A portion of a collage of galaxies included in the Herschel Reference Survey, in false color to show different dust temperatures. (Blue is colder, and red is warmer). Credit: ESA/Herschel/HRS-SAG2 and HeViCS Key Programmes/L. Cortese (Swinburne University)
While dust is easy to ignore in small quantities (says the writer looking at her desk), across vast reaches of space this substance plays an important role. Stick enough grains together, the theory goes, and you’ll start to form rocks and eventually planets. On a galaxy-size scale, dust may even effect how the galaxy evolves.
A new survey of 323 galaxies reveals that dust is not only affected by the kinds of stars in the vicinity, but also what the galaxy is made of.
“These dust grains are believed to be fundamental ingredients for the formation of stars and planets, but until now very little was known about their abundance and physical properties in galaxies other than our own Milky Way,” stated lead author Luca Cortese, who is from the Swinburne University of Technology in Melbourne, Australia.
“The properties of grains vary from one galaxy to another – more than we originally expected,” he added. “As dust is heated by starlight, we knew that the frequencies at which grains emit should be related to a galaxy’s star formation activity. However, our results show that galaxies’ chemical history plays an equally important role.”
Galaxies in the Herschel Reference Survey in infrared/submillimeter wavelengths (with the Herschel space telescope, at left) and the Sloan Digital Sky Survey (right). Herschel’s false-color image shows galaxies with cold dust (blue) and warm dust (red). Sloan highlights young stars (blue) and old stars (red). “Together, the observations plot young, dust-rich spiral/irregular galaxies in the top left, with giant dust-poor elliptical galaxies in the bottom right,” the European Space Agency stated. Credit: ESA/Herschel/HRS-SAG2 and HeViCS Key Programmes/Sloan Digital Sky Survey/ L. Cortese (Swinburne University)
Data was captured with two cameras on the just-retired Herschel space telescope: Spectral and Photometric Imaging Receiver (SPIRE) and Photodetecting Array Camera and Spectrometer (PACS). These instruments examined different frequencies of dust emission, which shows what the grains are made of. You can see a few of those galaxies in the image above.
“The dust-rich galaxies are typically spiral or irregular, whereas the dust-poor ones are usually elliptical,” the European Space Agency stated. “Dust is gently heated across a range of temperatures by the combined light of all of the stars in each galaxy, with the warmest dust being concentrated in regions where stars are being born.”
Astronomers initially expected that a galaxy with speedy star formation would display more massive and warmer stars in it, corresponding to warmer dust in the galaxy emitting light in short wavelengths.
“However, the data show greater variations than expected from one galaxy to another based on their star formation rates alone, implying that other properties, such as its chemical enrichment, also play an important role,” ESA said.
Comet c/2012 K1 PanSTARRS as imaged by Dan Crowson on February 22nd, 2014. Image credit: Dan Crowson, used with permission.
Get those binoculars ready: an icy interloper from the Oort cloud is about to grace the night sky.
The comet is C/2012 K1 PanSTARRS, and it’s currently just passed from the constellation Hercules into Corona Borealis and presents a good target for observers high in the sky in the hours before dawn. In fact, from our Tampa based latitude, K1 PanSTARRS is nearly at the zenith at around 6 AM local.
Observers currently place K1 PanSTARRS at magnitude +10.5 and brightening and showing a small condensed coma. Through the eyepiece, a comet at this stage will often resemble a fuzzy, unresolved globular star cluster.
And the good news is, K1 PanSTARRS will continue to brighten, headed northward through the early morning and then into the evening sky before reaching solar conjunction on August 9th, when it’ll actually pass behind the Sun for a few hours as seen from from our vantage point. We actually get two good apparitions of Comet K1 PanSTARRS: one for the northern hemisphere in the Spring and one for the southern hemisphere after it reaches perihelion and crosses south of the ecliptic plane in August.
And it’ll be worth keeping an eye out for K1 PanSTARRS online as well, as it passes into the view of SOHO’s LASCO C3 camera on August 2 before exiting its 15 degree field of view on August 16th.
This actually means the comet will reach opposition twice from our Earthbound vantage point: once on April 15th, and again on November 7th. And, as is often the case, this comet arrives six months early –or late, depending how you look at it- to be a fine naked eye object. Had K1 PanSTARRS reached perihelion in January, we’d have really been in for a show, with the comet only around 0.05 Astronomical Units (about 7.7 million kilometers) from the Earth!
The orbit of comet K1 PanSTARRS through the inner solar system. The yellow arrows denote the motion of the planets and the comet as seen from north of the ecliptic plane. Credit-NASA/JPL Horizons Solar System Dynamics generator.
