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I have a burning need to know stuff and I love asking awkward questions.

Saturday, July 04, 2015

Hubble Traces Subtle Signals of Water on Hazy Worlds 


December 3, 2013

Using the powerful eye of NASA's Hubble Space Telescope, two teams of scientists have found faint signatures of water in the atmospheres of five distant planets. The presence of atmospheric water was reported previously on a few exoplanets orbiting stars beyond our solar system, but this is the first study to conclusively measure and compare the profiles and intensities of these signatures on multiple worlds.

The five planets -- WASP-17b, HD209458b, WASP-12b, WASP-19b and XO-1b -- orbit nearby stars. The strengths of their water signatures varied. WASP-17b, a planet with an especially puffed-up atmosphere, and HD209458b had the strongest signals. The signatures for the other three planets, WASP-12b, WASP-19b and XO-1b, also are consistent with water.

"We're very confident that we see a water signature for multiple planets," said Avi Mandell, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., and lead author of an Astrophysical Journal paper, published today, describing the findings for WASP-12b, WASP-17b and WASP-19b. "This work really opens the door for comparing how much water is present in atmospheres on different kinds of exoplanets, for example hotter versus cooler ones."

The studies were part of a census of exoplanet atmospheres led by L. Drake Deming of the University of Maryland in College Park. Both teams used Hubble's Wide Field Camera 3 to explore the details of absorption of light through the planets' atmospheres. The observations were made in a range of infrared wavelengths where the water signature, if present, would appear. The teams compared the shapes and intensities of the absorption profiles, and the consistency of the signatures gave them confidence they saw water. The observations demonstrate Hubble's continuing exemplary performance in exoplanet research.

"To actually detect the atmosphere of an exoplanet is extraordinarily difficult. But we were able to pull out a very clear signal, and it is water," said Deming, whose team reported results for HD209458b and XO-1b in a Sept. 10 paper in the same journal. Deming's team employed a new technique with longer exposure times, which increased the sensitivity of their measurements.

The water signals were all less pronounced than expected, and the scientists suspect this is because a layer of haze or dust blankets each of the five planets. This haze can reduce the intensity of all signals from the atmosphere in the same way fog can make colors in a photograph appear muted. At the same time, haze alters the profiles of water signals and other important molecules in a distinctive way. The five planets are hot Jupiters, massive worlds that orbit close to their host stars. The researchers were initially surprised that all five appeared to be hazy. But Deming and Mandell noted that other researchers are finding evidence of haze around exoplanets.

"These studies, combined with other Hubble observations, are showing us that there are a surprisingly large number of systems for which the signal of water is either attenuated or completely absent," said Heather Knutson of the California Institute of Technology, a co-author on Deming's paper. "This suggests that cloudy or hazy atmospheres may in fact be rather common for hot Jupiters."

Hubble's high-performance Wide Field Camera 3 is one of few capable of peering into the atmospheres of exoplanets many trillions of miles away. These exceptionally challenging studies can be done only if the planets are spotted while they are passing in front of their stars. Researchers can identify the gases in a planet's atmosphere by determining which wavelengths of the star's light are transmitted and which are partially absorbed.

[I expect that if there is water on these ‘hot Jupiter’ planets then it also exists on any smaller rocky planets that might also be present in their star systems. That’s a fair assumption I think. Plus the fact that water can be detected by this method at all is a huge boost to finding planets that might have a sustainable and active biosphere. With luck we might even find one (or more) not too far away so we can go investigate!]

Thursday, July 02, 2015

Just Finished Reading: Escape to Earth edited by Ivan Howard (FP: 1963)

Yet another book that’s been sitting on my shelves for far too long. I think it’s one of the (large) pile I brought with me from London that I ‘bought’ off one of my team by paying for his left-over books in jars of coffee. Always a good deal I thought!

Anyway, this was a pretty standard collection of six short stories from 1952 – 1957. Readable if not exactly exciting they came across as typical of the age and the 50’s American culture they came from. They even had aliens using 50’s idiom without any pretence of it being anything other than contemporary speech aimed at contemporary teenagers. Sloppy but quite amusing in its way. About the only story that quite intrigued me was Doomsday’s Color-Press by Raymond F Jones which concerned a small town news editor using symbolic logic to manipulate events in her town in order to prove a theory of social control. Reading like an episode from The Twilight Zone it was quite clever and I found it interesting enough to give me much food for thought long after the story and the slim volume (a mere 173 pages) was finished. One definitely for SF addicts only.

[2015 Reading Challenge: A book of short stories – COMPLETE (20/50)]  

Monday, June 29, 2015

Just Finished Reading: Mystery in White – A Christmas Crime Story by J Jefferson Farjeon (FP: 1937)

Increasingly frustrated by the lack of movement of the train trapped in a snowdrift and the pressing realisation that time is ticking away the moments before Christmas Day a group of passengers consider their options. Some are keen to stay with the train in the warmth and security. Other, more adventurous souls are all for travelling light and making their way to a nearby side-line in the hope that they can catch a connecting train to a main branch from there. The decision is suddenly made with the abrupt departure of one member and the vow from the compartment bore that he is staying put no matter what. At first the going is comparatively easy. The snow has stopped and the way looks comparatively clear. But before long a wind appears out of nowhere and the intrepid passengers are caught in a blizzard. Battling dropping temperatures and snow blindness they stumble upon a house and discover that the door in unlocked and a welcome fire burns in the hearth. In the kitchen food is laid out as if their visit was expected. Calling out to the would-be occupants there is no reply but practicalities dictate that food is eaten, sodden clothes are dried and those in need retire to bed. Not long after the group have settled their growing sense of camaraderie and, to be honest fun, is ruined by the arrival of the carriage bore who decided after all that the train was not the place to remain – not least on his own. But something else has driven him out into the continuing heavy snow. For there has been a murder on the train in the very next compartment and there is a real possibility that one of the passengers drying themselves in the abandoned house is a killer. But there is a deeper mystery to be considered. Where are the occupants of the house and why had things been left as if in anticipation of guests? Why do things feel not ‘quite right’ and why does it look like some sort of scuffle happened in the kitchen moments before they arrived? Will all of them still be alive on Christmas morning?

This is one of a growing collection of British Library Crime Classics from the inter-war years. I’d picked a few likely looking ones but, so far at least, only bought this one. I do enjoy classic British crime novels (such as by Agatha Christie) so was already predisposed to like this one. In some ways it’s not that much of a crime novel. There are a few bodies but they happen ‘off stage’ and are talked about rather than actually discovered. There a tiny bit of violence but nothing to speak of. It’s all very gentile. Most of the characters are stereotypical (including a frankly hilarious Cockney) but fun in their own way. The brother/sister team who aid the ‘detective’ (who is a spiritualist rather than a detective as such) are pretty good in an upper-middle class sort of way. Their bantering is pretty good and generally entertaining. The spiritualist himself is good at figuring things out but doesn’t get everything quite right. The ‘reveal’ is telegraphed a fair bit in advance but is still OK even so. Overall this wasn’t a bad book if rather weak and wishy-washy for today’s hard bitten audience. Because of its gentleness the whole thing is rather comforting and you can’t help but feel nostalgic for a much simpler age (even with a war approaching – something that several of the characters mentioned much to my surprise). I think that I’ll be checking out more from this series. I’m sure that I shall be delighted by each of them.

[2015 Reading Challenge: A book set during Christmas – COMPLETE (19/50)]