BAA Mars Section: Dust Storm Alert

Dear Observers,

Images taken by Efrain Morales Rivera (Puerto Rico) in the last few days (May 21-24) clearly show a changeable bright yellow streak of dust at the IAU western (following) edge of Eysium. The bright cloud was very conspicuous in red light and was not related to the usual orographic cloud activity over Elysium Mons.

The Director had observed the area on May 16 without seeing the storm, while on May 23 the Elysium region was too near the morning terminator for the correct longitude to have been visible to him.

Evidence for previous telescopic dust storms in this area exists, but such events are very uncommon for Elysium, and sometimes the area has simply been a secondary focus of activity for another dust storm developing elsewhere, such as at the start of the 2001 planet-encircling storm.

If you are able to do so, please monitor the area and send me your reports. Secondary activity could occur elsewhere at any time now, though an image by Clyde Foster centred at longitude 101 degrees on May 24 shows that hemisphere to be free of dust.

Best wishes, Richard McKim

 

ASSOCIATION OF LUNAR & PLANETARY OBSERVERS

The lower set of images provide evidence for strong South to North straight-line winds in the Hellas crater during April and early May 2016 or Ls 130 to Ls 150. Hellas is immense with the South to North diameter about 1,300 miles that is roughly the distance from the US-Canada border to the Pan-handle of Texas. So with that diameter, a significant temperature gradient is likely in the South to North direction that can produce strong winds.  These detailed images by Clyde Foster and Efrain Riveras Morales show the results of these winds.

Saturn at opposition – Guide to finding Titan

SATURN is the lovely ringed planet of the solar system which is always lovely to see through any telescope, and with the rings now nicely on display it is wonderful sight.

On 3 June SATURN is at OPPOSITION and is presently moving through the 13^th sign of the zodiac (Ophiuchus), and can be seen above the bright orange star Antares. From late August until late November it can be seen in the evening sky, and then comes too close to the Sun for observation until late December. Saturn is in conjunction with Mars on 25 August when it will be (4° above). It will then be in conjunction with Venus (3° above) on 30 October. Saturn will then be very low in the SW soon after sunset. Both these occasions will make nice photo opportunities to look forward to.

Remember that as seen through an astronomical telescope Saturn is upside down with its South Pole uppermost and Eastern limb on the left.

You might observe Saturn you may like to look to see the planet’s largest Moon Titan, here is an ephemeris showing all of the Moon’s positions during 2016 which should be a useful guide.

Alert | Nova discovered in the Large Magellanic Cloud

ASTRO-PHOTOGRAPHERS in the southern hemisphere are encouraged to take images of the Large Magellanic Cloud to record a new nova that flared up on 10 May.

The Large Magellan Cloud is at the centre of attention as astronomers are observing a brightening Nova discovered at RA 05h 10m 32.58s DEC -69d 21m 30.4s. The Nova was at Mag 12 on 10 May, and Mag +11.6 on 13 May.

The Nova, known as MASTER OT J051032.58-692130.4 is of great interest because the Progenitor star was reportedly showing a 2.65 day eclipse-like period. It had the mean magnitude of  +20.64 and colour (V-I) = 0.27 mag. Such a period is unusually long for a classical nova system and makes one suspect a nova in a symbiotic binary (a so called vampire star) or even a V1309 Sco-like stellar merger event. Apart from the suggested eclipsing binary progenitor, observed properties of the nova so far are consistent with a classical nova outburst.

Celebrates the Transit of Mercury

The next Transit of Mercury will not take place until 11 November 2019 so this was a golden opportunity to see an event so rare ...

In my new program for May 'The music of the spheres' we take a look at how to observe the transit safely and what to look for with  Prof. Lucy Green (The Society for Popular Astronomy).

Then we look back at the Greek philosophers & famous astronomers who helped piece together the order of the Solar System we know today.

New Horizons Unique observations of KBO JR1

JR1 lies in the constellation of Libra (the scales) at RA 15h 40m 08s DEC –12 24’ 25”

Click on the images to enlarge

NASA's New Horizons spacecraft launched on January 19, 2006, flew past Jupiter to obtain a gravity assist in February 2007, and passed within 22,000 miles of Pluto on July 14, 2015. The 2003 Space Studies Board recommended that a “Kuiper Belt-Pluto Explorer" (which became New Horizons) investigate several KBOs (Kuiper Belt Objects), and that the value of those investigations would be increased with the number of KBO observed.

