Astronomy Archives

June 11, 2014December 23, 2015 by David Dickinson

An Astronomical Eloping: How Rare is a “Friday the 13th Honey Moon?”

The June 2012 "Honey Moon" rising. Photo credit: Stephen Rahn.

Ah, Friday the 13^th. Whether you fear it or it’s just your favorite slasher flick, it’s coming right around the bend later this week. And while it’s pretty much a non-event as far as astronomy is concerned, there’s bound to be some woo in the works, because the June Full Moon — dubbed the “Honey Moon” — falls on the same date.

Well, sort of. We made mention of this month’s Full Moon falling on Friday the 13^th in last week’s post on the occultation of Saturn by Earth’s Moon. We’re not out to alarm any triskaidekaphobics, but we always love the chance to have some fun with calendars in the name of astronomy.

What we’re seeing here is merely the intersection of three cycles of events… and nothing more. These sorts of things can be fun to calculate and can provide a teachable moment, even when that well meaning but often misinformed relative/coworker/stranger on Twitter sends it your way . Hey, some people golf or collect steel pennies, this is our shtick.

A “Friday the 13^th Honey Moon” is basically the subset of: 1. Fridays that fall on the 13^th day of the month (OK, that’s two input parameters, we know) that also 2. Fall in the month of June, and 3. Occur on a Full Moon.

Friday the 13^th occurs from one to three times a calendar year, so you can already see that one will occasionally happen to land on a Full Moon date fairly frequently… but how ‘bout in June? To this end, we compiled this handy listing of “Full Moons that fall on the 13th day of the month” — 15 in all — that occur from 1990 to 2030:

Full Moon's that fell on the 13th from 1990-2030 as reckoned in Universal Time. Only one (March 1998) fell on a Friday the 13th. Chart by author. — Full Moons that fell on the 13th from 1990-2030 as reckoned in Universal Time. Only two (March 1998 and June 2014) fall on a Friday the 13th. Chart by author.

That’s about one every two to three years. But you have to go aaaaall the way back to June 13^th, 1919 to find a Full Moon that fell on a Friday the 13^th in the month of June. This will next occur on June 13^th, 2098.

Of course, this is just an interesting intersection concerning the vagaries and nuances of our Gregorian calendar and the lunar cycle. You could just as easily see significance where there is none in the Full Moon coinciding with the next Superbowl or Academy Awards. Humans love to pick out patterns where often none exist.

(Fun homework assignment: When is the last/next total lunar eclipse that occurs on Friday the 13^th?)

And keep in mind, the instant of the Full Moon this week occurs on Friday at 4:13 UT… this means that from the U.S. Central time zone westward, the Full Moon actually falls on Thursday the 12^th.

The rising Moon just hours before Full on Thursday June 12th. Note Saturn to the upper right. Created using Stellarium.

Fun fact: the 13^th falls on a Friday more than any other day of the month! It’s true… in a span of 400 years following the institution of the Gregorian calendar in 1582, Friday fell on the 13^th a total of 688 times, while Thursday and Saturday the 13^th fell in last place at 684.

But there’s is something else that’s special about the June Full Moon. It also falls closest to the June solstice, marking the start of astronomical northern hemisphere summer and winter in the southern. This means that the Full Moon nearest the June solstice rides at its lowest to the southern horizon for northern hemisphere observers, but is high in the sky for observers south of the equator.

The June 2012 Full Honey (or do you say Strawberry?) Moon. Photo by author.

The June solstice this year falls on Saturday, June 21^st at 10:51 UT /6:51 AM EDT. The Full Moon closest to the June solstice is nearly, but not always, in June… It can occur up to July 6^th, and the last time it fell in July is 2012 and the next is 2015. The July Full Moon is known as the Full Buck Moon.

Our good friends over at Slooh will be webcasting the Full Honey Moon this Friday the starting at 1:30 UT/9:30 PM EDT (Thursday June 12^th) for two hours from its Canary Islands site and the Pontificia Universidad Católica de Chile observatory near Santiago, Chile. The broadcast will be hosted by Slooh astronomer Geoff Fox, astronomer and author of The Sun’s Heartbeat Bob Berman, and Slooh engineer Paul Cox.

