What is up with these dwarf galaxies? A survey of thousands of galaxies using the Sloan Digital Sky Survey reveals something interesting, which was first revealed by looking at the massive Andromeda Galaxy nearby Earth: dwarf galaxies orbiting larger ones are often in disc-shaped orbits and not distributed randomly, as astronomers expected.
The finding follows on from research in 2013 that showed that 50% of Andromeda’s dwarf galaxies are in a single plane about a million light-years in diameter, but only 300,000 light-years thick. Now with the larger discovery, scientists suspect that perhaps there is a yet-to-be found process that is controlling gas flow in the cosmos.
“We were surprised to find that a large proportion of pairs of satellite galaxies have oppositely directed velocities if they are situated on opposite sides of their giant galaxy hosts,” stated lead author Neil Ibata of Lycée International in France.
“Everywhere we looked, we saw this strangely coherent coordinated motion of dwarf galaxies,” added Geraint Lewis, a University of Sydney physicist. “From this we can extrapolate that these circular planes of dancing dwarfs are universal, seen in about 50 percent of galaxies. This is a big problem that contradicts our standard cosmological models. It challenges our understanding of how the universe works, including the nature of dark matter.”
The astronomers also speculated this could show something unexpected in the laws of physics, such as motion and gravity, but added it would take far more investigation to figure that out.
The Apollo 11 landing site imaged by the Lunar Reconnaissance Orbiter's camera in 2012. Visible is the LM (lunar module), Lunar Laser Ranging RetroReflector (LRRR), its discarded cover and the Passive Seismic Experiment Package (PSEP). The image was taken from 15 miles (24 kilometers) above the surface. Credit: NASA/GSFC/Arizona State University
Forty-five years ago yesterday, the Sea of Tranquility saw a brief flurry of activity when Neil Armstrong and Buzz Aldrin dared to disturb the ancient lunar dust. Now the site has lain quiet, untouched, for almost half a century. Are any traces of the astronauts still visible?
The answer is yes! Look at the picture above of the site taken in 2012, two years ago. Because erosion is a very gradual process on the moon — it generally takes millions of years for meteors and the sun’s activity to weather features away — the footprints of the Apollo 11 crew have a semi-immortality. That’s also true of the other five crews that made it to the moon’s surface.
In honor of the big anniversary, here are a few of NASA’s Lunar Reconnaissance Orbiter’s pictures of the landing sites of Apollo 11, Apollo 12, Apollo 14, Apollo 15, Apollo 16 and Apollo 17. (Apollo 13 was slated to land on the moon, but that was called off after an explosion in its service module.)
The Apollo 12 and Surveyor 3 landing sites in the Ocean of Storms on the moon. Visible is the descent stage of Intrepid (the lunar module) and the robotic craft Surveyor 3, which the astronauts took a sample from while they were on the surface. Also labelled are craters the astronauts visited. Credit: NASA/Goddard/Arizona State UniversityThe Apollo 14 landing site at Fra Mauro, imaged by the Lunar Reconnaissance Orbiter in 2011. At right is the descent stage of Antares, the lunar module. At far left, beside the cart tracks and marked by an arrow, is the Apollo Lunar Surface Experiment Package. Credit: NASA/GSFC/Arizona State UniversityThe Apollo 15 landing site at Hadley plains, taken by the Lunar Reconnaissance Orbiter from an altitude of 15.5 miles (25 kilometers) in 2012. Visible is the descent stage of Falcon (the lunar module), the Lunar Roving Vehicle (LRV) and the Apollo Lunar Surface Experiment Package (ALSEP). The site is marked by rover tracks. Credit: NASA Goddard/Arizona State UniversityThe Apollo 16 landing site in the Descartes Highlands, taken by the Lunar Reconnaissance Orbiter in 2010. Visible is the descent stage of lunar module (LM) Orion, the “parking spot” of the Lunar Roving Vehicle (LRV) and its tracks, the Apollo Lunar Science Experiment Package (ALSEP), a radioisotope generator (RTG) and the geophone line, which is part of the mission’s Active Seismic Experiment. Credit: NASA’s Goddard Space Flight Center/Arizona State UniversityThe Apollo 17 landing site at Taurus-Littrow taken by the Lunar Reconnaissance Orbiter in 2011. Visible is the descent stage of the lunar module Challenger, the Lunar Roving Vehicle (LRV) and its tracks, the Apollo Lunar Surface Experiment Package (ALSEP) and Geophone Rock. Credit: NASA’s Goddard Space Flight Center/ASU
