Archive for the ‘Astronomy’ Category

Saturn’s moon Janus


Cassini maintains its reputation for surprises right to the end. It’s the ‘moon resonances’ that maintain ring stability, but with a new twist.

For three decades, astronomers thought that only Saturn’s moon Janus confined the planet’s A ring – the largest and farthest of the visible rings.

But after poring over NASA’s Cassini mission data, Cornell astronomers now conclude that the teamwork of seven moons keeps this ring corralled, as Phys.org explains.

Without forces to hold the A ring in check, the ring would keep spreading out and ultimately disappear.

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Star KIC 8462852 in infrared (2MASS survey) and ultraviolet (GALEX) [credit: NASA]


One observer commented about “Tabby’s Star” that ‘every explanation that doesn’t involve aliens has some sort of problem’. Its nickname is the WTF star, reports Phys.org.

Round 5 a.m. on a Tuesday this past May, Tabetha “Tabby” Boyajian sat staring at a laptop, cross-legged on her couch in the living room of her Baton Rouge, La., home. The coffee table was cluttered with the artifacts of an all-nighter: an empty wine glass to calm her nerves alongside an empty coffee mug to fuel her through the night.

Since midnight, Boyajian had been downloading and analyzing data from the Las Cumbres telescopes—two on Maui, Hawaii, and two more on the Spanish island of Tenerife off the coast of West Africa—that sat trained on an F-type star, bigger and hotter than the sun, near the constellation Cygnus.

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Mercury [image credit: NASA]


The first photos of ice at Mercury’s poles were released in 2014 but this research goes a step further, as Phys.org reports. It finds that ‘the total area of the three sheets [is] about 3,400 square kilometers—slightly larger than the state of Rhode Island’.

The scorching hot surface of Mercury seems like an unlikely place to find ice, but research over the past three decades has suggested that water is frozen on the first rock from the sun, hidden away on crater floors that are permanently shadowed from the sun’s blistering rays.

Now, a new study led by Brown University researchers suggests that there could be much more ice on Mercury’s surface than previously thought.

The study, published in Geophysical Research Letters, adds three new members to the list of craters near Mercury’s north pole that appear to harbor large surface ice deposits.

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Where is Planet 9? [credit: NASA]


This may say something about what is not likely to be true about the mysterious, or mythical, Planet 9 but obviously it’s still all in the realms of theory. If it did form around the sun, how did it get to be so much further away from it than the known major planets in the solar system?

Astronomers at the University of Sheffield have shown that ‘Planet 9’ – an unseen planet on the edge of our solar system – probably formed closer to home than previously thought, reports Phys.org.

A team led by Dr Richard Parker from the University of Sheffield’s Department of Physics and Astronomy has found that Planet 9 is ‘unlikely’ to have been captured from another planetary system, as has previously been suggested, and must have formed around the sun.

The outskirts of the solar system have always been something of an enigma, with astronomers in the late 19th and early 20th centuries searching for a giant planet that wasn’t there, and the subsequent discovery of Pluto in 1930.

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Showing all of the Moon including the side we never see from Earth. Composite from images taken by the Lunar Orbiter

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Much media attention on this new paper this week. Is there a surprise lurking in the details now that the orbit period of the seventh planet has been confirmed?.

What the numbers in the diagram show is the orbits per planet in a fixed period (top row), the conjunctions per planet pair in the same period (second row), and the ratios that represents (third row).

The number of conjunctions of any two planets is the difference between the two orbit numbers in a given period, which in this case is equivalent to just under 1446 Earth days (see data below).

Apart from the obvious symmetry of the ratios, something else arose from the science paper.

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Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the largest astronomical project in the world –
Magellanic Clouds near top of image [credit: NASA / Ames]


It’s unimaginably vast: astronomers say ‘this structure is a 75,000 light-year long filament of gas and dust’. Trying to separate out the effects of gravity and magnetism here should be an interesting challenge.

A magnetic field appears to span the space between the Large and Small Magellanic Clouds, the two dwarf galaxies being consumed by our Milky Way Galaxy, reports Sky & Telescope via Sott.net.

For stargazers in the Northern Hemisphere, it’s easy to forget that the Milky Way is actively consuming two dwarf galaxies. Those in the Southern Hemisphere have a front row seat to watch our galaxy wreak havoc on the Large and Small Magellanic Clouds (LMC and SMC).

But there’s more to the story — the dwarfs are not only gravitationally interacting with the Milky Way but with each other as well.

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The Lined Wolf

Let’s face it: KIC 8462852 (also Tabby’s Star or Boyajian’s Star) is a weird star. Since its unusual light variations were discovered by citizen scientists using data of NASA’s Kepler space telescope in September 2015 many, many things have been written by professional and amateur astronomers, science communicators and “searchers of mysteries”, as an interesting hypothesis about its behavior was that it could be signs of activity associated with intelligent extraterrestrial life constructing a Dyson swarm. Of course, this just run wild in general media, and many astronomers since them have been asked by journalist to talk about “Mysterious Tabby’s Star”.

