5
Jan 11

A high C/O ratio and weak thermal inversion in the atmosphere of exoplanet WASP-12b

Source: Nature


Observations and model spectra for dayside thermal emission of WASP-12b.

Image credits: Nikku Madhusudhan, Joseph Harrington,Kevin B. Stevenson, Sarah Nymeyer, Christopher J. Campo, Peter J. Wheatley, Drake Deming,Jasmina Blecic, Ryan A. Hardy, Nate B. Lust, David R. Anderson, Andrew Collier-Cameron, Christopher B. T. Britt,William C. Bowman,Leslie Hebb, Coel Hellier, Pierre F. L. Maxted, Richard G. West, Don Pollacco

The carbon-to-oxygen ratio (C/O) in a planet provides critical information about its primordial origins and subsequent evolution. A primordial C/O greater than 0.8 causes a carbide-dominated interior, as opposed to the silicate-dominated composition found on Earth1; the atmosphere can also differ from those in the Solar System. The solar C/O is 0.54 . Here we report an analysis of dayside multi-wavelength photometry of the transiting hot-Jupiter WASP-12b that reveals C/O ≥ 1 in its atmosphere. The atmosphere is abundant in CO. It is depleted in water vapour and enhanced in methane, each by more than two orders of magnitude compared to a solar-abundance chemical-equilibrium model at the expected temperatures. We also find that the extremely irradiated atmosphere (T > 2,500 K) of WASP-12b lacks a prominent thermal inversion (or stratosphere) and has very efficient day–night energy circulation. The absence of a strong thermal inversion is in stark contrast to theoretical predictions for the most highly irradiated hot-Jupiter atmosphere. (read Nature)

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5
Jan 11

Andromeda’s once and future stars

Source: ESA/Space Science

Image credits: infrared: ESA/Herschel/PACS/SPIRE/J. Fritz, U. Gent; X-ray: ESA/XMM-Newton/EPIC/W. Pietsch, MPE; optical: R. Gendler

Two ESA observatories have combined forces to show the Andromeda Galaxy in a new light. Herschel sees rings of star formation in this, the most detailed image of the Andromeda Galaxy ever taken at infrared wavelengths, and XMM-Newton shows dying stars shining X-rays into space.(read more)

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5
Jan 11

Identity Parade Clears Cosmic Collisions of the Suspicion of Promoting Black Hole Growth

Source:ESA/Hubble


Image credits: NASA, ESA, M. Cisternas (Max-Planck Institute for Astronomy)

What happens when galaxies crash together? For years, these cosmic collisions have been blamed for triggering violent outbursts at the hearts of galaxies. Now, a remarkable piece of detective work has given a verdict: galactic mergers do not usually whet the appetite of the black holes that power these active galactic nuclei, meaning other, less dramatic phenomena are responsible.(read more)

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1
Jan 11

Quadrantids to begin the New Year


Quadrantid meteor is bright enough to be seen at twilight.
Image credit: Mila Zinkova

New year brings us the Quandrantids meteor shower. The shower has its maximum on January 3rd and 4th, but some meteors will probably be visible during all the period between January 1st and January 5th as Earth passes through the radiant.

The name Quadrantids comes from Quadrans Muralis, an obsolete constellation that is now part of Boötes. It lies between the end of the handle of the Big Dipper and the quadrilateral of stars marking the head of the constellation Draco.

The Quadrantids are an above average shower, with up to 40 meteors per hour at their peak, but some people have said that they have counted up to 120 per hour in dark sky locations. Of course best viewing will be from a dark location an the time will be after midnight. Look for meteors radiating from the constellation Bootes.

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1
Jan 11

Happy New Year 2011

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