Posted on by Jon Voisey

Forget Exoplanets. Let’s Talk Exomoons

An artist impression of an exomoon orbiting an exoplanet, could the exoplanet's wobble help astronomers? (Andy McLatchie)

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It wasn’t that long ago that astronomers began discovering the first planets around other stars. But as the field of exoplanetary astronomy explodes, astronomers have begun looking to the future and considering the possibility of detecting moons around these planets. Surprisingly, the potential for doing so may not be that far off.

Before exploring how we might detect satellites of distant planets, astronomers must first attempt to get an understanding of what they may be looking for. Fortunately, this question ties in well with the rapidly developing understanding of how solar systems form.

In general, there are three mechanisms by which planets may obtain satellites. The simplest is for them to simply form together from a single accretion disk. Another is that a massive impact may knock material off of a planet which forms into a satellite as astronomers believe happened with our own Moon. Some estimates have indicated that such impacts should be frequent and as many as 1 in 12 Earth like planets may have formed moons in this way. Lastly, a satellite may be a captured asteroid or comet as is likely for many of the moons of Jupiter and Saturn.

Each of these cases produces a different range of masses. Captured bodies are likely to be the smallest and therefor are unlikely to be detectable in the near future. Impact generated moons are expected to only be able to form bodies with 4% of the total mass of the planet and as such, are rather limited as well. The largest moons are thought to form in the disks around forming Jupiter like planets. These are the most likely to be detectable.

The first method by which astronomers may detect such moons is by the changes they would make in the wobble of the star that has been used to detect many extrasolar planets to date. Astronomers have already studied how a pair of binary stars may affect a binary star system may have on a third star it orbits. If the binary star is swapped out for a planet and a moon it turns out that the easiest systems to detect are massive moons that are distant from the planet, but close to the parent star. However, except in extreme cases, the amount of wobble that the pair could induce in the star is so small that it would be swamped by the convective motion of the star’s surface, making detection through this method nearly impossible.

Astronomers have begun detecting large numbers of exoplanets by transits, where the planet causes minor eclipses. Could astronomers also detect the presence of moons this way? In this case, the limit on detection would again be based on the size of the moon. Currently, the Kepler satellite is expected to detect planets similar in mass to Earth. If moons exist around a super-Jovian planet that are also similar in size to Earth, they too should be detected. However, forming moons this large is difficult. The largest moon in the solar system in Ganymede which is 40% of the diameter of Earth, putting it modestly below current detection thresholds, but potentially in reach of future exoplanet missions.

However, direct detection of the eclipses caused by transits isn’t the only way transits could be used to discover exomoons. In the past few years, astronomers have begun using the wobble of other planets on the ones they had already discovered to infer the existence of other planets in the system in the same way the gravitational tug of Neptune on Uranus allowed astronomers to predict Neptune’s existence before it was discovered. A sufficiently massive moon could cause detectable variations in when the transit of the planet would begin and end. Astronomers have already used this technique to place limits on the mass of potential moons around exoplanets HD 209458 and OGLE-TR-113b at 3 and 7 Earth masses respectively.

The first discovered exoplanet was discovered around a pulsar. The tug of this planet caused variation of the regular pulsation of the pulsar’s beat. Pulsars often beat hundreds to thousands of times per second and as such, are extremely sensitive indicators of the presence of planets. The pulsar PSR B1257+12 is known to harbor one planet that is a mere 0.04% the mass of Earth, which is well below the mass threshold of many moons. As such, variations in these systems, caused by moons would be potentially detectable with current technology. Astronomers have already used it to search for moons around the planet orbiting PSR B1620-26 and ruled out moons more than 12% the mass of Jupiter within half an Astronomical Unit (the distance between the Earth and Sun or 93 million miles) of the planet.

The last method by which astronomers have detected planets that could potentially be used for exomoons is direct observation. Since direct imaging of exoplanets has only become realized in the past few years, this option is likely still a ways off, but future missions like the Terrestrial Planet Finder Coronagraph may put it into the realm of possibility. Even if the moon is not fully resolved, the offset of the center of the dot of the pair may be detectable with current instruments.