After the Pluto flyby, NASA approved a thruster burn sequence to redirect New Horizons to 2014 MU69, with the final burn on November 4, 2015. This trajectory allows the spacecraft to reach 2014 MU69 on January 1, 2019. However this flyby will only occur if NASA approves an extended mission for New Horizons. In addition to the 2014 MU69 flyby, the proposed extended mission also includes distant observations of about 20 KBOs at viewing geometries impossible from the Earth, allowing close satellite and ring searches, measurement of surface properties, and precision orbit determination.

(15810) 1994 JR1 (hereafter JR1) is a Kuiper Belt Object in a 3:2 mean motion resonance with Neptune. It was discovered in 1994 with the Isaac Newton Telescope at the Roque de los Muchachos Observatory, making it the 13th KBO discovered (including Pluto-Charon) and the first resonant KBO after Pluto with a multi-year arc. Its proximity to Pluto (251 million miles) led de la Fuente Marcos & de la Fuente Marcos (2012) to propose that JR1 could be a quasi-satellite of Pluto (an object that spends an extended amount of time close to Pluto, but is not gravitationally bound), though this ending was uncertain given the quality of orbit determination.

The primary astronomical imager on New Horizons is the LOng Range Reconnaissance Imager (LORRI). LORRI first observed JR1 on November 2, 2015 in four sets of ten 4x4 images, spaced one hour apart. At the time of the observation, New Horizons was 172 million miles from the KBO, and seeing it at a solar phase angle of 26.7 degrees. LORRI observed JR1 again on April 7, 2016, at a distance of 66 million miles and solar phase angle of 58.5 degrees.

In addition to the New Horizons observations, the Hubble Space Telescope observed JR1 on November 2, 2015, almost simultaneously to the spacecraft observations. With this observation, the Wide Field Camera 3 obtained five images, two with the F606W (wide V) filter and three with the F814W (wide I) filter. This was the first time a KBO (other than Pluto and Charon) was observed from two very distant locations in the Solar System, and allowed the New Horizon’s science team to very precisely constrain the present location of JR1. The measured magnitude  was +22.7 and the magnitude in F814W was +22 .

JR1 is currently 251 million away from Pluto and on a very similar orbit. Because they are both in 3:2 resonant orbits with Neptune, both Pluto and JR1 are primarily perturbed by Neptune. However, Pluto and its five satellites is by far the most massive 3:2 resonant KBO system.

JR1 is primarily perturbed by Neptune, though is not trapped in a Kozai resonance, as its perihelion circulates. Pluto's argument of perihelion liberates every 3.8 million years, while JR1's argument circulates every 0.83 million years. This combines with the nodal regression of the two bodies to be in conjunction every 2.4 million years. Because of Pluto's eccentric and inclined orbit, the Pluto-JR1 distance at one of these conjunctions is highly variable, but can be as close as 46 million miles. During the conjunctions, Pluto does perturb JR1, but because the close approach distance is variable, Pluto's perturbation on JR1 is effectively chaotic. While this could be described as Pluto quasi-satellite behaviour, since JR1's orbit is still primarily controlled by Neptune, a more precise description would be a series of periodic Pluto scattering events, one of which JR1 is currently experiencing.  JR1 is a case of Pluto exerting its gravitation influence over a fellow 3:2 resonant object.

JR1 has a V-R of 0.76, making it a very red KBO. Unique New Horizons observations showed that JR1 has a high surface roughness of 375, indicating that it is potentially very cratered. They also showed that the rotational period of JR1 is 5.470.33 hours, faster than most KBOs, and enabled a reduction of radial uncertainty of JR1's position from 105 to 103. Neptune perturbations bring Pluto and JR1 close together every 2.4 million years, when Pluto can perturb JR1's orbit. Future ground-based photometry of JR1 would be useful to better constrain the period and opposition surge, and to allow preliminary estimates of JR1's shape and pole. These proof of concept distant KBO observations demonstrate that if the proposed New Horizons extended mission is approved, it will indeed be capable of observing dozens of distant KBOs during its flight through the Kuiper Belt.