But alas, such was not to be. At its best, K1 PanSTARRS will be hidden by the glare of the Sun at its very best, to emerge into the southern sky. The comet has a steeply inclined 142 degree retrograde orbit, and thus approaches the inner solar system from high above the ecliptic plane.
These coming last weeks of March are a great time to search out K1 PanSTARRS as the Moon reaches Last Quarter this weekend and heads towards New on March 30th, beginning a two week “moonless period for AM observing in early April. Projections by veteran comet observer Seiichi Yoshida suggest that K1 PanSTARRS will begin to brighten dramatically towards +8th magnitude through April. We first picked up the now posthumous comet ISON with binoculars around this magnitude last Fall. Keep in mind, like nebula and galaxies, the apparent brightness of a comet is spread out over its surface area. This can make a +10th magnitude comet much tougher to spot than a pinpoint +10 magnitude star.
We actually prefer our trusty Canon 15x45IS image stabilized binoculars for comet hunting… they’re powerful and easy to deploy on a cold March morning!
Here’s a handy list of notable events to watch for as Comet C/2012 K1 PanSTARRS crosses the springtime sky. Only passages of less than one degree near stars greater than magnitude +6 are mentioned except where otherwise noted:
March 17th: Comet C/2012 K1 PanSTARRS passes into the constellation Corona Borealis.
March 21st: Passes the +5.8 magnitude star Upsilon Coronae Borealis.
March 29th: Passes the +5.4 magnitude star Rho Coronae Borealis.
March 30th: The Moon reaches New phase.
The path of comet K1 PanSTARRS in one week intervals through March and April. Created using Stellarium.
April 2nd: Passes the +4.8 magnitude star Kappa Coronae Borealis.
April 7th: Passes the +5.2 magnitude star Mu Coronae Borealis.
April 10th: Passes into the constellation of Boötes.
April 10th: Passes the +5 magnitude wide binary pair Nu Boötis.
April 15th: Comet K1 PanSTARRS reaches opposition, rising opposite to the setting Sun and moving into the evening sky.
April 20th: K1 PanSTARRS becomes circumpolar for observers above 45 degrees north until May 25th.
April 26th: Passes into the constellation Ursa Majoris.
April 29th: Passes the bright +1.9th magnitude star Alkaid in the handle of the Big Dipper asterism. This is the brightest star that K1 PanSTARRS will pass near for this apparition, and Alkaid will make a great “finder” to spot the comet.
April 29th: The Moon reaches New phase.
April 30th: Approaches the +4.7 magnitude star 24 Canum Venaticorum.
The Spring path of comet K1 PanSTARRS from mid-March through late June. Credit: Starry Night Education Software.
May 1st: Passes less than 2 degrees from the galaxy M51… photo op!
May 3rd: Passes the 5.1 magnitude star 21 Canum Venaticorum.
May 6th: K1 PanSTARRS Reaches a maximum declination of 49.5 degrees north.
May 11th: Passes the 5.3 magnitude star 3 Canum Venaticorum.
May 14th: Passes into the constellation Ursa Major.
May 17th: Another great photo ops awaits astrophotographers, as the comet passes the +3.7 magnitude star Chi Ursae Majoris and the +12 magnitude galaxy NGC 3877.
May 25th: Passes the 3rd magnitude star Psi Ursae Majoris.
May 28th: The Moon reaches New phase.
May 28th: Passes the 4.7 magnitude star Omega Ursae Majoris.
June 7th Passes into the constellation Leo Minor.
June 15th: Passes the +4.5 magnitude star 21 Leo Minoris.
June 22nd: Passes into the constellation Leo.
July 1- Passes to within 40 degrees elongation from the Sun.
And from there, Comet K1 PanSTARRS reaches perihelion just outside of the Earth’s orbit at 1.05 A.U. on August 27, and plunges south across the celestial equator on September 15.
Video animation of comet C/2012 K1 PanSTARRS over the span of an evening. Credit: Dan Crowson of Dardenne Prairie Missouri, used with permission.
It’s also worth noting that K1 PanSTARRS will make its first of two approaches at a minimum distance of 1.471 A.U.s from Earth May 4th and will be moving at about a degree a day – twice the diameter of the Full Moon – before receding from us once more for a closer 1.056 A.U. approach to Earth on August 25th.
Discovered on May 19th, 2012 by the PanSTARRS telescope based on the island of Maui, Comet K1 PanSTARRS was first spotted at 8.7 A.U.s distant, well past the orbit of Jupiter. The PanSTARRS survey has been a prolific discoverer of asteroids and comets, including the brilliant comet C/2011 L4 PanSTARRS that graced dusk skies in March of last year.
