Archive for the ‘Astrophysics’ Category

Nir Shaviv is co-author along with Henrik Svensmark and others of a major new paper in Nature Communications titled Increased ionization supports growth of aerosols into cloud condensation nuclei. He has a write up at his Sciencebits blog. Here’s the introduction:

Our new results published today in nature communications provide the last piece of a long studied puzzle. We finally found the actual physical mechanism linking between atmospheric ionization and the formation of cloud condensation nuclei. Thus, we now understand the complete physical picture linking solar activity and our galactic environment (which govern the flux of cosmic rays ionizing the atmosphere) to climate here on Earth though changes in the cloud characteristics. In short, as small aerosols grow to become cloud condensation nuclei, they grow faster under higher background ionization rates. Consequently, they have a higher chance of surviving the growth without being eaten by larger aerosols. This effect was calculated theoretically and measured in a specially designed experiment conducted at the Danish Space Research Institute at the Danish Technical University, together with our colleagues Martin Andreas Bødker Enghoff and Jacob Svensmark.

shaviv-fig4

Figure 4: The correlation between the linearly detrended sea level measured using satellite altimetry (blue dots) and a model fit which includes just two components: The sun and el Niño southern oscillation. The excellent fit implies that the two components are by far the dominant source of sea level change on short time scales

Background:

It has long been known that solar variations appear to have a large effect on climate. This was already suggested by William Herschel over 200 years ago. Over the past several decades, more empirical evidence have unequivocally demonstrated the existence of such a link, as exemplified in the examples in the box below.

 

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Top row: artist concepts of the seven planets of TRAPPIST-1 with their orbital periods, distances from their star, radii, masses, densities and surface gravity as compared to those of Earth.
[Image credit: NASA/JPL-CALTECH]


Talkshop analysis of some of the data follows this brief report from Astrobiology at NASA.

A team of researchers has provided new information about putative planets in the outer regions of the TRAPPIST-1 system. Currently, seven transiting planets have been identified in orbit around the ultra cool red dwarf star. The scientists determined the lower bounds on the orbital distance and inclination (within a range of masses) of planets that could be beyond the seven inner planets.

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Very Large Array, New Mexico [image credit: NASA]


This was ‘the first radio detection and the first measurement of the magnetic field of a possible planetary mass object beyond our Solar System.’ It’s even bigger than Jupiter. Plenty of puzzles for scientists to investigate.

Astronomers have used the VLA to detect a possible planetary-mass object with a surprisingly powerful magnetic field some 20 light-years from Earth.

It can help scientists better understand magnetic processes on stars and planets, says the National Radio Astronomy Observatory.

Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array
(VLA) have made the first radio-telescope detection of a planetary-mass object beyond our Solar System. The object, about a dozen times more massive than Jupiter, is a surprisingly strong magnetic powerhouse and a “rogue,” traveling through space unaccompanied by any parent star.

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There’s a new paper coming out in Astronomy and Astrophysics from Wu, Usoskin et al that is of interest to us. It reconstructs solar activity over 9 millennia. When I get a copy of the data, I’ll compare it to Steinhilber et al’s 2012 effort.

solar-9k-usoskin

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salvador-projection

I was trained as an engineer and then did a degree in the History and philosophy of science.

I know how to calculate forces, I understand thermodynamics and radiative theory and I don’t ignore data inimical to any hypothesis.

After thirty years of monitoring and appraising the data, the global warming hypothesis and working out what really causes climatic change I’ve concluded that it ain’t CO2. The real causes of climatic change at the planetary scale are the enormous forces transferring energy between solar system bodies.

Jupiter and Saturn between them hold over 85% of the angular momentum of the system. Venus has, within an order of magnitude, the same gravitational force on the Earth-Moon system as Jupiter. The two of them have shaped the orbit of our Moon, whose tidal forces have a profound effect on the overturning circulation of Earth’s oceans, which contain 1000 times more heat than the atmosphere of which CO2 comprises 0.04%.

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Ian Robert George Wilson and Nikolay S Sidorenkov

Wilson and Sidorenkov, J Earth Sci Clim Change 2018, 9:1, p. 446

https://www.omicsonline.org/open-access/a-lunisolar-connection-to-weather-and-climate-i-centennial-times-scales-2157-7617-1000446.pdf

Abstract

Lunar ephemeris data is used to find the times when the Perigee of the lunar orbit points directly toward or away from the Sun, at times when the Earth is located at one of its solstices or equinoxes, for the period from 1993 to 2528 A.D. The precision of these lunar alignments is expressed in the form of a lunar alignment index (ϕ). When a plot is made of ϕ, in a frame-of-reference that is fixed with respect to the Perihelion of the Earth’s orbit, distinct periodicities are seen at 28.75, 31.0, 88.5 (Gleissberg Cycle), 148.25, and 208.0 years (de Vries Cycle). The full significance of the 208.0-year repetition pattern in ϕ only becomes apparent when these periodicities are compared to those observed in the spectra for two proxy time series. The first is the amplitude spectrum of the maximum daytime temperatures (Tm ) on the Southern Colorado Plateau for the period from 266 BC to 1997 AD. The second is the Fourier spectrum of the solar modulation potential (ϕm) over the last 9400 years. A comparison between these three spectra shows that of the nine most prominent periods seen in ϕ, eight have matching peaks in the spectrum of ϕm, and seven have matching peaks in the spectrum of Tm. This strongly supports the contention that all three of these phenomena are related to one another. A heuristic Luni-Solar climate model is developed in order to explain the connections between ϕ, Tm and ϕm.

