Posted on by Jon Voisey

Do Planets Rob Their Stars of Metals?

Artist's impression of the Solar Nebula. Image credit: NASA

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It has been known for several years that stars hosting planets are generally more rich in elements heavier than hydrogen and helium, known in astronomy as “metals”. These heavy elements help to form the cores of the forming planets and accelerate the formation process. However, a new study has helped to suggest that the opposite may also be true: Planets may make their host stars less metal rich than they should otherwise be.

The new research is led by Ivan Ramirez at the Carnegie Institution for Science. In it, the team analyzed the unusual exo-planetary system 16Cygni. The star system itself is a triple star system composed of two stars similar to the sun (A and B) as well as a red dwarf (C). The solar A star and the red dwarf form a tight binary system with the sun-like B star in a wider orbit of nearly 900 AU. 16CygniB was discovered to be host to a Jovian planet in 1996 making it one of the first systems known to contain an extrasolar planet.

The study analyzed the spectra of the two solar type stars and found that the one around which the planet orbits was notably lower in metals than the one in the binary orbit with the red dwarf. Because both stars should have formed from the same molecular cloud astronomers assume their initial compositions should be identical. Since both are similar masses, they should also have evolved similarly in their main-sequence life which should rule out divergence in their chemical fingerprints.

Similar properties have been noted in a 2009 paper by astronomers at the university of Porto in Portugal. In that study, the team compared our own Sun to other stars of similar composition and age. They discovered that the Sun had an odd feature: It was notably depleted in elements known as refractory metals when compared to volatile elements with low melting and boiling temperatures. The team suggested that those missing elements may have been stolen by forming planets. The newer study makes the same proposition.

Both teams note that the effect is not conclusive. They consider that 16CygA may have been polluted by heavy elements, possibly by the accretion of a planet or similar material. However, they note that if this was the case, they should also expect to see an additional amount of lithium. Yet the lithium abundance for the two stars match. The 2009 paper considers similar cases. They consider that the solar nebula may have been seeded by a nearby supernova that would enhance the abundances, but the enhanced elements do not seem to match the expected productions for any type of supernova. Still, with such a small number of systems for which this effect has been discovered, such cases of special pleading are still within the realm of statistical possibility. Future work will undoubtedly search for similar effects in other planetary systems. If confirmed, such elemental oddities could be considered as a sign of planetary formation.

Posted on by Ken Kremer

NASA Unveils Thrilling First Full Frame Images of Vesta from Dawn

Dawn snaps First Full-Frame Image of Asteroid Vesta. NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011. It was taken from a distance of about 3,200 miles (5,200 kilometers). Dawn entered orbit around Vesta on July 15, and will spend a year orbiting the body. After that, the next stop on its itinerary will be an encounter with the dwarf planet Ceres. The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig, Germany. The framing camera project is funded by NASA, the Max Planck Society and DLR. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

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NASA has just released the first full frame images of Vesta– and they are thrilling! The new images unveil Vesta as a real world with extraordinarily varied surface details and in crispy clear high resolution for the first time in human history.

Vesta appears totally alien and completely unique. “It is one of the last major uncharted worlds in our solar system,” says Dr. Marc Rayman, Dawn’s chief engineer and mission manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Now that we are in orbit we can see that it’s a unique and fascinating place.”

“We have been calling Vesta the smallest terrestrial planet,” said Chris Russell, Dawn’s principal investigator at the UCLA. “The latest imagery provides much justification for our expectations. They show that a variety of processes were once at work on the surface of Vesta and provide extensive evidence for Vesta’s planetary aspirations.”

Dawn launch on September 27, 2007 by a Delta II Heavy rocket from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer

The newly published image (shown above) was taken at a distance of 3,200 miles (5,200 kilometers) by Dawn’s framing camera as the probe continues spiraling down to her initial science survey orbit of some 1,700 miles (2,700 km) altitude. The new images show the entire globe all the way since the giant asteroid turns on its axis once every five hours and 20 minutes.

Vesta and its new moon – Dawn – are approximately 114 million miles (184 million kilometers) distant away from Earth.

“The new observations of Vesta are an inspirational reminder of the wonders unveiled through ongoing exploration of our solar system,” said Jim Green, planetary division director at NASA Headquarters in Washington.

