Posts Tagged ‘telescope’

NOAO: The Coolest Known White Dwarf: A Diamond In The Sky?

“Up above the world so high, like a diamond in the sky…” A team of astronomers, using multiple telescopes, has identified the coolest, faintest white dwarf star known. White dwarfs are the extremely dense end states of stars like our sun: after their nuclear fuel is exhausted, they collapse from the size of a star (about 1,000,000 miles across) to the size of the Earth (7,000 miles across). This white dwarf, located in the constellation Aquarius, is so cool that its carbon has crystallized—in other words, it’s like a diamond, with a mass similar to that of our sun.

The path to this discovery began when Dr. Jason Boyles, then a graduate student at West Virginia University, identified what astronomers refer to as a millisecond pulsar in this location. Pulsars are spinning neutron stars—the collapsed end state of a star many times more massive than our sun, but only about 20 miles across. Known as PSR J2222-0137, which simply identifies its position in the sky, this pulsar is spinning over 30 times a second. Its orientation is such that as it spins, a beam from its magnetic pole sweeps repeatedly past the earth, giving rise to regular blips of radio waves. (The pulsar is detected only in radio waves, not in visible light.) The observations also revealed that this pulsar is gravitationally bound to a companion star: the two orbit around each other every 2.45 days. It is this companion object that appears to be either another neutron star or, more likely, a remarkably cool white dwarf.

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NOAO: A Sharp Eye On Southern Binary Stars

Unlike our sun, with its retinue of orbiting planets, many stars in the sky orbit around a second star. These binary stars, with orbital periods ranging from days to centuries, have long been the primary tool for measuring basic quantities like the star’s mass. While masses of normal stars are now well determined, some binaries present special interest because their stars are unusual (e.g. very young) or because they may contain planets, gas clouds, or other stars.

Now, astronomers at the Cerro Tololo Inter-American Observatory (CTIO) and at the US Naval Observatory (USNO) are making use of the latest technology, speckle imaging, to measure the separation of close binary stars. By observing them over a period of years, their obits have been determined with exquisite precision.

Using the new speckle camera at the 4.1-m Southern Astrophysical Research Telescope (SOAR) in Chile with its novel electron-multiplication CCD detector, the team is able to measure the angular separation of stars down to 25 milli arcseconds: this is equivalent to measuring the size of a quarter atop the Empire State building in New York – from Washington, DC. This is over 2000 times better than the human eye can resolve. As Dr. Andrei Tokovinin, the lead author on the paper, said: “This camera surpasses adaptive-optics instruments at the 8-m telescopes, which work in the infrared and can only resolve binaries wider than 50 milli arcseconds.“

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NOAO/Gemini: Sakurai’s Object: Stellar Evolution In Real Time

Stellar lifetimes are measured in billions of years, so changes in their appearance rarely take place on a human timescale. Thus an opportunity to observe a star passing from one stage of life to another on a timescale of months to years is very exciting, as there are only a very few examples known. One such star is Sakurai’s Object (V4334 Sgr). First reported by a Japanese amateur astronomer in 1996 as a “nova-like object,” Sakurai’s Object had been only a few years before the faint central star of a planetary nebula. In the 1990’s Sakurai’s Object brightened by a factor of 10000. This brightening has been attributed to a final helium shell flash. In this process the burned out core of the star at the center of the planetary nebula re-ignites.

The final helium shell flash is violent, ejecting a cloud of dust and gas that forms a thick cocoon around the star blocking all visible light. By 2000 the dust cloud was so thick that Sakurai’s Object was not visible even with the Hubble Space Telescope (HST). Scientists at the National Optical Astronomy Observatory (NOAO) have been observing the sky in the area of Sakurai’s Object waiting for infrared radiation to break through the dust cloud. Infrared radiation penetrates dust much more efficiently than optical light. A detection of the infrared light would mean that the dust cloud is breaking apart, ultimately permitting light from the star to escape.

Using the Altair adaptive optics (AO) system with the Gemini North telescope on Mauna Kea in Hawai’i to compensate for distortions to starlight caused by the Earth’s atmosphere, two NOAO astronomers were able to observe the shell of escaping material around the star. According to Dr. Richard Joyce, who was in charge of the imaging program, “Using AO at Gemini gave us an unprecedented view into the heart of this object and showed us a number of faint stars where Sakurai’s Object should be.”

