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Archival Hubble Images Reveal Neptune’s “Lost” Inner Moon

October 9, 2013 1 comment

Neptune’s tiny, innermost moon, Naiad, has now been seen for the first time since it was discovered by Voyager’s cameras in 1989. Dr. Mark Showalter, a senior research scientist at the SETI Institute in Mountain View, California, announced the result today in Denver, Colorado, at the annual meeting of the Division for Planetary Sciences of the American Astronomical Society. He and collaborators Dr. Jack Lissauer of the NASA Ames Research Center, Dr. Imke de Pater of UC Berkeley, and Robert French of the SETI Institute, also released a dramatic new image of Neptune’s puzzling rings and ring-arcs, which were first imaged by Voyager.

“Naiad has been an elusive target ever since Voyager left the Neptune system,” said Dr. Showalter. From Earth, Neptune is 2 million times brighter than Naiad, and the two are separated by only one arcsecond. “This is equivalent to the width of a human hair from 50 feet away,” noted collaborator Lissauer. The team of astronomers needed to develop new techniques to suppress Neptune’s glare. Naiad was finally revealed, moving across a sequence of eight images taken during December 2004.

Strangely, Naiad appears to have veered significantly off course. The astronomers are puzzled by the fact that Naiad is now far ahead of its predicted orbital position. They wonder whether gravitational interactions with one of Neptune’s other moons may have caused it to speed up, although the details remain mysterious. Further observations will be needed in order to understand Naiad’s motion.

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Soft Shells And Strange Star Clusters

October 9, 2013 Leave a comment

Credit: ESA/Hubble & NASA

Credit: ESA/Hubble & NASA

PGC 6240 is an elliptical galaxy that resembles a pale rose in the sky, with hazy shells of stars encircling a very bright centre. Some of these shells are packed close to the centre of the galaxy, while others are flung further out into space. Several wisps of material have been thrown so far that they appear to be almost detached from the galaxy altogether.

Astronomers have studied PGC 6240 in detail due to this structure, and also because of its surrounding globular clusters — dense, tightly packed groups of gravitationally bound stars that orbit galaxies. Over 150 of these clusters orbit our own galaxy, the Milky Way, all composed of old stars.

All the globular clusters around a certain galaxy form at approximately the same time, giving them all the same age. This is echoed within the clusters — all the stars within a single cluster form at around the same time, too. Because of this, most galaxies have cluster populations of pretty similar ages, both in terms of overall cluster, and individual stars. However, PGC 6240 is unusual in that its clusters are varied — while some do contain old stars, as expected, others contain younger stars which formed more recently.

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Comet C/ISON Details Emerge As It Races Toward The Sun

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Scientists are unraveling more information on Comet C/2012 S1 (ISON) as it continues on its journey toward the Sun. Comet C/ISON will skim 730,000 miles above the Sun’s surface on Nov. 28 and has the potential to be readily visible from Earth starting in early December.

“We measured the rotational pole of the nucleus. The pole indicates that only one side of the comet is being heated by the Sun on its way in until approximately one week before it reaches it closest point to the Sun,” said Planetary Science Institute Research Scientist Jian-Yang Li, who led a team that imaged the comet.

“Since the surface on the dark side of the comet should still retain a large fraction of very volatile materials, the sudden exposure to the strong sunlight when it gets closer to the Sun than Mercury could trigger huge outbursts of material,” Li said.

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Diamond ‘Super-Earth’ May Not be Quite As Precious, UA Graduate Student Finds

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A planet 40 light years from our solar system, believed to be the first-ever discovered planet to consist largely of diamond, may in fact be of less exquisite nature, according to new research led by University of Arizona astronomy graduate student Johanna Teske.

Revisiting public data from previous telescope observations, Teske’s team analyzed the available data in more detail and concluded that carbon – the chemical element diamonds are made of – appears to be less abundant in relation to oxygen in the planet’s host star – and by extension, perhaps the planet – than was suggested by a study of the host star published in 2010.

“The 2010 paper found that ’55 Cancri,’ a star that hosts five planets, has a carbon-to-oxygen ratio greater than one,” Teske said. “This observation helped motivate a paper last year about the innermost planet of the system, the ‘super-Earth’ 55 Cancri e. Using observations of the planet’s mass and radius to create models of its interior that assumed the same carbon-to-oxygen ratio of the star, the 2012 paper suggested the planet contains more carbon than oxygen.”

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Mars Hand Lens Imager Sends Ultra High-Res Photo From Mars

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Credit: NASA/JPL-Caltech/MSSS/Planetary Science Institute

Credit: NASA/JPL-Caltech/MSSS/Planetary Science Institute

An instrument aboard NASA’s Curiosity rover has sent back to scientists on Earth an ultra high-resolution image of a penny the rover carried to Mars.

The coin was photographed by the Mars Hand Lens Imager (MAHLI) aboard Curiosity in northern Gale crater on Mars. The penny, a 1909 VDB penny minted in Philadelphia during the first year that Lincoln cents became available, is part of the MAHLI calibration target and came from Earth. The images were acquired on Oct. 2, on sol 411 – the 411th Martian day – of the mission.

“I’m so proud of how beautifully this camera has performed on Mars,” said R. Aileen Yingst, Planetary Science Institute Senior Scientist and deputy Principal Investigator for MAHLI. “I can’t wait to apply this newly available capability to real geologic targets on our way to Mt. Sharp.”

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A Close Look At The Toby Jug Nebula

October 9, 2013 Leave a comment

Credit: ESO

Credit: ESO

Located about 1200 light-years from Earth in the southern constellation of Carina (The Ship’s Keel), the Toby Jug Nebula, more formally known as IC 2220, is an example of a reflection nebula. It is a cloud of gas and dust illuminated from within by a star called HD 65750. This star, a type known as a red giant, has five times the mass of our Sun but it is in a much more advanced stage of its life, despite its comparatively young age of around 50 million years.

The nebula was created by the star, which is losing part of its mass out into the surrounding space, forming a cloud of gas and dust as the material cools. The dust consists of elements such as carbon and simple, heat-resistant compounds such as titanium dioxide and calcium oxide (lime). In this case, detailed studies of the object in infrared light point to silicon dioxide (silica) being the most likely compound reflecting the star’s light.

IC 2220 is visible as the star’s light is reflected off the grains of dust. This celestial butterfly structure is almost symmetrical, and spans about one light-year. This phase of a star’s life is short-lived and such objects are thus rare.

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First Ever Evidence Of A Comet Striking Earth

October 9, 2013 Leave a comment

Tutankhamun's brooch. (no copyright)

Tutankhamun’s brooch. (no copyright)

The first ever evidence of a comet entering Earth’s atmosphere and exploding, raining down a shock wave of fire which obliterated every life form in its path, has been discovered by a team of South African scientists and international collaborators, and will be presented at a public lecture on Thursday.

The discovery has not only provided the first definitive proof of a comet striking Earth, millions of years ago, but it could also help us to unlock, in the future, the secrets of the formation of our solar system.

“Comets always visit our skies – they’re these dirty snowballs of ice mixed with dust – but never before in history has material from a comet ever been found on Earth,” says Professor David Block of Wits University.

The comet entered Earth’s atmosphere above Egypt about 28 million years ago. As it entered the atmosphere, it exploded, heating up the sand beneath it to a temperature of about 2 000 degrees Celsius, and resulting in the formation of a huge amount of yellow silica glass which lies scattered over a 6 000 square kilometer area in the Sahara. A magnificent specimen of the glass, polished by ancient jewellers, is found in Tutankhamun’s brooch with its striking yellow-brown scarab.

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