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The largest volcano on Earth is Mauna Loa, which is one of the 5 volcanoes that make up the Big Island of Hawaii. When we talk about biggest volcano here, we’re talking about the volcano that has the biggest volume, and that’s Mauna Loa. It’s made up of an estimated 75,000 cubic kilometers of material.
Mauna Loa is an active shield volcano, and scientists think that it has been erupting for about 700,000 years; it emerged through the surface of the ocean about 400,000 years ago. The active magma for Mauna Loa comes from the Hawaiian hotspot. But the plate carrying the massive volcano is slowly carrying it away from the hotspot, and it will go extinct in the next 500,000 to 1 million years. It last erupted in 1984, and destroyed homes and villages in 1926 and 1950.
The volcano measures 4,169 meters above sea level, but that’s not its true height. Measured from the sea floor, Mauna Loa is really taller than 9,000 meters – that’s taller than Mount Everest. But Mauna Loa isn’t the tallest volcano, that’s actually its neighbor, Mauna Kea, which is about 40 meters taller.
The biggest volcano in the Solar System isn’t on Earth, but on Mars. Olympus Mons, on Mars, measures 27 km high, and has about 100 times the volume of Mauna Loa.
The largest island on Earth is Greenland, with a total land area of 2.2 million km2.
This is a bit of a complicated question because it’s hard to define the difference between an island and a continent. Both Antarctica and Australia are larger than Greenland, but they’re continents, so they’re out.
As you probably know, Greenland sits up near the Earth’s north pole, in between North America and Europe. More than 80% of the island is covered by glaciers, some of which can be more than a kilometer thick. With such an extreme environment, Greenland is sparsely populated; roughly 60,000 people live on the island, and most of those live in the capital city of Nuuk, on the southern island.
If you’re interested, the second largest island on Earth is New Guinea, with 785,000 square kilometers. And the third largest island is Borneo, with 748,000 km.
That’s the simple answer, now here’s the more complex one. Astronomers use the term “albedo” to define the amount of light that an object in the Solar System reflects. For example, if a planet was perfectly shiny, it would have an albedo of 1.00; it would reflect 100% of the light that hit it. If a planet was perfectly dark, it would have an albedo of 0, and so it would reflect 0% of the light that struck it.
The object with the highest albedo in the Solar System is Saturn’s moon Enceladus, with an albedo of 99%. On the other hand, asteroids can have albedos as low as 4%. The Earth’s moon has an albedo of about 7%. Can you imagine if we had Enceladus for a moon? Now that would be bright.
The albedo of the Earth is very important because it helps define the temperature of the planet. Fresh snow has an albedo of 90%, while the ocean has a very low albedo; land areas range from 0.1 to 0.4.
NASA’s Terra and Aqua satellites are constantly measuring the albedo of the Earth with their MODIS instruments, to help detect any evidence that the albedo is changing over time.
We have written many articles about the Earth for Universe Today. Here’s an article about how scientists track Earthshine on the Moon. And here’s a more detailed article about the albedo of the Moon.
NASA's Galaxy Evolution Explorer reveals, for the first time, dwarf galaxies forming out of nothing more than pristine gas likely leftover from the early universe. Credit: NASA/JPL-Caltech/DSS
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Apparently, dwarf galaxies can spring out of thin air.
Astronomers using NASA’s Galaxy Evolution Explorer have spotted unexpected new galaxies in the constellation Leo that appear to be forming out of nothing more than pristine gas, probably leftover from the early universe. The gas lacks both dark matter and metals — previously thought to be building blocks for galaxy formation.
Dwarf galaxies are relatively small collections of stars that often orbit around larger galaxies like our Milky Way. Though never seen before, the researchers say this new type of dwarf galaxy may be common throughout the more distant and early universe, when pristine gas was more pervasive. Their discovery appears in this week’s issue of the journal Nature.
The newly described dwarf galaxies are in the Leo Ring, a huge cloud of hydrogen and helium that traces a ragged path around two massive galaxies in the constellation Leo. The cloud is thought likely to be a primordial object, an ancient remnant of material that has remained relatively unchanged since the very earliest days of the universe. Identified about 25 years ago by radio waves, the ring cannot be seen in visible light.
