An artist’s impression of what the dust around a quasar might look like from a light year away. Credit Peter Z. Harrington
In the 1970s, astronomers discovered that the persistent radio source at the center of our galaxy was a supermassive black hole (SMBH). Today, this gravitational behemoth is known as Sagittarius A* and has a mass roughly 4 million times that of the Sun. Since then, surveys have shown that SMBHs reside at the center of most massive galaxies and play a vital role in star formation and galactic evolution. In addition, the way these black holes consume gas and dust causes their respective galaxies to emit a tremendous amount of radiation from their Galactic Centers.
These are what astronomers refer to as Active Galactic Nuclei (AGN), or quasars, which can become so bright that they temporarily outshine all the stars in their disks. In fact, AGNs are the most powerful compact steady sources of energy in the Universe, which is why astronomers are always trying to get a closer look at them. For instance, a new study led by the University of California, Santa Cruz (UCSC) indicates that scientists have substantially underestimated the amount of energy emitted by AGN by not recognizing the extent to which their light is dimmed by dust.
NASA Administrator Charles Bolden presents an award to Katherine Johnson, the African American mathematician, physicist, and space scientist, who calculated flight trajectories for John Glenn's first orbital flight in 1962, at a reception to honor members of the segregated West Area Computers division of Langley Research Center on Thursday, Dec. 1, 2016, at the Virginia Air and Space Center in Hampton, VA. Afterward, the guests attended a premiere of "Hidden Figures" a film which stars Taraji P. Henson as Katherine Johnson, Octavia Spencer as Dorothy Vaughan, and Janelle Monae as Mary Jackson. Photo Credit: NASA/Aubrey Gemignani
It’s a common reassurance made by adults to teens and adolescents who constantly face the threat of violence, cyberbullying, and ostracism: “It gets better.” Once you graduate, once you grow up and join the workforce, all the mistreatment and abuse will cease and people will appreciate you for who you are. All the hard work and perseverance you’ve shown over these many years will finally pay off.
Unfortunately, this is not always the case, and even the STEM fields are not immune. This was the conclusion reached by the Royal Astronomical Society (RAS) based on a recent survey of 650 astronomers and geophysicists. What they found was that in 44% of cases, respondents reported bullying and harassment in the workplace during the preceding year, which was disproportionately high for women and minorities.
A frame from the first-ever film of a solar eclipse. Image Credit: British Film Institute, Royal Astronomical Society.
The first film of a total solar eclipse has been restored by specialists at the British Film Institute (BFI) and made available for viewing. The film was taken in North Caroline in 1900 by Nevil Maskelyne. Maskelyne was a British man who was a magician turned film-maker. He took the film as part of a Royal Astronomical Society (RAS) expedition.
Artist’s impression of the cool red star and gas-giant planet NGTS-1b against the Milky Way. Credit: University of Warwick/Mark Garlick.
When it comes to how and where planetary systems form, astronomers thought they had a pretty good handle on things. The predominant theory, known as the Nebular Hypothesis, states that stars and planets form from massive clouds of dust and gas (i.e. nebulae). Once this cloud experiences gravitational collapse at the center, its remaining dust and gas forms a protoplanetary disk that eventually accretes to form planets.
However, when studying the distant star NGTS-1 – an M-type (red dwarf) located about 600 light-years away – an international team led by astronomers from the University of Warwick discovered a massive “hot Jupiter” that appeared far too large to be orbiting such a small star. The discovery of this “monster planet” has naturally challenged some previously-held notions about planetary formation.
Artist’s impression of the cool red star above NGTS-1b. Credit: University of Warwick/Mark Garlick.
The discovery was made using data obtained by the ESO’s Next-Generation Transit Survey (NGTS) facility, which is located at the Paranal Observatory in Chile. This facility is run by an international consortium of astronomers who come from the Universities of Warwick, Leicester, Cambridge, Queen’s University Belfast, the Geneva Observatory, the German Aerospace Center, and the University of Chile.