The Dark Side of Vesta Captured by Dawn
NASA's Dawn spacecraft obtained this image over the northern hemisphere with its framing camera on July 23, 2011. It was taken from a distance of about 3,200 miles (5,200 kilometers) away from the giant asteroid Vesta. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dawn was launched atop a Delta II Heavy booster rocket in September 2007, took a gravity assist as it flew past Mars and has been thrusting with exotic ion propulsion for about 70 percent of the time ever since.

Dawn will spend 1 year collecting science data in orbit around Vesta before heading off to the Dwarf Planet Ceres.

The science team has just completed their press briefing. Watch for my more detailed report upcoming soon.

And don’t forget JUNO launches on Aug 5 – It’s an exciting week for NASA Space Science and I’ll be reporting on the Jupiter orbiter’s blastoff and more – as Opportunity closes in on Spirit Point !

NASA’s groundbreaking interplanetary science is all inter connected – because Vesta and Ceres failed to form into full-fledged planets thanks to the disruptive influence of Jupiter.

Read my prior features about Dawn
Dawn Spirals Down Closer to Vesta’s South Pole Impact Basin
First Ever Vesta Vistas from Orbit – in 2D and 3D
Dawn Exceeds Wildest Expectations as First Ever Spacecraft to Orbit a Protoplanet – Vesta
Dawn Closing in on Asteroid Vesta as Views Exceed Hubble
Dawn Begins Approach to Asteroid Vesta and Snaps First Images
Revolutionary Dawn Closing in on Asteroid Vesta with Opened Eyes

Posted on by Jon Voisey

Japanese Astronomy Pushes on After Hard Year

Artists concept of Japan’s Akatsuki spacecraft at Venus. Credit: JAXA

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From faulty spacecraft to two damaged facilities, the past year has been a tough year for Japan’s astronomical programs. Yes despite the setbacks, Japan has already begun working to fix every problem they’ve faced in this difficult year.

The troubles started late last year as Japan’s Venus exploring spacecraft, Akatsuki failed to properly enter orbit around Venus. Ultimately, the failure was blamed on a faulty valve that didn’t allow the thruster to fire for the full length of the burn necessary to transfer into the correct orbit. Instead, the craft is now in a wide orbit around the Sun. The organization in charge of the probe, the Japan Aerospace Exploration Agency (JAXA) announced earlier this month that they will “attempt to reignite the damaged thruster nozzle” and, if the test goes well, can try again for an orbital insertion in November 2015.

The next setback came with the devastating March 11th earthquake which the facilities being used to study the samples returned from the sample and return mission Hayabusa were damaged. While the particles were safe, the sensitive accelerators that are used to study them suffered some damage. Restoration work is already underway and the teams in charge expect some operations to resume as early as this fall. Other instruments may take until early next year to resume operation. Despite the damage, the preliminary data (done before the Earthquake) has confirmed the particles are from the visited asteroid. They contain minerals such as olivine and iron sulfide contained in a rocky-type asteroid. No organic materials have been detected.

More recently, Japan’s flagship observatory, Subaru atop Mauna Kea, Hawaii, was damaged when coolant leaked onto several instruments as well as the primary mirror, halting operations early last month. According to the National Astronomical Observatory of Japan (NAOJ) which maintains the telescope, the mirror was washed with water which was successful in restoring its functionality. The primary camera, the Subaru Prime Focus Camera (Suprime-Cam) and its auxiliary equipment were also affected and are currently being inspected. However, the telescope has a second focus, known as a Nasmyth focus. Several instruments which make use of this focus, including the High Dispersion Spectograph, the 188-element Adaptive Optics system, the Infrared Camera and Spectrograph, and the High Contrast Instrument for the Subaru Next Generation Adaptive Optics, were all unaffected. With the cleaning of the mirror and the use of these instruments, the telescope was able to resume operations on the night of July 22.

With any luck, fortunes will continue to improve for Japan and their hard work and dedication can help them to overcome these issues. Ganbatte!