Is there a connection between late spring weddings, the June Full Moon and the modern term “honeymoon”? Well, the rising June Full Moon certainly takes on an amber color for northern hemisphere observers as it rises low through the sultry summer skies. The Moon’s orbit is actually tilted five degrees relative to the ecliptic, which means it alternates from “flat” to “hilly” about every 9 years varying from 18 to 28 degrees relative to the celestial equator. We’re approaching a flat year — known as minimum or minor lunar standstill — in 2015, after which the Moon’s apparent path across the sky will begin to widen once again towards 2024.

The ~9 year variation between major and minor lunar standstill. Credit Wikimedia Commons graphic in the Public Domain.

Bob Berman has this to say about the origin of the term: “Is this Full Moon of June the true origin of the word honeymoon, since it is amber, and since weddings were traditionally held this month? That phrase dates back nearly half a millennium to 1552, but one thing has changed: weddings have shifted, and are now most often held in August or September. The idea back then was that a marriage is like the phases of the Moon, with the Full Moon being analogous to a wedding. Meaning, it’s the happiest and ‘brightest’ time in a relationship.”

It’s also worth noting the June Full Moon was known as the Strawberry Moon to the Algonquin Indians of North America. Huh… and here we thought most weddings were in May.

Whatever the case, you can get out enjoy the rising Full Moon with that significant other this week… and don’t fear the Honey Moon.

June 10, 2014December 23, 2015 by Elizabeth Howell

Surprise! The Earth And Moon May Be 60 Million Years Older Than We Thought

Distance Between the Earth and Moon — The Earth rising over the Moon's surface, as seen by the Apollo 8 mission. Credit: NASA

Wondering why a new research team says the Earth and the Moon is 60 million years older than previously believed? Well, it’s a gas. It has to do with the proportion of different gas types that have stuck around since the Earth was formed about 4.5 billion years ago.

Since Earth had no solid surface at the time, traditional geology doesn’t really work — there’s no rock layers to examine, for example. So while the geologists caution we’ll likely never know for sure when the Earth came together, a new dating method for the gases show it was earlier than believed, they said.

To back up a step, the leading theory for how the Moon formed is that a Mars-sized object smashed into our planet, created a chain of debris, and over a long time gradually came together and formed the Moon. There’s been a flurry of news on this event in recent days. Different science groups have found evidence of the crash in Earth and Moon materials, and said it could explain why the Moon’s far side is so rugged compared to the near side.

For this study, Guillaume Avice and Bernard Marty (who are both geochemists from the University of Lorraine in Nancy, France) examined xenon gas in quartz found in Australia (previously believed to be 2.7 billion years old) and South Africa (3.4 billion years old).

64% illuminated waning gibbous Moon on August 26, 2013. Credit and copyright: Themagster3 on Flickr.

“Recalibrating dating techniques using the ancient gas allowed them to refine the estimate of when the Earth began to form,” stated the Goldschmidt Geochemistry Conference in Sacramento, California, where this was presented today (June 10). “This allows them to calculate that the Moon-forming impact is around 60 million years (+/- 20 m. y.) older than had been thought.”

This also affects calculations concerning when the Earth’s atmosphere formed. Since the atmosphere could not have stuck around after the big crash, this means that the previous estimate of 100 million years after the solar system’s formation wouldn’t work. So if the Earth and the Moon are 60 million years older, the Earth’s atmosphere formed about 40 million years after the solar system’s formation.

It’ll be interesting to see if other scientists agree with the analysis.

Source: Goldschmidt Geochemistry Conference

June 10, 2014December 23, 2015 by Elizabeth Howell

Mystery Solved? Why There are No Lunar ‘Seas’ On The Far Side Of The Moon

Composite image of the far side of the moon taken by the Lunar Reconnaissance Orbiter in 2009. Credit: NASA

In these days of daily image releases from Saturn, Mars, the Moon and other spots in the universe, it’s hard to remember just how exciting it was back in the 1950s and 1960s when a few images trickled out to the world at the time. Perhaps one of the biggest early surprises was how jagged and cragged the back side of the moon looked. Where were the lunar “seas” that we are familiar with on the Earth-facing side of the moon?

About 55 years after the first Soviet images of the farside were sent to Earth, a team of researchers led by graduate astrophysics student Arpita Roy (at Penn State University) may have an explanation.