And those are just the binocular comets that are scheduled to perform… remember, the next “big one” could come barreling in towards the inner solar system at any time to put on a memorable performance worthy of another comet Hyakutake or Hale-Bopp… just not TOO close!
– Be sure to send those comet pics in to Universe Today.
The BICEP telescope located at the south pole. Image Credit: CfA / Harvard
Astronomers have announced Nobel Prize-worthy evidence of primordial gravitational waves — ripples in the fabric of spacetime — providing the first direct evidence the universe underwent a brief but stupendously accelerated expansion immediately following the big bang.
“The implications for this detection stagger the mind,” said co-leader Jamie Bock from Caltech. “We are measuring a signal that comes from the dawn of time.”
BICEP2 (Background Imaging of Cosmic Extragalactic Polarization) scans the sky from the south pole, looking for a subtle effect in the cosmic microwave background (CMB) — the radiation released 380,000 years after the Big Bang when the universe cooled enough to allow photons to travel freely across the cosmos.
The CMB fills every cubic centimeter of the observable universe with approximately 400 microwave photons. The so-called afterglow of the big bang is nearly uniform in all directions, but small residual variations (on the level of one in 100,000) in temperature show a specific pattern. These irregularities match what would be expected if minute quantum fluctuations had ballooned to the size of the observable universe today.
So astronomers dreamed up the theory of inflation — the epoch immediately following the big bang (10-34 seconds later) when the universe expanded exponentially (by at least a factor of 1025) — causing quantum fluctuations to magnify to cosmic size. Not only does inflation help explain why the universe is so smooth on such massive scales, but also why it’s flat when there’s an infinite number of other possible curvatures.
While inflation is a pillar of big bang cosmology, it has remained purely a theoretical framework. Many astronomers don’t buy it as we can’t explain what physical mechanism would have driven such a massive expansion, let alone stop it. The results announced today provide a strong case in support of inflation.
The trick is in looking at the CMB where inflation’s signature is imprinted as incredibly faint patterns of polarized light — some of the light waves have a preferred plane of vibration. If a gravitational wave passes through the fabric of spacetime it will squeeze spacetime in one direction (making it hotter) and stretch it in another (making it cooler). Inflation will then amplify these quantum fluctuations into a detectable signal: the hotter and therefore more energetic photons will be visible in the CMB, leaving a slight polarization imprint.
E-modes (left side) look the same when reflected in a mirror. B-modes (right side) do not. Image Credit: Nathan Miller
This effect will create two distinct patterns: E-modes and B-modes, which are differentiated based on whether or not they have even or odd parity. In simpler terms: E-mode patterns will look the same when reflected in a mirror, whereas B-mode patterns will not.
E-modes have already been extensively detected and studied. While both are the result of primordial gravitational waves, E-modes can be produced through multiple mechanisms whereas B-modes can only be produced via primordial gravitational waves. Detecting the latter is a clean diagnostic — or as astronomers are putting it: “smoking gun evidence” — of inflation, which amplified gravitational waves in the early Universe.
“The swirly B-mode pattern is a unique signature of gravitational waves because of their handedness. This is the first direct image of gravitational waves across the primordial sky,” said co-leader Chao-Lin Kuo from Stanford University, designer of the BICEP2 detector.
Shown here are the actual B-mode polarization patterns provided by the BICEP2 Telescope. Image Credit: Harvard-Smithsonian Center for Astrophysics
The team analyzed sections of the sky spanning one to five degrees (two to 10 times the size of the full moon) for more than three years. They created a unique array of 512 detectors, which collectively operate at a frosty 0.25 Kelvin. This new technology enabled them to make detections at a speed 10 times faster than before.
The results are surprisingly robust, with a 5.9 sigma detection. For comparison, when particle physicists announced the discovery of the Higgs Boson in July, 2012 they had to reach at least a 5 sigma result, or a confidence level of 99.9999 percent. At this level, the chance that the result is erroneous due to random statistical fluctuations is only one in a million. Those are pretty good odds.
While the team was careful to rule out any errors, it will be crucial for another team to verify these results. The Planck spacecraft, which has been producing exquisite measurements of the CMB, will be reporting its own findings later this year. At least a dozen other teams have also been searching for this signature.
“This work offers new insights into some of our most basic questions: Why do we exist? How did the universe begin?” commented Harvard theorist Avi Loeb. “These results are not only a smoking gun for inflation, they also tell us when inflation took place and how powerful the process was.”