“This intriguing object has been studied for decades with world-class telescopes operating at radio and optical wavelengths,” said lead study author David Thilker of Johns Hopkins University in Baltimore. He added that no stars were ever seen in the gaseous regions before.
“But when we looked at the ring with the Galaxy Evolution Explorer, which is remarkably sensitive to ultraviolet light, we saw telltale evidence of recent massive star formation. It was really unexpected. We are witnessing galaxies forming out of a cloud of primordial gas.”
Our local universe contains two large galaxies, the Milky Way and the Andromeda galaxy, each with hundreds of billions of stars, and the Triangulum galaxy, with several tens of billions of stars. It also holds more than 40 much smaller dwarf galaxies, which have only a few billion stars. Invisible dark matter, detected by its gravitational influence, is a major component of both giant and dwarf galaxies with one exception — tidal dwarf galaxies.
Tidal dwarf galaxies condense out of gas recycled from other galaxies and have been separated from most of the dark matter with which they were originally associated. They are produced when galaxies collide and their gravitational masses interact. In the violence of the encounter, streamers of galactic material are pulled out away from the parent galaxies and the halos of dark matter that surround them.
Because they lack dark matter, the new galaxies observed in the Leo Ring resemble tidal dwarf galaxies, but they differ in a fundamental way. The gaseous material making up tidal dwarfs has already been cycled through a galaxy. It has been enriched with metals — elements heavier than helium — produced as stars evolve. “Leo Ring dwarfs are made of much more pristine material without metals,” Thilker said. “This discovery allows us to study the star formation process in gas that has not yet been enriched.”
Large, pristine clouds similar to the Leo Ring may have been more common throughout the early universe, Thilker said, and consequently may have produced many dwarf galaxies yet to be discovered that also lack dark matter.
The forming dwarf galaxies shine in the far ultraviolet spectrum, rendered as blue in the call-out on the right hand side of this image. Near ultraviolet light, also obtained by the Galaxy Evolution Explorer, is displayed in green, and visible light from the blue part of the spectrum here is represented by red. The clumps (in circles) are distinctively blue, indicating they are primarily detected in far ultraviolet light. The faint blue overlay traces the outline of the Leo Ring, a huge cloud of hydrogen and helium that orbits around two massive galaxies in the constellation Leo (left panel). Credit: NASA/JPL-Caltech/DSS
The first VLTI image is that of the double star Theta1 Orionis C in the Orion Nebula Trapezium. From these, and several other observations, the team of astronomers, led by Stefan Kraus and Gerd Weigelt from the Max-Planck Institute in Bonn, could obtain the full orbit of the two stars in the system, and derive the total mass of the two stars (47 solar masses) and their distance from us (1350 light-years).
The first VLTI image shows the double star Theta1 Orionis C in the Orion Nebula Trapezium. Credit: ESO
European astronomers are celebrating two of the first images ever made using near-infrared interferometry, and say they herald the dawn of a new era of stellar imaging.
A German-led team has captured images of the double star system Theta1 Orionis C with ESO’s Very Large Telescope Interferometer, which emulates a virtual telescope about 100 meters (328 feet) across. That discovery could lead to a calculation of the orbits and mass of the system. And a team of French astronomers has captured an image of the star T Leporis revealing a spherical molecular shell around the aged star — which appears, on the sky, as small as a two-story house on the Moon. Both feats were announced today by the European Organisation for Astronomical Research in the Southern Hemisphere (ESO).
“We were able to construct an amazing image, and reveal the onion-like structure of the atmosphere of a giant star at a late stage of its life for the first time,” said the ESO’s Antoine Mérand, a member of the T Leporis research team. “Numerical models and indirect data have allowed us to imagine the appearance of the star before, but it is quite astounding that we can now see it, and in colour.”
