects to search for DLAs. Although quasars can be very bright, they are rare and are comparatively small, only a fraction of a light year across, whereas galaxies are quite common and provide a 100 million-fold increase in area to probe DLAs.

“Using the galaxy technique, DLAs can be studied in large numbers to provide a 3-D tomographic picture of distribution of gas clouds in the early Universe and help complete our understanding of how galaxies formed and evolved over cosmic time,” O’Meara said.

Mauna Kea Observatories Put New Spin on Galaxy Formation

W. M. Keck Observatory press release…

A team of Australian researchers used two Maunakea-based observatories – Gemini North and W. M. Keck Observatory – to discover why some galaxies are clumpy rather than spiral in shape and it appears that low spin is to blame. The finding challenges an earlier theory that high levels of gas cause clumpy galaxies, and sheds light on the conditions that brought about the birth of most of the stars in the Universe. The finding was published today in The Astrophysical Journal.

Galaxy Velocity
The massively star-forming galaxies analyzed in this study have clumpy, turbulent gas shown here in false colors. Credit: W. M. Keck Observatory/Gemini Observatory/Hubble
“This result was obtained by a unique and unusual combination of TWO large telescopes,”said Swinburne University astronomer Professor Karl Glazebrook, co-author and leader of the survey team “We used Keck adaptive optics to probe the fine details of galaxy rotation and Gemini to look at the large scale distribution. This made possible a result that was not before known about the spin of early primitive galaxies. It is one of the most exciting results of my career.”

A combination of integral field spectroscopy data from Keck Observatory and Gemini Observatory was the key to obtaining measurements for a galaxy’s spin. Keck Observatory’s OSIRIS instrument collected data high spatial resolution in the galaxy centers, and the Gemini Multi-Object Spectrograph (GMOS) collected data for high surface brightness sensitivity out to large radii.

Lead author Dr. Danail Obreschkow, from The University of Western Australia (UWA) node of the International Centre for Radio Astronomy Research (ICRAR), said that ten billion years ago the Universe was full of clumpy galaxies, but these developed into more regular objects as they evolved; the majority of stars in the sky today, including our five billion-year-old Sun, were probably born inside these clumpy galaxies.

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New Laser Marks Ground Zero for Adaptive Optics Science

W. M. Keck Observatory press release…

Hawaii’s W. M. Keck Observatory has successfully deployed a $4 million laser system that provides a marked increase in the resolution and clarity of what are already the most scientifically productive telescopes on Earth. The new laser was projected on the sky for the first time on the evening of December 1, 2015 and will allow scientists from around the world to observe the heavens above Maunakea in unprecedented detail.

Keck 2 Lasing
The Keck 2 AO laser works the northern sky
“The Next Generation Laser System is the third generation of lasers at Keck Observatory, which has been pioneering Laser Guide Star Adaptive Optics on big telescopes since 2001,” said Jason Chin, the project manager for the new laser at Keck Observatory.

The first Laser Guide Star Adaptive Optics system on a large telescope was commissioned on the Keck II telescope in 2004 and, among many other firsts, helped reveal the black hole at the center of the Milky Way – one the most significant astronomical discoveries. The second laser system was installed in 2011 on the Keck I telescope, propelling Keck Observatory’s lead as the premiere Adaptive Optics research facility in the world. To date more than 240 science results from these laser systems have been published in astronomical journals.

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