The Eagle Prepares to Land. The Apollo 11 Lunar Module Eagle, in a landing configuration was photographed in lunar orbit from the Command and Service Module Columbia. Inside the module were Commander Neil A. Armstrong and Lunar Module Pilot Buzz Aldrin. The long rod-like protrusions under the landing pods are lunar surface sensing probes. Upon contact with the lunar surface, the probes sent a signal to the crew to shut down the descent engine. Image Credit: NASA
The Eagle Prepares to Land
The Apollo 11 Lunar Module Eagle, in a landing configuration was photographed in lunar orbit from the Command and Service Module Columbia. Inside the module were Commander Neil A. Armstrong and Lunar Module Pilot Buzz Aldrin. The long rod-like protrusions under the landing pods are lunar surface sensing probes. Upon contact with the lunar surface, the probes sent a signal to the crew to shut down the descent engine. Image Credit: NASA Watch the restored EVA video below and on NASA TV on July 20 starting at 10:39 p.m. EDT[/caption]
Man first walked on the Moon 45 years ago today on July 20, 1969 when American astronauts Neil Armstrong and Buzz Aldrin opened the hatch to the Apollo 11 Lunar Module Eagle, climbed down the ladder and set foot on the surface – marking mankind’s greatest achievement. They came in peace for all mankind!
You can relive the historic moment with the gallery of Apollo 11 NASA images collected here and by watching NASA’s restored video of the moonwalk, or extravehicular activity (EVA) by Armstrong and Aldrin – watch video below. The Apollo 11 EVA began at 10:39:33 p.m. EDT.
NASA TV is also broadcasting a replay of the historic moonwalk tonight (July 20) to commemorate the anniversary starting at 10:39 p.m. EDT, with the restored footage of Armstrong and Aldrin’s historic steps on the lunar surface.
You can view the NASA TV Apollo 11 EVA webcast – here.
The Eagle had landed on the Moon’s desolate surface on the Sea of Tranquility (see map below) barely 6 hours earlier at 4:18 p.m EDT. And only 30 seconds of fuel remained as Armstrong searched for a safe landing spot.
Neil Armstrong was the commander of the three man crew of Apollo 11, which included fellow moonwalker Buzz Aldrin and Command module pilot Michael Collins.
Here is NASA’s restored video of the Apollo 11 EVA on July 20, 1969:
Video Caption: Original Mission Video as aired in July 1969 depicting the Apollo 11 astronauts conducting several tasks during extravehicular activity (EVA) operations on the surface of the moon. The EVA lasted approximately 2.5 hours with all scientific activities being completed satisfactorily. The Apollo 11 EVA began at 10:39:33 p.m. EDT on July 20, 1969 when Astronaut Neil Armstrong emerged from the spacecraft first. While descending, he released the Modularized Equipment Stowage Assembly on the Lunar Module’s descent stage.
The trio blasted off atop a 363 foot-tall Saturn V rocket from Launch Complex 39A on their bold, quarter of a million mile moon mission from the Kennedy Space Center , Florida on July 16, 1969 to fulfill the lunar landing quest set by President John F. Kennedy early in the decade.
The three-stage Saturn V generated 7.5 million pounds of thrust and propelled the trio into space and immortality.
Apollo 11 Official Crew Portrait. Official crew photo of the Apollo 11 Prime Crew. From left to right are astronauts Neil A. Armstrong, Commander; Michael Collins, Command Module Pilot; and Edwin E. Aldrin Jr., Lunar Module Pilot. Image Credit: NASA
The Apollo 11 mission was truly a global event.
Armstrong and Aldrin safely touched down at the Sea of Tranquility on the lunar surface on July 20, 1969 at 4:18 p.m EDT as hundreds of millions across the globe watched in awe and united in purpose.
“Houston, Tranquility Base here. The Eagle has landed !,” Armstrong called out and emotional applause erupted at Mission Control – “You got a bunch of guys about to turn blue.”