Using a full array of fully-robotic compact telescopes, this photometric survey is one of several projects meant to compliment the Kepler Space Telescope. Like Kepler, it monitors distant stars for signs of sudden dips in brightness, which are an indication of a planet passing in front of (aka. “transiting”) the star, relative to the observer. When examining data obtained from NGTS-1, the first star to be found by the survey, they made a surprising discovery.
Based on the signal produced by its exoplanet (NGTS-1b), they determined that it was a gas giant roughly the same size as Jupiter and almost as massive (0.812 Jupiter masses). Its orbital period of 2.6 days also indicated that it orbits very close to its star – about 0.0326 AU – which makes it a “hot Jupiter”. Based on these parameters, the team also estimated that NGTS-1b experiences temperatures of approximately 800 K (530°C; 986 °F).
The discovery threw the team for a loop, as it was believed to be impossible for planets of this size to form around small, M-type stars. In accordance with current theories about planet formation, red dwarf stars are believed to be able to form rocky planets – as evidenced by the many that have been discovered around red dwarfs of late – but are unable to gather enough material to create Jupiter-sized planets.
Artist’s concept of Jupiter-sized exoplanet that orbits relatively close to its star (aka. a “hot Jupiter”). Credit: NASA/JPL-Caltech)
As Dr. Daniel Bayliss, an astronomer with the University of Geneva and the lead-author on the paper, commented in University of Warwick press release:
“The discovery of NGTS-1b was a complete surprise to us – such massive planets were not thought to exist around such small stars. This is the first exoplanet we have found with our new NGTS facility and we are already challenging the received wisdom of how planets form. Our challenge is to now find out how common these types of planets are in the Galaxy, and with the new NGTS facility we are well-placed to do just that.”
What is also impressive is the fact that the astronomers noticed the transit at all. Compared to other classes of stars, M-type stars are the smallest, coolest and dimmest. In the past, rocky bodies have been detected around them by measuring shifts in their position relative to Earth (aka. the Radial Velocity Method). These shifts are caused by the gravitational tug of one or more planets that cause the planet to “wobble” back and forth.
In short, the low light of an M-type star has made monitoring them for dips in brightness (aka. the Transit Method) highly impractical. However, using the NGTS’s red-sensitive cameras, the team was able to monitored patches of the night sky for many months. Over time, they noticed dips coming from NGTS-1 every 2.6 days, which indicated that a planet with a short orbital period was periodically passing in front of it.
Artist’s impression of the planet orbiting a red dwarf star. Credit: ESO/M. Kornmesser
They then tracked the planet’s orbit around the star and combined the transit data with Radial Velocity measurements to determine its size, position and mass. As Professor Peter Wheatley (who leads NGTS) indicated, finding the planet was painstaking work. But in the end, its discovery could lead to the detection of many more gas giants around low-mass stars:
“NGTS-1b was difficult to find, despite being a monster of a planet, because its parent star is small and faint. Small stars are actually the most common in the universe, so it is possible that there are many of these giant planets waiting to found. Having worked for almost a decade to develop the NGTS telescope array, it is thrilling to see it picking out new and unexpected types of planets. I’m looking forward to seeing what other kinds of exciting new planets we can turn up.”
Within the known Universe, M-type stars are by far the most common, accounting for 75% of all stars in the Milky Way Galaxy alone. In the past, the discovery of rocky bodies around stars like Proxima Centauri, LHS 1140, GJ 625, and the seven rocky planets around TRAPPIST-1, led many in the astronomical community to conclude that red dwarf stars were the best place to look for Earth-like planets.
The discovery of a Hot Jupiter orbiting NGTS-1 is therefore seen as an indication that other red dwarf stars could have orbiting gas giants as well. Above all, this latest find once again demonstrates the importance of exoplanet research. With every find we make beyond our Solar System, the more we learn about the ways in which planets form and evolve.