© Astrophysical Journal Letters 16 May 2016 [This article is an edited extract by R. Pearson].

Congratulations to NASA’s Award winning New Horizons team

NASA's New Horizons spacecraft is hundreds of millions of miles and almost 10 months beyond its July 2015 exploration of Pluto – but here on Earth, the honours for that historic achievement continue.

New Horizons mission team members display the National Air and Space Museum's Current Achievement Trophy, awarded on April 5, 2016. (Credit: Eric Long, National Air and Space Museum, Smithsonian Institution)

The mission team was recently awarded the prestigious National Air and Space Museum Trophy for Current Achievement, an annual honour that recognizes the significant accomplishments of a scientific or technological project. New Horizons was saluted for accomplishing the first direct investigation of Kuiper Belt objects at the outer margins of the planetary system and producing astonishing new images and scientific data – while cost-effectively executing a mission that has changed the nation's approach to solar system exploration.

"In completing the first reconnaissance of the solar system, the flyby of Pluto was not the end of something, but instead, I believe, a new beginning," said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute (SwRI), when accepting the trophy for the team during a ceremony at the museum on April 5. "We showed how much the public craves bold exploration, and we showed just how much exploration can teach us about nature when we visit new places with capabilities never before brought to bear."

Astronomy & Space October 2015 --- Pluto out of the Darkness

The following week, during the opening ceremony of the 32nd Space Symposium in Colorado Springs, Colorado, on April 11, the Space Foundation presented the team with the 2016 John L. "Jack" Swigert Jr. Award for Space Exploration. The foundation gives the annual award for the most significant accomplishments in advancing the exploration of space during the previous year.

The team was also honoured later in April with an Edison Award for Science. Named for famed inventor Thomas Edison, the international awards honour excellence in areas such as new product and service development, marketing, human-cantered design and innovation. Read more about the Edison Award winners here.

The New Horizons spacecraft flew past Pluto and its five moons on July 14, 2015, providing the first close-up look at this system on the planetary frontier. The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, designed, built, and operates the New Horizons spacecraft, and manages the mission for NASA's Science Mission Directorate. In addition to being the home of the mission principal investigator, SwRI, based in San Antonio, leads the science team, payload operations and science planning. New Horizons is the first mission in NASA's New Frontiers Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.

Star birth in the Large Magellanic Cloud

In this image from ESO’s Very Large Telescope (VLT), light from blazing blue stars energises the gas left over from the stars’ recent formation. The result is a strikingly colourful emission nebula, called LHA 120-N55, in which the stars are adorned with a mantle of glowing gas. Astronomers study these beautiful displays to learn about the conditions in places where new stars develop.

LHA 120-N55, or N55 as it is usually known, is a glowing gas cloud in the Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way located about 163 000 light-years away. N55 is situated inside a supergiant shell, or super bubble called LMC 4. Super bubbles, often hundreds of light-years across, are formed when the fierce winds from newly formed stars and shockwaves from supernova explosions work in tandem to blow away most of the gas and dust that originally surrounded them and create huge bubble-shaped cavities.

The material that became N55, however, managed to survive as a small remnant pocket of gas and dust. It is now a standalone nebula inside the super bubble and a grouping of brilliant blue and white stars — known as LH 72 — also managed to form hundreds of millions of years after the events that originally blew up the super bubble. The LH 72 stars are only a few million years old, so they did not play a role in emptying the space around N55. The stars instead represent a second round of stellar birth in the region.

The recent rise of a new population of stars also explains the evocative colours surrounding the stars in this image. The intense light from the powerful, blue–white stars is stripping nearby hydrogen atoms in N55 of their electrons, causing the gas to glow in a characteristic pinkish colour in visible light. Astronomers recognise this tell-tale signature of glowing hydrogen gas throughout galaxies as a hallmark of fresh star birth.

While things seem quiet in the star-forming region of N55 for now, major changes lie ahead. Several million years hence, some of the massive and brilliant stars in the LH 72 association will themselves go supernova, scattering N55’s contents. In effect, a bubble will be blown within a super bubble, and the cycle of starry ends and beginnings will carry on in this close neighbour of our home galaxy.