T Leporis at a resolution of about 4 milli-arcseconds, captured with the VLTI. Credit: ESO
Interferometry is a technique that combines the light from several telescopes, resulting in a vision as sharp as that of a giant telescope with a diameter equal to the largest separation between the telescopes used. Achieving this requires the VLTI system components to be positioned to extraordinary accuracy over the 100 meters (328 feet) and maintained throughout the observations — a formidable technical challenge.
When doing interferometry, astronomers must often content themselves with fringes, the characteristic pattern of dark and bright lines produced when two beams of light combine, from which they can model the physical properties of the object studied. But, if an object is observed on several runs with different combinations and configurations of telescopes, it is possible to put these results together to reconstruct an image of the object. This is what has now been done with ESO’s VLTI, using the 1.8-meter (6 foot) auxiliary telescopes.
The new T Leporis results are set to appear in a letter to the editor in Astronomy and Astrophysics, by lead author Jean-Baptiste Le Bouquin, also of the ESO, and his colleagues. The image of Theta1 Orionis C, in the Orion Nebula Trapezium, is reported in an Astronomy and Astrophysics article led by Stefan Kraus at the Max-Planck-Institut für Radioastronomie in Germany.
Although it is only 15 by 15 pixels across, the reconstructed image of T Leporis shows an extreme close-up of a star 100 times larger than the Sun, a diameter corresponding roughly to the distance between the Earth and the Sun. This star is, in turn, surrounded by a sphere of molecular gas, which is about three times as large.
T Leporis, in the constellation of Lepus (the Hare), is located 500 light-years from Earth. It belongs to the family of Mira stars, well known to amateur astronomers. These are giant variable stars that have almost extinguished their nuclear fuel and are losing mass. They are nearing the end of their lives as stars, and will soon die, becoming white dwarfs. The Sun will become a Mira star in a few billion years, engulfing the Earth in the dust and gas expelled in its final throes.
Mira stars are among the biggest factories of molecules and dust in the Universe, and T Leporis is no exception. It pulsates with a period of 380 days and loses the equivalent of the Earth’s mass every year. Since the molecules and dust are formed in the layers of atmosphere surrounding the central star, astronomers would like to be able to see these layers. But this is no easy task, given that the stars themselves are so far away — despite their huge intrinsic size, their apparent radius on the sky can be just half a millionth that of the Sun.
“Obtaining images like these was one of the main motivations for building the Very Large Telescope Interferometer,” Mérand said. “We have now truly entered the era of stellar imaging.”
If you’ve seen an image of the Milky Way from above or below, you will certainly notice that it has a spiral structure. Not all galaxies are created equal, though, as there are many, known as elliptical galaxies, that are blob-like, while others have irregular shapes. Ours is of a class of galaxies called barred spirals, because it has a rectangular bar in the middle of the galactic disk.
The Milky Way has four main spiral arms: the Norma and Cygnus arm, Sagittarius, Scutum-Crux, and Perseus. The Sun is located in a minor arm, or spur, named the Orion Spur. The galactic disk itself is about 100,000 light years across, and the bar at the center is estimated to be about 27,000 light years long.
Why is the Milky Way a spiral? This is due to its rotation, or rather, the rotation of matter inside the galactic disk around the center. It’s not as if the stars themselves stay in the spiral arms, and rotate around the center of the galaxy, though: if they did this, the arms would wind in tighter and tighter over time (2 billion years or so), since the stars in the center revolve faster than those further out.
The spirals are actually what is called a density wave or standing wave. The best way to describe this is the analogy of a traffic jam: cars travel on a busy road in a city, bunching up in jams over the course of a day at certain sections. But the cars move through the jam eventually, and other cars pile up behind them in the jam. The wave is at a certain location, with bunches of matter piling up there for a while, then moving on to be replaced by other matter. As dust and gas is compressed in the spirals, it is heated up and results in the formation of new stars. This star formation makes the trailing edge of the spiral brighter, and places the density wave “ahead”, where dimmer, redder stars are starting to be compressed.