Posted on by Jason Rhian

Chasing Rockets, Chasing History: One Journalist’s Video Reflections

Following the space program is an exhausting business - but one that provides for amazing images and memories. Photo Credit: Jason Rhian

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CAPE CANAVERAL Fla. – As one might imagine covering the space program is a exciting vocation. Some professionals focus on writing articles or taking pictures others work with television stations or online media outlets to provide video and commentary. I have selected to attempt to do all of the above. This can be rather challenging. During the final launch of Atlantis for example, I conducted interviews with a variety of guests up until the launch, from there I operated two camcorders and a DSLR camera (for stills).

Doing things this way provides outlets with a wealth of different types of content to choose from. This also means that a lot of material is not used. This article will cover some of the things that ended up on the cutting room floor. What was not used – might surprise you.

SpaceX Surprises

Of the NewSpace organizations that have made their presence known out at Kennedy Space Center – Space Exploration Technologies or SpaceX has had the most significant impact. Lately the firm has worked to get the media out, as much as possible, to see what the company is doing. NASA and many of the established aerospace companies have a hands off approach – essentially you report on what they allow you to report. SpaceX? They allowed this reporter to climb underneath the Falcon 9 and even have it spun on command. Check it out:

Shuttle Memories

Trying to accurately record and report the historic nature of what took place at Kennedy Space Center this summer was challenging. I took every opportunity I could to record what was happening and then relay that to the public. What I will always remember from this time was how open the members of NASA were and how they really tried to work with you to get the story out. To get a taste of what it was like, check out this compilation of shuttle videos from STS-133 through STS-135:

Launches

Whilst following the shuttle, the last two years have been punctuated by a number of awesome unmanned flights as well (not including the launch of the Falcon 9 which you can see above). The second OTV space plane, SBIRS, AEHF-1 and an impressive night launch of a Delta IV Heavy all helped to keep me on the road to Cape Canaveral:

Memorable Interviews

I’ve been privileged to interview many important people within the space community. That however does not mean that their interviews will stick out in my mind. Some of the ones that I remember best are from people that have always been a joy to work with. Stephanie Stilson is one of those people, she always has a kind word and a great quote. Greg Johnson is another, bombastic and easy-going, he has no problem whatsoever veering off of the official NASA script. To separate the two interviews I included a clip of the media being escorted up onto LC39A. Click below to watch:

Experiencing History

It is not every day that one gets to train along with the astronauts. I had the opportunity to do so on STS-135. I flew in the back of the Shuttle Training Aircraft (STA) as Commander Chris Ferguson practiced landing the shuttle. To date, this has to be the high point of my career:

Over the last two years I have been bombarded by folks stating that I should report things “their” way. Some want me to go hyper-technical, so that only an engineer could understand what I was saying. While I’m sure some folks wouldn’t mind breaking out a flight manual to keep up with the jargon – that really isn’t what I’m trying to accomplish. Others tell me to keep it as simple as possible and to never state anything that could be construed as negative – but that doesn’t reflect reality. I try to come in somewhere in the middle. The public should know that this is a highly technical endeavor – but they should also know that it is exciting, that this tale is not one without issues and that I try to show it all, the good, the bad and the awesome.

Posted on by Nancy Atkinson

New Impact Rate Count Lays Nemesis Theory to Rest

Barringer Crater, also known as Meteor Crater, in Arizona. This crater was formed around 50,000 years ago by the impact of a nickel-iron meteorite. Near the top of the image, the visitors center, complete with tour buses on the parking lot, provides a sense of scale. Credit: National Map Seamless Viewer/US Geological Service

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From a Max Planck Institute for Astronomy press release:

Is the Earth more likely or less likely to be hit by an asteroid or comet now as compared to, say, 20 million years ago? Several studies have claimed to have found periodic variations, with the probability of giant impacts increasing and decreasing in a regular pattern. Now a new analysis by Coryn Bailer-Jones from the Max Planck Institute for Astronomy (MPIA), published in the Monthly Notes of the Royal Astronomical Society, shows those simple periodic patterns to be statistical artifacts. His results indicate either that the Earth is as likely to suffer a major impact now as it was in the past, or that there has been a slight increase impact rate events over the past 250 million years.

The results also lay to rest the idea of the existence of an as-yet undetected companion star to the Sun, dubbed “Nemesis.”

