Institute of Astronomy

Astronomy News

NASA's Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons Pluto Mission

15 October 2014 - 6:00pm

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The Kuiper Belt is a vast disk of icy debris left over from our Sun's formation 4.6 billion years ago. Kuiper Belt objects (KBOs) are a unique class of solar-system body that has never been visited by interplanetary spacecraft. They contain well-preserved clues to the origin of our solar system. NASA's New Horizons probe will fly by Pluto in mid-2015 and then continue across the Kuiper Belt on its way toward interstellar space. The Hubble Space Telescope was used to do a deep sky survey to identify KBOs that the New Horizons spacecraft could potentially visit on its outbound trajectory. The deep sky survey was successful, and Hubble found targetable KBOs for New Horizons.

NASA’s Hubble Telescope Finds Potential Kuiper Belt Targets for New Horizons Pluto Mission

15 October 2014 - 5:00pm
Peering out to the dim, outer reaches of our solar system, NASA’s Hubble Space Telescope has uncovered three Kuiper Belt objects (KBOs) the agency’s New Horizons spacecraft could potentially visit after it flies by Pluto in July 2015.

ESA confirms the primary landing site for Rosetta

15 October 2014 - 2:19pm
ESA has given the green light for its Rosetta mission to deliver its lander, Philae, to the primary site on 67P/Churyumov-Gerasimenko on 12 November, in the first-ever attempt at a soft touchdown on a comet.

Construction Secrets of a Galactic Metropolis

15 October 2014 - 11:00am
Astronomers have used the APEX telescope to probe a huge galaxy cluster that is forming in the early Universe and revealed that much of the star formation taking place is not only hidden by dust, but also occurring in unexpected places. This is the first time that a full census of the star formation in such an object has been possible.

Astrophysics: How tiny galaxies form stars

15 October 2014 - 1:00am

Astrophysics: How tiny galaxies form stars

Nature 514, 7522 (2014). doi:10.1038/514310a

Authors: Bruce Elmegreen

Observations of two faint galaxies with a low abundance of elements heavier than helium show that the galaxies have an efficiency of star formation less than one-tenth of that of the Milky Way and similar galaxies. See Letter p.335

Inefficient star formation in extremely metal poor galaxies

15 October 2014 - 1:00am

Inefficient star formation in extremely metal poor galaxies

Nature 514, 7522 (2014). doi:10.1038/nature13820

Authors: Yong Shi, Lee Armus, George Helou, Sabrina Stierwalt, Yu Gao, Junzhi Wang, Zhi-Yu Zhang & Qiusheng Gu

The first galaxies contain stars born out of gas with few or no ‘metals’ (that is, elements heavier than helium). The lack of metals is expected to inhibit efficient gas cooling and star formation, but this effect has yet to be observed in galaxies with an oxygen abundance (relative to hydrogen) below a tenth of that of the Sun. Extremely metal poor nearby galaxies may be our best local laboratories for studying in detail the conditions that prevailed in low metallicity galaxies at early epochs. Carbon monoxide emission is unreliable as a tracer of gas at low metallicities, and while dust has been used to trace gas in low-metallicity galaxies, low spatial resolution in the far-infrared has typically led to large uncertainties. Here we report spatially resolved infrared observations of two galaxies with oxygen abundances below ten per cent of the solar value, and show that stars formed very inefficiently in seven star-forming clumps in these galaxies. The efficiencies are less than a tenth of those found in normal, metal rich galaxies today, suggesting that star formation may have been very inefficient in the early Universe.

NASA Mission Provides Its First Look at Martian Upper Atmosphere

14 October 2014 - 5:00pm
NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has provided scientists their first look at a storm of energetic solar particles at Mars, produced unprecedented ultraviolet images of the tenuous oxygen, hydrogen, and carbon coronas surrounding the Red Planet, and yielded a comprehensive map of highly-variable ozone in the atmosphere underlying the coronas.

Dust to dust

14 October 2014 - 1:00am

Dust to dust

Nature 514, 7522 (2014). doi:10.1038/514273b

What lessons can be learned from the presentation of the gravitational-waves story?