Overall, if the explosion of knowledge on planetary systems continues, astronomers should be capable of detecting exomoons within the near future. The possibility already exists for some cases, like pulsar planets, but due to their rarity, the statistical likelihood of finding a planet with a sufficiently large moon is low. But as equipment continues to improve, making detection thresholds lower for various methods, the first exomoons should come into view. Undoubtedly, the first ones will be large. This will beg the question of what sorts of surfaces and potentially atmospheres they may have. In turn, this would inspire more questions about what life may exist.

Source:
The Detectability of Moons of Extra-Solar Planets – Karen M. Lewis

Posted on by Tammy Plotner

Hubble Telescope Directly Observes Quasar Accretion Disc Surrounding Black Hole

A team of scientists has used the NASA/ESA Hubble Space Telescope to observe a quasar accretion disc — a brightly glowing disc of matter that is slowly being sucked into its galaxy’s central black hole. Their study makes use of a novel technique that uses gravitational lensing to give an immense boost to the power of the telescope. The incredible precision of the method has allowed astronomers to directly measure the disc’s size and plot the temperature across different parts of the disc. Image credit: NASA, ESA, J.A. Munoz (University of Valencia)

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Thanks to the magic of the NASA/ESA Hubble Space Telescope, a team of international astronomers have made an incredible observation – a quasar accretion disc surrounding a black hole. By employing a technique known as gravitation lensing, the researchers have been able to get an accurate size measurement and spectral data. While you might not think this exciting at first, know that this type of observation is akin to spotting individual grains of sand on the Moon!

Of course, we know we can’t see a black hole – but we’ve learned a lot about them with time. One of their properties is a bright, visible phenomenon called a quasar. These glowing discs of matter are engaged in orbit around the black hole, much like a coil on an electric stove. As energy is applied, the “coil” heats up and unleashes bright radiation.

“A quasar accretion disc has a typical size of a few light-days, or around 100 billion kilometres across, but they lie billions of light-years away. This means their apparent size when viewed from Earth is so small that we will probably never have a telescope powerful enough to see their structure directly,” explains Jose Munoz, the lead scientist in this study.

Because of the diminutive size of the quasar, most of our understanding of how they work has been based on theory… but great minds have found a way to directly observe their effects. By employing the gravity of stars in an intervening galaxy like a scanning microscope, astronomers have been able to observe the quasar’s light as the stars move. While most of these types of features would be too small to see, the gravitation lensing effect ramps up the strength of the quasar’s light and allows study of the spectra as it cruises across the accretion disc.

This diagram shows how Hubble is able to observe a quasar, a glowing disc of matter around a distant black hole, even though the black hole would ordinarily be too far away to see clearly. Credit: NASA and ESA

By observing a group of gravitationally lensed quasars, the team was able to paint a vivid color portrait of the activity. They were able to pick out small changes between single images and spectral shifts over a period of time. What causes these kaleidoscopic variances? For the most part, it’s the different properties in the gases and dust of the lensing galaxies. Because they travel at different angles to the quasar’s light, scientists were even able to distinguish extinction laws at work.

But there was something special about one of the quasars. Says the Hubble Team, “There were clear signs that stars in the intervening galaxy were passing through the path of the light from the quasar. Just as the gravitational effect due to the whole intervening galaxy can bend and amplify the quasar’s light, so can that of the stars within the intervening galaxy subtly bend and amplify the light from different parts of the accretion disc as they pass through the path of the quasar’s light.”

By documenting these color changes, the team could build a profile of the accretion disc. Unlike our Earthly electric stove coil which glows red as it heats up, the accretion disc of a black hole turns blue as it gets closer to the event horizon. By measuring the blue hue, the team was able to measure the disc diameter and the various tints gave them an indicator of distances from its center. In this case, they found that the disc is between four and eleven light-days across (approximately 100 to 300 billion kilometres). Of course, these are only rough estimates, but considering just how far away we’re looking at such a small object gives these types of observations great potential for future studies… and even improvements on accuracy.

“This result is very relevant because it implies we are now able to obtain observational data on the structure of these systems, rather than relying on theory alone,” says Munoz. “Quasars’ physical properties are not yet well understood. This new ability to obtain observational measurements is therefore opening a new window to help understand the nature of these objects.”

Original Story Source: ESA/Hubble News Release. For Further Reading: A Study of Gravitational Lens Chromaticity With the Hubble Space Telescope.

