Cosmology: Cool start to hydrogen ionization

Nature 506, 7487 (2014). doi:10.1038/nature13051

Authors: Judd D. Bowman

Simulations of the cosmos cast doubt on assumptions about the temperature of primordial hydrogen gas when it was ionized by the first stars and galaxies, complicating the interpretation of ongoing observations. See Letter p.197

The observable signature of late heating of the Universe during cosmic reionization

Nature 506, 7487 (2014). doi:10.1038/nature12999

Authors: Anastasia Fialkov, Rennan Barkana & Eli Visbal

Models and simulations of the epoch of reionization predict that spectra of the 21-centimetre transition of atomic hydrogen will show a clear fluctuation peak, at a redshift and scale, respectively, that mark the central stage of reionization and the characteristic size of ionized bubbles. This is based on the assumption that the cosmic gas was heated by stellar remnants—particularly X-ray binaries—to temperatures well above the cosmic microwave background at that time (about 30 kelvin). Here we show instead that the hard spectra (that is, spectra with more high-energy photons than low-energy photons) of X-ray binaries make such heating ineffective, resulting in a delayed and spatially uniform heating that modifies the 21-centimetre signature of reionization. Rather than looking for a simple rise and fall of the large-scale fluctuations (peaking at several millikelvin), we must expect a more complex signal also featuring a distinct minimum (at less than a millikelvin) that marks the rise of the cosmic mean gas temperature above the microwave background. Observing this signal, possibly with radio telescopes in operation today, will demonstrate the presence of a cosmic background of hard X-rays at that early time.

Astrophysics: Hydrogen river could fuel stars

Nature 506, 7486 (2014). doi:10.1038/506008c

The discovery of a faint filament of hydrogen gas streaming across space could help to explain how some galaxies maintain their pace of star formation.D. J. Pisano from West Virginia University in Morgantown used the Robert C. Byrd Green Bank Telescope to identify a

Cosmology: Planck team replies to data 'anomalies'

Nature 506, 7486 (2014). doi:10.1038/506034c

Author: Jan Tauber

We would like to clarify some points arising from your News report on the debate over data from the European Space Agency's Planck mission (see Naturehttp://doi.org/q8t; 2013).The cosmological parameters estimated by the Planck Collaboration are statistically compatible with those estimated by

Imagine living on a planet with seasons so erratic you would hardly know whether to wear Bermuda shorts or a heavy overcoat. That is the situation on a weird, wobbly world found by NASA's Kepler space telescope. The planet wobbles wildly on its spin axis, much like a child's top.

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Imagine living on a planet with seasons so unpredictable you would hardly know what to wear: Bermuda shorts or a heavy overcoat! That's the situation on a weird world found by NASA's planet-hunting Kepler space telescope. The planet, designated Kepler-413b, is located 2,300 light-years away in the constellation Cygnus. It circles a close pair of orange and red dwarf stars every 66 days. But what makes this planet very unusual is that it wobbles, or precesses, wildly on its spin axis, much like a child's top. The planet's orbit is tilted with respect to the plane of the binary star's orbit. Over an 11-year period, the planet's orbit too would appear to wobble as it circles around the star pair. All of this complex movement leads to rapid and erratic changes in seasons.

Imagine living on a planet with seasons so erratic you would hardly know whether to wear Bermuda shorts or a heavy overcoat. That is the situation on a weird, wobbly world found by NASA's planet-hunting Kepler space telescope.

The best measurement yet of the Pinwheel Galaxy's mass shows that its halo is oddly devoid of stars, putting a wrinkle in a key theory of galactic growth
    

A super-dry day at the European Southern Observatory's Paranal site shows promise for infrared astronomy. New MNRAS paper by Kerber et al.

https://www.ras.org.uk/news-and-press/news-archive/254-news-2014/2391-super-dry-day-at-eso-paranal


Super dry day at ESO Paranal
www.ras.org.uk
On 5 July 2012, a plume of Antarctic air descended over the European Southern Observatory's (ESO) Paranal site in Chile. The home of the Very Large Telescope, Paranal is 2635 m above sea level and is almost always one of the best sites in the world for optical and near-infrared astronomy.

Astronomy produces a lot of carbon emissions, but it could be one of the greenest sciences if observatories harness their solar and wind resources
    

The closest star to the sun, Alpha Centauri B, is just the right type to host a planet even better suited to life than Earth
    

NASA researchers plan to create the coldest spot in the known Universe--inside the International Space Station. The device, known as the Cold Atom Lab, could discover new forms of matter and novel quantum phenomena.

NASA is inviting the public to help astronomers discover embryonic planetary systems hidden among data from the agency's Wide-field Infrared Survey Explorer (WISE) mission through a new website, DiskDetective.org.

The first sighting of wind from a young solar twin suggests that our sun was a weakling in its youth, which might have allowed Mars to play host to water
    

ESO's Very Large Telescope has been used to create the first ever map of the weather on the surface of the nearest brown dwarf to Earth. An international team has made a chart of the dark and light features on WISE J104915.57-531906.1B, which is informally known as Luhman 16B and is one of two recently discovered brown dwarfs forming a pair only six light-years from the Sun. The new results are being published in the 30 January 2014 issue of the journal Nature.

A telescope to find thousands of planets beyond our Solar System is the hot favourite for selection as Europe's next medium-class space science mission.

Astronomers using NASA's Hubble Space Telescope and Europe's Herschel Space Observatory have pieced together the evolutionary sequence of compact elliptical galaxies that erupted and burned out early in the history of the universe.

Astronomers using NASA's Hubble Space Telescope and Europe's Herschel Space Observatory have pieced together the evolutionary sequence of compact elliptical galaxies that erupted and burned out early in the history of the universe.

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A certain class of massive galaxies in the early universe lived fast and died young. By "died" astronomers mean that the galaxies had completed building stars just 3 billion years after the big bang. By contrast, our 12-billion-year-old Milky Way galaxy continues making stars today. When star formation stops, the aging stellar population looks redder in the star-forming galaxies that are more bluish. The nickname for the essentially "burned-out" galaxies is "red and dead."

Following last week's wake-up of the Rosetta comet-chaser, ESA's flight controllers have conducted the first in a series of health checks aimed at assessing how well it came through 31 months of hibernation.