Wilson_Sidorenkov_Fig_04

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Distant galaxies [image credit: phys.org]


Does the exception prove the rule, or is the rule on shaky ground? Nobody knows.

Scientists have imaged a “transparent” galaxy that may have no dark matter, reports BBC Science.

An unusually transparent galaxy about the size of the Milky Way is prompting new questions for astrophysicists.

The object, with the catchy moniker of NGC1052-DF2, appears to contain no dark matter.

If this turns out to be true, it may be the first galaxy of its kind – made up only of ordinary matter. Currently, dark matter is thought to be essential to the fabric of the Universe as we understand it.

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Spiral galaxy [image credit: BBC]


Researchers refer here to ‘regularity in galaxies’.

Astronomers have discovered that all galaxies rotate once every billion years, no matter how big they are, reports Phys.org.

The Earth spinning around on its axis once gives us the length of a day, and a complete orbit of the Earth around the Sun gives us a year.

“It’s not Swiss watch precision,” said Professor Gerhardt Meurer from the UWA node of the International Centre for Radio Astronomy Research (ICRAR).

“But regardless of whether a galaxy is very big or very small, if you could sit on the extreme edge of its disk as it spins, it would take you about a billion years to go all the way round.”

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Cyclones in Jupiter’s atmosphere [image credit: NASA]


Octagon and pentagon (8:5) shapes at the poles, with groups of cyclones in a 9:6 (= 3:2) polar ratio. Fascinating.

Jupiter’s poles are blanketed by geometric clusters of cyclones and its atmosphere is deeper than scientists suspected, says Phys.org.

These are just some of the discoveries reported by four international research teams Wednesday, based on observations by NASA’s Juno spacecraft circling Jupiter.

One group uncovered a constellation of nine cyclones over Jupiter’s north pole and six over the south pole. The wind speeds exceed Category 5 hurricane strength in places, reaching 220 mph (350 kph).

The massive storms haven’t changed position much—or merged—since observations began.

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Solar wind at Mars [image credit: universetoday.com]


The researchers say ‘the solar wind likely only had a very small direct effect on the amount of Mars atmosphere that has been lost over time.’ This makes them suspect that ‘a magnetic field is not as important in shielding a planet’s atmosphere as the planet’s gravity itself.’ It was always hard to see how the magnetic shield theory worked when Venus with its dense atmosphere has little magnetism.

The Red Planet’s low gravity and lack of magnetic field makes its outermost atmosphere an easy target to be swept away by the solar wind, but new evidence from ESA’s Mars Express spacecraft shows that the Sun’s radiation may play a surprising role in its escape, reports Phys.org.

Why the atmospheres of the rocky planets in the inner solar system evolved so differently over 4.6 billion years is key to understanding what makes a planet habitable.

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Image credit: phys.org


When does absence of evidence become evidence of absence? Dark matter has never been detected despite years of effort. Here we have ‘a universal phenomenon that demands new explanations’, says the lead researcher. Galaxies in disc-shaped planes appear to mirror what we see with solar systems – like ours – and their planets.

An international team of astronomers led by the University of Basel in Switzerland has looked at the movement and distribution of satellite galaxies in the constellation Centaurus A and finds that their observations call into question the existence of dark matter, says The Space Reporter.

The findings are reported in the journal Science.

Dark matter is a hypothetical type of invisible matter that has never been directly observed because it does not emit or interact with electromagnetic radiation. Its existence has been inferred by its apparent influences on visible matter and light.

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Triton: Neptune’s odd moon

Posted: January 27, 2018 by oldbrew in Astrophysics, exploration
Tags: ,

Neptune and Triton (below) [credit: NASA]


Triton has the second-biggest ratio of moon-to-planet to Neptune, being only lower than the ratio between Earth and its own Moon. As well as having over 400 times the mass of any other Neptunian moon, Triton has some peculiarities about its environment, including the fact that it orbits backward to Neptune’s rotation and seems to have undergone a huge melt in the past, as Space.com explains. NASA believes it has similarities to Pluto. In 2006, a model published in Nature suggested Triton was originally a member of a binary system that orbited the sun.

Triton is the largest of Neptune’s moons. Discovered in 1846 by British astronomer William Lassell — just weeks after Neptune itself was found — the moon showed some strange characteristics as astronomers learned more about it.