They say it’s due to the violent way that the Moon formed — likely after a Mars-sized object collided with our Earth, creating a sea of debris that gradually coalseced into the Moon we see today. The huge crash and gathering together heated up both our planet and the Moon, but the Moon got cooler first because it was smaller.

Since the Earth was still hot — radiating at more than 2,500 degrees Celsius (4,500 degrees Fahrenheit) — and the Moon very close to the planet, the heat of the Earth had quite the effect. The far side of the Moon cooled down while the near side remained very hot.

“This gradient was important for crustal formation on the moon. The moon’s crust has high concentrations of aluminum and calcium, elements that are very hard to vaporize,” Penn State stated.

Calcium and aluminum are the first elements that “snow out” as rock vapor cools, and they would have remained in the atmosphere on the Moon’s far side. (The near side was too hot.)

“Thousands to millions of years later, these elements combined with silicates in the Moon’s mantle to form plagioclase feldspars, which eventually moved to the surface and formed the Moon’s crust,” Penn State added. “The farside crust had more of these minerals and is thicker.”

The seas themselves were formed after huge meteors crashed into the Moon’s Earth-facing side, rupturing the crust and letting the basaltic lava beneath burst forth. The crust on the far side was too thick for the meteors to penetrate, in most cases, leaving the rugged surface we are familiar with today.

The research was published yesterday (June 9) in Astrophysical Journal Letters. And by the way, there’s been a flurry of news in recent days about the Earth and the Moon’s formation: the “signal” in Earth’s crust and the oxygen signature on the Moon.

Source: Penn State University

June 9, 2014March 1, 2017 by Fraser Cain

Why is the Moon Leaving Us?

Goodbye Moon. Every year, the Moon slips a few centimeters away from us, slowing down our day. Why is the Moon drifting away from us, and how long will it take before the Earth and the Moon are tidally locked to each other?

We had a good run, us and the Moon. Grab your special edition NASA space tissues because today we’re embarking on a tale of orbital companionship, childhood sweethearts and heartache.

You could say we came from the same part of town. A long time ago the Mars-sized object Theia, collided with the Earth and the Moon was formed out of the debris from the collision.

We grew up together. Counting from the very beginning, this relationship has lasted for 4.5 billion years. We had some good times. Some bad times. Gravitationally linked, arm in arm, inside our solar family sedan traversing the galaxy.

But now, tragedy. The Moon, OUR Moon, is moving on to brighter horizons. We used to be much closer when we were younger and time seemed to fly by much faster. In fact, 620 million years ago, a day was only 21 hours long. Now they’ve dragged out to 24 hours and they’re just getting longer, and the Moon is already at a average distance of 384,400 km. It almost feels too far away.

If we think back far enough to when we were kids, there was a time when a day was just 2 – 3 hours long, and the Moon was much closer. It seemed like we did everything together back then. But just like people, massive hunks of rock and materials flying through space change, and their relationships change as well.

Our therapist told us it wasn’t a good idea to get caught up on minutiae, but we’ve done some sciencing using the retroreflector experiments placed by Apollo astronauts, and it looks as though the Moon has always had one foot out the door.

Today it’s drifting away at 1-2 cm/year. Such heartache! We just thought it seemed like the days were longer, but it’s not just an emotional effect of seeing our longtime friend leaving us, there’s a real physical change happening. Our days are getting 1/500th of a second longer every century.

I can’t help but blame myself. If only we knew why. Did the Moon find someone new? Someone more attractive? Was it that trollop Venus, the hottest planet in the whole solar system? It’s really just a natural progression. It’s nature. It’s gravity and tidal forces.

And no, that’s not a metaphor. The Earth and the Moon pull at each other with their gravity. Their shapes get distorted and the pull of this tidal force creates a bulge. The Earth has a bulge facing towards the Moon, and the Moon has a more significant bulge towards the Earth.

A series of photos combined to show the rise of the July 22, 2013 ‘super’ full moon over the Rocky Mountains, shot near Vail, Colorado, at 10,000ft above sea level in the White River National Forest. Moon images are approximately 200 seconds apart. Credit and copyright: Cory Schmitz

These bulges act like handles for gravity, which slows down their rotation. The process allowed the Earth’s gravity to slow the Moon to a stop billions of years ago. The Moon is still working on the Earth to change its ways, but it’ll be a long time before we become tidally locked to the Moon.