Every discovery we make also advances our understanding of how likely we may be to discover life out there somewhere. For in the end, what greater scientific goal is there than determining whether or not we are alone in the Universe?
Artist’s impression of the supernova flare seen in the Large Magellanic Cloud on February 23rd, 1987. Credit: CAASTRO / Mats Björklund (Magipics).
Thirty years ago, a star that went by the designation of SN 1987A collapsed spectacularly, creating a supernova that was visible from Earth. This was the largest supernova to be visible to the naked eye since Kepler’s Supernova in 1604. Today, this supernova remnant (which is located approximately 168,000 light-years away) is being used by astronomers in the Australian Outback to help refine our understanding of stellar explosions.
Led by a student from the University of Sydney, this international research team is observing the remnant at the lowest-ever radio frequencies. Previously, astronomers knew much about the star’s immediate past by studying the effect the star’s collapse had on the neighboring Large Magellanic Cloud. But by detecting the star’s faintest hisses of radio static, the team was able to observe a great deal more of its history.
The team’s findings, which were published yesterday in the journal Monthly Notices of the Royal Astronomical Society, detail how the astronomers were able to look millions of years farther back in time. Prior to this, astronomers could only observe a tiny fraction of the star’s life cycle before it exploded – 20,000 years (or 0.1%) of its multi-million year life span.
Artist’s impression of the star in its multi-million year long and previously unobservable phase as a large, red supergiant. Credit: CAASTRO / Mats Björklund (Magipics)
As such, they were only able to see the star when it was in its final, blue supergiant phase. But with the help of the Murchison Widefield Array (MWA) – a low-frequency radio telescope located at the Murchison Radio-astronomy Observatory (MRO) in the West Australian desert – the radio astronomers were able to see all the way back to when the star was still in its long-lasting red supergiant phase.
In so doing, they were able to observe some interesting things about how this star behaved leading up to the final phase in its life. For instance, they found that SN 1987A lost its matter at a slower rate during its red supergiant phase than was previously assumed. They also observed that it generated slower than expected winds during this period, which pushed into its surrounding environment.
Joseph Callingham, a PhD candidate with the University of Sydney and the ARC Center of Excellence for All-Sky Astrophysics (CAASTRO), is the leader of this research effort. As he stated in a recent RAS press release:
“Just like excavating and studying ancient ruins that teach us about the life of a past civilization, my colleagues and I have used low-frequency radio observations as a window into the star’s life. Our new data improves our knowledge of the composition of space in the region of SN 1987A; we can now go back to our simulations and tweak them, to better reconstruct the physics of supernova explosions.”
Aerial photograph of the core region of the MWA telescope. Credit: mwatelescope.org
The key to finding this new information was the quiet and (some would say) temperamental conditions that the MWA requires to do its thing. Like all radio telescopes, the MWA is located in a remote area to avoid interference from local radio sources, not to mention a dry and elevated area to avoid interference from atmospheric water vapor.
As Professor Gaensler – the former CAASTRO Director and the supervisor of the project – explained, such methods allow for impressive new views of the Universe. “Nobody knew what was happening at low radio frequencies,” he said, “because the signals from our own earthbound FM radio drown out the faint signals from space. Now, by studying the strength of the radio signal, astronomers for the first time can calculate how dense the surrounding gas is, and thus understand the environment of the star before it died.”
These findings will likely help astronomers to understand the life cycle of stars better, which will come in handy when trying to determine what our Sun has in store for us down the road. Further applications will include the hunt for extra-terrestrial life, with astronomers being able to make more accurate estimates on how stellar evolution could effect the odds of life forming in different star systems.
In addition to being home to the MWA, the Murchison Radio-astronomy Observatory (MRO) is also the planned site of the future Square Kilometer Array (SKA). The MWA is one of three telescopes – along with the South African MeerKAT array and the Australian SKA Pathfinder (ASKAP) array – that are designated as a Precursor for the SKA.