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ESA’s Billion Star Surveyor: UCL’s Contribution

December 18, 2013 Leave a comment

On Thursday 19 December at 09:12 GMT, a satellite designed to unlock the secrets of the birth and evolution of the Milky Way Galaxy will be launched by the European Space Agency.

UCL’s Mullard Space Science Laboratory has played a major part in the satellite – named Gaia – for 12 years, developing the instrument that will measure the speed, temperature, size and age of over a billion stars in our galaxy.

Gaia’s mission is to slowly scan the sky, rotating every six hours, and survey the whole sky some hundred times in its six year mission. It has two extraordinarily stable telescopes, each focussing on the same huge array of 106 electronic detectors, the biggest ever either launched into orbit or on any Earth-based telescope.

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Neutrinos On Ice Now The Coolest New Astronomy Tool

November 21, 2013 Leave a comment

The IceCube Lab. Credit: Sven Lidstrom. IceCube/NSF

The IceCube Lab. Credit: Sven Lidstrom. IceCube/NSF

A massive telescope buried in the Antarctic ice has detected 28 record-breaking, extremely high-energy neutrinos — elementary particles that likely originate outside our solar system. The achievement, which comes nearly 25 years after the pioneering idea of detecting neutrinos in ice, provides the first solid evidence for astrophysical neutrinos from cosmic accelerators and has been hailed as the dawn of a new age of astronomy. The team researchers that detected the neutrinos with the new IceCube Neutrino Observatory in Antarctica, which includes Penn State scientists, will publish a paper describing the detections on 22 November 2013 in the journal Science.

“While it is premature to speculate about the precise origin of these neutrinos, their energies are too high to be produced by cosmic rays interacting in the Earth’s atmosphere, strongly suggesting that they are produced by distant accelerators of subatomic particles elsewhere in our galaxy, or even farther away,” said Penn State Associate Professor of Physics Tyce DeYoung, the deputy spokesperson of the IceCube Collaboration.

The neutrinos had energies greater than 1,000,000,000,000,000 electron volts or, as the scientists say, 1 peta-electron volt (PeV). Two of these neutrinos had energies many thousands of times higher than the highest-energy neutrino that any man-made particle accelerator has ever produced.

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Gemini Observatory Press Release/Image Release

Credit: Gemini Observatory/AURA

Credit: Gemini Observatory/AURA

Gemini Observatory’s latest tool for astronomers, a second-generation infrared instrument called FLAMINGOS-2, has “traveled a long road” to begin science observations for the Gemini scientific community. Recent images taken by FLAMINGOS-2 during its last commissioning phase dramatically illustrate that the instrument was worth the wait for astronomers around the world who are anxious to begin using it.

“It’s already one of our most requested instruments at the Gemini telescopes,” remarks Nancy Levenson, Gemini’s Deputy Director and Head of Science. “We see a long and productive life ahead for FLAMINGOS-2 once astronomers really start using it later this year.”

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A New View On The Origin Of Dark Matter And Dark Energy – Image Of M31 Heralds The Dawn Of HSC –

 31 captured by Hyper Suprime-Cam (HSC) Credit: HSC Project/NAOJ

31 captured by Hyper Suprime-Cam (HSC) Credit: HSC Project/NAOJ

A stunning image of M 31 captured by Subaru Telescope’s Hyper-Suprime Cam (HSC) displays the fruits of international collaboration and technological sophistication aligned with cutting-edge science. In addition to providing information about a nearby galaxy that resembles our own, this image demonstrates HSC’s capability to fulfill Subaru Telescope’s intention of producing a large-scale survey of the Universe. The combination of a large mirror, a wide field of view, and sharp imaging represents a giant step into a new era of observational astronomy and will contribute to answering questions about the nature of dark energy and matter. It marks another successful stage in HSC’s commissioning process, which involves checking all of HSC’s capabilities before it is ready for open use.

HSC’s first beautiful image of M 31 gives an answer to the question: Does HSC really deliver what it promises in terms of image quality? It displays a resounding “yes” by demonstrating the sharp, detailed resolution of which the camera is capable across the wide field of view that it embraces. The image indicates why this powerful instrument is unique within the domain of current observational technology, enabling high-resolution images from observations with a large primary mirror (8.2 m) and large field of view (1.5 degrees).

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