When you see an image of the Milky Way like the one above, it’s not actually a photo of our galaxy. Since we inhabit the disk and have no way (currently) of going above or below, images of the Milky Way are generated by computers or artists. Astronomers have determined that the Milky Way is a spiral galaxy by mapping the movements of stars and hydrogen clouds in the disk.
The Milky Way is far from being the only spiral galaxy in the Universe. To view images of other spiral galaxies, go to the aptly-named Spiral Galaxies website, or NASA’s Astronomy Picture of the Day Spiral Galaxy Index.
Exoplanets like the Earth might be more common than we think. Image Credit: ESO
With the upcoming launch in March of the Kepler mission to find extrasolar planets, there is quite a lot of buzz about the possibility of finding habitable planets outside of our Solar System. Kepler will be the first satellite telescope with the capability to find Earth-size and smaller planets. At the most recent meeting of the American Association for the Advancement of Science (AAAS) in Chicago, Dr. Alan Boss is quoted by numerous media outlets as saying that there could be billions of Earth-like planets in the Milky Way alone, and that we may find an Earth-like planet orbiting a large proportion of the stars in the Universe.
“There are something like a few dozen solar-type stars within something like 30 light years of the sun, and I would think that a good number of those — perhaps half of them would have Earth-like planets. So, I think there’s a very good chance that we’ll find some Earth-like planets within 10, 20, or 30 light years of the Sun,” Dr. Boss said in an AAAS podcast interview.
Dr. Boss is an astronomer at the Carnegie Institution of Washington Department of Terrestrial Magnetism, and is the author of The Crowded Universe, a book on the likelihood of finding life and habitable planets outside of our Solar System.
“Not only are they probably habitable but they probably are also going to be inhabited. But I think that most likely the nearby ‘Earths’ are going to be inhabited with things which are perhaps more common to what Earth was like three or four billion years ago,” Dr. Boss told the BBC. In other words, it’s more likely that bacteria-like lifeforms abound, rather than more advanced alien life.
This sort of postulation about the existence of extraterrestrial life (and intelligence) falls under the paradigm of the Drake Equation, named after the astronomer Frank Drake. The Drake Equation incorporates all of the variables one should take into account when trying to calculate the number of technologically advanced civilizations elsewhere in the Universe. Depending on what numbers you put into the equation, the answer ranges from zero to trillions. There is wide speculation about the existence of life elsewhere in the Universe.
To date, the closest thing to an Earth-sized planet discovered outside of our Solar System is CoRoT-Exo-7b, with a diameter of less than twice that of the Earth.
The speculation by Dr. Boss and others will be put to the test later this year when the Kepler satellite gets up and running. Set to launch on March 9th, 2009, the Kepler mission will utilize a 0.95 meter telescope to view one section of the sky containing over 100,000 stars for the entirety of the mission, which will last at least 3.5 years.
The prospect of life existing elsewhere is exciting, to be sure, and we’ll be keeping you posted here on Universe Today when any of the potentially billions of Earth-like planets are discovered!
Ice core from Mars? Not quite. But this aggregation of soil grains, from Antarctica ice, derived from the same process now proposed for the Red Planet (Credit: Hans Paerl, University of North Carolina at Chapel Hill).
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Ice core from Mars? Not quite. But this aggregation of soil grains, from Antarctica ice, derived from the same process now proposed for the Red Planet (Credit: Hans Paerl, University of North Carolina at Chapel Hill)
The puzzling Meridiani Planum deposits on Mars — discovered by NASA’s Opportunity rover — could be remnants of a massive ancient ice field, according to a new study online in Nature Geoscience.
Paul Niles of NASA’s Johnson Space Center and Joseph Michalski, of Université Paris-Sud, analysed the chemistry, sedimentology and geology of the Meridiani Planum deposits using data from Opportunity. They suggest that sulphate formation and chemical weathering occurred within an ice deposit as massive as today’s polar ice caps on Mars. Once the ice sublimed away in a warmer climate, the remaining sediments kept their chemical signature, the authors suggest.
The new theory gets around a weakness in the previous belief, that the deposits were formed in a wet, shallow basin — because no evidence of such a basin has been found yet. But it comes with its own baggage: there’s not much evidence of massive ice in the region, either.