Evidence for Young Lunar Volcanism

13 October 2014 - 6:15am
NASA's Lunar Reconnaissance Orbiter has found strong evidence of geologically young volcanic activity on the moon. Some deposits appear to be less than 100 million years old, corresponding to Earth's Cretaceous period, the heyday of dinosaurs.

Lunar volcanoes suggest the moon may still be warm

12 October 2014 - 6:00pm
Newly found patches on the moon suggest lunar volcanism lasted far longer than thought - and that radioactive elements may keep the interior warm today






'IMPs' on moon point to recent lava flows

12 October 2014 - 6:00pm
Newly found "irregular mare patches" suggest lunar volcanism lasted nearly a billion years longer than thought






Desktop sonic black hole emits Hawking radiation

12 October 2014 - 6:00pm
A model black hole that traps sound instead of light has been caught emitting quantum particles - it could be the first time theoretical Hawking radiation has been seen






Explosive meteors may have seasonal peaks

10 October 2014 - 3:02pm
Powerful incoming meteors like the rock responsible for last year's explosion over Chelyabinsk, Russia, may not be completely random after all






Time-out for blog while catalogue production is underway

10 October 2014 - 11:14am

Credit: ESA/ATG medialab; background: ESO/S. Brunier

We started this blog just over one year ago and what a year it has been! We've had the excitement of  the launch, the fabulous first-light image, the challenges of some aspects of commissioning and, more recently, the relief and satisfaction of getting the 'go' for science, and even the first of Gaia's science alerts.

Now that science data have started to flow, the main activity for scientists working on the mission is preparing for the first catalogue release, planned for summer 2016. So while they are busy with that important task, we will take a break on the blog.

But don't worry, this doesn't mean that there will be no news or updates about the Gaia mission. You will be able to keep in touch with the mission via our websites (Space Science Portal,  Science & Technology, and Cosmos), and you can also follow the progress of Gaia via Twitter (@ESAGaia) and using the Gaia Mission app (for iPhones) which can be downloaded from iTunes.

Thanks to all of you for following us through this exciting first year!

The Gaia Team and Blog Editors

 

Hubble reveals most detailed exoplanet weather map ever [heic1422]

9 October 2014 - 7:00pm
A team of scientists using the NASA/ESA Hubble Space Telescope have made the most detailed map ever of the temperature of an exoplanet's atmosphere, and traced the amount of water it contains. The planet targeted for both of the investigations was the hot-Jupiter exoplanet WASP-43b.

Mapping the weather on WASP-43b

9 October 2014 - 7:00pm

A team of scientists, including astronomers from the University of Cambridge, have made the most detailed map ever of the temperature of an exoplanet’s atmosphere, and traced the amount of water it contains. The planet targeted for both of the investigations was the hot-Jupiter exoplanet WASP-43b, which is about 261 light years away in the Sextans constellation.

WASP-43b is a planet the size of Jupiter, but with double the mass and an orbit much closer to its parent star than any planet in the Solar System. It has one of the shortest years ever measured for an exoplanet of its size — lasting just 19 hours.

A team of astronomers working on two companion studies have now created detailed weather maps of WASP-43b, using data from the NASA/ESA Hubble Space Telescope. One study mapped the temperature at different layers in the planet’s atmosphere, and the other traced the amount and distribution of water vapour within it — detail is shown in the video created by the team.

“Our observations are the first of their kind in terms of providing a two-dimensional map of the planet’s thermal structure,” said Kevin Stevenson from the University of Chicago, lead author of the thermal map study. “These maps can be used to constrain circulation models that predict how heat is transported from an exoplanet's hot day side to its cool night side.”

The planet has different sides for day and night because it is tidally locked, meaning that it keeps one hemisphere facing the star, just as the Moon keeps one face toward Earth. The Hubble observations show that the exoplanet has winds that howl at the speed of sound from a day side that is hot enough to melt iron — soaring above 1500 degrees Celsius — to the pitch-black night side that sees temperatures plunge to a comparatively cool 500 degrees Celsius.

To study the atmosphere of WASP-43b the team combined two previous methods of analysing exoplanets for the first time.

By looking at how the parent star’s light filtered through the planet’s atmosphere — a technique called transmission spectroscopy — they determined the water abundance of the atmosphere on the boundary between the day and night hemispheres.

