* Astronomy

Blobrana · L

RE: Titan

Blobrana · L

Life 'not as we know it' possible on Saturn's moon Titan

Liquid water is a requirement for life on Earth. But in other, much colder worlds, life might exist beyond the bounds of water-based chemistry.
Taking a simultaneously imaginative and rigidly scientific view, Cornell chemical engineers and astronomers offer a template for life that could thrive in a harsh, cold world - specifically Titan, the giant moon of Saturn.
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Blobrana · L

Title: Ethyl cyanide on Titan: Spectroscopic detection and mapping using ALMA
Author: M. A. Cordiner, M. Y. Palmer, C. A. Nixon, P. G. J. Irwin, N. A. Teanby, S. B. Charnley, M. J. Mumma, Z. Kisiel, J. Serigano, Y.-J. Kuan, Y.-L. Chuang, K.-S. Wang

We report the first spectroscopic detection of ethyl cyanide (C₂H₅CN) in Titan's atmosphere, obtained using spectrally and spatially resolved observations of multiple emission lines with the Atacama Large Millimeter/submillimeter array (ALMA). The presence of C₂H₅CN in Titan's ionosphere was previously inferred from Cassini ion mass spectrometry measurements of C₂H₅CNH⁺. Here we report the detection of 27 rotational lines from C₂H₅CN (in 19 separate emission features detected at >3sigma confidence), in the frequency range 222-241 GHz. Simultaneous detections of multiple emission lines from CH₃N, CH₃CN and CH₃CCH were also obtained. In contrast to HC₃N, CH₃CN and CH₃CCH, which peak in Titan's northern (spring) hemisphere, the emission from C₂H₅CN is found to be concentrated in the southern (autumn) hemisphere, suggesting a distinctly different chemistry for this species, consistent with a relatively short chemical lifetime for C₂H₅CN. Radiative transfer models show that most of the C₂H₅CN is concentrated at altitudes 300-600 km, suggesting production predominantly in the mesosphere and above. Vertical column densities are found to be in the range (2-5)x10¹⁴ cm^-2.

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Blobrana · L

Winter is coming... to Titan's south pole

Gigantic polar clouds of hydrogen cyanide roughly four times the area of the UK are part of the impressive atmospheric diversity of Titan, the largest moon of Saturn, a new study led by Leiden Observatory, the Netherlands Institute for Space Research and the University of Bristol has found. The research is published today in Nature.
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Blobrana · L

Titan's swirling polar cloud is cold and toxic

The international Cassini mission has revealed that a giant, toxic cloud is hovering over the south pole of Saturn's largest moon, Titan, after the atmosphere has cooled in a dramatic fashion.
Scientists analysing data from the mission found that this giant polar vortex contains frozen particles of the toxic compound hydrogen cyanide.
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Blobrana · L

Cassini Watches Mysterious Feature Evolve in Titan Sea

NASA's Cassini spacecraft is monitoring the evolution of a mysterious feature in a large hydrocarbon sea on Saturn's moon Titan. The feature covers an area of about 100 square miles (260 square kilometers) in Ligeia Mare, one of the largest seas on Titan. It has now been observed twice by Cassini's radar experiment, but its appearance changed between the two apparitions.
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Blobrana · L

Title: HST observations of the limb polarisation of Titan
Author: Andreas Bazzon, Hans Martin Schmid, Esther Buenzli

Titan is an excellent test case for detailed studies of the scattering polarisation from thick hazy atmospheres. We present the first limb polarisation measurements of Titan, which are compared as a test to our limb polarisation models. Previously unpublished imaging polarimetry from the HST archive is presented which resolves the disk of Titan. We determine flux-weighted averages of the limb polarisation and radial limb polarisation profiles, and investigate the degradation and cancellation effects in the polarisation signal due to the limited spatial resolution of our observations. Taking this into account we derive corrected values for the limb polarisation in Titan. The results are compared with limb polarisation models, using atmosphere and haze scattering parameters from the literature.
In the wavelength bands between 250 nm and 2000 nm a strong limb polarisation of about 2-7 % is detected with a position angle perpendicular to the limb. The fractional polarisation is highest around 1 micron. As a first approximation, the polarisation seems to be equally strong along the entire limb. The detected polarisation is compatible with expectations from previous polarimetric observations taken with Voyager 2, Pioneer 11, and the Huygens probe.
Our results indicate that ground-based monitoring measurements of the limb-polarisation of Titan could be useful for investigating local haze properties and the impact of short-term and seasonal variations of the hazy atmosphere of Titan. Planets with hazy atmospheres similar to Titan are particularly good candidates for detection with the polarimetric mode of the upcoming planet finder instrument at the VLT. Therefore, a good knowledge of the polarisation properties of Titan is also important for the search and investigation of extra-solar planets.

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Blobrana · L

Cassini Tracks Clouds Developing Over a Titan Sea

NASA's Cassini spacecraft recently captured images of clouds moving across the northern hydrocarbon seas of Saturn's moon Titan.
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Blobrana · L

Saturn moon may host its own Dead Sea

Titan, Saturn's largest moon, may have its own Dead Sea. A fake lake simulating conditions there hints that the moon may host ethane pools brimming with benzene, just as the Dead Sea on Earth is packed with salt.
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Blobrana · L

Ocean on Saturn Moon Could be as Salty as the Dead Sea

Scientists analyzing data from NASAs Cassini mission have firm evidence the ocean inside Saturn's largest moon, Titan, might be as salty as the Earth's Dead Sea.
The new results come from a study of gravity and topography data collected during Cassini's repeated flybys of Titan during the past 10 years. Using the Cassini data, researchers presented a model structure for Titan, resulting in an improved understanding of the structure of the moon's outer ice shell. The findings are published in this weeks edition of the journal Icarus.
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