Posted on by Jean Tate

Big Bang Timeline

A fraction of a second after the big bang, the universe underwent inflation - but what does that mean? credit: NASA/WMAP
Time line of the Universe (Credit: NASA/WMAP Science Team)

The Big Bang timeline is basically just a list of relative times at which the major events in the history of the universe occurred, per the collection of theories, models, and hypotheses which together form what is called the Big Bang theory.

The start – when time began, when t = 0 – is not actually part of the Big Bang timeline (!), contrary to popular belief. That’s because the two theories of physics which are at the heart of the Big Bang theory – General Relativity (GR) and the Standard Model (of particle physics; SM for short) – are mutually incompatible, and that incompatibility becomes so intolerable that saying anything about what happened in the first Planck second (approx 10-43 second) is meaningless.

In fact, the closer to the Planck regime – when GR and the SM are utterly incompatible – the less reliable are our descriptions … but the relative times are nonetheless pretty good.

Actually, that’s not quite true … what is relatively certain are temperatures; forces, matter, and radiation interact in very distinct ways, depending on the temperature (and pressure, or density), but converting from temperature back to time depends on various parameters which are not so well pinned down. However, once the average mass-energy density of the universe, today, is estimated, the clock can be wound back with some confidence (it’s ~six hydrogen atoms per cubic meter, or about 7 x 10-27 kg/m3).

Around 10-35 seconds leptons and baryons were created (the strong force became a distinct force), and inflation caused the universe to expand so much that the part which later became our observable universe was both flat (no curvature, in the GR sense) and incredibly smooth (with only tiny variations in density due to quantum effects).

At around 10-11 seconds the electromagnetic and weak force became distinct.

And by about a microsecond the universe underwent another phase change … it was no longer a quark-gluon plasma, but hadrons formed (protons and neutrons).

When t = 1 second (more or less), nuclear reactions produced light nuclides, such as deuterium and helium-3 (before this time the universe was too hot for them to form) – Big Bang nucleosynthesis.

The earliest part of the universe we can still see, directly, happened when the electrons and protons (and other nuclei) combined to form hydrogen atoms; this is the recombination era, and we see it today as the cosmic microwave background … and gravity took over as the dominant force (before this it was electromagnetism – the universe was ‘radiation dominated’ – and before that, at the time of nucleosynthesis, the strong and weak forces ruled).

The rest, as they say, is history … the Dark Ages (during which the first stars were formed), the era of recombination (when stars and quasars ionized the diffuse hydrogen), galaxy formation, … and then about 13.4 billion years later we observed the skies and worked out the timeline!

There’s a lot of good material on the web on the Big Bang timeline; here are some: John Baez (who’s always worth reading) has a brief timeline, in terms of temperature; there’s a more extensive one from the University of Wisconsin-Madison, and perhaps the best, A Brief History of the Universe (University of Cambridge).

Want to explore more? Here are some of the many Universe Today articles on the Big Bang timeline: Cosmologists Look Back to Cosmic Dawn, A Star as Old as the Universe, and Book Review: The Mystery of the Mission Antimatter.

Astronomy Cast has several episodes for you to explore, to learn more about the Big Bang timeline; here are a few: The Big Bang and Cosmic Microwave Background, Inflation, and this 2009 Questions Show.

Sources:
http://en.wikipedia.org/wiki/Timeline_of_the_Big_Bang
http://www.damtp.cam.ac.uk/research/gr/public/bb_history.html

Posted on by Tega Jessa

What was the Largest Tornado Ever Recorded?

Determining the biggest tornado can be a tricky endeavor. First of all, there is no direct absolute way to measure the width of a tornado. There is also the fact that a tornado can be ranked by many factors such as wind speed, level of destruction caused, drop in barometric pressure, or the length of travel path. Each of these play a role in determining the overall power of a tornado.

Another problem is that in many cases like in the Tornado Alley of the Midwestern United States, a storm system often produces multiple tornadoes. This can make it difficult to measure an individual tornado since it destructive force is combined with that of other tornadoes spawned by the same storm system.

While there is no definitive method there are some records that can give us a general idea about some of the greatest tornadoes in recorded history. The most powerful tornadoes tend to be in the United States, but there are others that can compete in other parts of the world.

