Institute of Astronomy

Feed aggregator

Astrophysics: Portrait of a doomed star

Astronomy News - 6 August 2014 - 1:00am

Astrophysics: Portrait of a doomed star

Nature 512, 7512 (2014). doi:10.1038/512034a

Authors: Stephen Justham

Some stars explode in thermonuclear supernovae, but understanding of why this occurs comes mainly from indirect clues. Now, the progenitor of a member of a strange class of such explosions may have been detected directly. See Letterp.54

A luminous, blue progenitor system for the type Iax supernova 2012Z

Astronomy News - 6 August 2014 - 1:00am

A luminous, blue progenitor system for the type Iax supernova 2012Z

Nature 512, 7512 (2014). doi:10.1038/nature13615

Authors: Curtis McCully, Saurabh W. Jha, Ryan J. Foley, Lars Bildsten, Wen-fai Fong, Robert P. Kirshner, G. H. Marion, Adam G. Riess & Maximilian D. Stritzinger

Type Iax supernovae are stellar explosions that are spectroscopically similar to some type Ia supernovae at the time of maximum light emission, except with lower ejecta velocities. They are also distinguished by lower luminosities. At late times, their spectroscopic properties diverge from those of other supernovae, but their composition (dominated by iron-group and intermediate-mass elements) suggests a physical connection to normal type Ia supernovae. Supernovae of type Iax are not rare; they occur at a rate between 5 and 30 per cent of the normal type Ia rate. The leading models for type Iax supernovae are thermonuclear explosions of accreting carbon–oxygen white dwarfs that do not completely unbind the star, implying that they are ‘less successful’ versions of normal type Ia supernovae, where complete stellar disruption is observed. Here we report the detection of the luminous, blue progenitor system of the type Iax SN 2012Z in deep pre-explosion imaging. The progenitor system's luminosity, colours, environment and similarity to the progenitor of the Galactic helium nova V445 Puppis suggest that SN 2012Z was the explosion of a white dwarf accreting material from a helium-star companion. Observations over the next few years, after SN 2012Z has faded, will either confirm this hypothesis or perhaps show that this supernova was actually the explosive death of a massive star.

Comets up close

Astronomy News - 5 August 2014 - 6:08pm
Rosetta's visit to comet 67P breaks new ground, but we have seen five others from close range in the past

Rosetta probe set to catch comet

Astronomy News - 5 August 2014 - 6:04pm
Europe's long travelling satellite is set to rendezvous with one of the strangest objects in the solar system.

Binary star to spill celestial secrets

Astronomy News - 5 August 2014 - 1:00am

Binary star to spill celestial secrets

Nature 512, 7512 (2014). http://www.nature.com/doifinder/10.1038/512013a

Author: Alexandra Witze

Close approach and violent interaction of stars in η Carinae system will provide rare insight into stellar enigma.

Rosetta:Rosetta arrives at comet 67P/C-G - follow the event live

Astronomy News - 4 August 2014 - 4:26pm
On 6 August, after a decade-long journey through space, ESA’s Rosetta will become the first spacecraft in history to rendezvous with a comet. Follow the event marking this momentous occasion at ESA's Spacecraft Operations Centre at Darmstadt, Germany.

Amazing New Photo of Rosetta Comet

Astronomy News - 2 August 2014 - 8:52pm
As the European Space Agency's Rosetta spacecraft closes to within 1000 km of Comet 67P/Churyumov-Gerasimenko, the Rosetta science team has released a new image and made the first temperature measurements of the comet's core. The temperature data show that 67P is too hot to be covered in ice and must instead have a dark, dusty crust.

Rosetta:Rosetta takes comet's temperature

Astronomy News - 1 August 2014 - 1:33pm
ESA's Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust.

Comet mission must not keep space fans in the dark

Astronomy News - 31 July 2014 - 5:57pm
The European Space Agency should change tack and not sit on pictures from a pioneering mission to a comet, says space science writer Daniel Fischer






NASA's Fermi Space Telescope Reveals New Source of Gamma Rays

Astronomy News - 31 July 2014 - 5:00pm
Observations by NASA's Fermi Gamma-ray Space Telescope of several stellar eruptions, called novae, firmly establish these relatively common outbursts almost always produce gamma rays, the most energetic form of light.