The Meridiani represent one of the flattest areas on the Martian surface, with long, rolling smooth plains, linear dunes and ridges. Based on the number of craters, scientists have speculated that it formed early in the Hesperian Era, roughly 3.8 billion years ago.
The intriguing place — right at the crosshairs of zero degrees longitude and zero degrees latitude — was initially spotted by the Mars Thermal Emission Spectrometer aboard NASA’s Mars Global Surveyor (1996-2006). It was then chosen as the landing site for NASA’s rover Opportunity, in 2004.
“Immediately upon touchdown, when we turned on the cameras for the first time and looked out on the plains, it became obvious that it was a different kind of place on Mars than we’d ever been before,” Michalski said.
Since then, the place has been the object of numerous chemistry studies which have generated a handful of competing theories about how its odd sulfate deposits might have formed. The prevailing theory, fronted by scientists on the Mars Exploration Rovers team, has it that the Meridiani Planum was once a shallow evaporation basin which was periodically wet, where wind helped drive away the moisture and left the deposits behind. Other scientists have proposed a catastrophic event like a volcano or major impact, perhaps with volcanic aerosols altering layered rocks at the surface. Microscopic image of Meridiani Planum sediments. Image of outcrop of sediments at Meridiani Planum inside Endurance crater taken by the microscopic imager on sol 145 (Credit: NASA/JPL/Cornell/USGS).
But Michalski and Niles say the deposits formed when the area was covered with thick ice. Dust trapped within the ice would have warmed in the presence of sunlight, causing minor melting nearby. And because the ice also contained volcanic aerosols, the water that formed would have been highly acidic, and reacted with the dust, yielding the perplexing products in pockets within the ice that became the deposits when the ice sublimed. The same process happens to a limited extent in the Earth’s polar regions, Michalski said. The Meridiani Planum is near the equator, where large ice fields are lacking today. The authors propose that the ice could have formed in ancient times, when the poles were in a different place or when the Martian axis of rotation was at a different angle.
Michalski said the new theory gets around a lot of the sticking points in the older ones.
“It doesn’t require a basin to be present; it doesn’t require the groundwater,” he said. “We like a lot of aspects of the MER team’s hypothesis. One of the big problems is that you have to have a lot of acidic water in that situation.”
Brian Hynek, an atmospheric and space physicist at the University of Colorado in Boulder, had proposed a volcanic origin for the deposits in the past, but he said there are strengths to the new theory as well. For starters, he said, the ice pocket hypothesis could explain why salts of varying water solubility co-exist so closely in the Meridiani Planum deposits.
“The volume of the Meridiani deposits is similar to the amount of sediment contained within the layered ice-rich deposits at Mars’s south pole,” he added. “And sublimation of a sufficiently large dusty ice deposit would provide a convincing source for all the sediment, which other models have failed to provide.”
But he said there are shortfalls to the new theory too: No model has allowed for the necessarily massive ice deposits at the Martian equator, for example, and it’s curious how the dust and aerosols “could aggregate into consistent sand-sized particles” in the examined bedrock.
Hynek said of all the theories that could explain the strange deposits in the Meridiani Planum, none has emerged yet as a clear winner: “All have their strengths and all have significant weaknesses. I don’t think we’ve solved this mystery yet.”
Michalski is less cautious about the implications of the new work.
“We’re able to propose this process for the Meridiani deposits because there are a lot of data,” he said. “We think that it’s likely that the other sulfate deposits on Mars could have been formed by the same mechanism.”
The switch to digital will eliminate the Big Bang channel.
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The switch from analog to digital television broadcasting signals in the United States , which was originally scheduled for February 17th, has been postponed until June 12th, 2009. To those anticipating the higher-quality picture and more reliable signal that this switch will afford, the delay is surely a downer, though some stations may begin broadcasting digital signals before this date. You may be surprised, though, that the change in signal may no longer allow you to see leftover radiation from the Big Bang in the static on your television screen.