The title of most devastating tornado goes to the Tri-State tornado of 1925. The twister traveled through three states and killed 698 people. This makes it the deadliest tornado in US history. It also had the longest track and duration traveling a distance of over 200 miles and lasting 3.5 hours. Even then this is just for the United States. The deadliest tornado in the world occurred in 1989 in Bangladesh taking over 1300 lives.

The closest measure to the Biggest tornado would be the widest damage path. This the with of the destruction a tornado causes not it actual size. This measure is a good estimate for the actual width of the tornado’s funnel cloud. The storm that holds the record occurred in Wilber-Halland Nebraska. The tornado had a destruction path with a width of over two miles. The tornado destroyed most of the buildings in the area.

As you can see you define the largest tornado by many factors. This just shows the various ways in which we as casual observers can measure and determine the power of a tornado. This provides an interesting insight into what makes a tornado so destructive and hard to predict. It is also important to remember once again that tornadoes rarely occur as singular phenomenons. A group of smaller tornadoes in an outbreak can be as effectively powerful and destructive as one major tornado.

If you enjoyed this article there are other pieces on Universe Today that you will loved to read. There is an interesting article about the winds on Venus. There is also another interesting article on Global warming.

You can also check out resources online. There is a great article about Tornadoes on National Oceanic and Atmospheric Administration website There is another interesting piece on tornadoes on the University Corporation for Atmospheric Research website.

You can also check out Astronomy Cast. Episode 151 talks about atmospheres.

Posted on by Nancy Atkinson

The Sound of Saturn’s Rings

This wonderful video was posted by Jennifer Ouellette on Discovery News, and I just had to share it. The sounds are actual recordings picked up by the Cassini spacecraft. I have heard the eerie audio before, but never had previously seen it paired up with moving images from the mission. The radio emissions, called Saturn kilometric radiation, are generated along with Saturn’s auroras, or northern and southern lights. Cassini’s Radio and Plasma Wave Science (RPWS) instrument takes high-resolution measurements that allow scientists to convert the radio waves into audio recordings by shifting the frequencies down into the audio frequency range.
Continue reading “The Sound of Saturn’s Rings”

Posted on by Abby Cessna

Types of Clouds

Clouds around Olympus Mons

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There are numerous types of clouds, but they are generally classified differently. Some organizations classify them into two main groups while others organize them into three or four groups or even more. The National Weather Service divides clouds into three groups – low, medium, and high clouds.  In meteorology, there are 27 types of clouds with nine in each of the three categories – low, medium, and high.

The lowest level is between the surface and up to two kilometers in the atmosphere. Low level clouds include cumulus, stratocumulus, stratus, and cumulonimbus clouds. Cumulus clouds are one of the most well known types. They are the puffy clouds that look like sheep or clumps of cotton balls. They usually occur where warm air rises and forms condensation when it hits cool air. Stratocumulus clouds are also rounded clouds, but they are darker than cumulus clouds. Stratus clouds are flatter and more horizontal. They are the type of clouds that makes a day seem hazy and cloudy.

The medium level is measured at different elevations depending on the region. This depends on a number of factors including elevation and weather. In the polar region, the middle clouds are between two and four kilometers high; in the temperate regions, these clouds are between two and seven kilometers. They are between two and eight kilometers high in the tropical regions. The mid level clouds are altocumulus, altostratus, and nimbostratus. Altocumulus clouds are somewhat patchy, round forms that are white or grey. The often come before a cold front and also predict thunderstorms. Because these clouds look darker they can seem intimidating.

Altostratus clouds are part of the stratus family of clouds. They are like a sheet of clouds somewhere in between the nimbostratus and cirrostratus in color and often turn the whole sky grey. The nimbostratus clouds are very dark grey sheets of clouds. They look similar to other stratus types, but are much darker.

High altitude clouds are also located at different heights depending on region. They can be found between three and 18 kilometers depending on the region. They are found at a much higher altitude in the tropical regions. The clouds at high altitudes are different cirrus clouds and include cirrus, cirrocumulus, and cirrostratus clouds. Cirrus clouds are the thin, wispy clouds found high in the atmosphere. Because of their thin appearance, they are sometimes called mare’s tail; these clouds form when ice vapor freezes high in the sky. Cirrocumulus clouds appear to be a sheet of tiny cumulus clouds, so they almost look as though they are ripples on a pond. Cirrostratus clouds are a mix between cirrus and stratus clouds. They are thin, but resemble a sheet like stratus clouds. Often, they appear to form a halo around the Sun because they are so thin.