This slowing rotation means energy is lost by the Earth. This energy is transferred to the Moon which is speeding up, and as we’ve talked about in previous episodes the faster something orbits, the further and further it’s becomes from the object it’s orbiting.

Will it ever end? We’re so attached, it seems like it’ll take forever to figure out who’s stuff belongs to who and who gets the dog. Fear not, there is an end in sight. 50 billion years from now, 45 billion years after the Sun has grown weary of our shenanigans and become a red giant, when the days have slowed to be 45 hours long, the Moon will consider itself all moved into its brand new apartment ready to start its new life.

What about the neighbors down the street? How are the other orbital relationships faring. I know there’s a lot of poly-moon-amory taking place out there in the Solar System. We’re not the only ones with Moons tidally locked. There’s Phobos and Deimos to Mars, many of the moons of Jupiter and Saturn are, and Pluto and Charon are even tidally locked to each other, forever. Now’s that’s real commitment. So, in the end. The lesson here is people and planets change. The Moon just needs its space, but it still wants to be friends.

What do you think? If you were writing a space opera about the Earth and the Moon break-up, what was it that finally came between them? Tell us in the comments below.

June 9, 2014December 29, 2015 by Susie Murph

Carnival of Space #357

Carnival of Space. Image by Jason Major.

Welcome, come in to the 357th Carnival of Space! The carnival is a community of space science and astronomy writers and bloggers, who submit their best work each week for your benefit. I’m Susie Murph, part of the team at Universe Today and now, on to this week’s stories!

We’re going to start off with a double blast from the past, courtesy of CosmoQuest! This week, they’re featuring Stuart Robbins’s blog post from January 13, 2012, titled “Perspective on the Apollo 15 Landing Site.” He explores the region of the Moon that is the current home of the MoonMappers images that YOU are still mapping and exploring today – the Apollo 15 landing site area. It’s a neat place and we can study a lot of things there. Due to a quirk of optics and angles, you can even imagine you’re flying towards it.

Next, we stay with Cosmoquest’s Moon Mappers as they highlight the interesting discovery that the groundbreaking Soviet Lunakhod 2 lunar rover traveled farther than earlier estimated on it’s mission in 1972. Visit MoonMappers at Cosmoquest for more great stories!

Moving through history, we travel over to io9’s Space blog for a history of the American Space Shuttle disasters is a grim reminder of the danger of space travel. Just released is Major Malfunction, a documentary on the two Shuttle catastrophes. Major malfunction is an understatement for the destruction of Space Shuttle Challenger moments after launch in 1986, and the loss of Space Shuttle Columbia during re-entry in 2003.

Next at io9, we visit Mars to view the magnificent Draa, which are ancient landforms created from waves of sand. Check out the article and it’s images here.

We also have another article from io9, which new astronaut Reid Wiseman recounts his first adventurous days in space.

Now we’ll jump over for some gorgeous views from the Chandra X-Ray Observatory! One of their new images is a glorious view of the Whirlpool spiral galaxy which radiates with fantastic points of x-ray light. These image is breath-taking!

Want more gorgeous images? Visit Brownspaceman.com to see his discussion of the Tulip Nebula, which is a composite image which also maps the emissions from this incredible nebula.

Next, we head over to the Meridani Journalfor coverage of a major find in the search for exoplanets. A new world which is more than twice as large as Earth and about 17 times heavier has been discovered, a sort of “mega-Earth” as some have referred to it.

The NextBigFuture Blog lives up to it’s name by bringing us two interesting stories from Elon Musk and his company SpaceX. First, he points out that the key is reusability. Musk said the crewed Dragon is designed to land softly back on Earth and be rapidly turned around for another flight — possibly on the same day. Spacex is aiming for 10 flights without any significant refurbishment for the Dragon v2. The thing that will have to be refurbished is the main heat shield. Further improved heat shield materials [later versions of PICA-X] would mean Spacex could aim for 100 reusable flights.

We then head over to the Urban Astronomer, where recent observations of a very near pair of brown dwarf objects has led to something new: We’re watching the weather on stars themselves!

Finally, we return to Universe Today for some interesting potential missions. First, the B612 Foundation’s privately-funded Sentinel mission, once launched and placed in orbit around the Sun in 2018, will hunt for near-Earth asteroids down to about 140 meters in size using the most advanced infrared imaging technology, without government red tape to hamper the mission. Next, the NASA Innovative Advanced Concepts office announced a dozen far-flung drawing-board proposals that have received $100,000 in Phase 1 funding for the next 9-12 months, one of which is a balloon for exploring Titan. We’re looking forward to hearing about these projects and many others in the coming years.