In particular, this theme soon captured the attention of some of my friends at the Instituto de Astrofísica de Canarias (IAC, Spain), as they weekly produce an amazing ~2h science communication podcast Coffee Break: Señal y Ruido (Signal to noise). I’m proud to participate in this podcast from…

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Astrophysicist Ian Wilson has emailed me to ask for a brainstorming session at the talkshop to assist him. Ian writes:

“I was wondering if you or your colleagues (e.g. oldbrew) could help me work out the solution to the following lunar puzzle”

Drift_01

The Conundrum

The diagram below shows the Perigee of the lunar orbit pointing at the Sun at 0.0 days. In addition, the diagram shows the Perigee of the lunar orbit once again pointing at the Sun after one Full Moon Cycle (FMC) = 411.78443025 days. It takes more than 1.0 sidereal year (= 365.256363004 days) for the Perigee to realign with the Sun because of the slow pro-grade (clockwise) precession of the lunar line-of-apse once every 8.85023717 sidereal years.

1.0 FMC falls short of 15 anomalistic months (= 413.31824817 days) by 1.53381792 days (= 1.5117449198O). During these 1.5117449198 days the Perigee end of the lunar line-of-apse rotates by 0.17081406in a prograde direction, producing an overall movement of the line-of-apse (red line) of 1.34093086O (= 1.5117449198O – 0.17081406O) with respect to the Earth-Sun line (blue line).

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The 1,100 year orbit of ‘DeeDee’

The solar system’s dwarf-planet population is about to increase by one, reports Space.com. The far-flung object 2014 UZ224 — informally known as DeeDee, for “Distant Dwarf” — is about 395 miles wide (635 kilometers), new observations reveal.

That means the frigid object probably harbors enough mass to be shaped into a sphere by its own gravity, entitling it to “dwarf planet” status, researchers said.

Astronomers first spotted DeeDee in 2014 using the optical Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile (though they didn’t announce the discovery until 2016).
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Size comparison of GJ 1132 b (aka Gliese 1132 b) with Earth [credit: Wikipedia]


Early indications from models suggest that ‘an atmosphere rich in water and methane would explain the observations very well.’

Astronomers have detected an atmosphere around the super-Earth GJ 1132b, reports the Max Planck Institute for Astronomy.

This marks the first detection of an atmosphere around a low-mass Super-Earth, in terms of radius and mass the most Earth-like planet around which an atmosphere has yet been detected.

Thus, this is a significant step on the path towards the detection of life on an exoplanet. The team, which includes researchers from the Max Planck Institute for Astronomy, used the 2.2 m ESO/MPG telescope in Chile to take images of the planet’s host star GJ 1132, and measuring the slight decrease in brightness as the planet and its atmosphere absorbed some of the starlight while passing directly in front of their host star.

While it’s not the detection of life on another planet, it’s an important step in the right direction: the detection of an atmosphere around the super-Earth GJ 1132b marks the first time an atmosphere has been detected around a planet with a mass and radius close to that of Earth (1.6 Earth masses, and 1.4 Earth radii).
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The largest ‘TNOs’

This is about the ‘no-name’ dwarf planet 2007 OR10, which has the unusual property of being 3 times further from the Sun at aphelion (furthest) than at perihelion (nearest).

Everybody gets a moon! With the discovery of a small moon orbiting the third-largest dwarf planet, all the large objects that orbit beyond Neptune now have satellites, reports New Scientist.

Trans-Neptunian objects (TNOs) spend most or all of their orbits beyond Neptune. Last April, the dwarf planet Makemake became the ninth of the ten TNOs with diameters near or above 1,000 kilometres known to have a moon.

So when dwarf planet 2007 OR10 was found to be rotating more slowly than expected, it was suspected that a moon might be the culprit.
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Exoplanets up to 90 times closer to their star than Earth is to the Sun.

Exoplanets up to 90 times closer to their star than Earth is to the Sun.


We did know something about this system already, but more work has led to today’s announcement.

Astronomers have never seen anything like this before, says Space.com: Seven Earth-size alien worlds orbit the same tiny, dim star, and all of them may be capable of supporting life as we know it, a new study reports. 

“Looking for life elsewhere, this system is probably our best bet as of today,” study co-author Brice-Olivier Demory, a professor at the Center for Space and Habitability at the University of Bern in Switzerland, said in a statement. 
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Proposed path of Planet 9 around the sun with Neptune and several notable TNOs for reference [credit: Wikipedia]

Proposed path of Planet 9 around the sun with Neptune and several notable TNOs for reference [credit: Wikipedia]


Researchers suggest the pair may have got too close to the hypothetical Planet Nine, resulting in their current orbits.

The dynamical properties of these asteroids, observed spectroscopically for the first time using the Gran Telescopio CANARIAS, suggest a possible common origin and give a clue to the existence of a planet beyond Pluto, the so-called ‘Planet Nine’, reports Phys.org.

In the year 2000 the first of a new class of distant solar system objects was discovered, orbiting the Sun at a distance greater than that of Neptune: the “extreme trans Neptunian objects” (ETNOs). Their orbits are very far from the Sun compared with that of the Earth.