Universe Today has articles on stratus clouds and cloud types.

For more information, check out cloud classifications and types of clouds.

Astronomy Cast has an episode on Earth you will want to check out.

Posted on by Jean Tate

What is Beta Radiation?

Radiation Belts on Saturn. Image credit: NASA/JPL/SSI

Beta radiation is radiation due to beta particles, which are electrons (or, sometimes, positrons); mostly, when you come across the words ‘beta radiation’, what is meant is what is produced by beta decay (radioactive decay which produces beta particles … either electrons or positrons).

Within a few years of Becquerel’s discovery of radioactivity (in 1896), its heterogeneous nature was discovered … and the three (then) known components given the memorable names alpha radiation, beta radiation, and gamma radiation. And, in 1900, Becquerel showed that beta radiation was composed of particles which have the same charge-to-mass ratio as electrons (which had been discovered only a few years’ earlier). The realization – by Irène and Frédéric Joliot-Curie, in 1934 – that some beta radiation is composed of positrons, rather than electrons, had to wait until positrons themselves were discovered (in 1932).

Some fun facts about beta radiation:

* beta radiation is in between alpha and gamma in terms of its penetrating power; typically it goes a meter or so in air

* like all kinds of radioactive decay, beta decay occurs because the final state of the nucleus (the one decaying) has a lower energy than the initial one (the difference is the energy of the emitted beta particle and neutrino)

* beta decay involves only the weak interaction (or force), unlike alpha and gamma decay

* the key to the specifics of beta decay is the emission of a neutrino (or antineutrino), postulated by Pauli (in 1931) and combined into a model by Fermi, in 1934 (though it wasn’t until 1956 that the neutrino was detected, and the 1960s for the existence of carriers of the weak force – the three bosons W–, W+, and Z0 – to be hypothesized).

* beta radiation has the characteristics we observe it to have because key constants in the weak interaction have the values they have (no theory in physics predicts what those values are … yet); had those values been just a teensy bit different in the early universe, we would not be here today (this is part of an idea called the anthropic principle).

Here are some of the Universe Today stories that are related to beta radiation New Insights on Magnetars, Superstrings Could Be Detectable As They Decay, and Don’t ‘Supermassive’ Me: Black Holes Regulate Their Own Mass.

Two Astronomy Cast episodes are well worth a listen, as they provide further insights into beta radiation The Strong and Weak Nuclear Forces, and Nucleosynthesis: Elements from Stars.

Sources: EPA, Wikipedia

Posted on by John Carl Villanueva

Sea of Tranquility

Apollo 11 landed on the Moon on July 20, 1969.

The Sea of Tranquility is the landing site of Apollo 11, the mission that gave mankind its first ever walk on the Moon.

Walk? Yes, that’s right. The Sea of Tranquility is not actually a sea, so Neil Armstrong didn’t have to walk on water. In fact, there isn’t a single sea on the lunar surface. The Sea of Tranquility is actually a lunar mare. Now, although the plural of ‘mare’, ‘maria’, is a Latin word that means ‘seas’, these maria don’t have water in them.

Lunar maria were named as such because early astronomers mistook these areas as seas. You see, when you look at the Moon, particularly its near side (well, we don’t actually get to see the far side), i.e., the side which practically constantly stares at us at night, you’ll notice certain features that are darker than others.

Compare the Moon to a grey-scale model of the Earth, and you’ll easily mistake those dark patches for seas. By the way, in case you’ve been reading article titles (not the entire article) on this site lately, you might recall us mentioning water on the Moon. There’s water alright … underneath the surface, so even assuming that they’re plentiful, they don’t qualify as seas.

Let’s go back to our main topic. Called Mare Tranquillitatis in Latin, the Sea of Tranquility is found in the Tranquillitatis basin of the Moon and is composed of basalt. Maria are seen from Earth as relatively dark because the lighter colored areas are much elevated than them and hence are better illuminated by light coming from the Sun.

Whenever color is processed and extracted from multiple photographs, the Sea of Tranquility gives off a slightly bluish shade. This is believed to be caused by the relatively higher metal content in the area.

The actual landing site of Apollo 11’s lunar module is now named Statio Tranquillitatis or Tranquility Base. To the north of that specific area you’ll find three small craters aptly named Aldrin, Collins, and Armstrong, the privileged crew of Apollo 11.