That’s right – when you are between channels on an analog television, the snow that you see on the screen is made up of interference from background signals that the antenna on your TV is picking up. Some of the “snow” is from other transmissions here on Earth, and some is from other radio emissions from space. Part of that interference – about 1% or less – comes from background radiation leftover from the Big Bang, called the Cosmic Microwave Background (CMB). The same is true for FM radios – when the radio is tuned to a frequency that is between stations, part of the hiss that you hear, called “white noise”, is leftover radiation from the Big Bang some 13.7 billion years ago.
In other words, your TV and radio are telescopes, good for receiving transmissions here on Earth, but really, really bad telescopes for viewing the Universe (a 1:100 signal-to-noise ratio is pretty poor). Why does your TV or radio allow you to tune into the Big Bang, however poorly? Analog television signals are basically radio waves that your television picks up, decodes, and turns into an image on your television using what’s called a cathode ray tube (CRT) in older televisions, and in newer TVs, plasma displays.
These analog signals are broadcast between 7-1002 Mhz, and TV tuners are designed to receive in this range. The CMB peaks in the microwave, at around 160 Ghz, but the frequency of CMB photons can be lower than 100 Mhz (.1 Ghz). Your television antenna is constantly being bombarded by these signals, but when it’s tuned to a specific station the overwhelming intensity of the signal at that frequency makes a crisp picture on your screen, and drowns out everything else. When your TV or radio isn’t tuned into a channel that is brodcasting clearly, it picks up whatever radio transmissions are available and displays those transmissions as the black and white static that is oh-so annoying when you are trying to acrobatically align your TV antenna and stand in just the right place to clearly show your favorite program. Here’s a short clip from First Science explaining the CMB and white noise.
Digital signals eliminate the interference while watching a program because instead of broadcasting the picture as a radio wave which communicates to the CRT or plasma screen what to “paint” on the screen by the frequency of the signal, all a digital signal communicates is a 1 or 0, and the digital converter takes care of decoding and sending information as to what the picture and sound on your screen should look like.
In fact, it was annoying “noise” that led to the discovery of the Cosmic Microwave Background in the first place. In 1965, Arno Penzias and Robert Wilson had built a Dicke radiometer for Bell Telephone Laboratories to use in radio astronomy and satellite communication experiments. Their instrument kept receiving a background signal that they could not account for. After trying everything imaginable to eliminate the noise (including removing the pigeon droppings from the telescope), they finally realized that the signal wasn’t “noise”, but photons from the Big Bang. Penzias and Wilson share the 1978 Nobel Prize in physics for this discovery, and the CMB has since been studied as a way to learn more about the beginnings of the Universe.
Arno Penzias and Robert Wilson in front of the Horn Antenna. Image Credit: AIP Niels Bohr Library
Televisions manufactured after March 1, 2007 for the U.S. are required to have Digital Television (DTV) tuners or be DTV ready. Some broadcasters are already transmitting TV programs in both analog and digital formats, but they will all be required to broadcast only in digital format after June 12, 2009. If you have an older television that doesn’t contain a built-in DTV tuner, you will have to buy a digital converter box. So, if you want to see static created by the CMB, unplugging the converter after June 12th will suffice. If you have a newer TV that only has a digital tuner, you will sadly be unable to experience that small percentage of influence the ancient event of the Big Bang has on something quotidian as the television in your living room.
And the V we’re taking a stereo look at on Valentine’s Day is V838 Monocerotis – an unusual “light echo” from a variable star. If you’re curious to know more about what you’re looking at, then prepare to take a 20,000 light year journey across space and step inside…
Like all our our “stereo” image produced for UT by Jukka Metsavainio, two versions are presented here. The one above is parallel vision – where you relax your eyes and when you are a certain distance from the monitor screen the two images will merge into one to produce a 3D version. The second – which appears below – is crossed vision. This is for those who have better success crossing their eyes to form a third, central image where the dimensional effect occurs. Jukka’s visualizations of what Hubble images would look like if we were able to see them in dimension come from studying the object, its known field star distances and the different wavelengths of light. Are you ready to “cross” the boundary? Then let’s rock…
V838 Monocerotis Cross-Vision by Jukka Metsavainio
When you’re ready to come back to your seat, let’s talk just a little bit about what V838 Monocerotis is and what we currently know about it.