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Jupiter-sized exoplanet [Wikipedia]


It seems the planetary structure of our solar system is an oddity compared to most of the exoplanetary systems so far discovered. On the other hand it’s easier to find planets close to their stars than those a long way away, so what is known so far might not be giving us the whole picture.

An international research team led by Université de Montréal astrophysicist Lauren Weiss has discovered that exoplanets orbiting the same star tend to have similar sizes and a regular orbital spacing, says Phys.org.

This pattern, revealed by new W. M. Keck Observatory observations of planetary systems discovered by the Kepler Telescope, could suggest that most planetary systems have a different formation history than the solar system.

Thanks in large part to the NASA Kepler Telescope, launched in 2009, many thousands of exoplanets are now known. This large sample allows researchers to not only study individual systems, but also to draw conclusions on planetary systems in general.

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cr-atmos

Illustration of cosmic rays interacting with the atmosphere. A proton with energy of 100 GeV interact at the top of the atmosphere and produces a cascade of secondary particles who ionize molecules when traveling through the air. One 100 GeV proton hits every m2 at the top of the atmosphere every second.

H/T GWPF: Researchers have claimed a breakthrough in understanding how cosmic rays from supernovas react with the sun to form clouds, which impact the climate on Earth.

The findings have been described as the “missing link” to help resolve a decades long controversy that has big implications for climate science.

Lead author, Henrik Svensmark, from The Technical University of Denmark has long held that climate models had greatly underestimated the impact of solar activity.

He says the new research identified the feedback mechanism through which the sun’s impact on climate was varied.

Professor Svensmark’s theories on solar impact have caused a great deal of controversy within the climate science community and the latest findings are sure to provoke new outrage.

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Star system has record eight exoplanets

Posted: December 14, 2017 by oldbrew in Astronomy, Astrophysics, News
Tags: ,

Kepler Space Telescope [credit: NASA]


The two nearest planets to the star Kepler-90 (90b and 90c) are very close to a 5:4 (i.e. first order) orbit ratio.

Nasa finds a distant star circled by eight planets, equal to the complement in our own Solar System, BBC News reports.

It’s the largest number of worlds ever discovered in a planetary system outside our own.

The star known as Kepler-90, is just a bit hotter and larger than the Sun; astronomers already knew of seven planets around it.

The newly discovered world is small enough to be rocky, according to scientists.

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Intense X-ray flares thought to be caused by a black hole devouring a star [credit: NASA]


Who’s afraid of the big bad black hole now? Its imagined powers have been seriously overrated, according to new research. This poses unexpected problems for theorists.

Black holes are famous for their muscle: an intense gravitational pull known to gobble up entire stars and launch streams of matter into space at almost the speed of light, says Phys.org.

It turns out the reality may not live up to the hype.

In a paper published today in the journal Science, University of Florida scientists have discovered these tears in the fabric of the universe have significantly weaker magnetic fields than previously thought.

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Although the author appears sold on the idea of trace gases controlling the temperature of planetary atmospheres, the discussion about planets and water is worth a look. The answer to the question may depend on more powerful space telescopes like the James Webb.

Wherever we find water on Earth, we find life writes Elizabeth Tasker at Many Worlds.

It is a connection that extends to the most inhospitable locations, such as the acidic pools of Yellowstone, the black smokers on the ocean floor or the cracks in frozen glaciers.

This intimate relationship led to the NASA maxim, “Follow the Water”, when searching for life on other planets.

Yet it turns out you can have too much of a good thing.

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Juno probe


There’s nothing like observation for contradicting, or supporting, theory and the Juno probe has already upset a few ideas that scientists had about Jupiter.

Since it established orbit around Jupiter in July of 2016, the Juno mission has been sending back vital information about the gas giant’s atmosphere, magnetic field and weather patterns, as Universe Today reports.

With every passing orbit – known as perijoves, which take place every 53 days – the probe has revealed more interesting things about Jupiter, which scientists will rely on to learn more about its formation and evolution.

During its latest pass, the probe managed to provide the most detailed look to date of the planet’s interior. In so doing, it learned that Jupiter’s powerful magnetic field is askew, with different patterns in its northern and southern hemispheres.

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Orbiting dust cloud – artists’ impression [credit: Karen L. Teramura]


An orbiting cloud of dust round ‘Tabby’s star’ may lack excitement for casual observers, but there it is – probably.

University of Arizona astronomer Huan Meng and co-authors have found the long-term dimming of KIC 8462852 — a main-sequence F-type star located in the constellation Cygnus, about 1,480 light-years from Earth — appears to be weaker at longer infrared (IR) wavelengths of light and stronger at shorter ultraviolet (UV) wavelengths, reports Sci-News.com.

Such reddening is characteristic of dust particles and inconsistent with more fanciful ‘alien megastructure’ concepts, which would evenly dim all wavelengths of light.

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