That’s it for this week’s Carnival! See you all next time!

And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.

June 6, 2014December 23, 2015 by Elizabeth Howell

Titan Balloon Among Far-Out Concepts NASA Selects For Funding

Artist's conception of the Titan Aerial Daughtercraft on Titan, a moon of Saturn. Credit: NASA

Sometimes a good idea takes some tinkering. You have a thought that it will work, but what it really requires is you take some money and time and test it out in a small form. This principle is sound if you’re trying to do home renovation (a paint splash on a wall can let you see if the color will work) and it is especially true if you’re planning a multi-million dollar mission to another planet.

This is the thought behind the NASA Innovative Advanced Concepts office, which announced a dozen far-flung drawing-board proposals that received $100,000 in Phase 1 funding for the next 9-12 months. There are vehicles to explore the soupy moon of Titan, a design to snag a tumbling asteroid, and other ideas to explore the solar system. (But be patient: These testbed ideas would take decades to come to fruition, if they are even accepted for further study and funding.) Check out a full list of the concepts below.

Titan Aerial Daughtercraft: A small rotorcraft that can touch down from a balloon or lander, with the idea being that it can jump between several spots to do close-up views. It would then bring its samples back to the “mothership” and possibly recharge there as well. “The autonomy needed for this concept is also applicable to exciting rotorcraft mission concepts for Mars and to in-situ exploration of Enceladus,” the description stated, referring to an icy moon of Saturn.

Titan Submarine: A small submarine would dive into Kraken Mare on Saturn’s moon, and there would be plenty to explore: 984 feet (300 meters) of depth, stretching across 621 miles (1,000 km). “Kraken Mare is comparable in size to the Great Lakes and represents an opportunity for an unprecedented planetary exploration mission,” the description stated. It would explore “chemical composition of the liquid, surface and subsurface currents, mixing and layering in the ‘water’ column, tides, wind and waves, bathymetry, and bottom features and composition.”

Comet Hitchhiker: This would be a “tethered” spacecraft that swings from comet to comet to explore icy bodies in the solar system. “First, the spacecraft harpoons a target as it makes a close flyby in order to attach a tether to the target. Then, as the target moves away, it reels out the tether while applying regenerative brake to give itself a moderate (<5g) acceleration as well as to harvest energy,” the description stated.

Artist's conception of the Weightless Rendezvous And Net Grapple to Limit Excess Rotation (WRANGLER). Credit: NASA — Artist’s conception of the Weightless Rendezvous And Net Grapple to Limit Excess Rotation (WRANGLER). Credit: NASA

Weightless Rendezvous And Net Grapple to Limit Excess Rotation (WRANGLER): This idea would capture space debris and small asteroids. It will use a small nanosatellite equipped with a “net capture device” and a winch. “The leverage offered by using a tether to extract angular momentum from a rotating space object enables a very small nanosatellite system to de-spin a very massive asteroid or large spacecraft,” the description stated.

The Aragoscope: A telescope that would look through an opaque disk at a distant object, which is different from the usual mirror arrangement.”Rather than block the view, the disk boosts the resolution of the system with no loss of collecting area,” the description states. This architecture … can be used to achieve the diffraction limit based on the size of the low cost disk, rather than the high cost telescope mirror.”

Mars Ecopoiesis Test Bed: A machine that would test how well bacteria from Earth could survive on Mars, which could be a precursor to “terraforming” the planet to make it more like our own. Researchers would select “pioneer organisms” and put them into a device that would embed itself into the Martian regolith (soil) in an area that would have liquid water. It would “completely seal itself to avoid planetary contamination, release carefully selected earth organisms (extremophiles like certain cyanobacteria), sense the presence or absence of a metabolic product (like O2), and report to a Mars-orbiting relay satellite,” the description states.

Artist's conception of ChipSats. Credit: NASA — Artist’s conception of ChipSats. Credit: NASA

ChipSats: Instead of having an orbiter and a lander in separate missions, why not put them in one? While there have been combinations before (e.g. Cassini/Huygens), this is a bit different: This concept would have a set of tiny sensor chips (ChipSats) that deploy from a larger mothership to make a landing on a distant planet or moon.