Hubble Shows Farthest Lensing Galaxy Yields Clues to Early Universe

Astronomy News - 31 July 2014 - 5:00pm
Astronomers using NASA's Hubble Space Telescope have unexpectedly discovered the most distant galaxy that acts as a cosmic magnifying glass.

Hubble Shows Farthest Lensing Galaxy Yields Clues to Early Universe

Astronomy News - 31 July 2014 - 3:00pm

Get larger image formats

Astronomers using NASA's Hubble Space Telescope have unexpectedly discovered the most distant cosmic magnifying glass yet, produced by a monster elliptical galaxy. The galaxy, seen here as it looked 9.6 billion years ago, is so massive that its gravity bends, magnifies, and distorts light from objects behind it, a phenomenon called gravitational lensing. In the Hubble image, the galaxy is the red object in the enlarged view at left.

Rosetta:Catching up with the comet's coma

Astronomy News - 31 July 2014 - 11:13am
With the incredible images of comet 67P/Churyumov-Gerasimenko's nucleus grabbing most of the attention over the last few weeks, we shouldn't forget about the comet's coma. Of course, you can still find the most recent image of the nucleus later on in this post, but first let's talk about coma and activity.

Mystery of lemon-shaped Moon solved

Astronomy News - 30 July 2014 - 6:14pm
Tides and spin gave the Moon its strange lemon shape more than four billion years ago, research reveals.

ALMA Finds Double Star with Weird and Wild Planet-forming Discs

Astronomy News - 30 July 2014 - 6:00pm
Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have found wildly misaligned planet-forming gas discs around the two young stars in the binary system HK Tauri. These new ALMA observations provide the clearest picture ever of protoplanetary discs in a double star. The new result also helps to explain why so many exoplanets — unlike the planets in the Solar System — came to have strange, eccentric or inclined orbits. The results will appear in the journal Nature on 31 July 2014.

Leaving Earth made the moon lemon-shaped

Astronomy News - 30 July 2014 - 6:00pm
The moon has odd lemon-like bulges on each side. A new model shows they were caused by the pull of Earth's gravity when the moon was young






Pigeon paradox reveals quantum cosmic connections

Astronomy News - 30 July 2014 - 6:00pm
A thought experiment has exposed a new kind of quantum link that could connect every particle in the universe, all the time






AUDIO: Why the Moon is shaped like a lemon

Astronomy News - 30 July 2014 - 5:54pm
Professor of planetary sciences Ian Garrick-Bethell explains what gave the Moon its unusually distorted shape.

Astronomers weigh up Milky Way

Astronomy News - 30 July 2014 - 1:11am
The Milky Way is lighter than previously thought and is only about half the mass of a neighbouring galaxy, researchers conclude.

The tidal–rotational shape of the Moon and evidence for polar wander

Astronomy News - 30 July 2014 - 1:00am

The tidal–rotational shape of the Moon and evidence for polar wander

Nature 512, 7513 (2014). doi:10.1038/nature13639

Authors: Ian Garrick-Bethell, Viranga Perera, Francis Nimmo & Maria T. Zuber

The origin of the Moon’s large-scale topography is important for understanding lunar geology, lunar orbital evolution and the Moon’s orientation in the sky. Previous hypotheses for its origin have included late accretion events, large impacts, tidal effects and convection processes. However, testing these hypotheses and quantifying the Moon’s topography is complicated by the large basins that have formed since the crust crystallized. Here we estimate the large-scale lunar topography and gravity spherical harmonics outside these basins and show that the bulk of the spherical harmonic degree-2 topography is consistent with a crust-building process controlled by early tidal heating throughout the Moon. The remainder of the degree-2 topography is consistent with a frozen tidal–rotational bulge that formed later, at a semi-major axis of about 32 Earth radii. The probability of the degree-2 shape having both tidal-heating and frozen shape characteristics by chance is less than 1%. We also infer that internal density contrasts eventually reoriented the Moon’s polar axis by 36 ± 4°, to the configuration we observe today. Together, these results link the geology of the near and far sides, and resolve long-standing questions about the Moon’s large-scale shape, gravity and history of polar wander.