Giant impacts by comets or asteroids have been linked to several mass extinction events on Earth, most famously to the demise of the dinosaurs 65 million years ago. Nearly 200 identifiable craters on the Earth’s surface, some of them hundreds of kilometers in diameter, bear witness to these catastrophic collisions.

Understanding the way impact rates might have varied over time is not just an academic question. It is an important ingredient when scientists estimate the risk Earth currently faces from catastrophic cosmic impacts.

Since the mid-1980s, a number of authors have claimed to have identified periodic variations in the impact rate. Using crater data, notably the age estimates for the different craters, they derive a regular pattern where, every so-and-so-many million years (values vary between 13 and 50 million years), an era with fewer impacts is followed by an era with increased impact activity, and so on.

One proposed mechanism for these variations is the periodic motion of our Solar System relative to the main plane of the Milky Way Galaxy. This could lead to differences in the way that the minute gravitational influence of nearby stars tugs on the objects in the Oort cloud, a giant repository of comets that forms a shell around the outer Solar System, nearly a light-year away from the Sun, leading to episodes in which more comets than usual leave the Oort cloud to make their way into the inner Solar System – and, potentially, towards a collision with the Earth. A more spectacular proposal posits the existence of an as-yet undetected companion star to the Sun, dubbed “Nemesis”. Its highly elongated orbit, the reasoning goes, would periodically bring Nemesis closer to the Oort cloud, again triggering an increase in the number of comets setting course for Earth.

For MPIA’s Coryn-Bailer-Jones, these results are evidence not of undiscovered cosmic phenomena, but of subtle pitfalls of traditional (“frequentist”) statistical reasoning. Bailer-Jones: “There is a tendency for people to find patterns in nature that do not exist. Unfortunately, in certain situations traditional statistics plays to that particular weakness.”

That is why, for his analysis, Bailer-Jones chose an alternative way of evaluating probabilities (“Bayesian statistics”), which avoids many of the pitfalls that hamper the traditional analysis of impact crater data. He found that simple periodic variations can be confidently ruled out. Instead, there is a general trend: From about 250 million years ago to the present, the impact rate, as judged by the number of craters of different ages, increases steadily.

There are two possible explanations for this trend. Smaller craters erode more easily, and older craters have had more time to erode away. The trend could simply reflect the fact that larger, younger craters are easier for us to find than smaller, older ones. “If we look only at craters larger than 35 km and younger than 400 million years, which are less affected by erosion and infilling, we find no such trend,” Bailer-Jones explains.

On the other hand, at least part of the increasing impact rate could be real. In fact, there are analyses of impact craters on the Moon, where there are no natural geological processes leading to infilling and erosion of craters, that point towards just such a trend.

Whatever the reason for the trend, simple periodic variations such as those caused by Nemesis are laid to rest by Bailer-Jones’ results. “From the crater record there is no evidence for Nemesis. What remains is the intriguing question of whether or not impacts have become ever more frequent over the past 250 million years,” he concludes.

Read the paper: “Bayesian time series analysis of terrestrial impact cratering.”

For more information, see Max Planck Institute for Astronomy website.

Posted on by Tammy Plotner

Alone In The Dark?

This is the portion of sky in which astronomers found the Segue 1 dwarf galaxy. Can you see it? Credit: Marla Geha

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Two years ago, Marla Geha, a Yale University astronomer, Joshua Simon from the Carnegie Institution of Washington, and their colleagues discovered something unusual while studying with the Keck II telescope and information for the Sloan Digital Sky Survey. Their observations turned up a contrasting group of stars which all appeared to be moving in unison – not just a moving cluster of similar stars which could have been torn away from the nearby Sagittarius dwarf galaxy. The team knew they were on to something, but a competing group of astronomers at Cambridge University was skeptical. Too bad… there was a dark treasure right there before their eyes.