Apollo 11 commander Neil Armstrong stands on the moon’s surface on July 20, 1969, the first human to do so. Credit: NASA/CBS/YouTube (screenshot)
Armstrong carried all of humanity with him when he stepped off the footpad of NASA’s Apollo 11 Lunar Module and became the first representative of the human species to walk on the surface of another celestial body.
Armstrong’s first immortal words:
“That’s one small step for [a] man, one giant leap for mankind.”
During their 2 ½ hours moonwalk Armstrong and Aldrin unveiled a plaque on the side of the lunar module. Armstrong read the words;
“Here men from the planet Earth first set foot upon the moon. July 1969 A.D. We came in peace for all mankind.”
On the Lunar Surface – Apollo 11 astronauts trained on Earth to take individual photographs in succession in order to create a series of frames that could be assembled into panoramic images. This frame from fellow astronaut Buzz Aldrin’s panorama of the Apollo 11 landing site is the only good picture of mission commander Neil Armstrong on the lunar surface. Credit: NASA
The duo collected about 50 pounds (22 kg) of priceless moon rocks and set out the first science experiments placed by humans on another world. The moon rocks were invaluable in informing us about the origin of the Earth – Moon system.
Aldrin on the Moon. Astronaut Buzz Aldrin walks on the surface of the moon near the leg of the lunar module Eagle during the Apollo 11 mission. Mission commander Neil Armstrong took this photograph with a 70mm lunar surface camera. While astronauts Armstrong and Aldrin explored the Sea of Tranquility region of the moon, astronaut Michael Collins remained with the command and service modules in lunar orbit. Image Credit: NASA
Altogether Armstrong and Aldrin spent about 21 hours on the moon’s surface. Then they said goodbye to the greatest adventure and fired up the LM ascent engine to rejoin Michael Collins circling above in the Apollo 11 Command Module.
Neil Armstrong and Buzz Aldrin plant the US flag on the Lunar Surface during 1st human moonwalk in history 45 years ago on July 20, 1969 during Apollo 1l mission. Credit: NASA
Following the triumphant moonwalk and docking, the crew set their sights for the journey back to the Home Planet.
Apollo 11 logo
The Apollo 11 mission ended with a successful splash down off Hawaii on July 24.
The crew, NASA and America achieved President Kennedy’s challenge of men walking on the Moon before the decade was out and returning safely to Earth.
Armstrong passed away at age 82 on August 25, 2012 due to complications from heart bypass surgery. Read my prior tribute articles: here and here
Surviving crew members Aldrin and Collins will join NASA Administrator Charles Bolden at a ceremony on Monday at the Kennedy Space Center.
Bootprint. A close-up view of astronaut Buzz Aldrin’s bootprint in the lunar soil, photographed with the 70mm lunar surface camera during Apollo 11’s sojourn on the moon. Image Credit: NASA
Altogether a dozen Americans have walked on the Moon during NASA’s five additional Apollo lunar landing missions. No human has returned since the final crew of Apollo 17 departed the Moon’s surface in December 1972.
One legacy of Apollo is the International Space Station (ISS) where six astronauts and cosmonauts work together on science research to benefit mankind.
Notably, the Cygnus commercial cargo ship berthed at the ISS on the 45th anniversary of the Apollo 11 liftoff bringing over 3600 pounds of science experiments and supplies to the station.
NASA’s next big human spaceflight goals are building commercial ‘space taxis’ to low Earth orbit in this decade, an asteroid retrieval mission in the 2020s and voyages to Mars in the 2030s using the new SLS rocket and Orion deep space crew capsule currently under development.
Stay tuned here for Ken’s Earth & Planetary science and human spaceflight news.