Posted on by Jon Voisey

Borexino Collaboration Detects pep Neutrinos

View from inside the Borexino neutrino detector. Image Credit: Borexino Collaboration
View from inside the Borexino neutrino detector. Image Credit: Borexino Collaboration

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Solar neutrino physics has quieted down over the past decade. In the past, it had been a source of major excitement and puzzlement for scientists as they struggled to detect these elusive particles emitted from the fusion reactions in the center of the Sun. Although difficult to detect, they provide the most direct probe of the Solar core. Once astronomers learned to detect them and solved the Solar neutrino problem, they were able to confirm their understanding of the main nuclear reaction that powers the sun, the proton-proton (pp) reaction. But now, astronomers have for the first time, detected the neutrinos of another, far rarer nuclear reaction, the proton-electron-proton (pep) reaction.

At any given time, several separate fusion processes are converting the Sun’s hydrogen into helium, creating energy as a byproduct. The main reaction requires the formation of deuterium (hydrogen with an extra neutron in the nucleus) as the first step in a series of events that leads to the creation of stable helium. This typically takes place by the fusion of two protons which ejects a positron, a neutrino, and a photon. However, nuclear physicists predicted an alternative method of creating the necessary deuterium. In it, a proton and electron fuse first, forming a neutron and a neutrino, and then they join with a second proton. Based on solar models, they predicted that only 0.23% of all Deuterium would be created by this process. Given the already elusive nature of neutrinos, the diminished production rate has made these pep neutrinos even more difficult to detect.

While they may be hard to detect, pep neutrinos are readily distinguishable from ones created by the pp reaction. The key difference is the energy they carry. Neutrinos from the pp reaction have a range of energy up to a maximum of 0.42 MeV, while pep neutrinos carry a very select 1.44 MeV.

However, to pick out these neutrinos, the team had to carefully clean the data of signals from cosmic ray strikes which create muons that could then interact with carbon inside the detector to generate a neutrino with similar energy that might create a false positive. In addition, this process would also create a free neutron. To eliminate these, the team rejected all signals of neutrinos that occurred within a short amount of time from a detection of a free neutron. Overall, this indicated that the detector received 4,300 muons passing through it per day, which would generate 27 neutrons per 100tons of detector liquid, and similarly, 27 false positives.

Removing these detections, the team still found a signal of neutrinos with the appropriate energy and used this to estimate the total amount of pep neutrinos flowing through every square centimeter to be about 1.6 billion, per second, which they note is in agreement with predictions made by the standard model used to describe the interior workings of the Sun.

Aside from further confirming astronomers understanding of the processes that power the Sun, this finding also places constraints on another fusion process, the CNO Cycle. While this process is expected to be minor in the Sun (making only ~2% of all helium produced), it is expected to be more efficient in hotter, more massive stars and dominate in stars with 50% more mass than the Sun. Better understanding the limits of this process would help astronomers to clarify how those stars work as well.

Posted on by Jason Major

Senate Approves Bill Funding JWST

Full scale model of the JWST at the EADS Astrium in Munich. Credit: EADS Astrium

This afternoon the U.S. Senate approved H.R. 2112, a FY 2012 bill from Maryland Senator Barbara Mikulski that would fund the James Webb Space Telescope to launch in 2018. This is another step forward for the next-generation space telescope, which many have called the successor to Hubble… all that now remains is for the House to reconcile.

“We are creating the building blocks that we need for a smarter America. Our nation is in an amazing race – the race for discovery and new knowledge, the race to remain competitive,” Chairwoman Mikulski said. “This bill includes full funding of the James Webb Telescope to achieve a 2018 launch. The Webb Telescope supports 1,200 jobs and will lead to the kind of innovation and discovery that have made America great. It will inspire America’s next generation of scientists and innovators that will have the new ideas that lead to new products and new jobs.”

Full scale model of the JWST at the EADS Astrium in Munich. Credit: EADS Astrium

The bill was approved by a vote of 69 to 30.

Thanks to everyone who contacted their representatives in support of the JWST and to all the websites out there that helped make it simple to do so… and of course to all the state representatives who listened and stood behind the JWST!

In addition to continued funding for the telescope the 2012 bill also allots the National Aeronautics and Space Administration $17.9 billion (still a reduction of $509 million or 2.8 percent from the 2011 enacted level) and preserves NASA’s portfolio balanced among science, aeronautics, technology and human space flight investments, including the Orion Multipurpose Crew Vehicle, the heavy lift Space Launch System, and commercial crew development.