An image of a small section (0.4%) of the UDS field - showing a series of very distant galaxies as they appeared 9 billion years ago. Credit: Omar Almaini, University of Nottingham
This past Monday (June 27th), the National Astronomy Meeting – which is hosted by the Royal Astronomy Society – kicked off at the University of Nottingham in the UK. As one of the largest professional conferences in Europe (with over 500 scientists in attendance), this annual meeting is an opportunity for astronomers and scientists from a variety of fields to present that latest in their research.
And of the many presentations made so far, one of the most exciting came from a research team from the University of Nottingham’s School of Physics and Astronomy, which presented the latest near-infrared images obtained by the Ultra Deep Survey (UDS). In addition to being a spectacular series of pictures, they also happened to be the deepest view of the Universe to date.
The UDS survey, which began in 2005, is one of the five projects that make up the UKIRT’s Infrared Deep Sky Survey (UKIDSS). For the sake of their survey, the UDS team relies on the Wide Field Camera (WFCAM) on the United Kingdom Infrared Telescope in Mauna Kea, Hawaii. At 3.8-metres in diameter, the UKIRT is the world’s second largest telescope dedicated to infrared astronomy.
As Professor Omar Almaini, the head of the University of Nottingham research team, explained to Universe Today via email:
“The UDS is by far the deepest near-infrared survey over such a large, contiguous area (0.8 sq degrees). There is only one other similar survey, which is known as UltraVISTA. It covers a larger area (1.5 sq degree) but is not quite so deep. Together the UDS and UltraVISTA should revolutionize studies of the high-redshift Universe over the next few years.”
An optical/IR image taken with the United Kingdom Infrared Telescope as part of the UDS. Credit: nottingham.ac.uk
Ultimately, the goal of UDS is shed light on how and when galaxies form, and to chart their evolution over the course of the last 13 billion years (roughly 820 million years after the Big Bang). For over a decade, the UDS has been observing the same patch of sky repeatedly, relying on optical and infrared imaging to ensure that the light of distant objects (which is redshifted due to the profound distances involved) can be captured.
“Stars emit most of their radiation at optical wavelengths, which is redshifted to the near-infrared at high redshift,” said Almaini. “Near-infrared surveys therefore provide the least biased census of galaxies in the early Universe and the best measurements of the stellar mass. Deep optical surveys will only detect galaxies that are bright in the rest-frame ultraviolet, so they are biased against galaxies that are obscured by dust, or those that have stopped forming stars.”
In total, the project has accumulated more than 1000 hours of exposure time, detecting over two hundred and fifty thousand galaxies – several hundred of which were observed within the first billion years after the Big Bang. The final images, which were released yesterday and presented at the National Astronomy Meeting, showed an area four times the size of the full Moon, and at an unprecedented depth.
Data previously released by the UDS project has already led to several scientific advances. These include studies of the earliest galaxies in the Universe after the Big Bang, measurements on the build-up of galaxies over time, and studies of the large-scale distribution of galaxies to measure the influence of dark matter.
Research into the USD images is inspiring scientific research, which includes studies into dark matter. Credit: Max-Planck Institute for Astrophysics
With this latest release, many more are anticipated, with astronomers around the world spending the next few years studying the early stages of galaxy formation and evolution. As Almaini put it:
“With the UDS (and UltraVISTA) we now have the ability to study large samples of galaxies in the distant Universe, rather than just a handful. With thousands of galaxies at each epoch we can perform detailed comparisons of the evolving galaxy populations, and we can also study their large-scale structure to understand how they trace the underlying cosmic web of dark matter. With large samples we can also look for rare but important populations, such as those in transition.”
“A key aim is to understand why many massive galaxies abruptly stop forming stars around 10 billion years ago, and also how they transform from disk-like systems into elliptical galaxies. We have recently identified a few hundred examples of galaxies in the process of transformation at early times, which we are actively studying to understand what is driving the rapid changes.”
