Institute of Astronomy

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An ultrahot gas-giant exoplanet with a stratosphere

Astronomy News - 3 August 2017 - 9:10am
Infrared radiation emitted from a planet contains information about the chemical composition and vertical temperature profile of its atmosphere. If upper layers are cooler than lower layers, molecular gases will produce absorption features in the planetary thermal spectrum. Conversely, if there is a stratosphere—where temperature increases with altitude—these molecular features will be observed in emission. It has been suggested that stratospheres could form in highly irradiated exoplanets, but the extent to which this occurs is unresolved both theoretically and observationally. A previous claim for the presence of a stratosphere remains open to question, owing to the challenges posed by the highly variable host star and the low spectral resolution of the measurements. Here we report a near-infrared thermal spectrum for the ultrahot gas giant WASP-121b, which has an equilibrium temperature of approximately 2,500 kelvin. Water is resolved in emission, providing a detection of an exoplanet stratosphere at 5σ confidence. These observations imply that a substantial fraction of incident stellar radiation is retained at high altitudes in the atmosphere, possibly by absorbing chemical species such as gaseous vanadium oxide and titanium oxide.

Astronomy: Ozone-like layer in an exoplanet atmosphere

Astronomy News - 3 August 2017 - 9:10am
The nature of exoplanetary atmospheres is hotly debated. The thermal spectrum of an exoplanet called a hot Jupiter reveals the presence of an analogue of Earth's ozone layer, although its composition is unknown. See Letter p.58

Exomoon candidate, fake peer review and a telescope problem

Astronomy News - 3 August 2017 - 9:09am
The week in science: 28 July–3 August 2017.

Enormous exoplanet has an atmosphere hot enough to boil iron

Astronomy News - 3 August 2017 - 9:07am

A planet nearly double the size of Jupiter and 900 light years away has a glowing stratosphere and an atmosphere hot enough that iron there exists as a vapour

Cutting-edge Adaptive Optics Facility Sees First Light

Astronomy News - 3 August 2017 - 9:06am
The Unit Telescope 4 (Yepun) of ESO’s Very Large Telescope (VLT) has now been transformed into a fully adaptive telescope. After more than a decade of planning, construction and testing, the new Adaptive Optics Facility (AOF) has seen first light with the instrument MUSE, capturing amazingly sharp views of planetary nebulae and galaxies. The coupling of the AOF and MUSE forms one of the most advanced and powerful technological systems ever built for ground-based astronomy.

Fast radio bursts may be dark matter ‘stars’ hitting black holes

Astronomy News - 2 August 2017 - 9:01am

The mysterious FRBs we’ve been tracking for a decade could be created by clumps of dark matter particles dancing along the edges of black holes

An Earth-like Atmosphere May Not Survive Proxima b’s Orbit

Astronomy News - 2 August 2017 - 9:00am
Portal origin URL: An Earth-like Atmosphere May Not Survive Proxima b’s OrbitPortal origin nid: 406545Published: Monday, July 31, 2017 - 13:11Featured (stick to top of list): noPortal text teaser: An Earth-like planet outside the solar system may not be able to keep a grip on its atmosphere, leaving the surface exposed to harmful stellar radiation and reducing its potential for habitability.Portal image: Artist’s impression shows a view of the surface of the planet Proxima b orbiting the red dwarf star Proxima CentauriScience Categories: Sun

ESA, NASA’s SOHO Reveals Rapidly Rotating Solar Core

Astronomy News - 2 August 2017 - 9:00am
Portal origin URL: ESA, NASA’s SOHO Reveals Rapidly Rotating Solar CorePortal origin nid: 406593Published: Tuesday, August 1, 2017 - 09:29Featured (stick to top of list): noPortal text teaser: After four decades of searching, solar scientists have at long last found evidence of a type of seismic wave in our Sun, thanks to ESA and NASA's Solar and Heliospheric Observatory, or SOHO.Portal image: illustration of SOHO and a cross-section of the SunScience Categories: Sun

The Hunt for Asteroids

Astronomy News - 2 August 2017 - 9:00am
Video Length: 3:19

NASA is hunting for Near-Earth Objects, while also working on ways to defend Earth against them.

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Video Links: The Hunt for Asteroids - mp4YouTubeVimeo

NASA’s Voyager Spacecraft Still Reaching for the Stars After 40 Years

Astronomy News - 2 August 2017 - 8:59am
Humanity’s farthest and longest-lived spacecraft, Voyager 1 and 2, achieve 40 years of operation and exploration this August and September. Despite their vast distance, they continue to communicate with NASA daily, still probing the final frontier.

Gravity waves detected in Sun's interior reveal rapidly rotating core

Astronomy News - 2 August 2017 - 8:58am

Scientists using the ESA/NASA SOHO solar observatory have found long-sought gravity modes of seismic vibration that imply the Sun's core is rotating four times faster than its surface.

Not just stars

Astronomy News - 2 August 2017 - 8:57am

The shortlisted images in this year's Insight Astronomy Photographer of the Year have now been selected.

Building blocks of alien cells found on Saturn’s largest moon

Astronomy News - 31 July 2017 - 9:13am

The discovery of two compounds that could help make cells only adds to Titan’s image as the most promising place in our solar system to look for alien life

NASA Selects Proposals to Study Sun, Space Environment

Astronomy News - 31 July 2017 - 9:12am
NASA has selected nine proposals under its Explorers Program that will return transformational science about the Sun and space environment and fill science gaps between the agency’s larger missions; eight for focused scientific investigations and one for technological development of instrumentation.

First exomoon might have been spotted 4000 light years away

Astronomy News - 28 July 2017 - 9:15am

Astronomers may have found the first exomoon around a distant planet, and have asked to use Hubble to confirm whether the tantalising hints are a real discovery

A Tale of Three Stellar Cities

Astronomy News - 28 July 2017 - 9:11am
Using new observations from ESO’s VLT Survey Telescope, astronomers have discovered three different populations of young stars within the Orion Nebula Cluster. This unexpected discovery adds very valuable new insights for the understanding of how such clusters form. It suggests that star formation might proceed in bursts, where each burst occurs on a much faster time-scale than previously thought.

Galactic David and Goliath [heic1712]

Astronomy News - 28 July 2017 - 9:03am

The gravitational dance between two galaxies in our local neighbourhood has led to intriguing visual features in both as witnessed in this new NASA/ESA Hubble Space Telescope image. The tiny NGC 1510 and its colossal neighbour NGC 1512 are at the beginning of a lengthy merger, a crucial process in galaxy evolution. Despite its diminutive size, NGC 1510 has had a significant effect on NGC 1512's structure and amount of star formation.

Signal may be from first 'exomoon'

Astronomy News - 28 July 2017 - 9:02am

A team of astronomers has potentially discovered the first known moon located beyond the Solar System.

Significant and variable linear polarization during the prompt optical flash of GRB 160625B

Astronomy News - 27 July 2017 - 9:35am
Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent—consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source. By contrast, optical and γ-ray observations during the prompt phase have led to discordant and often controversial results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.

Thirty Meter Telescope: Alternative telescope site is a good back-up

Astronomy News - 27 July 2017 - 9:35am
Your report on discussions about a possible location for the Thirty Meter Telescope (TMT) calls for some clarification (Naturedoi.org/b9px (2017); see also Naturedoi.org/b9pz; 2016). Although the TMT board's preferred site is Mauna Kea in Hawaii, the alternative