Swarm Flyby Gravimetry: While whizzing by a comet or asteroid, a single spacecraft would release a swarm of tiny probes. “By tracking those probes, we can estimate the asteroid’s gravity field and infer its underlying composition and structure,” the description stated.

Probing icy worlds concept: How thick is the ice on Jupiter’s Europa or Ganymede, or Saturn’s Enceladus? Open question, and makes it hard to predict how tough of a drill one would need to probe the ice — or how well life could survive. This concept would send a probe to one of these locations and receive “a naturally occurring signal generated by interactions of deep penetrating cosmic ray neutrinos” to better get a sense of the depth. This could allow for maps of the ice.

The cracked ice surface of Europa. Credit: NASA/JPL

Heliopause Electrostatic Rapid Transit System (HERTS): This would be a mission that goes deep into the solar-system and out to the heliopause, the spot where the sun’s sphere of influence gives way to the interstellar medium. Using no propellant, the spacecraft would use solar wind protons to bring it out into the solar system. “The propulsion system consists of an array of electrically biased wires that extend outward 10 to 30 km [6.2 miles to 18.6 miles] from a rotating spacecraft,” the researchers stated.

3D Photocatalytic Air Processor: A new design to make it easier to generate oxygen on a spacecraft, using “abundant high-energy light in space,” the proposal states. ” The combination of novel photoelectrochemistry and 3-dimensional design allows tremendous mass saving, hardware complexity reduction, increases in deployment flexibility and removal efficiency.”

PERIapsis Subsurface Cave OPtical Explorer (PERISCOPE): A way to probe caves on the moon from orbit. Using a concept called “photon time-of-flight imaging”, the researchers say they would be able to bounce the signal off of the walls of the canyon to peer into the crevice and see what is there.

June 5, 2014December 23, 2015 by Elizabeth Howell

‘Cosmic Zombie’ Star Triggered This Explosion In Nearby Galaxy

An infrared image of N103B, the remainders of a supernova that exploded about 1,000 years ago in the Large Magellanic Cloud, which is one of the closest galaxies to the Milky Way. Credit: NASA/JPL-Caltech/Goddard

It might be a bad idea to get close to dead stars. Like a White Walker from Game of Thrones, this “cosmic zombie” white dwarf star was dangerous even though it was just a corpse of a star like our own. The result from this violence is still visible in the Spitzer Space Telescope picture you see above.

Astronomers believe the giant star was shedding material (a common phenomenon in older stars), which fell on to the white dwarf star. As the gas built up on the white dwarf over time, the mass became unstable and the dwarf exploded. What’s left is still lying in a pool of gas about 160,000 light-years away from us.

“It’s kind of like being a detective,” stated Brian Williams of NASA’s Goddard Space Flight Center, who led the research. “We look for clues in the remains to try to figure out what happened, even though we weren’t there to see it.”

This explosion in the Large Magellanic Cloud — one of the closest satellite galaxies to Earth — is known as a Type 1a supernova, but it’s a rare breed of that kind. Type 1as are best known as “standard candles” because their explosions have a consistent luminosity. Knowing how luminous the supernova type is allows astronomers to estimate distance based on its apparent brightness; the fainter the supernova is, the further away it is.

Most Type 1as happen when two orbiting white dwarfs smash into each other, but this scenario is more akin to something that Earthlings saw in 1604. Informally called Kepler’s supernova, because it was discovered by astronomer Johannes Kepler, astronomers believe this arose from a red giant and white dwarf interaction. The evidence left for this conclusion showed the supernova leftovers embedded in dust and gas.

Investigators have submitted their results to the Astrophysical Journal.

Source: NASA Jet Propulsion Laboratory

June 4, 2014December 23, 2015 by Elizabeth Howell

Move Over, Gravity: Black Hole Magnetic Fields May Have Powerful Pull

Artist rendering of a supermassive black hole. Credit: NASA / JPL-Caltech.

It’s oft-repeated that black holes are powerful gravity wells, because they represent a dense concentration of matter in one location. But what about their magnetic fields? A new study suggests that this force could be at least as strong as gravity in supermassive black holes, the singularities that lurk in the center of many galaxies.

Simulations of magnetic fields of gas falling into these beasts suggest that this action — if the gas carries a magnetic field — makes the field stronger until it equals gravity.