The lunar module of Apollo 11 was not the only spacecraft to have landed on the Sea of Tranquility. There was also the Ranger 8 spacecraft … although “crash landed” is a more appropriate term. It wasn’t a failed mission though, since it was really meant to impact the lunar surface after taking pictures throughout its flight before striking the Moon.

Some people actually think the Apollo missions, particularly the lunar landings, were part of an elaborate hoax. Click on this link to read what the Japanese SELENE Lunar Mission discovered.

NASA has a huge collection of reliable links related to the Apollo missions.

Episodes about the moon from Astronomy Cast. Lend us your ears!

Shooting Lasers at the Moon and Losing Contact with Rovers
The Moon Part I

Posted on by Tammy Plotner

Introduction to the Messier Objects

Charles Messier was born on June 26, 1730 in Lorraine, France. In 1744 at age fourteen, he saw the “Great Comet” appear in the skies above Lorraine and four years later in 1748, witnessed an annular solar eclipse. Perhaps it was these inspiring events that led Charles to a lifelong love of astronomy. In 1751, his excellence in handwriting brought him a job as assistant to Navy Astronomer, Joseph Delisle at the Paris Observatory. It was there that Messier learned to keep accurate records of astronomical observations and the first known entry made by Messier was the transit of Mercury across the Sun in 1753.

At the time, discovering a comet made an astronomer not only noteworthy in the eyes of their peers, but quite famous as well. In 1757 the big search was on for the Comet Halley – predicted to return during that year. While Charles wasn’t the first to locate it, he quickly came to realize during his “sweeps” that there were many objects which could be mistaken as cometary – yet remained in fixed positions. Thus began the Messier Catalog, and its first entry in 1758 was M1, the “Crab Nebula”. While Messier was compiling his catalog of non-cometary objects, he also discovered a genuine comet in 1763 and two more in 1764.

Charles’ catalog was published in several editions as it was amended and the first 45 entries was printed in 1771. In its classic form, it contained 103 entries. In later years, after careful study of his notes, Dr. Helen Sawyer Hogg and Dr. Owen Gingerich would suggest that another four to six objects should be added to bring the total to 110 – the Messier Catalog we know today. Not all of the objects were his original discovery – a fact which he made clear in his notes – and it is rather ironic that what Messier thought of to be “nuisance nebula” that might confuse the comet hunter would later become his major claim to fame. With his small telescopes aimed towards the night sky, he would give future generations of astronomers one of the finest sets of targets for mid-northern latitudes to enjoy.


It isn’t long before the novice astronomer becomes aware of the “Messier List” – and rightly so. This wonderful collection of deep sky gems are easily accessible to a small telescope and most can even be perceived in binoculars. A large majority of the objects can be conquered easily with modest instruments under less than perfect sky conditions, a few can be seen with the unaided eye and some are quite challenging. As a whole, they make for great nights of study, piquing both interest and intellect, as well as observing skills. They range from vague misty patches to grand swaths of stellar landscape!

The Messier Objects (as presented here), contain proper sky coordinates for setting circles or entry into GoTo systems. You’ll also find included a rough map of location, descriptions, scientific information and history. Do not be disappointed if your observations don’t match the grand photos that accompany each article. It is unfortunate that photography can’t always depict what can be seen at the eyepiece, but do rejoice that you are catching a smudge that’s such a huge distance away! Do not give up if you don’t find a particular object easily… Conquering the Messier list takes time and patience. There are also many fine organizations that offer awards for observing the Messier List and instructions for participation can be easily found on the web. Most of all? Enjoy your observations!

Charles Messier (archival image), Messier Objects Poster courtesy of SEDS.

Posted on by Tammy Plotner

Messier 110


Object Name: Messier 110
Alternative Designations: M110, NGC 205
Object Type: E6p Elliptical Galaxy
Constellation: Andromeda
Right Ascension: 00 : 40.4 (h:m)
Declination: +41 : 41 (deg:m)
Distance: 2900 (kly)
Visual Brightness: 8.5 (mag)
Apparent Dimension: 17×10 (arc min)


Locating Messier 110: M110 is easily located with smaller telescopes as the northeastern companion galaxy of M31 – the Great Andromeda Galaxy. It can be spotted as a small hazy patch in larger binoculars from a dark sky site and easily begins to display structure with a mid-sized telescope. While it isn’t as grand as its nearby neighbor, most backyard astronomers would find this bright little galaxy far more interesting if it were on its own! It is well suited to a small amount of light pollution and makes for an excellent suburban challenge.