Along with the subject of galaxy surveys and large scale structure, “galaxy formation and evolution” and “galaxy surveys and large scale structure” were two of the 2016 National Astronomy Meeting’s main themes. Naturally, the UDS release fit neatly into both categories. The others themes included the Sun, stars and planetary science, gravitational waves, modified gravity, archeoastronomy, astrochemistry, and education and outreach.
The Meeting will run until tomorrow (Friday, July 1st), and also included a presentations on the latest infrared images of Jupiter, which were taken by the ESO in preparation for the Juno spacecraft’s arrival on July 4th.
An Apollo 17 astronaut digs in the lunar regolith to study the mechanical behavior of moon dust. Credit: NASA
That video above is perhaps the ultimate off-roading adventure: taking a rover out for a spin on the moon. Look past the cool factor for a minute, though, and observe the dust falling down around that astronaut.
The crew aboard Apollo 16 (as well as other Apollo missions) had a lot of problems with regolith. It got into everything. It was so abrasive that it wore away some equipment in days. It smelled funny and probably wasn’t all that good to breathe in, either. Many have said that when we return to the moon, dust must be dealt with for long-term survival.
Things could get worse at sunrise and sunset. One new study (not peer-reviewed yet) finds a “serious risk” that rovers “could be engulfed in dust.” That’s because lunar dust appears to have electrostatic properties that, somehow, is triggered by changes in sunlight. (NASA is already doing some serious investigation into this matter using its orbiting missions.)
What the researchers did, in conjunction with ONERA (The French Center of Aerospace Research) was conduct simulations for two types of lunar regions — the terminator (the day/night boundary) and an area experiencing full sunlight.
“Dust particles were introduced into the simulation over a period of time, when both the surface and the rover were in electrical equilibrium,” the Royal Astronomical Society stated.
“In both the test cases, dust particles travel upwards above the height of the rover, but results suggest that they move in different directions. On the day side, the particles are pushed outwards and on the terminator the dust travels upwards and inwards above the rover, regrouping in the vacuum above it. The terminator simulation began with a region void of dust which was later filled by lunar dust particles.”
The bottom line? A lunar rover could accumulate a significant amount of dust on the moon, especially if it’s sitting at or near the terminator. This could be addressed by using dome-shaped rovers that would see the dust fall off, added lead author Farideh Honary, a physicist at the University of Lancaster, in a statement.
The work was presented at the RAS National Astronomy Meeting today (July 3). A paper has been submitted to the Journal for Geophysical Research, so more details should be forthcoming if and when it is published.
A Hubble Space Telescope image of the galaxy studied by Marianne Heida. The white circle marks the centre of the galaxy and the red circle marks the position of the suspected offset black hole. Image: STScI / NASA
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Supermassive black holes are thought to lie at the center of most large galaxies. But off in a distant remote galaxy, astronomers have possibly found a giant black hole that appears to be in the process of being expelled from the galaxy at high speed. This newly-discovered object was found by Marianne Heida, a student at Utrecht University in the Netherlands, and confirmed by an international team of astronomers who say the black hole was likely kicked out of its galaxy as a result of the merger of two smaller black holes.
Heida discovered the bizarre object, called CXO J122518.6+144545 during her final undergraduate project while doing research at the SRON Netherlands Institute for Space Research. To make the discovery she had to compare hundreds of thousands of X-ray sources, picked up by chance, with the positions of millions of galaxies. X-rays are also able to penetrate the dust and gas that surround black holes, with the bright source appearing as a starlike point. This object was very bright; however, it wasn’t at the center of a galaxy.
Super-massive black holes easily weigh more than 1 billion times the mass of the sun. So how could such a heavy object be hurled away from the galaxy at such high speeds? Astronomers say the expulsion can take place under special conditions when two black holes merge. The merger process creates a new black hole, and supercomputer models suggest that the larger black hole that results is shot out away at high speed, depending on the direction and speed in which the two black holes rotate before their collision.