It also supports funding for the NOAA.

“We are creating the building blocks that we need for a smarter America. Our nation is in an amazing race – the race for discovery and new knowledge, the race to remain competitive.”

– U.S. Senator Barbara A. Mikulski

Of course, we must remember that spending and allocation of funds is not necessarily creating funds. As with everything, money has to come from somewhere and it remains to be seen how this will affect other programs within NASA. Not everyone is in agreement that this is the best course of action for the Administration at this point, not with the overall reduction of budget being what it is.

Read the bill summary here.

You can show your continued support for the JWST by liking the Save the James Webb Space Telescope Facebook page and – even more importantly – by contacting your congressperson and letting them know you care!

Posted on by VirtualAstro

Faulkes Team Images Trojan Jupiter Comet

Jupiter Comet

Based on an observation posted on the Near Earth Object confirmation page from an image taken by A. D. Grauer using the mount Lemmon observatory, Faulkes telescope team members Nick Howes, Giovanni Sostero and Ernesto Guido along with University of Glamorgan student Antos Kasprzyk and amateur astronomer Iain Melville, imaged what is potentially some of the first direct evidence for a Trojan Jupiter Comet

Comet P/2010 TO20 (LINEAR-GRAUER) was immediately recognised by the team from looking at the orbit to be a highly unusual object, but it was only when the images came through from the faulkes observations that the true nature of the object became clear

The observations showed a distinct cometary appearance, with a sharp central condensation, compact coma and a wide, fan-shaped tail.

This is no ordinary comet, and supports the theory and initial spectral observation work by a team using the keck telescope in Hawaii. Closer analysis of their object (part of a binary known as the Patroclus pair) showed that it was made of water ice and a thin layer of dust, but at the time of writing, no direct images of a Jupiter Trojan showing evidence of a coma and tail had been taken.

The Faulkes teams above image, combined with the original observations by Grauer clearly show a cometary object, thus confirming the Keck team’s hypothesis.

According to the CBET released today “After two nights of observations of Grauer’s comet had been received at the Minor Planet Center.
Spahr realized that this object was identical with an object discovered a year ago by the LINEAR project (discovery observation tabulated below; cf. MPS 351583) that appeared to be a Jupiter Trojan minor planet.”

The observations have now proved it is not a minor planet, but a comet.

This discovery could provide new clues about the evolution of the Solar System, suggesting that the Gas Giants formed closer to the Sun and as they moved further away, they caused massive perturbations with Kuiper Belt objects, trapping some in their own orbits.

Nick Howes on the Faulkes team said “When we first saw the preliminary orbit, we knew it was a quite remarkable object” Howes also added “To have a University Student also involved is terrific for the degree program at Glamorgan and also for the Faulkes project. We’d like to extend our congratulations to Al Grauer” for his detection of this groundbreaking new comet” and we’re immensely proud to be part of the CBET released by the IAU confirming its nature

References:
Space Is Ace
Spacedaily.com
Remanzacco Observatory

Posted on by Tammy Plotner

Black Hole Secrets… Water Vapor Gives Clues To Star Formation

Artist's Concept of Water Vapor in Black Hole Disk - Credit: Leiden University

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A eye-opening discovery has been made by an international team of scientists led by astronomer Paul van der Werf (Leiden University, The Netherlands). They have discovered a black hole in the early Universe located about 12 billion light years away that’s surrounded by a nearly impenetrable disk of gas and dust. The halo isn’t the surprise, however… but the presence of star formation in dense water vapor is.

Using the sensitive radio telescopes of IRAM (Institut de Radioastronomie Millimétrique) at the Plateau de Bure in the French Alps, the team was searching for the signs of water vapor around a quasar – a distant galaxy which gathers its luminosity from the growth of a black hole which weighs in at hundreds of millions times more mass than Sol.

“Water in cosmic clouds is normally frozen to ice, but the ice can be evaporated by the strong radiation of the quasar or of young stars. Therefore we decided to search for water vapor in this object.” says van der Werf. “It is located so far away that we are looking back in time, to an era where the Universe was only 10% of its present age. This is one of the first searches ever conducted to find water in the early Universe.”