Aldrin Gazes at Tranquility Base. Astronaut and Lunar Module pilot Buzz Aldrin is pictured during the Apollo 11 extravehicular activity on the moon. He had just deployed the Early Apollo Scientific Experiments Package. In the foreground is the Passive Seismic Experiment Package; beyond it is the Laser Ranging Retro-Reflector (LR-3). In the left background is the black and white lunar surface television camera and in the far right background is the Lunar Module “Eagle.” Mission commander Neil Armstrong took this photograph with the 70mm lunar surface camera. Image credit: NASABeginning the Mission. The Apollo 11 crew leaves Kennedy Space Center’s Manned Spacecraft Operations Building during the pre-launch countdown. Mission commander Neil Armstrong, command module pilot Michael Collins, and lunar module pilot Buzz Aldrin prepare to ride the special transport van to Launch Complex 39A where their spacecraft awaited them. Liftoff occurred 38 years ago today at 9:32 a.m. EDT, July 16, 1969. Image credit: NASALaunch of Apollo 11. On July 16, 1969, the huge, 363-feet tall Saturn V rocket launches on the Apollo 11 mission from Pad A, Launch Complex 39, Kennedy Space Center, at 9:32 a.m. EDT. Onboard the Apollo 11 spacecraft are astronauts Neil A. Armstrong, commander; Michael Collins, command module pilot; and Edwin E. Aldrin Jr., lunar module pilot. Apollo 11 was the United States’ first lunar landing mission. While astronauts Armstrong and Aldrin descended in the Lunar Module “Eagle” to explore the Sea of Tranquility region of the moon, astronaut Collins remained with the Command and Service Modules “Columbia” in lunar orbit. Image credit: NASAApollo 11 liftoff from Pad 39 at the Kennedy Space Center on July 16, 1969. Credit: NASAApollo 11 landing site on the Moon at the Sea of Tranquility on July 20, 1969
NASA's Curiosity Mars rover used the Mars Hand Lens Imager (MAHLI) camera on its arm to catch the first images of sparks produced by the rover's laser being shot at a rock on Mars. Credit: NASA/JPL-Caltech/MSSS
Curiosity has zapped hundreds of Red Planet rocks with her powerful laser blaster during her lifetime and has now caught the sparks flying for the first time as they happened – as seen in new photos and video above and below released this week by NASA.
As the NASA rover’s million watt Chemistry and Camera (ChemCam) instrument fired multiple laser shots at a rock fortuitously named “Nova” the team commanded her arm-mounted Mars Hand Lens Imager (MAHLI) high resolution imaging camera to try and capture the action as it occurred, for the first time. And they succeeded.
Curiosity blasted the baseball sized “Nova” rock target over 100 times on July 12, 2014, or Sol 687.
Since the nail biting touchdown nearly two years ago on Aug. 5, 2012 inside Gale Crater, ChemCam has aimed the laser instrument at more than 600 rock or soil targets and fired more than 150,000 laser shots.
Here’s a NASA/JPL video showing the laser flash:
Video Caption: The sparks that appear on the baseball-sized rock (starting at :17) result from the laser of the ChemCam instrument on NASA’s Curiosity Mars rover hitting the rock. Credit: NASA/JPL-Caltech/MSSS
ChemCam is used to determine the composition of Martian rocks and soils at a distance of up to 25 feet (8 meters) yielding preliminary data for the scientists and engineers to decide if a target warrants up close investigation and in rare cases sampling and drilling activities.
ChemCam works through a process called laser-induced breakdown spectroscopy. The laser hits a target with pulses to generate sparks, whose spectra provide information about which chemical elements are in the target.
Successive laser shots are fired in sequence to gradually blast away thin layers of material. Each shot exposes a slightly deeper layer for examination by the ChemCam spectrometer.
As Curiosity fired deeper into “Nova” it showed an increasing concentration of aluminum as the sequential laser blasts penetrated through the uninteresting dust on the rock’s surface. Silicon and sodium were also detected.
“This is so exciting! The ChemCam laser has fired more than 150,000 times on Mars, but this is the first time we see the plasma plume that is created,” said ChemCam Deputy Principal Investigator Sylvestre Maurice, at the Research Institute in Astrophysics and Planetology, of France’s National Center for Scientific Research and the University of Toulouse, France, in a statement.
“Each time the laser hits a target, the plasma light is caught and analyzed by ChemCam’s spectrometers. What the new images add is confirmation that the size and shape of the spark are what we anticipated under Martian conditions.”
A Martian target rock called “Nova,” shown here, displayed an increasing concentration of aluminum as a series of laser shots from NASA’s Curiosity Mars rover penetrated through dust on the rock’s surface. This pattern is typical of many rocks examined with the rover’s laser-firing ChemCam. Credit: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS
The SUZ sized rover is driving as swiftly as possible to the base of Mount Sharp which dominates the center of Gale Crater and reaches 3.4 miles (5.5 km) into the Martian sky – taller than Mount Rainier.