Not only does inflation succeed in explaining the origin of cosmic structure — how the cosmic web formed from the smooth aftermath of the big bang — but it makes wilder predictions as well. The model seems to produce not just one universe, but rather an ensemble of universes, otherwise known as a multiverse. This collection of universes has no end and no beginning, continuing to pop up eternally.
Today’s results provide a stronger case for “eternal inflation,” which gives a new perspective on our desolate place within the cosmos. Not only do we live on a small planet orbiting one star out of hundreds of billions, in one galaxy out of hundreds of billions, but our entire universe may just be one bubble out of a vast cosmic ocean of others.
The detailed paper may be found here.
The full set of papers are here.
An FAQ summarizing the data is here.
Mars photographed during part of its rotation from Melbourne, Australia on March 8. The bright "cap" marks Hellas, now covered in wintertime frost and clouds. Credit: Maurice Valimberti
Earth’s changing weather always makes life interesting. Seeing weather on other planets through a telescope we sense a kinship between our own volatile world and the fluttering image in the eyepiece. With the April 8 opposition of Mars rapidly approaching, you won’t want to miss a striking meteorological happening right now on the Red Planet.
Map showing the most prominent dark features on Mars. Hellas is at upper right. Credit: A.L.P.O.
Winter’s already well underway in the planet’s southern hemisphere and there’s no better place to see it than over Hellas, Mars’ biggest impact crater. Hellas formed some 4 billion years when a small asteroid crashed into the young planet and left a scar measuring 1,400 miles (2,300 km) wide and 26,465 feet (7,152 meters) deep. Point your telescope in its direction in the next few weeks and you’ll see what looks at first like the planet’s south polar cap. Don’t be deceived. That’s Hellas coated in dry ice frost and filled with wintertime clouds.
The Hellas impact basin, also known as Hellas Planitia, is 1,400 miles wide. After Mars’ Utopia Planitia and the moon’s South Pole-Aitken Basin, Hellas is the third largest confirmed crater in the solar system.
Right now, Mars’ northern hemisphere, along with the north polar cap, are tipped our way. Though the cap is rapidly vaporizing as the northern summer progresses, you can still spot it this month as a small dab of white along the northern limb in 6-inch (15 cm) and larger telescopes. Use a magnification upwards of 150x for the best views. The south polar cap can’t be seen because it’s tipped beyond the southern limb.
Mars from Athens, Greece on March 14, 2014 with Hellas (top), Syrtis Major and both morning and evening limb water clouds. The winter-whitened Hellas impact basin is best seen using magnifications of 150x or higher. Credit: Manos Kardasis
Along with nearby Syrtis Major, Hellas was one of the first features discovered with the telescope. Even in summer its pale floor stands out against the darker volcanic features of the planet. Though windswept and bitter cold now, Hellas’ great depth makes it one of the warmest places on Mars during the summer months. Mid-summer atmospheric pressure has been measured at more than 10 millibars, more than twice the planet’s mean. Afternoon high temperatures reach near the freezing point (32 F / 0 C) with nighttime lows around -50 F (-45 C). Winter temperatures are much more severe with lows around -22o F (-140 C). Carbon dioxide condenses as frost and whitens the floors of many craters during this time.
Mars photographed by the Mars Global Surveyor shows the equally prominent Syrtis Major and the Hellas impact basin. Syrtis Major is an ancient, low relief shield volcano. Credit; NASA/JPL/Malin Space Systems
We can only see Hellas when that hemisphere is turned in our direction; this happens for about a week and a half approximately once a month. European observers are favored this week with Hellas well placed near the planet’s central meridian from 1 – 4 a.m. local time. Why the outrageous hour? Mars rises around 10 p.m. but typically looks soft and mushy in the telescope until it’s high enough to clear the worst of atmospheric turbulence 2 – 3 hours later. North and South American observers will get their turn starting this Saturday March 22nd around 12:30 – 1 a.m. Good Hellas viewing continues through early April.
Mars at 1 a.m. CDT on successive nights starting March 21, 2014. Notice how planetary features appear to rotate slowly eastward night to night. Created with images from Meridian
Like Earth, Mars revolves from west to east on its axis, but because it rotation period is 37 minutes longer than Earth’s, Hellas and all Martian features appear to drift slowly eastward with each succeeding night. A feature you observed face-on at midnight one night will require staying up until 2:30 a.m. a week later for Mars to “rotate it back” to the same spot. To keep track of the best times to look for Hellas or anything else on Mars, I highly recommend the simple, free utility called Meridian created by Claude Duplessis. Set your time zone and you’ll know exactly the best time to look.