A shocking revelation? Not really. Water vapor has been discovered before. In this instance, however, the water amounted to about 1,000 trillion times the volume found on Earth. What’s more… it’s forming stars. It’s a dense disk, so thick that light barely escapes, and star propagation is rapid.

“Water molecules are sensitive to infrared radiation, so we could use the water vapor detected as a cosmic infrared light meter. With this method we found that essentially all radiation is locked up in the gas disk surrounding the black hole.” team member Marco Spaans (University of Groningen, The Netherlands) explains. “This trapped radiation is so intense that it will build up enormous pressure and eventually blow away the gas and dust clouds surrounding the black hole.”

These findings add a new complexity to our understanding of black holes and the galaxies which hold them. Team member Alicia Berciano Alba (ASTRON, The Netherlands) says: “There is a mysterious relation between the masses of black holes in the centers of galaxies and the masses of the galaxies themselves, as if the formation of both is regulated by the same process. Our results show that these opaque gas disks, which will be ultimately blown away by the intense pressure of the trapped radiation, probably play a key role in this process.” IRAM director Pierre Cox, co-author of the paper, adds: “This discovery opens new possibilities for studying galaxies in the early Universe, using water molecules that probe regions closest to the central black hole, that are otherwise difficult to explore.”

Keep on going, because the IRAM team is up to the task and continuing to look for other sources of water vapor in the early Universe!

Original Story Source: Leiden University New Release. For Further Reading: Water vapor emission reveals a highly obscured, star forming nuclear region in the QSO host galaxy APM 08279+5255 at z=3.9.

Posted on by Tammy Plotner

Two New Globular Star Clusters Discovered By VISTA

This image from VISTA is a tiny part of the VISTA Variables in the Via Lactea (VVV) survey that is systematically studying the central parts of the Milky Way in infrared light. On the right lies the globular star cluster UKS 1 and on the left lies a much less conspicuous new discovery, VVV CL001 — a previously unknown globular, one of just 160 known globular clusters in the Milky Way at the time of writing. The new globular appears as a faint grouping of stars about 25% of the width of the image from the left edge, and about 60% of the way from bottom to top. Credit: ESO/D. Minniti/VVV Team

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Where there once was 158, there is now more… Globular clusters, that is. Thanks to ESO’s VISTA survey telescope at the Paranal Observatory in Chile, the Via Lactea (VVV) survey has cut through the gas and dust of the Milky Way to reveal the first star cluster that is far beyond our center. But keep your eyes on the prize, because as dazzling as the cluster called UKS 1 is on the right is, the one named VVV CL001 on the left isn’t as easy to spot.

Need more? Then keep on looking, because VVV CL001 isn’t alone. The next victory for VISTA is VVV CL002, which is shown in the image below. What makes it special? It’s quite possible that VVV CL002 is the closest of its type to the center of our galaxy. While you might think discoveries of this type are commonplace, they are actually out of the ordinary. The last was documented in 2010 and it’s only through systematically studying the central parts of the Milky Way in infrared light that new ones turn up. To add even more excitement to the discovery, there is a possibility that VVV CL001 is gravitationally bound to UKS 1, making it a binary pair! However, without further study, this remains unverified.

This image from VISTA is a tiny part of the VISTA Variables in the Via Lactea (VVV) survey that is systematically studying the central parts of the Milky Way in infrared light. In the centre lies the faint newly found globular star cluster, VVV CL002. This previously unknown globular, which appears as an inconspicuous concentration of faint stars near the centre of the picture, lies close to the centre of the Milky Way. Credit: ESO/D. Minniti/VVV Team

Thanks to the hard work of the VVV team led by Dante Minniti (Pontificia Universidad Catolica de Chile) and Philip Lucas (Centre for Astrophysics Research, University of Hertfordshire, UK) we’re able to feast our eyes on even more. About 15,000 light years away on the other side of the Milky Way, they’ve turned up VVV CL003 – an open cluster. Due the intristic faintness of these new objects, it’s a wonder we can see them at all… In any light!

Original Story Source: ESO Press Release.