Not to be dissuaded, Simon, Geha and their group returned to Keck and turned the photographic eye of the telescope’s Deep Extragalactic Imaging Multi-Object Spectrograph (DEIMOS) towards their target area. Even though it was only about 1,000 small, dim stars, they wanted to know how they migrated both in respect to the Milky Way and to each other. Named Segue 1, the target the team was looking at could possibly have 3,400 times more mass than can be accounted for by its visible stars… a galaxy dominated by dark matter and salted with a handful of ancient suns. If the 1,000 or so stars were all there was to Segue 1, with just a touch of dark matter, the stars would all move at about the same speed, said Simon. But the Keck data show they do not. Instead of moving at a steady 209 km/sec relative to the Milky Way, some of the Segue 1 stars are moving at rates as slow as 194 kilometers per second while others are going as fast as 224 kilometers per second.

Using the DEIMOS instrument on the Keck II telescope, astronomers could identify which stars were moving together as a group. They are circled here in green Credit: Marla Geha

“That tells you Segue 1 must have much more mass to accelerate the stars to those velocities,” Geha explained. The paper confirming Segue 1’s dark nature appeared in the May 2011 issue of The Astrophysical Journal. “The mass required to cause the different star velocities seen in Segue 1 has been calculated at 600,000 solar masses. But there are only about 1,000 stars in Segue 1, and they are all close to the mass of our Sun,” Simon said. “Virtually all of the remainder of the mass must be dark matter.”

But the information from DEIMOS didn’t stop there… It also revealed an eclectic collection of nearly primordial metal-poor stars. The researchers managed to gather iron data on six stars in Segue 1 with the Keck II telescope, and a seventh Segue 1 star was measured by an Australian team using the Very Large Telescope. Of those seven, three proved to have less than one 2,500th as much iron as the Sun. “That suggests these are some of the oldest and least evolved stars that are known,” said Simon. This is fascinating data considering investigations for stars of this type out of the Milky Way’s billions have produced less than 30. “In Segue 1 we already have 10 percent of the total in the Milky Way,” Geha said. “For studying these most primitive stars, dwarf galaxies are going to be very important.”

By subtracting out all the other objects in the image and leaving the Segue I member stars, the “darkest galaxy” emerges. Credit: Marla Geha

By confirming Segue 1’s massive concentration of dark matter, other types of research into this dark galaxy’s lifestyle now become more dedicated. The space-based Fermi Gamma Ray Telescope has also been looking its way in hopes of catching a gamma-ray event created by the collision and annihilation of pairs of dark matter particles. So far the Fermi telescope has not detected anything of the sort, which isn’t entirely surprising and doesn’t mean the dark matter isn’t there, said Simon.

“The current predictions are that the Fermi telescope is just barely strong enough or perhaps not quite strong enough to see these gamma rays from Segue 1,” Simon explained. So there are hopes that Fermi will detect at least the hint of a collision. “A detection would be spectacular,” said Simon. “People have been trying to learn about dark matter for 35 years and not made much progress. Even a faint glow of the predicted gamma rays would be a powerful confirmation of theoretical predictions about the nature of dark matter.”

Let’s hope Segue 1 isn’t alone in the dark.

Original News Source: Keck Observatory Science News.

Posted on by Ken Kremer

JUNO Orbiter Mated to Mightiest Atlas rocket for Aug. 5 Blastoff to Jupiter

Hoisting Juno at Launch Pad 41 to bolt atop most powerful Atlas Rocket. At Space Launch Complex 41, a crane is lowered over the nose of the Atlas payload fairing enclosing the Juno spacecraft in preparation for its lift to the top of the Atlas rocket stacked in the Vertical Integration Facility. Juno is scheduled to launch Aug. 5 aboard the most powerful ever United Launch Alliance Atlas V rocket from Cape Canaveral Air Force Station in Florida. The solar-powered spacecraft will orbit Jupiter's poles 33 times to find out more about the gas giant's origins, structure, atmosphere and magnetosphere and investigate the existence of a solid planetary core. Credit: NASA/Cory Huston

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In less than one week’s time, NASA’s $1.1 Billion Juno probe will blast off on the most powerful Atlas V rocket ever built and embark on a five year cruise to Jupiter where it will seek to elucidate the mysteries of the birth and evolution of our solar system’s largest planet and how that knowledge applies to the remaining planets.

The stage was set for Juno’s liftoff on August 5 at 11:34 a.m. after the solar-powered spacecraft was mated atop the Atlas V rocket at Space Launch Complex 41 at Cape Canaveral and firmly bolted in place at 10:42 a.m. EDT on July 27.