We orbit the Sun at a mean distance of one astronomical unit (1 AU which is 150 million kilometres) but the ETNOs orbit at more than 150 AU. To give an idea of how far away they are, Pluto’s orbit is at around 40 AU and its closest approach to the Sun (perihelion) is at 30 AU. This discovery marked a turning point in Solar System studies, and up to now, a total of 21 ETNOs have been identified.

Recently, a number of studies have suggested that the dynamical parameters of the ETNOs could be better explained if there were one or more planets with masses several times that of the Earth orbiting the Sun at distances of hundreds of AU.
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gr_prob
The research team thinks its results are ‘difficult to understand in terms of dark matter’, reports Phys.org. The study was earlier reported here.

The distribution of normal matter precisely determines gravitational acceleration in all common types of galaxies, a team led by Case Western Reserve University researchers reports.

The team has shown this radial acceleration relation exists in nearby high-mass elliptical and low-mass spheroidal galaxies, building on last year’s discovery of this relation in spiral and irregular galaxies.

This provides further support that the relation is tantamount to a new natural law, the researchers say.
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HR 8799 system [image credit: Many Worlds]

HR 8799 system [image credit: Many Worlds]


It can’t get much more obvious than this. The report says ‘it’s a one-two-four-eight resonance’ of the orbits of these massive planets, but we find it’s much nearer to 1:2:4:9, with the outer planet taking 450 years for one orbit.

The era of directly imaging exoplanets has only just begun, but the science and viewing pleasures to come are appealingly apparent says Many Worlds.

This evocative movie of four planets more massive than Jupiter orbiting the young star HR 8799 is a composite of sorts, including images taken over seven years at the W.M. Keck observatory in Hawaii. The movie clearly doesn’t show full orbits, which will take many more years to collect.

The closest-in planet circles the star in around 49 years [report incorrectly says 40]; the furthest takes more than 400 years. But as described by Jason Wang,  an astronomy graduate student at the University of California, Berkeley, researchers think that the four planets may well be in resonance with each other.
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Still from pulsar animation.  [Image credit: NASA]

Still from pulsar animation. [Image credit: NASA]


The exoplanet revolution began 25 years ago today. On Jan. 9, 1992, astronomers Alex Wolszczan and Dale Frail published a paper in the journal Nature announcing the discovery of two planets circling an incredibly dense, rapidly rotating stellar corpse known as a pulsar.

It was a landmark find: while several alien-world “candidates” had recently been spotted, Wolszczan and Frail provided the first confirmation that planets exist beyond our own solar system, reports Mike Wall.

“From the very start, the existence of such a system carried with it a prediction that planets around other stars must be common, and that they may exist in a wide variety of architectures, which would be impossible to anticipate on the basis of our knowledge of the solar system alone,” Wolszczan, who’s based at Pennsylvania State University, wrote in a note about the pulsar planets for the “Name Exoworlds” contest sponsored by the International Astronomical Union.
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aliens1
Aliens might be the ‘Hollywood solution’ but those tend to be fictional. On the other hand, plausible explanations are elusive.

Astronomers may have to think a little harder to solve the mystery of Boyajian’s star reports Space.com.

In September 2015, Yale University’s Tabetha Boyajian and her colleagues reported that the star KIC 8462852 has dimmed dramatically multiple times over the past seven years, once by an astounding 22 percent. 

NASA’s planet-hunting Kepler space telescope spotted these dimming events. But the brightness dips of “Boyajian’s star,” as it has come to be known, were far too significant to be caused by an orbiting planet, so astronomers began thinking of alternative explanations.

Researchers have come up with many possible causes for the dimming, including a swarm of broken-apart comet fragments, variability in the activity of the star itself, a cloud of some sort in the interstellar medium between Kepler and Boyajian’s star, and, most famously, an orbiting “megastructure” built by an alien civilization to collect stellar energy.

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I’m working away for the next fortnight, with no internet access. So I thought I’d put up something for the bright denizens of the talkshop to chew on while I’m gone. Bode’s Law is a heuristic equation which gives the approximate distance to the first seven major planets plus Ceres. reasonably well, but then goes completely off the rails as you can see in Figure 1 below.

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titus-bode_law

Figure 1 Titius-Bode equation (red) vs planets (blue)

I’ve always thought the Titius-Bode equation to be a fudge. It doesn’t relate to any physical concepts that have anything to do with orbits or gravity. So I’ve come up with something better.

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Subaru telescope, Hawaii (far left) [image credit: Wikipedia]

Subaru telescope, Hawaii (far left) [image credit: Wikipedia]


Being able to measure things like the mass, temperature and atmospheric composition of exoplanets should generate some interesting new data for analysis, with possible implications for climate theory.

A team of scientists and engineers led by Princeton researchers recently reported the successful operation of a new instrument for the Subaru Telescope in Hawaii that will allow astronomers to make direct observations of planets orbiting nearby stars.

The instrument, dubbed CHARIS, was designed and built by a team led by N. Jeremy Kasdin, a professor of mechanical and aerospace engineering. It allows astronomers to isolate light reflecting from planets larger than Jupiter and then analyze the light to determine details about the planets’ size, age and atmospheric constituents.

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