In order to make the map more detailed the team also measured the water abundances and temperatures at different longitudes. To do this they took advantage of the precision and stability of Hubble’s instruments to subtract more than 99.95% of the light from the parent star, allowing them to study the light coming from the planet itself — a technique called emission spectroscopy. By doing this at different points of the planet’s orbit around the parent star they could map the atmosphere across its longitude.

“We have been able to observe three complete rotations — three years for this distant planet — during a span of just four days,” explained Jacob Bean from the University of Chicago, leader of the research project. “This was essential in allowing us to create the first full temperature map for an exoplanet and to probe its atmosphere to find out which elements it held and where.”
Finding the proportions of the different elements in planetary atmospheres provides vital clues to understanding how planets formed.

“Because there’s no planet with these tortured conditions in the Solar System, characterising the atmosphere of such a bizarre world provides a unique laboratory with which to acquire a better understanding of planet formation and planetary physics,” said Nikku Madhusudhan of Cambridge’s Institute of Astronomy, co-author of both studies. “In this case the discovery fits well with pre-existing models of how such planets behave.”

The team found that WASP-43b reflected very little of its host star’s light. An atmosphere like that on Earth, with clouds that reflect most of the sunlight, is not present on WASP-43b, but the team did find water vapour in the planet’s atmosphere.

“The planet is so hot that all the water in its atmosphere is vapourised, rather than condensed into the icy clouds we find on Jupiter,” said team member Laura Kreidberg of the University of Chicago, lead author of the study mapping water on the planet.

Water is thought to play an important role in the formation of giant planets. Astronomers theorise that comet-like bodies bombard young planets, delivering most of the water and other molecules that we observe. However, the water abundances in the giant planets of the Solar System are poorly known because water is locked away as ice, deep in their atmospheres which makes it difficult to identify.

“Space probes have not been able to penetrate deep enough into Jupiter’s atmosphere to obtain a clear measurement of its water abundance. But this giant planet is different,” added Derek Homeier of the École Normale Supérieure de Lyon, co-author of the studies. “WASP-43b’s water is in the form of a vapour that can be much more easily traced. So we could not only find it, we were able to directly measure how much there is and test for variations along the planet’s longitude.”

In WASP-43b the team found the same amount of water as we would expect for an object with the same chemical composition as the Sun.

“This tells us something fundamental about how the planet formed,” added Kreidberg.“Next, we aim to make water-abundance measurements for different planets to explore their chemical abundances and learn more about how planets of different sizes and types come to form around our own Sun and the stars beyond it.”

The results are presented in two new papers, one on the thermal mapping of the planet’s atmosphere — published online in Science Express on 9 October — and the other on mapping the water content of the atmosphere — published in The Astrophysical Journal Letters on 12 September.

Adapted from European Space Agency press release.

Two new studies have been used to make the most detailed weather map for a planet outside the solar system, where typical daytime highs reach 1500 degrees Celsius and winds exceed the speed of sound.

The atmosphere of such a bizarre world provides a unique laboratory with which to acquire a better understanding of planet formation and planetary physicsNikku MadhusudhanNASA, ESA, and Z. Levay (STScI)Exoplanet WASP-43b orbits its parent star

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Hubble Maps the Temperature and Water Vapor on an Extreme Exoplanet

9 October 2014 - 7:00pm

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Located 260 light-years away, exoplanet WASP-43b is no place to call home. It is a world of extremes, where seething winds howl at the speed of sound from a 3,000-degree-Fahrenheit day side, hot enough to melt steel, to a pitch-black night side with plunging temperatures below 1,000 degrees Fahrenheit. The Hubble Space Telescope has been used to make the most detailed global map yet of the thermal glow from this turbulent world. The astronomers were also able to map temperatures at different layers of the world's atmosphere and traced the amount and distribution of water vapor. The Jupiter-sized planet lies so close to its orange dwarf host star that it completes an orbit in just 19 hours. The planet is also gravitationally locked so that it keeps one hemisphere facing the star.

NASA's Hubble Maps the Temperature and Water Vapor on an Extreme Exoplanet

9 October 2014 - 5:00pm
A team of scientists using NASA’s Hubble Space Telescope has made the most detailed global map yet of the glow from a turbulent planet outside our solar system, revealing its secrets of air temperatures and water vapor.