Posted on by Tammy Plotner

Wake Up! The Orionid Meteor Shower Peaks On October 20…

Orionid Meteor Shower: The above image shows brilliant multiple meteor streaks that can all be connected to a single point in the sky just above the belt of Orion, called the "radiant." The Orionids take place in mid-October and the parent comet is Halley. Comet Halley is actually responsible for two known meteor showers: The other is the Eta Aquarids, which are visible every May. Image Credit and Copyright: Tunc Tezel

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Do you hate to get up early? Then stay up late, because it’s infrequent that both the northern and southern hemispheres have a chance to catch an annual meteor shower. Right now the Earth is heading into the complex Orionid stream, and while the skies won’t be perfectly dark, they aren’t going to be bad. Where and when do you watch? Follow me…

As the Earth slowly orbits the Sun, it passes into one of the debris streams left by Comet Halley and the material returns as the Orionid meteor shower. While it won’t be a “meteor storm”, what you can expect to see is one of the most predictable and reliable meteor showers of the year. Even if it’s a few days early (or late), take advantage of any clear skies and begin your observations because activity is up.

The Orionids produce an average of 10-20 meteors per hour maximum, and best activity begins before local midnight on October 20th, and reaches its peak as Orion stands high to the south about two hours before local dawn on October 21st. With only partial slice of Moon in the late evening/early morning, this looks to be the year’s last, best meteor shower!

“Every year around this time Earth glides through a cloud of dusty debris from Halley’s Comet,” explains Bill Cooke of the NASA Marshall Space Flight Center. “Bits of dust, most no larger than grains of sand, disintegrate in Earth’s atmosphere and become shooting stars.”

“It’s not an intense shower,” he says, “but it is a pretty one.”

Although Comet Halley has now departed the inner Solar System, its debris trail remains well organized – allowing us to predict when this meteor shower will occur. The Earth first enters the stream at the beginning of October and does not leave until the beginning of November. This makes your chances of “catching a falling star” above average!

“Earth comes close to the orbit of Halley’s Comet twice a year, once in May and again in October,” explains Don Yeomans, manager of NASA’s Near-Earth Object Program at the Jet Propulsion Laboratory. Orionid meteoroids strike Earth’s atmosphere traveling 66 km/s or 148,000 mph,” he continued. These meteors are very fast, and although faint (average magnitude 3), occasional fireballs do leave persistent trails that shimmer in the upper atmosphere. It’s the “Oooooh!” effect!

For best success, get away from city lights. Face south-southeast in the northern hemisphere and almost overhead in the southern – then relax and enjoy the stars of the Winter Milky Way. The radiant is near Betelguese, but may occur from any part of the sky. When the Moon rises, try positioning yourself so a house, tree, or other obstruction helps to reduce the glare. The meteor watching experience is much more comfortable if you include a reclining lawn chair, blanket, and thermos of your favorite beverage. Nothing spoils watching quicker than “meteor neck”.

Clouded out? Don’t despair. You don’t always need eyes or perfect weather to keep the watch. Tune an FM radio to the lowest frequency that doesn’t receive a clear signal. An outdoor FM antenna pointed to the zenith increases your chances – but isn’t essential. Simply turn up the static and listen. Those hums, whistles, beeps, bongs, and occasional snatches of signals are distant transmissions being reflected off a meteor’s ion trail!

Posted on by Jon Voisey

Is M85 Missing a Black Hole?

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The conventional wisdom of galaxies is that they should have a central massive black hole (CMBH). The presence of such objects has been confirmed in our own galaxy as well as numerous other galaxies, including the Andromeda galaxy (M31) and even some dwarf galaxies. The mass of these objects, several million times the mass of the Sun, has been found to be related to many properties of galaxies as a whole, indicating that their presence may be critical in the formation and evolution of galaxies as a whole. As such, finding a massive galaxy without a central black hole would be quite surprising. Yet a recent study by astronomers from the University of Michigan Ann Arbor seems to have found an exception: The well known M85.

To determine the mass of the CMBH, the team used the spectrograph on board the Hubble Space Telescope to examine the pull the central object had on stars in the nearby vicinity. The higher this mass is, the more quickly the stars should orbit. This orbital velocity is detected as a shift in the color of the light, blue as the stars move towards us, red as they move away. The amount the light is shifted is dependent on just how fast they move.

Doppler shift of gas and dust caused by M84's supermassive black hole. Image Credit: Gary Bower, Richard Green (NOAO), the STIS Instrument Definition Team, and NASA
Doppler shift of gas and dust caused by M84's supermassive black hole. Image Credit: Gary Bower, Richard Green (NOAO), the STIS Instrument Definition Team, and NASA
This technique has been used previously in other galaxies, including another large elliptical of similar brightness in the Messier catalog, M84. This galaxy had its CMBH probed by Hubble in 1997 and was determined to have a mass of 300 million solar masses.

