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Saturday, October 20, 2018

El-Nino Imminent this year

After nearly four months of waiting for El Niño, the switch is likely to be flipped on this winter. Rejoice, my fellow Ninoheads.

There are signs that El Niño, a climate phenomenon characterized by a warming of waters in the eastern tropical Pacific, is “imminent” according to an update released on Thursday by the International Research Institute for Climate and Society (IRI). It will arrive just in time for winter to rearrange the world’s weather, including ushering in a warmer-than-normal winter for much of the U.S.

The latest update on El Niño that included input from human researchers at IRI and the National Oceanic and Atmospheric Administration (NOAA) was released on Oct. 11. It gave strong odds that El Niño would form in the next month or so. The update released on Thursday uses models only, and finds the odds to be even higher. It puts the chances we’ll see an El Niño from winter until early spring of 2019 at an 85-90 percent.

The conditions in and above the Pacific seem to agree. NOAA defines El Niño as when ocean temperatures in a region of the eastern tropical Pacific (dubbed NINO3.4 in climate nerd talk) are 0.5 degrees Celsius (0.9 degrees Fahrenheit) above normal for three months in a row. That region is currently just over that threshold, and a big pulse of warm water below the surface that’s working its way across the Pacific should help El Niño conditions blossom. It’s not likely to be a blockbuster El Niño, but it should still have enough of an impact as it propagates through the atmosphere to affect weather patterns elsewhere.

And as it so happens, the El Niño update on Thursday coincided with NOAA’s winter weather outlook. Meteorologists know how El Niño can tip the odds one way or the other for certain types of weather, so the outlook is pretty confident in showing higher odds of warmth across much of the U.S. save the Southeast. The outlook also shows wet weather for the southern tier of the country, while the Northern Rockies are likely to be drier than normal. The wet weather in the Southwest would certainly be a relief, since the region is in the grips of an intense drought.

El Niño is far from the only natural climate shift to affect weather. You’ve got your Arctic Oscillation and your Madden-Julian Oscillation (to say nothing of the unnatural shift driven by human-caused climate change). And a forecast for, say, increased odds of a warmer-than-normal winter in Spokane does not mean there will be no cold spells. Sometimes winter just has to winter.

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Thursday, October 18, 2018

New Solar System Found

Researchers have identified a young star with four Jupiter and Saturn-sized planets in orbit around it, the first time that so many massive planets have been detected in such a young system. The system has also set a new record for the most extreme range of orbits yet observed: the outermost planet is more than a thousand times further from the star than the innermost one, which raises interesting questions about how such a system might have formed.

The star is just two million years old – a 'toddler' in astronomical terms – and is surrounded by a huge disc of dust and ice. This disc, known as a protoplanetary disc, is where the planets, moons, asteroids and other astronomical objects in stellar systems form.

The star was already known to be remarkable because it contains the first so-called hot Jupiter—a massive planet orbiting very close to its parent star – to have been discovered around such a young star. Although hot Jupiters were the first type of exoplanet to be discovered, their existence has long puzzled astronomers because they are often thought to be too close to their parent stars to have formed in situ.

Now, a team of researchers led by the University of Cambridge have used the Atacama Large Millimeter/submillimeter Array (ALMA) to search for planetary 'siblings' to this infant hot Jupiter. Their image revealed three distinct gaps in the disc, which, according to their theoretical modelling, were most likely caused by three additional gas giant planets also orbiting the young star. Their results are reported in the Astrophysical Journal Letters.

The star, CI Tau, is located about 500 light years away in a highly-productive stellar 'nursery' region of the galaxy. Its four planets differ greatly in their orbits: the closest (the hot Jupiter) is within the equivalent of the orbit of Mercury, while the farthest orbits at a distance more than three times greater than that of Neptune. The two outer planets are about the mass of Saturn, while the two inner planets are respectively around one and 10 times the mass of Jupiter.

The discovery raises many questions for astronomers. Around 1% of stars host hot Jupiters, but most of the known hot Jupiters are hundreds of times older than CI Tau. "It is currently impossible to say whether the extreme planetary architecture seen in CI Tau is common in hot Jupiter systems because the way that these sibling planets were detected—through their effect on the protoplanetary disc – would not work in older systems which no longer have a protoplanetary disc," said Professor Cathie Clarke from Cambridge's Institute of Astronomy, the study's first author.

According to the researchers, it is also unclear whether the sibling planets played a role in driving the innermost planet into its ultra-close orbit, and whether this is a mechanism that works in making hot Jupiters in general. And a further mystery is how the outer two planets formed at all.

"Planet formation models tend to focus on being able to make the types of planets that have been observed already, so new discoveries don't necessarily fit the models," said Clarke. "Saturn mass planets are supposed to form by first accumulating a solid core and then pulling in a layer of gas on top, but these processes are supposed to be very slow at large distances from the star. Most models will struggle to make planets of this mass at this distance."

The task ahead will be to study this puzzling system at multiple wavelengths to get more clues about the properties of the disc and its planets. In the meantime, ALMA – the first telescope with the capability of imaging planets in the making – will likely throw out further surprises in other systems, re-shaping our picture of how planetary systems form.