Magnetic fields can affect properties such as how luminous black holes appear (in radio) and how powerful the jets emanating from the singularity are. The scientists speculate that when you see bright jets from a black hole, this could imply a strong magnetic field indeed.

A computer simulation of gas (yellow) falling into a black hole, and jets emanating from the singularity. Credit: Alexander Tchekhovskoy (LBNL)

“Surprisingly, the magnetic field strength around these exotic objects is comparable to the magnetic field produced in something more familiar: a magnetic resonance imaging (MRI) machine that you can find in your local hospital,” the Max Planck Institute for Radio Astronomy stated.

“Both supermassive black holes and MRI machines produce magnetic fields that are roughly 10,000 times stronger than the Earth’s surface magnetic field, which is what guides an ordinary compass.”

New information on how strong the magnetic fields was based on recent work with the Very Long Baseline Array, a networked group of radio telescopes in the United States. Specifically, the information came from a program named MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) that looks at jets around several hundred supermassive black holes.

The researchers emphasized that more observational research will be needed to supplement the simulations. The work will be published today in Nature. Leading the research was Mohammad Zamaninasab, a past researcher at Max Planck.

Source: Max Planck Institute for Radio Astronomy

June 4, 2014December 23, 2015 by David Dickinson

Discovered: Two New Planets for Kapteyn’s Star

An artist's conception of the planets orbiting Kapteyn's Star (inset) and the stream of stars associated with an ancient galaxy merger. Credit: image courtesy of Victor Robles, James Bullock, and Miguel Rocha at University of California Irvine and Joel Primack at University of California Santa Cruz.

The exoplanet discoveries have been coming fast and furious this week, as astronomers announced a new set of curious worlds this past Monday at the ongoing American Astronomical Society’s 224th Meeting being held in Boston, Massachusetts.

Now, chalk up two more worlds for a famous red dwarf star in our own galactic neck of the woods. An international team of astronomers including five researchers from the Carnegie Institution announced the discovery this week of two exoplanets orbiting Kapteyn’s Star, about 13 light years distant. The discovery was made utilizing data from the HIRES spectrometer at the Keck Observatory in Hawaii, as well as the Planet Finding Spectrometer at the Magellan/Las Campanas Observatory and the European Southern Observatory’s La Silla facility, both located in Chile.

The Carnegie Institution astronomers involved in the discovery were Pamela Arriagada, Ian Thompson, Jeff Crane, Steve Shectman, and Paul Butler. The planets were discerned using radial velocity measurements, a planet-hunting technique which looks for tiny periodic changes in the motion of a star caused by the gravitational tugging of an unseen companion.

“That we can make such precise measurements of such subtle effects is a real technological marvel,” said Jeff Crane of the Carnegie Observatories.

Kapteyn’s Star (pronounced Kapt-I-ne’s Star) was discovered by Dutch astronomer Jacobus Kapteyn during a photographic survey of the southern hemisphere sky in 1898. At the time, it had the highest proper motion of any star known at over 8” arc seconds a year — Kapteyn’s Star moves the diameter of a Full Moon across the sky every 225 years — and held this distinction until the discovery of Barnard’s Star in 1916. About a third the mass of our Sun, Kapteyn’s Star is an M-type red dwarf and is the closest halo star to our own solar system. Such stars are thought to be remnants of an ancient elliptical galaxy that was shredded and subsequently absorbed by our own Milky Way galaxy early on in its history. Its high relative velocity and retrograde orbit identify Kapteyn’s Star as a member of a remnant moving group of stars, the core of which may have been the glorious Omega Centauri star cluster.

The worlds of Kapteyn’s Star are proving to be curious in their own right as well.

“We were surprised to find planets orbiting Kapteyn’s Star,” said lead author Dr. Guillem Anglada-Escude, a former Carnegie post-doc now with the Queen Mary University at London. “Previous data showed some irregular motion, so we were looking for very short period planets when the new signals showed up loud and clear.”

The location of Kapteyn's Star in teh constellation Pictor. Created using Stellarium. — The location of Kapteyn’s Star in the constellation Pictor. Created using Stellarium.