This new image was acquired using the Focal Reducer and low dispersion Spectrograph (FORS2) instrument attached to ESO's VLT. It was taken as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

Explore the Summer Skies

Saturn at opposition on 03 June: 04 June Aldebaran 0.5 degrees S of the Moon 
05 June Mercury greatest W elongation 24.2 deg: 06 Venus at superior conjunction
11 June Jupiter 1.5 deg N of the Moon:  19 Saturn 3.3 deg S of the Moon
20 June The Summer solstice   [Click on the sky chart to enlarge].

The Swan in the sky

The Summer sky

Evidence For Ejection of Protostars by Filaments in the Orion Nebula

Opaque filamentary structures have been recognized in the interstellar medium (ISM) for well over a century. As already pointed out by Barnard, the undulating form and uniform width of these structures cry out for an explanation: “These [structures] are especially striking in RA = 19h23m DEC = +10° 25’, where they cover a space over 1° wide and form a rather complicated system of twisting and turnings of dark lanes....The strange thing about all such lanes is that they always are of uniform width throughout their ramifications. This must have some meaning beyond mere chance” (Barnard 1905). See B/W image.

While Barnard himself does not appear to have ever heard such an explanation, it seems difficult to conceive of any other than near-critical magnetic fields, I.e., systems with comparable magnetic and gravitational potential energy. Of course, by now it is well known from cosmological simulations (which are well matched by observations) that gravity alone can produce filamentary structures.

However, these never have Barnard’s “twisting and turnings” because such morphologies would be unstable under the influence of gravity alone. They require a competition to gravity from a restoring force. While the general understanding that stars form from collapsing clouds of gas goes back more than 300 years (Kant 1755), the fact that such clouds are embedded in gas filaments has only become clear over the last 50 years with the discovery, and gradually improving measurement, of Class 0 and Class I Protostars directly superposed on filamentary structures in Orion, Aquila, Taurus, etc. (e.g., Andr´e et al. 2014; Stutz & Kainulainen 2015).

The discovery by Heiles (1997) that the Orion A filament (the largest nearby star-forming such structure) is enveloped in a helical magnetic field greatly clarified the nature of these filaments.

The observations show magnetic field lines changing direction as they cross the filament, from into & out of the plane of the sky. Since these are one-dimensional (1-D) projections of an intrinsically 3-D field structure, they cannot be uniquely interpreted by themselves. However, given that circular (or more generally, helical) fields, which would be generated primarily by currents moving along the filaments, are the form that is necessary to confine filaments of approximately uniform thickness, the Heiles (1997) observations constituted a “smoking gun”. Moreover, polarization measurements by Matthews & Wilson (2000) provide information in a second dimension that confirms this picture. That is, under the assumption that this polarization arises from dust grains aligned by either paramagnetic inclusions or radioactive torques, the field lines pass over the filament perpendicular to its axis. See their Figure 1. Subsequent observations confirm these results (Poidevin et al. 2010, 2011).

From Herschel data. This allows us to estimate the gravitational potential on all scales from the resolution limit (about 0.04 pc) to 8.5 pc. This sets the stage to examine the kinematics of the stars and gas in a new light and to derive far-reaching conclusions.

In particular, we argue for a new “slingshot mechanism” that “ejects” Protostars from the dense filaments that nurtured them, thereby cutting off their accretion of new gas. That is, the filaments are always undergoing transverse acceleration, and the nascent Protostars are accelerated with them. When the protostar system becomes sufficiently massive to decouple from the filament, it is released. See for a schematic diagram of the process. As with a terrestrial hunter’s slingshot, no impulse is imparted to the projectile at the moment of release. Rather, it is the filament that accelerates away from the protostar. As with the hunter, so with the Hunter.

Astronomy & Astrophysics manuscript. March 23, 2016 (Abridged).

© Amelia M. Stutz1 and © Andrew Gould1;2
1 Max-Planck-Institute for Astronomy, K¨onigstuhl 17, 69117 Heidelberg, Germany
2 Dept. of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH, USA

Pluto’s Moon Hydra is dominated by ‘Water ice’

The surface of Hydra, Pluto's outermost small moon, is dominated by nearly pristine water ice -- confirming hints that scientists picked up in New Horizons images showing Hydra's highly reflective surface.