“We’re about to start our journey to Jupiter to unlock the secrets of the early solar system,” said Scott Bolton, the mission’s principal investigator from the Southwest Research Institute in San Antonio. “After eight years of development, the spacecraft is ready for its important mission.”

Inside the Vertical Integration Facility at Space Launch Complex 41, the Juno spacecraft, enclosed in an Atlas payload fairing, is in position on top of its Atlas launch vehicle. The spacecraft was prepared for launch in the Astrotech Space Operations' payload processing facility in Titusville, Fla. Credit: NASA/Cory Huston

The launch window for Juno extends from Aug. 5 through Aug. 26. The launch time on Aug. 5 opens at 11:34 a.m. EDT and closes at 12:43 p.m. EDT. Juno is the second mission in NASA’s New Frontiers program.

JUNO’s three giant solar panels will unfurl about five minutes after payload separation following the launch, said Jan Chodas, Juno’s project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif.

The probe will cartwheel through space during its five year trek to Jupiter.

Upon arrival in July 2016, JUNO will fire its braking rockets and go into polar orbit and circle Jupiter 33 times over about one year. The goal is to find out more about the planet’s origins, interior structure and atmosphere, observe the aurora, map the intense magnetic field and investigate the existence of a solid planetary core.

Hoisting Juno inside the payload fairing at Space Launch Complex 41. Credit: NASA/Cory Huston

“Juno will become the first polar orbiting spacecraft at Jupiter. Not only are we over the poles, but we’re getting closer to Jupiter in our orbit than any other spacecraft has gone,” Bolton elaborated at a briefing for reporters at the Kennedy Space Center. “We’re only 5,000 kilometers above the cloud tops and so we’re skimming right over those cloud tops and we’re actually dipping down beneath the radiation belts, which is a very important thing for us. Because those radiation belts at Jupiter are the most hazardous region in the entire solar system other than going right to the sun itself.”

“Jupiter probably formed first. It’s the largest of all the planets and in fact it’s got more material in it than all the rest of the solar system combined. If I took everything in the solar system except the sun, it could all fit inside Jupiter. So we want to know the recipe.”

Watch for my continuing updates and on-site launch coverage of Juno, only the 2nd probe from Earth to ever orbit Jupiter. Galileo was the first.

Posted on by Steve Nerlich

Astronomy Without A Telescope – The Unlikeliness Of Being

The Search for ExtraTerrestrial Intelligence could be a waste of time according to a recent statistical analysis of the likelihood of life arising spontaneously on habitable-zone exoplanets out there in the wider universe (and let's face it - when have predictive statistics ever got it wrong?) Credit: SETI Institute.

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History has proved time and again that mathematical modelling is no substitute for a telescope (or other data collection device). Nonetheless, some theoreticians have recently put forward a statistical analysis which suggests that life is probably very rare in the universe – despite the apparent prevalence of habitable-zone exoplanets, being found by the Kepler mission and other exoplanet search techniques.

You would be right to be skeptical, given the Bayesian analysis undertaken is based on our singular experience of abiogenesis – being the origin of life from non-life, here on Earth. Indeed, the seemingly rapid abiogenesis that occurred on Earth soon after its formation is suggested to be the clinching proof that abiogenesis on habitable-zone exoplanets must be rare. Hmm…

Bayes theorem provides a basis for estimating the likelihood that a prior assumption or hypothesis (e.g. that abiogenesis is common on habitable-zone exoplanets) is correct, using whatever evidence is available. Its usage is nicely demonstrated in solving the Monty Hall problem.

Go here for the detail, but in a nutshell:
There are three doors, one with a car behind it and the other two have goats. You announce which door you will pick – knowing that it carries a 1/3 probability of hiding the car. Then Monty Hall, who knows where the car is, opens another door to reveal a goat. So, now you know that door always had a zero probability of hiding the car. So, the likelihood of the remaining door hiding the car carries the remaining 2/3 probability of the system, since there was always an absolute 1/1 probability that the car was behind one of the three doors. So, it makes more sense for you to open that remaining door, instead of the first one you picked.