Mars on March 8, 2014 shows clouds over Hellas and evening limb clouds. Credit: Chin Wei Loon
While you’re out watching the Martian winter at work, don’t forget to also look for the shrinking north polar cap and bright, patchy clouds along the planet’s morning (east) and evening limbs. You can use the map above to try and identify the many subtle, gray-toned features named after lands in classic antiquity by 19th century Italian astronomer and Mars aficionado Giovanni Schiaparelli.
I will you success in seeing Hellas and encourage you to share your observations with us here at Universe Today.
A 2014 image of NGC 2174 by the Hubble Space Telescope. Credit: NASA/ESA and the Hubble Heritage Team (STScI/AURA)
Billowing gas clouds and young stars feature in this February Hubble Space Telescope image, released as the telescope approaches its 24th birthday this coming April. The telescope has seen a lot of drama over the years, but in this case, thankfully the excitement is taking place 6,400 light-years away. Here you can see starbirth in action in the nebula NGC 2174, which is sometimes called the Monkey Head Nebula.
“This region is filled with young stars embedded within bright wisps of cosmic gas and dust. Dark dust clouds billow outwards, framed against a background of bright blue gas. These striking hues were formed by combining several Hubble images taken through different coloured filters, revealing a broad range of colours not normally visible to our eyes,” the European Space Agency wrote.
“These vivid clouds are actually a violent stellar nursery packed with the ingredients needed for building stars. The recipe for cooking up new stars is quite inefficient, and most of the ingredients are wasted as the cloud of gas and dust disperses. This process is accelerated by the presence of fiercely hot young stars, which triggers high-speed winds that help to blow the gas outwards.”
Hubble’s dramatic history includes a deformed mirror, a rescue mission, and a nearly last-minute decision to do a shuttle flight for repairs and upgrades when the shuttle program was wrapping up. You can read more about Hubble’s colorful history at the Space Telescope Science Institute.
This detailed map of the cosmic microwave background is created from seven years worth of data. It shows the "seed" structures of galaxies in the infant Universe. Image Credit: NASA
Last week the Harvard-Smithsonian Center for Astrophysics (CfA) stated rather nonchalantly that they will be hosting a press conference on Monday, March 17th, to announce a “major discovery.” Without a potential topic for journalists to muse on, this was as melodramatic as it got.
But then the Guardian posted an article on the subject and the rumors went into overdrive. The speculation is this: a U.S. team is on the verge of confirming they have detected primordial gravitational waves — ripples in the fabric of spacetime that carry echoes of the big bang nearly 14 billion years ago.
If there is evidence for gravitational waves, it will be a landmark discovery, ultimately changing the face of physics.
Not only are gravitational waves the last untested prediction of Albert Einstein’s General Theory of Relativity, but primordial gravitational waves will allow astronomers to glimpse the universe in its infancy.
“It’s been called the Holy Grail of cosmology,” Hiranya Peiris, a cosmologist from University College London, told the Guardian. “It would be a real major, major, major discovery.” Any convincing evidence would almost certainly lead to a Nobel prize.
The signal is rumored to have been found by a telescope known as BICEP (Background Imaging of Cosmic Extragalactic Polarization), which scans the sky from the south pole, looking for a subtle effect in the cosmic microwave background (CMB): the radiation released 380,000 years after the big bang when space became transparent to light and photons were allowed to travel freely across the universe.
The South Pole Telescope (left) and BICEP (right). Image Credit: Dana Hrubes
While the CMB has been mapped in exquisite detail, astronomers think that hidden within the map is a second fingerprint, which would reveal gravitational waves. Its radiation was scattered toward us from the universe’s earliest atoms, similar to the way blue light is scattered toward us from the atoms in the sky. And just as the sky is slightly polarized — the waves have a preferred orientation — so is the CMB (on the level of a few percent).
Cosmologists are digging through the data, searching for a subtle twist in the polarized light, known as B-modes. If a gravitational wave moves through the fabric of spacetime, it will squeeze spacetime in one direction (the universe will look a little hotter) and stretch it in another (the universe will look a little cooler). The photons will scatter with a preferred direction, leaving a slightly polarized imprint on the CMB, due to the passing gravitational wave.
Not only will detecting this slight polarization pattern in the CMB allow astronomers to uncover evidence of primordial gravitational waves but they will provide proof that immediately after the big bang the universe expanded exponentially — inflated — by at least a factor of 1025. While the theory of inflation is a pillar of big bang cosmology and helps explain key features of the observable universe today (i.e. why the universe is outstandingly uniform on such massive scales), many physicists don’t buy it. It remains a theoretical framework because we can’t explain what physical mechanism would have driven such a massive expansion, let alone stop it.