The primary source of light that you’re seeing in here comes from a variable star – the 838th variable star discovered in the constellation of Monocerotis – which underwent a very strange reaction early in 2002. At first astronomers believed it to be a pretty normal nova event, but it didn’t take long to realize this was something altogether different than anything they’d ever witnessed.
When it first began to brighten on January 10, 2002, the light curve measurements began. These graphs show the intensity of light as a function of time – and they came back as ordinary… a white dwarf shedding accumulated hydrogen gas from its binary neighbor. By February 6th, it had reached its maximum visual brightness and started to dim again, just as expected – but only weeks later the infrared wavelength began to do some very strange things – it brightened unexpectedly and did it again just a few more weeks later! This was something astronomers had simply never witnessed…
According to Howard Bond; “Some classes of stars, including novae and supernovae, undergo explosive outbursts that eject stellar material into space. In 2002, the previously unknown variable star V838 Monocerotis brightened suddenly by a factor of ~104. Unlike a supernova or nova, it did not explosively eject its outer layers; rather, it simply expanded to become a cool supergiant with a moderate-velocity stellar wind. Superluminal light echoes were discovered as light from the outburst propagated into the surrounding, pre-existing circumstellar dust. At its maximum brightness (it) was temporarily the brightest star in the Milky Way. The presence of the circumstellar dust implies that previous eruptions have occurred, and spectra show it to be a binary system. When combined with the high luminosity and unusual outburst behaviour, these characteristics indicate that V838 Mon represents a hitherto unknown type of stellar outburst, for which we have no completely satisfactory physical explanation.”
At the time, V838 expanded in size to the point where it would have filled our solar system to the size of Jupiter’s orbit and output a million times the luminosity of our own Sun – changes that happened in an abnormal time span of just months. Since science did have pre-eruption photographs, V838 was thought to be an under luminous F-type dwarf – much like Sol – which deepened the mystery even further. Just what could cause it to go against the laws of thermodynamics?
According to R. Tylenda; “The eruption phase, which lasted till mid-April 2002, resulted from a very strong energy burst, which presumably took place in last days of January at the base of the stellar envelope inflated in pre-eruption. The burst produced an energy wave, which was observed as a strong luminosity flash in the beginning of February, followed by a strong mass outflow in form of two shells, which was observed as an expanding photosphere in later epochs. In mid-April, when the outflow became optically transparent and most of its energy radiated away, the object entered the decline phase during which V838 Mon was evolving along the Hayashi track. This we interpret as an evidence that the main energy source during decline was due to gravitational contraction of the object envelope inflated in eruption. Late in 2002 a dust formation started in the expanding shells which gave rise to a strong infrared excess observed in 2003.”
Since then we’ve learned the V838 eruptive star may have just been entering the main sequence at the time, and we also know it has a B-type companion that’s also just come aboard the main sequence train. This type of information doesn’t add up to a nova event which occurs to older, white dwarfs… even though it may be something we don’t yet understand. It’s possible that V838 Monocerotis may be a post-asymptotic giant branch star – about to end – but again, it doesn’t fit the spectral patterns. According to some evidence, V838 Monocerotis may be a very massive supergiant that experience “carbon flash”… making their way towards the Wolf-Rayet star end of the chapter. It’s possible that the event could have been a “mergeburst” – where a main sequence and pre-main sequence star combined forces – or even a planetary captured event which triggered deuterium fusion.
And maybe we’ll never know in our lifetimes…
No matter if we understand precisely what created it or not, we can still enjoy the wonderful “light echo” produced by V838 Monocerotis, imaged by the Hubble Telescope and visualized for dimension by Jukka. He understands how the light reflects from clouds of interstellar matter between the star and point of the observer. He knows which wavelengths arrived into the camera lens first and which arrived last…
And we’re grateful to have the chance to look straight into the “heart” of this unusual phenomena!