What You Are Looking At: Classified as a dwarf spheroidal galaxy, M110 enjoys its life some 2.9 million years away from our solar system on the outskirts of the Andromeda Galaxy. Despite its diminuative size, its an active little galaxy with a system of 8 globular clusters in a halo around it. “We present measurements of ages, metallicities and [?/Fe] ratios for 16 globular clusters (GCs) in NGC 147, 185 and 205 and of the central regions of the diffuse galaxy light in NGC 185 and 205. Our results are based on spectra obtained with the SCORPIO multislit spectrograph at the 6-m telescope of the Russian Academy of Sciences. We include in our analysis high-quality Hubble Space Telescope/WFPC2 photometry of individual stars in the studied GCs to investigate the influence of their horizontal branch (HB) morphology on the spectroscopic analysis. All our sample GCs appear to be old (T > 8 Gyr) and metal-poor ([Z/H]??1.1) , except for the GCs Hubble V in NGC 205 (T= 1.2 ± 0.6 Gyr, [Z/H]=?0.6 ± 0.2) , Hubble VI in NGC 205 (T= 4 ± 2 Gyr, [Z/H]=?0.8 ± 0.2) and FJJVII in NGC 185 (T= 7 ± 3 Gyr, [Z/H]=?0.8 ± 0.2) . The majority of our GCs sample has solar [?/Fe] enhancement in contrast to the halo population of GCs in M31 and the Milky Way.” says M.E. Sharina (et al). “The HB morphologies for our sample GCs follow the same behaviour with metallicity as younger halo Galactic GCs. We show that it is unlikely that they bias our spectroscopic age estimates based on Balmer absorption-line indices. Spectroscopic ages and metallicities of the central regions in NGC 205 and 185 coincide with those obtained from colour–magnitude diagrams. The central field stellar populations in these galaxies have approximately the same age as their most central GCs (Hubble V in NGC 205 and FJJIII in NGC 185), but are more metal-rich than the central GCs.”

But globular clusters are old… Are there new stars forming inside of M110? “NGC 205 is a peculiar dwarf elliptical galaxy hosting in its center a population of young blue stars. Their origin is still matter of debate, the central fresh star formation activity possibly being related to dynamical interactions between NGC 205 and M31. The star formation history around the NGC 205 central nucleus is investigated in order to obtain clues to the origin of the young stellar population. Methods. Deep HST/ACS CCD photometry is compared with theoretical isochrones and luminosity functions to characterize the stellar content of the region under study and compute the recent SF rate. Our photometry reveals a previously undetected blue plume of young stars.” says L. Monaco (et al). “Our analysis suggests that (they) were produced between approximately 62 Myr and 335 Myr ago in the NGC 205 inner regions, with a latest minor episode occurring 25 Myr ago. The excellent fit of the observed luminosity function of young main sequence stars obtained with a model having a constant star formation rate argues against a tidally triggered star formation activity over the last 300 Myr. Rather, a constant SF may be consistent with NGC 205 being on its first interaction with M 31.”

Is that all? The let’s stir up the interstellar medium… “In order to understand what determines the properties of the interstellar medium (ISM) and the relation of that ISM to star formation, it is important to observe the ISM in a variety of environments unlike our solar neighborhood. One example of an environment different from the solar neighborhood is the interior of the dwarf elliptical galaxy NGC 205, a companion of M31.” says L.M. Young and K. Yo. “Though it is an elliptical, NGC 205 has long been classified as peculiar, because it has dust clouds and signs of recent star formation near its center. Therefore, given the general deficiency of gas and star formation in elliptical galaxies, NGC 205 presents an excellent opportunity to study the properties of the interstellar medium”

Having such a dominate neighbor isn’t easy, either. According to the work of K.M. Howley (et al): “NGC 205, a close satellite of the M31 galaxy, is our nearest example of a dwarf elliptical galaxy. Photometric and kinematic observations suggest NGC 205 is undergoing tidal distortion from its interaction with M31. Despite earlier attempts, the orbit and progenitor properties of NGC 205 are not well known. We perform an optimized search for these unknowns by combining a genetic algorithm with restricted N-body simulations of the interaction. Coupled with photometric and kinematic observations as constraints, this allows for an effective exploration of the parameter space. We represent NGC 205 as a static Hernquist potential with embedded massless test particles serving as tracers of surface brightness. We explore three distinct, initially stable test particle configurations: cold rotating disk, warm rotating disk, and hot, pressure-supported spheroid. Each model reproduces some, but not all, of NGC 205’s observed features, leading us to speculate that a rotating progenitor with substantial pressure support could match all of the observables.”