Inflation is the only mechanism with the ability to amplify gravitational waves, born from quantum fluctuations in gravity itself, into a detectable signal.
“If a detection has been made, it is extraordinarily exciting,” Andrew Jaffe, a cosmologist from Imperial College, London, told the Guardian. “This is the real big tick-box that we have been waiting for. It will tell us something incredibly fundamental about what was happening when the universe was only 10-34 seconds old.”
But even if the rumors prove true, it’s crucial to remain skeptical. Extracting the signal is extremely tricky. The CMB’s temperature varies by a few parts in 100,000. In comparison, B-modes account for just one part in 10 million in the CMB temperature distribution.
The microwaves also travel across the entire observable universe first. Only last year the signal was detected in the CMB for the first time using the South Pole Telescope, but it was in fact distorted by intervening clusters of galaxies and not intrinsic to the CMB itself.
The announcement will be made on Monday at noon EST.
Comet C/2014 E2 Jacques photographed from Siding Spring Observatory on March 14, 2014. Credit: Rolando Ligustri
Congratulations to Cristovao Jacques and the SONEAR team! On March 13 they snared C/2014 E2 (Jacques) in CCD images taken with a 0.45-meter (17.7-inch) wide-field reflector at the SONEAR (Southern Observatory for Near Earth Asteroids Research) observatory near Oliveira, Brazil. A very preliminary orbit indicates its closest approach to the sun will occur on June 29 at a distance of 56 million miles followed two weeks later by a relatively close flyby of Venus of 0.09 a.u. or 8.4 million miles (13.5 million km). If a comet approached Earth this closely so soon after perihelion, it would be a magnificent sight. Of course, watching from Venus isn’t recommended. Even if we could withstand its extreme heat and pressure cooker atmosphere, the planet’s perpetual cloud cover guarantees overcast skies 24/7.
Comet Jacques travels across the deep southern sky in early spring as seen from mid-northern latitudes. Approximate positions are shown through April 4. Stellarium
It’s the team’s second comet discovery this year after turning up C/2014 A4 (SONEAR) in January. Comet Jacques has been tracking across northern Centaurus since discovery. Over the next few nights, it straddles the border with Hydra where it will be visible low in the southern sky around for northern hemisphere observers from about midnight to 2 a.m. If you live on a Caribbean island and points south your view will be even better.
Steven Tilley’s animation of Comet C/2014 E2 Jacques over 35 minutes on March 13, 2014
Comet Jacques exhibits a dense, fairly bright 2-arc-minute coma or cometary atmosphere with a short northward-pointing tail. Brightness estimates have been hard to come by, but it appears the comet may be around magnitude +11.5 – 12 or within range of an 8-inch (20-cm) or larger telescope. One thing’s for certain. In the coming weeks, E2 will be approaching both the Earth and the sun and brightening as it slowly gains altitude in the evening sky.
Another view of the comet on March 13 through a 0.5-meter (19.5-inch) telescope. Credit: Ernesto Guido, Nick Howes, Martino Nicolini
Shortly after perihelion, Comet Jacques will shine brightest at around magnitude +10-10.5 (though it could be brighter) and remain nearly this bright as it swings north from Orion into Perseus from mid-July to mid- August. Closest approach to Earth occurs on Aug. 29-30 at 54 million miles (87 million km). It will join Comet Oukameiden – predicted to reach binocular visibility in late August – to offer comet lovers much to look forward to as the summer wanes.
It’s a tough old universe out there. A young star has lots to worry about, as massive stars just beginning to shine can fill a stellar nursery with a gale of solar wind.
No, it’s not a B-movie flick: the “Death Stars of Orion” are real. Such monsters come in the form of young, O-type stars.
And now, for the first time, a team of astronomers from Canada and the United States have caught such stars in the act. The study, published in this month’s edition of The Astrophysical Journal, focused on known protoplanetary disks discovered by the Hubble Space Telescope in the Orion Nebula.
These protoplanetary disks, also known as “tadpoles” or proplyds, are cocoons of dust and gas hosting stars just beginning to shine. Much of this leftover material will go on to aggregate into planets, but nearby massive O-Type stars can cause chaos in a stellar nursery, often disrupting the process.
“O-Type stars, which are really monsters compared to our Sun, emit tremendous amounts of ultraviolet radiation and this can play havoc during the development of young planetary systems,” said astronomer Rita Mann in a recentpress release. Mann works for the National Research Council of Canada in Victoria and is lead researcher on the project
Scientists used the Atacama Large Millimeter Array (ALMA) to probe the proplyds of Orion in unprecedented detail. Supporting observations were also made using the Submillimeter Array in Hawaii.