Astronomers discover the ‘Mighty Mouse’ of stellar remnants

8 October 2014 - 6:00pm

“You might think of this pulsar as the ‘Mighty Mouse’ of stellar remnants,” said Fiona Harrison of the California Institute of Technology. “It has all the power of a black hole but with much less mass.”

The discovery, made with NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), is helping astronomers better understand mysterious sources of fierce X-rays, called ultraluminous X-ray sources, or ULXs. Before now, all ULXs were thought to be black holes. New data from NuSTAR show that at least one ULX, about 12 million light-years away in the galaxy Messier 82 (M82), is actually a pulsar.

“The pulsar appears to be eating the equivalent of a black hole diet,” said Harrison, NuSTAR principal investigator.

The discovery, reported in the October 9 issue of the journal Nature, will help astronomers understand how black holes gorge, and grow, so quickly – an important event in the formation of galaxies and structures in the universe.

“This is a surprising and fascinating discovery,” said Professor Andy Fabian of Cambridge’s Institute of Astronomy, one of the paper’s co-authors. “The true nature of ULXs has remained hidden since their discovery about 20 years ago and now one of them is shown to be a pulsar which is nearly 100 times brighter than it should be, according to current accretion ideas. We're all wondering how many other ULXs are similar.”

ULXs are generally thought to be black holes feeding, or accreting, off companion stars. They are suspected to be the long-sought medium-size black holes – missing links between smaller, stellar-size black holes and the gargantuan ones that dominate the hearts of all galaxies. But research into the true nature of ULXs is ongoing.

NuSTAR didn't initially set out to study the two ULXs in M82. Astronomers had been observing a recent supernova in M82, when they noticed a pulse of bright X-rays coming from a point nearby – what turned out to be the ULX called M82 X-2. Black holes don't pulse, but pulsars do.

Pulsars belong to a class of stars called neutron stars. Like black holes, neutron stars are the burnt-out cores of exploded stars, only puny in mass by comparison. Pulsars, discovered by Cambridge’s Jocelyn Bell and Antony Hewish in 1967, are neutron stars that send out beams of light. As the star spins, these beams intercept Earth like lighthouse beacons, producing a pulsed signal.

“We took it for granted that the powerful ULXs must be massive black holes,” said Matteo Bachetti, lead author of the paper from the University of Toulouse. “When we first saw the pulsations in the data, we thought they must be from another source.”

NASA's Chandra X-ray Observatory and Swift satellite had also been monitoring M82 to study the same supernova, and confirm that the intense X-rays of M82 X-2 were coming from a pulsar.

“Having a diverse array of telescopes in space means that they can help each other out,” said Paul Hertz, director of NASA's astrophysics division in Washington. “When one telescope makes a discovery, others can be called in for backup.”

The key to NuSTAR's discovery was in its sensitivity to X-rays in the highest-energy ranges as well as its ability to precisely measure the timing of the signals. This timing capability allowed the astronomers to measure a pulse rate from M82 X-2 of 1.37 seconds. They also measured its energy output at the equivalent of 10 million suns, or 10 times more than what was measured before – a big punch for something about the mass of the sun and half the size of Cambridge.

How is this puny dead star radiating so fervently? Astronomers aren't sure, but they say it is likely due to a lavish feast of the cosmic kind. As is the case with black holes, the gravity of a neutron star can pull matter off companion stars. As the matter is dragged into the neutron star, it heats up and glows with X-rays. If the pulsar is indeed feeding off surrounding matter, it is doing so at such an extreme rate to have theorists scratching their heads.

Astronomers are planning follow-up observations with NuSTAR, Swift and Chandra to help explain the bizarre behavior. The NuSTAR team will also look at more ULXs, and it's possible they could turn up more pulsars. At this point, it is not clear if the M82 X-2 is an oddball or if more ULXs beat with the pulse of dead stars. NuSTAR, a relatively small telescope, has thrown a big loop into the mystery of black holes.

Adapted from NASA press release.

An international team of astronomers has found a pulsating, dead star beaming with the energy of about 10 million suns. This is the brightest pulsar – a dense stellar remnant left over from a supernova explosion – ever recorded.

The true nature of ULXs has remained hidden since their discovery about 20 years agoAndy FabianNASA/JPL-Caltech

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