It’s curious that nearby stars such as Kapteyn’s, Teegarden’s and Barnard’s star, though the site of many early controversial claims of exoplanets pre-1990’s, have never joined the ranks of known worlds which currently sits at 1,794 and counting until the discoveries of Kapteyn B and C. Kapteyn’s star is the 25th closest to our own and is located in the southern constellation Pictor. And if the name sounds familiar, that’s because it made our recent list of red dwarf stars for backyard telescopes. Shining at magnitude +8.9, Kapteyn’s star is visible from latitude 40 degrees north southward.

Kapteyn B and C are both suspected to be rocky super-Earths, at a minimum mass of 4.5 and 7 times that of Earth respectively. Kapteyn B orbits its primary once every 48.6 days at 0.168 A.U.s distant (about 40% of Mercury’s distance from our Sun) and Kapteyn C orbits once every 122 days at 0.3 A.U.s distant.

This is really intriguing, as Kapteyn B sits in the habitable zone of its host star. Though cooler than our Sun, the habitable zone of a red dwarf sits much closer in than what we enjoy in our own solar system. And although such worlds may have to contend with world-sterilizing flares, recent studies suggest that atmospheric convection coupled with tidal locking may allow for liquid water to exist on such worlds inside the “snow line”.

And add to this the fact that Kapteyn’s Star is estimated to be 11.5 billion years old, compared with the age of the universe at 13.7 billion years and our own Sun at 4.6 billion years. Miserly red dwarfs measure their future life spans in the trillions of years, far older than the present age of the universe.

A comparison of habitable zones of Sol-like versus Red dwarf stars. Credit: Chewie/Ignacio Javier under a Wikimedia Commons 3.0 license). — A comparison of habitable zones of Sol-like versus red dwarf stars. Credit: Chewie/Ignacio Javier under a Wikimedia Commons 3.0 license).

“Finding a stable planetary system with a potentially habitable planet orbiting one of the very nearest stars in the sky is mind blowing,” said second author and Carnegie postdoctoral researcher Pamela Arriagada. “This is one more piece of evidence that nearly all stars have planets, and that potentially habitable planets in our galaxy are as common as grains of sand on the beach.”

Of course, radial velocity measurements only give you lower mass constraints, as we don’t know the inclination of the orbits of the planets with respect to our line of sight. Still, this exciting discovery could potentially rank as the oldest habitable super-Earth yet discovered, and would make a great follow-up target for the direct imaging efforts or the TESS space telescope set to launch in 2017.

“It does make you wonder what kind of life could have evolved on those planets over such a long time,” added Dr Anglada-Escude. And certainly, the worlds of Kapteyn’s Star have had a much longer span of time for evolution to have taken hold than Earth… an exciting prospect, indeed!

-Read author Alastair Reynolds’ short science fiction piece Sad Kapteyn accompanying this week’s announcement.

June 3, 2014December 23, 2015 by Elizabeth Howell

Galaxy Violence Revealed! Cosmic Crash Shows Cluster Crunch

Galaxy clusters MACS J0717+3745 colliding about five billion light-years away from Earth. This is a composite image of visible light from the Hubble Space Telescope (background), X-ray data from the Chandra X-Ray Observatory (blue) and radio waves from the Very Large Array (red).Credit: Van Weeren, et al.; Bill Saxton, NRAO/AUI/NSF; NASA

Shock waves! Fast-moving particles! Magnetic fields! This image has it all. Behold the merging galaxy clusters MACS J0717+3745 about five billion light-years from our planet.

That funny red thing you see in the center is new data from the Karl G. Jansky Very Large Array showing a spot where “shocks caused by the collisions are accelerating particles that then interact with magnetic fields and emit the radio waves,” officials at the National Radio Astronomical Observatory stated.

“The complex shape of this region is unique; we’ve never spotted anything like this before,” stated Reinout van Weeren, an Einstein Fellow at the Harvard-Smithsonian Center for Astrophysics. “The shape probably is the result of the multiple ongoing collisions.”

This is a composite image of new exposures from VLA and the Chandra X-Ray Observatory, with an older image from the Hubble Space Telescope. And if you take a second look, there’s also a black hole: “The straight, elongated radio-emitting object is a foreground galaxy whose central black hole is accelerating jets of particles in two directions,” NRAO added. “The red object at bottom-left is a radio galaxy that probably is falling into the cluster.”

Astronomers presented their findings at the American Astronomical Society meeting this week in Boston.

Source: NRAO