And, the team of astronomers say, there could be more of these “recoiling” black holes out there. “We have found even more of this strange class of X-ray sources,” said Heida. “However, for these objects we first of all need accurate measurements from NASA’s Chandra satellite to pinpoint them more precisely.”
If this object is not a recoiling black hole, other possibilities are that it could possibly be either a very blue type IIn supernova or a ULX (ultra-luminous X-ray source) with a very bright optical counterpart.
Finding more of these expelled black holes will provide a better understanding of the characteristics of black holes before they merge. In the future, astronomers hope to even observe this process with the planned LISA satellite, which will be able to measure the gravity waves that the two merging black holes emit. Further research will provide more insight into how supermassive black holes are created.
Artist concept of Methane-Ethane lakes on Titan (Credit: Copyright 2008 Karl Kofoed). Click for larger version.
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Could there be life on Titan? If so, one astrobiologist says humans probably couldn’t be in the same room with a Titanian and live to tell about it. “Hollywood would have problems with these aliens” said Dr. William Bains. “Beam one onto the Starship Enterprise and it would boil and then burst into flames, and the fumes would kill everyone in range. Even a tiny whiff of its breath would smell unbelievably horrible. But I think it is all the more interesting for that reason. Wouldn’t it be sad if the most alien things we found in the galaxy were just like us, but blue and with tails?”
While giving an obvious nod to the recent movie “Avatar,” Bains’ research provides insight to the difficulties we might encounter – beyond cultural – if we ever meet up with alien life. There could be unintended harmful consequences for one species, or both.
Bains is working to find out just how extreme the chemistry of life can be. Life on Titan, Saturn’s largest moon, represents one of the more bizarre scenarios being studied. While images sent back by the Cassini/Huygens mission might make Titan look Earth-like and maybe even inviting, it has a thick atmosphere of frozen, orange smog. At ten times our distance from the Sun, it is a frigid place, with a surface temperature of -180 degrees Celsius. Water is permanently frozen into ice and the only liquid available is liquid methane and ethane.
So instead of water based-life (like us), life on Titan would likely be based on methane.
“Life needs a liquid; even the driest desert plant on Earth needs water for its metabolism to work. So, if life were to exist on Titan, it must have blood based on liquid methane, not water. That means its whole chemistry is radically different. The molecules must be made of a wider variety of elements than we use, but put together in smaller molecules. It would also be much more chemically reactive,” said Bains.
Additionally, Bains said a metabolism running in liquid methane would have to be built of smaller molecules than terrestrial biochemistry.
“Terrestrial life uses about 700 molecules, but to find the right 700 there is reason to suppose that you need to be able to make 10 million or more,” Bains said. “The issue is not how many molecules you can make, but whether you can make the collection you need to assemble a metabolism.”
Bains said doing such assembling is like trying to find bits of wood in a lumber-yard to make a table.
“In theory you only need 5,” he said. “But you may have a lumber-yard full of offcuts and still not find exactly the right five that fit together. So you need the potential to make many more molecules than you actually need. Thus the 6-atom chemicals on Titan would have to include much more diverse bond types and probably more diverse elements, including sulphur and phosphorus in much more diverse and (to us) unstable forms, and other elements such as silicon.”
Energy is another factor that would affect the type of life that could evolve on Titan. With Sunlight a tenth of a percent as intense on Titan’s surface as on the surface of Earth, energy is likely to be in short supply.
“Rapid movement or growth needs a lot of energy, so slow-growing, lichen-like organisms are possible in theory, but velociraptors are pretty much ruled out,” said Bains.
Whatever life may be on Titan, at least we know there won’t be a Jurassic Park.
Bains, whose research is carried out through Rufus Scientific in Cambridge, UK, and MIT in the USA, is presenting his research at the National Astronomy Meeting in Glasgow, Scotland on April 13, 2010.