During Year 1 on Mars, Earth’s emissary has already accomplished her primary objective of discovering a habitable zone on the Red Planet that contains the minerals necessary to support microbial life in the ancient past when Mars was far wetter and warmer billions of years ago.
To date, Curiosity’s odometer totals over 5.1 miles (8.4 kilometers) since landing inside Gale Crater on Mars in August 2012. She has taken over 166,000 images.
1 Martian Year on Mars! Curiosity treks to Mount Sharp in this photo mosaic view captured on Sol 669, June 24, 2014. Navcam camera raw images stitched and colorized. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com
Curiosity still has about another 2.4 miles (3.9 kilometers) to go to reach the entry way at a gap in the treacherous sand dunes at the foothills of Mount Sharp sometime later this year.
Stay tuned here for Ken’s continuing Curiosity, Opportunity, Orion, SpaceX, Boeing, Orbital Sciences, commercial space, MAVEN, MOM, Mars and more planetary and human spaceflight news.
Images from the Lunar Reconaissance Orbiter showing pits on the lunar surface. The images are each 222 meters (728 feet) wide. Credit: NASA/GSFC/Arizona State University
Just look at that new video from NASA showing the first moon landing site in three dimensions. It’s tempting to touch on the surface nearby the Eagle lander there in the center and do some prospecting.
You’ll notice a lot of craters in that video, which is based on Lunar Reconnaissance Orbiter data. Across the moon’s surface, a separate study saw the spacecraft investigate 200 extremely steep-walled craters, known as “pits”.
These would be fascinating places to send astronauts for scientific study. Not only that, they’re actually one of the safest spots possible on the moon, according to a new study.
“Pits would be useful in a support role for human activity on the lunar surface,” stated lead researcher Robert Wagner of Arizona State University.
“A habitat placed in a pit — ideally several dozen meters back under an overhang — would provide a very safe location for astronauts: no radiation, no micrometeorites, possibly very little dust, and no wild day-night temperature swings.”
And if you look at the picture below, you can see at least one of those pits is in the Sea of Tranquility — the approximate landing area where Apollo 11 touched down 45 years ago this week. The pits were found mainly using a computer algorithm that scanned LRO photos, although a few of the craters were previously identified with the Japanese Kaguya spacecraft.
Large craters or lunar “seas” (ancient, solidified lava flows) are the locations where most of these pits are found. How they were formed is being investigated, but there are some hypotheses. Perhaps a meteorite impact caused a collapse, or perhaps molten rock flows under the surface gradually lost their lava, leaving voids.
Lunar Reconnaissance Orbiter. Image Credit: NASA
To learn more, the researchers say more LRO images would be great (only 40% of the surface imaged had the appropriate lighting conditions for this study) and in the future, we’d need to get much closer-up than pictures taken from orbit.
“The ideal follow-up, of course, would be to drop probes into one or two of these pits, and get a really good look at what’s down there,” added Wagner.
“Pits, by their nature, cannot be explored very well from orbit — the lower walls and any floor-level caves simply cannot be seen from a good angle. Even a few pictures from ground-level would answer a lot of the outstanding questions about the nature of the voids that the pits collapsed into. We’re currently in the very early design phases of a mission concept to do exactly this, exploring one of the largest mare pits.”
Apollo 11 commander Neil Armstrong stands on the moon's surface on July 20, 1969, the first human to do so. Credit: NASA/CBS/YouTube (screenshot)
Thanks to NASA putting the video up on YouTube, we’re fortunate enough today to watch the CBS coverage of Apollo 11 landing on the moon, and Neil Armstrong’s first steps, 45 years ago this week.
Legendary broadcaster Walter Cronkite, who died five years ago yesterday amid 40th anniversary celebrations, helmed the moon coverage for CBS. His quotes from that night are so much a part of history that they’ve even appeared in Hollywood; the 1995 movie Apollo 13 had an edited version of his remarks playing over the first steps.
But in the live coverage, Cronkite showed why he was so good — he had the courage to wait to make a statement until all the facts were available. Armstrong’s first words while standing on the moon ended in static. Cronkite, who must have felt pressure to immediately repeat what Armstrong said, waited until he could get confirmation.
Armstrong’s first words on the moon as heard on television were “That’s one small step for man, one giant leap for mankind.” But starting around the word “leap”, static interfered and the word “mankind” was almost unintelligible.