When this method was applied to M85 the team did not discover a shift that would be indicative of a black hole with a mass expected for a galaxy of such size. Using another, indirect method of determining the CMBH mass by looking at the the amount of overall light from the galaxy, which is generally correlated with black hole mass, would indicate that M85 should contain a black hole of 300 million to 2 billion solar masses. Yet this study indicates that, if M85 contains a central black hole at all, the upper limit for the black hole would be around 65 million solar masses.

This study is not the first to report a non-detection for the galaxy, a 2009 study led by Alessandro Capetti from Osservatorio Astronoimco di Torino in Italy, searched M85 for signs of radio emission from the black hole region. Their study was unable to detect any significant radio waves from the core which, if M85 had a significant black hole, should be present, even with a small amount of gas feeding into the core.

Overall, these studies demonstrate a significant shortcoming in secondary methods of black hole mass estimation. Such indirect methods have been previously used with confidence and have even been the basis for studies drawing the connection between galaxy evolution and black hole mass. If cases like M85 are more common that previously thought, it may prompt astronomers to rethink just how connected black holes and a galaxies properties really are.

Posted on by Jon Voisey

Was the “First Photographed UFO” a Comet?

First photograph of a UFO sighting, taken 12 August 1883 by Jose Bonilla.
First photograph of a UFO sighting, taken 12 August 1883 by Jose Bonilla.

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On August 12th, 1883, Mexican astronomer José Bonilla was preparing to study the Sun at the recently opened Zacatecas Observatory. However, the Sun’s surface was marred by numerous objects quickly travelling across its disk. Over the course of the day and the next, Bonilla exposed several wet plates to take images of the 447 objects he would observe. They weren’t released publicly until January 1st, 1886 when they were published in the magazine L’Astronomie. Since then, UFOlogists have crowed these photographs as the first photographic evidence of UFOs. The chief editor of L’Astronomie passed the observations off as migrating animals, but a new study proposes the observation was due to the breakup of a comet that nearly hit us.

The only piece of evidence the authors, led by Hector Manterola at the Universidad Nacional Autónoma de México, use to suggest that this was a comet in the process of breaking up, was the descriptions of the objects as being “fuzzy” in nature and leaving dark trails behind them. Assuming this were the case, the authors consider how close the object would have been. Since astronomers at observatories in Mexico City, or Puebla had not reported the objects, this would imply that they did not cross the disc of the Sun from these locations due to parallax. As such, the maximum distance the object could have been is roughly 80,000 km, roughly 1/5th the distance to the moon.

But the team suggests the fragments may have passed even closer. By the time comets reach the inner solar system, they have a significant velocity of some tens of kilometers per second. In such a case, to transverse the disc of the Sun in the time reported by Bonilla (a third to a full second), the object would have been, at most, at a distance of ~8,000km.

At such distances, the overall size of the fragments would be in rough agreement of sizes of other fragmented comets such as 73P/Schwassmann-Wachmann 3, which gave off several fragments in 2006. Based on the number of fragments, estimated sizes, and density of an average comet, the authors estimate that the mass may be anywhere between 2 x 1012 and 8 x 1015 kg. While this is a very large range (three orders of magnitude), it roughly brackets the range of known comets, again making it plausible. The upper range of this mass estimate is on par with Mars’ moon Deimos, which is generally held to be similar in mass to the progenitor of the impact that killed the dinosaurs.

One oddity is that one would likely expect such a close breakup to result in a meteor storm. The timing of these events is just before the annual Perseid meteor shower, but reports for that year, such as this one, do not depict it as being exceptional, or having a different radiant than should be expected. Instead, it notes that 157 of the 186 meteors observed on the 11th were definitively Perseids, and that the “year’s display cannot be reckoned as a fine one by any means.” Meanwhile, the Leonid meteor shower (peaking in November), was exceptional that year, generating an estimated 1,000 meteors an hour, but again, no records seem to indicate an unusual origin.

In total, I find the characterization of Bonilla’s observation as a comet plausible, but generally unconvincing. However, if it were a fragmented comet, we’re very lucky it wasn’t any closer.