ALMA saw “first light” in 2011, and has already achieved some first rate results.
“ALMA is the world’s most sensitive telescope at high-frequency radio waves (e.g., 100-1000 GHz). Even with only a fraction of its final number of antennas, (with 22 operational out of a total planned 50) we were able to detect with ALMA the disks relatively close to the O-star while previous observatories were unable to spot them,” James Di Francesco of the National Research Council of Canada told Universe Today. “Since the brightness of a disk at these frequencies is proportional to its mass, these detections meant we could measure the masses of the disks and see for sure that they were abnormally low close to the O-type star.”
The ALMA antennae on the barren plateau of Chajnantor. Credit: ALMA (ESO/NAOJ/NRAO).
ALMA also doubled the number of proplyds seen in the region, and was also able to peer within these cocoons and take direct mass measurements. This revealed mass being stripped away by the ultraviolet wind from the suspect O-type stars. Hubble had been witness to such stripping action previous, but ALMA was able to measure the mass within the disks directly for the first time.
And what was discovered doesn’t bode well for planetary formation. Such protostars within about 0.1 light-years of an O-type star are consigned to have their cocoon of gas and dust stripped clean in just a few million years, just a blink of a eye in the game of planetary formation.
With a O-type star’s “burn brightly and die young” credo, this type of event may be fairly typical in nebulae during early star formation.
“O-type stars have relatively short lifespan, say around 1 million years for the brightest O-star in Orion – which is 40 times the mass of our Sun – compared to the 10 billion year lifespan of less massive stars like our Sun,” Di Francesco told Universe Today. “Since these clusters are typically the only places where O-stars form, I’d say that this type of event is indeed typical in nebulae hosting early star formation.”
It’s common for new-born stars to be within close proximity of each other in such stellar nurseries as M42. Researchers in the study found that any proplyds within the extreme-UV envelope of a massive star would have its disk shredded in short order, retaining on average less than 50% the mass of Jupiter total. Beyond the 0.1 light year “kill radius,” however, the chances for these proplyds to retain mass goes up, with researchers observing anywhere from 1 to 80 Jupiter masses of material remaining.
The findings in this study are also crucial in understanding what the early lives of stars are like, and perhaps the pedigree of our own solar system, as well as how common – or rare – our own history might be in the story of the universe.
There’s evidence that our solar system may have been witness to one or more nearby supernovae early in its life, as evidenced by isotopic measurements. We were somewhat lucky to have had such nearby events to “salt” our environment with heavy elements, but not sweep us clean altogether.
“Our own Sun likely formed in a clustered environment similar to that of Orion, so it’s a good thing we didn’t form too close to the O-stars in its parent nebula,” Di Francesco told Universe Today. “When the Sun was very young, it was close enough to a high-mass star so that when it blew up (went supernova) the proto-solar system was seeded with certain isotopes like Al-26 that are only produced in supernova events.”
This is the eventual fate of massive O-type stars in the Orion Nebula, though none of them are old enough yet to explode in this fashion. Indeed, it’s amazing to think that peering into the Orion Nebula, we’re witnessing a drama similar to what gave birth to our Sun and solar system, billions of years ago.
The Orion Nebula is the closest active star forming region to us at about 1,500 light years distant and is just visible to the naked eye as a fuzzy patch in the pommel of the “sword” of Orion the Hunter. Looking at the Orion Nebula at low power through a small telescope, you can just make out a group of four stars known collectively as the Trapezium. These are just such massive hot and luminous O-Type stars, clearing out their local neighborhoods and lighting up the interior of the nebula like a Chinese lantern.
And thus science fact imitates fiction in an ironic twist, as it turns out that “Death Stars” do indeed blast planets – or at least protoplanetary disks – on occasion!
Be sure to check out a great piece on ALMA on a recent episode of CBS 60 Minutes:
Read the abstract and the full (paywalled) paper on ALMA Observations of the Orion Proplyds in The Astrophysical Journal.
Artist's conception of the Milky Way galaxy. Credit: Nick Risinger
Is it stretching it too far to think of a Lord of the Rings-esque “Entmoot” when reading the phrase “Council of Giants”? In this case, however, it’s not trees gathering in a circle, but galaxies.
A new map of the galactic neighborhood shows how the Milky Way may be restricted by a bunch of galaxies surrounding and constricting us with gravity.
“All bright galaxies within 20 million light years, including us, are organized in a ‘Local Sheet’ 34-million light years across and only 1.5 million light years thick,” stated Marshall McCall of York University in Canada, who is the sole author of a paper on the subject.