This compositional data (infrared spectra) was gathered with the Ralph/Linear Etalon Imaging Spectral Array (LEISA) instrument on July 14, 2015, from a distance of 150,000 miles (240,000 kilometres). It shows the unmistakable signature of crystalline water ice: a broad absorption from 1.50 to 1.60 microns and a narrower water-ice spectral feature at 1.65 microns.

The Hydra spectrum is similar to that of Pluto's largest moon, Charon, which is also dominated by crystalline water ice. But Hydra's water-ice absorption bands are even deeper than Charon's, suggesting that ice grains on Hydra's surface are larger or reflect more light at certain angles than the grains on Charon. Hydra is thought to have formed in an icy debris disk produced when water-rich mantles were stripped from the two bodies that collided to form the Pluto-Charon binary some 4 billion years ago. Hydra's deep water bands and high reflectance imply relatively little contamination by darker material that has accumulated on Charon's surface over the past 4 billion years.

Why does Hydra's ice seem to be cleaner than Charon's? One theory is that micrometeorite impacts continually refresh the surface of Hydra by blasting off contaminants. This process would have been ineffective on the much larger Charon, whose much stronger gravity retains any debris created by these impacts.

Mercury in stunning detail new Mercury elevation map released

Data from NASA’s MESSENGER mission have been used to create this animation of the first global digital elevation model (DEM) of Mercury, revealing in stunning detail the topography across the entire innermost planet and paving the way for scientists to fully characterize its geologic history. Mercury’s surface is coloured according to the topography of the surface, with regions with higher elevations coloured brown, yellow, and red, and regions with lower elevations shown in blue and purple. The MESSENGER spacecraft was launched on Aug. 3, 2004, and began orbiting Mercury on March 17, 2011. It spent four years capturing images and information about the planet closest to the sun in unprecedented detail.

3D Universe ‘frozen in’ at the time of the Big Bang

The question of why space is three dimensional (3D) and not some other number of dimensions has puzzled philosophers and scientists since ancient Greece. Space-time overall is four-dimensional, or (3+1)-dimensional, where time is the fourth dimension. It's well-known that the time dimension is related to the second law of thermodynamics: time has one direction (forward) because entropy (a measure of disorder) never decreases in a closed system such as the universe.

In a new paper published in EPL, researchers have proposed that the second law of thermodynamics may also explain why space is 3D.

"A number of researchers in the fields of science and philosophy have addressed the problem of the (3+1)-dimensional nature of space-time by justifying the suitable choice of its dimensionality in order to maintain life, stability and complexity," co-author Julian Gonzalez-Ayala, at the National Polytechnic Institute in Mexico and the University of Salamanca in Spain, told Phys.org.

"The greatest significance of our work is that we present a deduction based on a physical model of the universe dimensionality with a suitable and reasonable scenario of space-time. This is the first time that the number 'three' of the space dimensions arises as the optimization of a physical quantity."

The scientists propose that space is 3D because of a thermodynamic quantity called the Helmholtz free energy density. In a universe filled with radiation, this density can be thought of as a kind of pressure on all of space, which depends on the universe's temperature and its number of spatial dimensions.

Here the researchers showed that, as the universe began cooling from the moment after the big bang, the Helmholtz density reached its first maximum value at a very high temperature corresponding to when the universe was just a fraction of a second old, and when the number of spatial dimensions was approximately three.

The key idea is that 3D space was "frozen in" at this point when the Helmholtz density reached its first maximum value, prohibiting 3D space from transitioning to other dimensions.

This is because the second law allows transitions to higher dimensions only when the temperature is above this critical value, not below it. Since the universe is continuously cooling down, the current temperature is far below the critical temperature needed to transition from 3D space to a higher dimensional space. In this way, the researchers explain, spatial dimensions are loosely analogous to phases of matter, where transitioning to a different dimension resembles a phase transition such as melting ice—something that is possible only at high enough temperatures.

"In the cooling process of the early universe and after the first critical temperature, the entropy increment principle for closed systems could have forbidden certain changes of dimensionality," the researchers explained.

The proposal still leaves room for higher dimensions to have occurred in the first fraction of a second after the big bang when the universe was even hotter than it was at the critical temperature.

Extra dimensions are present in many cosmological models, most notably string theory. The new study could help explain why, in some of these models, the extra dimensions seem to have collapsed (or stayed the same size, which is very tiny), while the 3D space continued to grow into the entire observable universe.