Did M110 form from M31, or is it just hanging on the coattails of its big brother? Let’s ask the Isaac Newton Telescope. “The initial results of this survey could not have been more surprising: despite exhibiting a near pristene disk, M31’s halo is full of substructure and points to a history of accretion and disruption. Metal-poor/young stars are coded blue whilst metal rich/older stars are coded red. This spectacular image shows in amazing detail the wealth of information that the INT is helping to reveal about the structure of this previously invisible region of galaxies. The most obvious piece of substructure visible is the giant stellar stream (visible in the south-east). This extends to near the edge of our survey —a projected distance of some 60kpc. In fact, by examining the systematic shift in the luminosity function of the stream as a function of galactocentric radius, we find its actual length is much greater than 100kpc. The similarity of the colour of this feature with the loop of material at the north of the survey suggests a connection: deep follow-up imaging using HST/ACS confirms that they possess the same stellar population. It seems likely that the northern feature is an extension of the stream, after it has passed very close to the centre of the potential of M31.” says Alan McConnachie (et al). “A second large stellar stream candidate has also been identified. The progenitor of this feature appears to be the satellite galaxy NGC 205, although this awaits spectroscopic confirmation. This object has long been known to be tidally perturbed but it is only now that the full extent of its disruption is becoming clear.”

History: M110 was discovered by Charles Messier on August 10, 1773. In his notes he writes: “I examined, under a very good sky, the beautiful nebula of the girdle of Andromeda [M31], with my achromatic refractor, which I had made to magnify 68 times, for creating a drawing like the one of that in Orion [M42] (Mem. de l’acad. 1771, pag. 460). I saw that [nebula] which C. [Citizen] Legentil discovered on October 29, 1749 [M32]. I also saw a new, fainter one, placed north of the great [nebula], which was distant from it about 35′ in right ascension and 24′ in declination. It appeared to me amazing that this faint nebula has escaped [the discovery by] the astronomers and myself, since the discovery of the great [nebula] by Simon Marius in 1612, because when observing the great [nebula], the small is located in the same field [of view] of the telescope. I will give a drawing of that remarkable nebula in the girdle of Andromeda, with the two small which accompany it.”

Caroline Herschel independently discovered M110 on August 27, 1783, little more than 10 years after Messier, and William Herschel numbered it H V.18 when he cataloged it on October 5, 1784 and placed in his notes: “.. There is a very considerable, broad, pretty faint, small nebula near it [M31]; my Sister [Caroline] discovered it August 27, 1783, with a Newtonian 2-feet sweeper. It shews the same faint colour with the great one, and is, no doubt, in the neighborhood of it. It is not [M32] ..; but this is about two-thirds of a degree north preceding it, in a line parallel to Beta and Nu Andromedae.”

M110 would later be cataloged by John Herschel and poetically observed by Admiral Smyth: “A large faintish nebula of an oval form, with its major axis extending north and south. It it between the left arm and robes of Andromeda, a little to the np [North Preceding, NW] of 31 Messier; and was discovered by Miss Herschel in 1783, with a Newtonian 2-foot [FL] sweeper. It lies between two sets of stars, consisting of four each, and each disposed like the figure 7, the preceding group being the smallest; besides other telescopic stars to the south, This mysterious apparition was registered by H [William Herschel] as 30′ long and 12′ broad, but only half that size by his son; and there was a faint suspicion of a nucleus. This doubt must stand over for the present, – for whatever was a matter of uncertainty in the 20-foot reflector, would have no chance of definition in my instrument. It was carefully differentiated with Beta Andromedae.”

Enjoy this great little galaxy!