In this story, Monty Hall opening the door with a goat represents new data. It doesn’t allow you to definitively determine where the car is, but it does allow you to recalculate the likelihood that your prior hypothesis (that the car is behind the first door you picked) is correct.

Applying Bayesian analysis to the problem of abiogenesis on habitable-zone exoplanets is a bit of a stretch. Speigel and Turner argue that the evidence we have available to us – that life began quite soon after the Earth became habitable – contributes nothing to estimating the likelihood that life arises routinely on habitable-zone exoplanets.

They remind us that we need to acknowledge the anthropic nature of the observation we are making. We are here after 3.5 billion years of evolution – which has given us the capacity to gather together the evidence that life began here 3.5 billion years ago, shortly after the Earth first became habitable. But that is only because this is how things unfolded here on Earth. In the absence of more data, the apparent rapidity of abiogenesis here on Earth could just be a fluke.

Stromatolites - which were a fairly early form of life on Earth. Earth became inhabited by such early life shortly after it became habitable. This might seem suggestive that life is somewhat inevitable when the conditions are right. But a statistician is never going to buy such an argument when it's based on a single example.

This is a fair point, but a largely philosophical one. It informs the subsequent six pages of Spiegel and Turner’s Bayesian analysis, but it is not a conclusion of that analysis.

The authors seek to remind us that interviewing one person and finding that she or he likes baked beans does not allow us to conclude that all people like baked beans. Yes agree, but that’s just statistics – it’s not really Bayesian statistics.

If we are ever able to closely study an exoplanet that has been in a habitable state for 3.5 billion years and discover that either it has life, or that it does not – that will be equivalent to Monty Hall opening another door.

But for now, we might just be a fluke… or we might not be. What we need is more data.

Further reading: Spiegel and Turner. Life might be rare despite its early emergence on Earth: a Bayesian analysis of the probability of abiogenesis.

Posted on by Tammy Plotner

Chandra Captures Enticing Evidence Of Black Hole’s Bondi Radius

The galaxy NGC 3115 is shown here in a composite image of data from NASA's Chandra X-ray Observatory and the European Southern Observatory's Very Large Telescope (VLT). Credit: X-ray: NASA/CXC/Univ. of Alabama/K.Wong et al, Optical: ESO/VLT

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Those who are interested in black holes are familiar with the event horizon, but the Chandra X-Ray Observatory is giving us an even more detailed look into the structure surrounding these enigmas by imaging the inflowing hot gases. Galaxy NGC 3115 contains a supermassive black hole at its heart and for the first time astronomers have evidence of a critical threshold known as the “Bondi radius”.

Located approximately 32 million light years from the Solar System in the constellation of Sextans, NGC 3115 is a prime candidate for study. Contained in its nucleus is a billion-solar-mass black hole which is stripping away hot gases from nearby stars which can be imaged in X-ray. “The Chandra data are shown in blue and the optical data from the VLT are colored gold. The point sources in the X-ray image are mostly binary stars containing gas that is being pulled from a star to a stellar-mass black hole or a neutron star. The inset features the central portion of the Chandra image, with the black hole located in the middle.” says the team. “No point source is seen at the position of the black hole, but instead a plateau of X-ray emission coming from both hot gas and the combined X-ray emission from unresolved binary stars is found.”

In order to see the machination of the black hole at work, the Chandra team eradicated the signal given off by the binary stars, separating it from the super-heated gas flow. By observing the gas at varying distances the team could then pinpoint a threshold where the gas first becomes impacted by the supermassive black hole’s gravity and begins moving towards the center. This point is known as the Bondi radius.

“As gas flows toward a black hole it becomes squeezed, making it hotter and brighter, a signature now confirmed by the X-ray observations. The researchers found the rise in gas temperature begins at about 700 light years from the black hole, giving the location of the Bondi radius.” says the Chandra team. “This suggests that the black hole in the center of NGC 3115 has a mass of about two billion times that of the Sun, supporting previous results from optical observations. This would make NGC 3115 the nearest billion-solar-mass black hole to Earth.”

Original Story Source: Chandra News Further Reading: Resolving the Bondi Accretion Flow toward the Supermassive Black Hole of NGC 3115 with Chandra.