“The Milky Way and Andromeda are encircled by twelve large galaxies arranged in a ring about 24-million light years across. This ‘Council of Giants’ stands in gravitational judgment of the Local Group by restricting its range of influence.”
The “Council of Giants” is shown in this diagram based on 2014 research from York University. It shows the brightest galaxies within 20 million light-years of the Milky Way. The galaxies in yellow are the “Council.” (You can see a larger image if you click on this.) Credit: Marshall McCall / York University.
Here’s why McCall thinks this is the case. Most of the Local Sheet galaxies (the Milky Way, Andromeda, and 10 more of the 14 galaxies) are flattened spiral galaxies with stars still forming. The other other two galaxies are elliptical galaxies where star-forming ceased long ago, and of note, this pair lie on opposite sides of the “Council.”
“Winds expelled in the earliest phases of their development might have shepherded gas towards the Local Group, thereby helping to build the disks of the Milky Way and Andromeda,” the Royal Astronomical Society stated. The spin in this group of galaxies, it added, is unusually aligned, which could have occurred due to the influence of the Milky Way and Andromeda “when the universe was smaller.”
The larger implication is the Local Sheet and Council likely came to be in “a pre-existing sheet-like foundation composed primarily of dark matter”, or a mysterious substance that is not measurable by conventional instruments but detectable on how it influences other objects. McCall stated that on a small scale, this could help us understand more about how the universe is constructed.
Looped movie of the hydrogen jet in the sample chamber. Credit: Sven Toleikis/DESY
In astronomy we love focusing on the bigger picture. We’re searching for exoplanets in the vast hope that we may begin to paint a picture of how planetary systems form; We’re using the Hubble Space Telescope to peer into the earliest history of the cosmos; And we’re building gravitational wave detectors in order to better understand the physical laws that dominate our universe.
All the while we continue to learn about our very own neighborhood. Only recently we learned that Europa has geysers, Mars was perhaps once a lush planet, and comets can in fact disintegrate. Discoveries in our solar system alone never cease to amaze.
For the first time researchers are able to probe the hidden interiors of gas giants such as Jupiter and Saturn. With very little experimental knowledge about the hydrogen deep within such planets, we have always had to rely on mathematical models. But now, researchers have simulated the lower atmospheric layers of these planets in the lab.
The team of physicists led by Dr. Ulf Zastrau from the University of Jena heated cold liquid hydrogen to resemble the dense liquid hydrogen deep within a gas giant’s atmospheric layers.
The team used an X-ray laser operated by a national research center in Germany, Deutsches Elektronen-Synchrotron (DESY), to heat the liquid hydrogen, nearly instantaneously, from -253 to +12,000 degrees Celsius. Initially the X-ray heats only the electrons. But because each electron is bound to a proton, they transfer heat to the proton until a thermal equilibrium is reached. The molecular bonds break during this process, and a plasma of electrons and protons is formed.
In just under a trillionth of a second, physicists are able to create a plasma that’s thought to be radically similar to the plasma deep within the atmospheres of our beloved gas giants.
But first the team had to create cold hydrogen. While it’s abundant throughout the universe, it’s hard to get our hands on the stuff here on Earth. Instead researchers cooled gaseous hydrogen to -253 degrees Celsius using liquid helium. This was a very temperamental process, requiring precise temperature control. If the hydrogen got too cold it would freeze and the researchers would have to use a small heater to re-liquefy it. At the end of the day a jet of cold liquid hydrogen with a diameter no greater than 20 micrometers would flow into a vacuum.
Physicists would then shoot intense pulses of the X-ray laser at the cold hydrogen. They could control the precise timing of the X-ray laser’s “flash” in order to study the properties of liquid hydrogen. The first half of the flash heats up the hydrogen, but the second half of the flash is delayed by varying lengths, which allows the team to understand exactly how thermal equilibrium is established between the electrons and the protons.
The experimental results provide information on the liquid hydrogen’s thermal conductivity and its internal energy exchange, which are both crucial to better understanding gas giants. The experiments will have to be repeated at other temperatures and pressures in order to create a detailed picture of the entire planetary atmosphere.
“Hopefully the results will provide us among others with an experimentally based answer to the question, why the planets discovered outside our solar system do not exist in all imaginable combinations of properties as age, mass, size or elemental composition, but may be allocated to certain groups,” said Dr. Thomas Tschentscher, scientific director of the European XFEL X-ray laser in a press release.
The paper has been accepted in the scientific journal Physical Review Letters and is available for download here.