“I didn’t understand,” Cronkite said after a pause. ” ‘One small step for man.’ But I didn’t get the second phrase.”
Cronkite waited, saying he would like to know what the phrase was. Armstrong talked on about the powder on the moon’s surface. About 30 seconds passed, then Cronkite had his answer from somebody: “His quote was, ‘That’s one small step for man, one giant leap for mankind.’ ”
CBS broadcaster Walter Cronkite reacts moments after Apollo 11 landed on the moon on July 20, 1969. Credit: NASA/CBS/YouTube (screenshot)
Decades later, Cronkite recalled how he felt on that night in his 1996 biography, A Reporter’s Life:
That first landing on the moon was indeed, the most extraordinary story of our time and almost as remarkable a feat for television as the space flight itself. To see Neil Armstrong, 240,000 miles out there, as he took that giant step for mankind onto the moon’s surface, was a thrill beyond all the other thrills of that flight. All those thrills tumbled over each other so quickly that the goose pimples from one merged into the goose pimples from the next.
Cronkite also poked fun at his own reporting, saying he was speechless when lunar module Eagle landed despite having the same number of years as NASA to get ready for it.
” ‘Oh boy! Whew! Boy!’ These were my first words, profundity to be recorded for the ages. They were all I could utter,” Cronkite wrote.
Do watch the entire broadcast, it’s a joy, but the first steps take place around 22:55.
The rise of the Milky Way and a spectacular lightning display in Mersing, Malaysia on June 28, 2014. Credit and copyright: Justin Ng.
Here’s another beautiful astrophoto, courtesy of photographer Justin Ng from Singapore. He’s currently on a photography trip to Malaysia and by chance captured this absolutely stunning view.
“Knowing that the sky would clear after sunset, I led a group of photographers to this location to film a time-lapse of the rising Milky Way above a lonely boat,” Justin explained via email, “but what happened soon after we started shooting was amazing. We were treated to a spectacular lightning display for about an hour from 9:30pm onwards before the clouds caught up with the rising Milky Way and dominated the skies eventually.”
The image is a result of stacking 12 photos (11 shots of lightnings and 1 shot for everything else) from his time-lapse sequence.
We’re looking forward to seeing the timelapse!
See more images from his current trip here, and you can see more of Justin’s fantastic astrophotography at his website, on G+, Facebook and Twitter.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Interior of Jupiter. Image Credit: NASA / R. J. Hall
It’s likely that Jupiter-like planets’ origins root back to either the rapid collapse of a dense cloud or small rocky cores that glom together until the body is massive enough to accrete a gaseous envelope.
Although these two competing theories are both viable, astronomers have, for the first time, seen the latter “core accretion” theory in action. By studying the exoplanet’s host star they’ve shed light on the composition of the planet’s rocky core.
“Our results show that the formation of giant planets, as well as terrestrial planets like our own Earth, leaves subtle signatures in stellar atmospheres”, said lead author and PhD student Marcelo Tucci Maia from University of São Paulo, Brazil, in a press release.
Maia and colleagues pointed the 3.5-meter Canada-France-Hawaii Telescope toward the constellation Cygnus, in order to take a closer look at two Sun-like stars in the distant 16 Cyg triple-star system. Both stars, having formed together from the same gaseous disk over 10 billion years ago and having reached the same mass, are nearly solar twins.
But only one star, 16 Cygni B, hosts a giant planet. By decomposing the light from the two stars into their wavelengths and looking at the difference between the two stars, the team was able to detect signatures left from the planet formation process on 16 Cygni B.
It’s the perfect laboratory to study the formation of giant planets.
Difference in chemical composition between the stars 16 Cyg A and 16 Cyg B, versus the condensation temperature of the elements in the proto-planetary nebula. Image Credit: M. Tucci Maia, J. Meléndez, I. Ramírez.
Maia and colleagues found that the star 16 Cygni A is enhanced in all chemical elements relative to 16 Cygni B. Hence, the metals removed from 16 Cygni B were most likely removed from the protoplanetary disk in order to form the planet.
On top of the overall deficiency in all elements, 16 Cygni B has an added deficiency in the refractory elements — those with high condensation temperatures that form dust grains more easily — such as iron, aluminum, nickel, magnesium, scandium, and silicon. This helps verify what astronomers have expected all along: rocky cores are rich in refractory elements.
The team was able to decipher that these missing elements likely created a rocky core with a mass of about 1.5 to 6 Earth masses, which is similar to the estimate of Jupiter’s core.
“16 Cyg is a remarkable system, but certainly not unique,” said coauthor Ivan Ramírez from the University of Texas. “It is special because it is nearby; however, there are many other binary stars with twin components on which this experiment could be performed. This could help us find planet-host stars in binaries in a much more straightforward manner compared to all other planet-finding techniques we have available today.”
The results were accepted for publication in The Astrophysical Journal Letters and are available online.
Dazzlimg Sirius, with its white dwarf companion to the lower left. Credit: NASA, ESA, H. Bond (STScI) and M. Barstow (University of Leicester).
Looking for something off beat to observe? Some examples of curious astronomical objects lie within the reach of the dedicated amateur armed with a moderate-sized backyard telescope. With a little skill and persistence, you just might be able to track down a white dwarf star. Unlike splashy nebulae or globular clusters, a white dwarf star will just appear as a speck, a tiny dot in the field of view of your telescope’s eyepiece. But just as in the case of observing other exotic objects such as red giants and quasars, part of the thrill of tracking down these astrophysical beasties is in knowing just what it is that you’re seeing. Heck, many amateur astronomers fail to realize that any white dwarf stars are within range of their instruments and have never tracked one down.
The astrophysical nature of white dwarf stars was first uncovered in the early 20th century. Most of the early white dwarf stars discovered were companions in binary star systems and this allowed astronomers to gauge their mass by following the orbital motion of such pairs over time. Soon, astronomers realized that they were looking at something peculiar, a new type of compact but massive stellar object that stubbornly refused to be pigeon-holed along the main sequence of the freshly conceived Hertzsprung-Russell diagram.
Today, we know that white dwarf stars are the remnants of stars which have long since passed the Red Giant stage. We say that a white dwarf is a degenerate star, and no, this not a commentary on its moral state. The Chandrasekhar limit gives us an upper limit in size for a white dwarf at about 1.4 solar masses, beyond which electron degeneracy pressure can no longer act against the inward pull of gravity. Our Sun will one day become a white dwarf, over 6 billion years from now. Think of cramming the mass of our star into the volume of the Earth and you have some idea just how dense a white dwarf is: a cubic centimetre of white dwarf weighs 250 about tons, and two cup fulls of white dwarf would weigh more than a Nimitz-class aircraft carrier.
Think of a white dwarf as a cooling ember of a star long past its hydrogen fusing prime. And white dwarfs will cool down to infrared radiating black dwarfs over trillions of years, far longer than the present 13.7 billion year age of the universe. In fact, the age of white dwarfs currently observed is one on the underpinning tenets of modern Big Bang cosmology.
All amazing stuff. In any event, here is a baker’s half dozen of white dwarf stars that you can find with a telescope tonight. A more extensive list of the nearest white dwarfs to the Earth can be found on Sol Station.
The orbit of Sirius B. Wikimedia Commons image in the Public Domain.
Sirius B: This is the nearest white dwarf to the Earth at 8.6 light years distant. Shining at magnitude +8.5, Sirius B would be a cinch to see, if only dazzling Sirius A — the brightest star in our sky at magnitude -1.5 — were not nearby. Sirius B orbits its primary once every 50 years and will reach a maximum separation of 11.5” from its primary in 2025, a prime time to cross it off of your life list in the coming decade. Blocking the primary just out of the field of view, or using an occulting bar eyepiece is key to finding Sirius B.
Sirius B was discovered by American telescope maker Alvan Graham Clark in 1862. The Dogon people of Mali also have some curious myths surrounding the star Sirius.
Constellation: Canis Major
Right Ascension: 6 Hours 45’
Declination: -16° 43’
The apparent orbit of Procyon B through 2039. Graphic created by the author.
Procyon B: Located 11.5 light years distant, Procyon B was discovered in 1896 by John Martin Schaeberle from the Lick observatory. Shining at magnitude +10.7, the chief difficultly with spotting this white dwarf, as with Sirius B, is that it has a companion about 10 magnitudes – that’s 10,000 times brighter – nearby just 4.3” away.
Constellation: Canis Minor
Right Ascension: 7 hours 39’
Declination: +5 13’
The location of GJ 440 (HIP 57367) in the southern sky. Credit: Starry Night Education Software.
-LP145-141: Also known as GJ 440, LP145-141 is one of the best southern hemisphere white dwarf stars on the list. LP145-141 is a solitary white dwarf shining at magnitude +11.5. Located 15 light years distant, LP145-141 is thought to be a member of the nearby Wolf 219 Moving Group of stars.
Constellation: Musca
Right Ascension: 11 Hours 46’
Declination: -64° 50’
The location of Van Maanen’s Star in the constellation Pisces. Credit: Stellarium
-Van Maanen’s Star: Shining at magnitude +12.4 and located 14.1 light years distant, Van Maanen’s star is the closest solitary white dwarf to Earth and the best example of a white dwarf for small telescopes. Discovered by Ariaan van Maanen in 1917, Van Maanen’s Star also has a very high proper motion of 3” per year.
Constellation: Pisces
Right Ascension: 00 Hours 49’
Declination: 05° 23’
The 40 Omicron Eridani system. Image by Author
-40 Omicron Eridani B: This is a great one to track down. The triple system of 40 Omicron Eridani b contains a fine example of a red and white dwarf orbiting a main sequence star. Located 16.5 light years distant and shining at magnitude +9.5, Omicron Eridani was the first white dwarf star discovered in 1783 by Sir William Herschel, although its true nature wasn’t deduced until 1910. Omicron Eridani B is currently 82” from its primary, an easy split.
Constellation: Eridanus
Right Ascension: 4 Hours 15’
Declination: 7° 39’
-Stein 2051: Rounding off the list and located just over 18 light years distant, Stein 2051 is another example of a red dwarf/white dwarf pair. Stein 2051 b shines at a similar brightest to Van Maanen’s star at magnitude +12.4.
Constellation: Camelopardalis
Right Ascension: 04 Hours 31’
Declination: +58° 59’
Let us know about your trials and triumphs in hunting down these fascinating objects!
Comet 67P/C-G photographed on July 14, 2014 from a distance of approximately 12 000 km.
Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
I thought the photos earlier this week were amazing. This little movie, made of 36 ‘smoothed’ or interpolated images of Comet 67P/Churyumov-Gerasimenko, takes it to the next level, showing the comet’s complex shape even more clearly as Rosetta nudges ever closer to its target. Some have likened it to a duck, a boot and even a baby’s foot. The original photos used for the animation were more pixelated, but a technique known as “sub-sampling by interpolation” was used to smooth out the pixels for a more natural look. Be aware that because of processing, 67P C-G appears smoother than it might be. While the surface looks textured, including what appears to be a small crater atop the duck’s head, we have to be careful at this stage not to over-interpret – some of the details are artifacts.
Raw pixelated image of the comet (left) and after smoothing. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
No one knows yet how such an unusual shape formed in the first place. Possibly the comet is a ‘contact binary’ made of two separate comets or two parts of larger, shattered comet that stuck together during a low-velocity collision. This may have happened more 4 billion years ago when the icy building blocks of the planets and comets were numerous and collisions far more frequent than they are today. Contact binaries aren’t uncommon; we see them in asteroids and comets alike.
* The comet may have once been a more spherical object but after many trips around the sun developed an asymmetrical shape from ice vaporization and outgassing.
* A near-catastrophic impact blasted away a huge chunk of comet ice.
* The strong gravitational pull experienced during a close pass of a large planet like Jupiter or Saturn may have pulled it into an irregular shape.
* A large outburst could have weakened a region on the comet’s surface that later crumbled away.
Detailed view of the likely contact binary asteroid 25143 Itokawa visited by the Japanese spacecraft Hayabusa in 2005. Credit: JAXA
“We will need to perform detailed analyses and modelling of the shape of the comet to determine how best we can fly around such a uniquely shaped body, taking into account flight control and astrodynamics, the science requirements of the mission, and the landing-related elements like landing site analysis and lander-to-orbiter visibility,” said Rosetta Mission Manager Fred Jansen. ” But with fewer than 10,000 km to go before the August 6th rendezvous, our open questions will soon be answered.”
In the meantime, keep the photos and movies coming. We can’t get enough.