Top M110 image credit, Palomar Observatory courtesy of Caltech, M110 courtesy of J.C. Cuillandre, CFHT, M110 Image by Lowell Observatory, M110 by Adam Block/NOAO/AURA/NSF, Messier’s Andromeda and Companion Sketch (public image) and M110 image courtesy of NOAO/AURA/NSF.

Posted on by Tammy Plotner

Messier 109

Object Name: Messier 109
Alternative Designations: M109, NGC 3992
Object Type: Sbc Barred Spiral Galaxy
Constellation: Ursa Major
Right Ascension: 11 : 57.6 (h:m)
Declination: +53 : 23 (deg:m)
Distance: 55000 (kly)
Visual Brightness: 9.8 (mag)
Apparent Dimension: 7×4 (arc min)


Locating Messier 109: Locating M109 is a snap. It’s position is less than a degree southeast of Gamma Ursae Majoris – Phecda – the inside bottom corner star of the Big Dipper asterism. But just because it is easy to find doesn’t mean it is easy to see! Although it is considered rather large, the outer spiral arms are quite faint and only the bright central bar and nucleus region show well to smaller telescopes. Messier 109 will require dark, clear skies and at least mid-sized aperture to begin seeing details.

What You Are Looking At: This member of the Ursa Major Galaxy Cloud is about 55 million light years away from Earth and running away from us at an approximate speed of 1142 kilometers per second. However, it is not alone… It has companion galaxies as well – companions that may be contributing to M109’s bright central bar. “Detailed neutral hydrogen observations have been obtained of the large barred spiral galaxy NGC 3992 and its three small companion galaxies, UGC 6923, UGC 6940, and UGC 6969. For the main galaxy, the HI distribution is regular with a low level radial extension outside the stellar disc. However, at exactly the region of the bar, there is a pronounced central H I hole in the gas distribution. Likely gas has been transported inwards by the bar and because of the emptiness of the hole no large accretion events can have happened in recent galactic times.” says R. Bottemar (et al).

“The gas kinematics is very regular and it is demonstrated that the influence of the bar potential on the velocity field is negligible. A precise and extended rotation curve has been derived showing some distinct features which can be explained by the non-exponential radial light distribution of NGC 3992. The decomposition of the rotation curve gives a slight preference for a sub maximal disc, though a range of disc contributions, up to a maximum disc situation fits nearly equally well. For such a maximum disc contribution, which might be expected in order to generate and maintain the bar, the required mass-to-light ratio is large but not exceptional.”

And indeed its spiral structure is what makes it beautiful. Says K. Wilke: “For the intermediate-type barred galaxies NGC 3992 and NGC 7479 stationary models are constructed which reproduce in a consistent manner the observed distribution of the luminous matter and the observed gas kinematics in the inner disk regions affected by the bar. We present 2D fits to the observed NIR luminosity distributions that consist of three components: a bulge, a bar, and a disk. By projection to the reference frame of the galaxy, artificial rotation curves for every model are obtained and are compared with the observed rotation curves of the HII-gas. The parameters of the NGC 3992- and NGC 7479-models are optimized by computing and evaluating a large number of models with different parameter sets. This iterative procedure results in final models that accurately reproduce the morphological structure of NGC 3992 and NGC 7479 as well as the observed kinematics of the HII-gas.”

Because Messier 109 has a slightly different structure to its arms, it makes it a great place for astronomers to discover how starforming regions evolve. According to the work of J. P. Cepa and J. E. Beckman: “The present study estimates the efficiency ratio for massive star formation between the arms and the interarm discs of three grand design spirals. The estimate is based on H mapping observations of theHii regions in the galaxies. We find that this efficiency ratio is 10 in the zones between the Lindbalad resonances and the radius which we infer to be co-rotation, dropping to values close to unity at these three resonance raddii. these results point to a dominant influence of resonance structure in stimulating star formation in grand design spirals.”

However, Messier 109 isn’t just producing new stars. It’s magnetic halo is producing ultra high energy cosmic rays! “The study of the propagation of ultra-high-energy cosmic rays (UHECRs) is a key step to unveiling the secret of their origin. Up to now only the influence of the galactic and extragalactic magnetic fields was considered. In this article we focus our analysis on the influence of the magnetic field of the galaxies standing between possible UHECR sources and us. Our main approach is to start from the well-known galaxy distribution up to 120 Mpc.” says Pascal Chardonnet and Alvise Mattei. “We use the most complete galaxy catalog: the LEDA catalog. Inside a sphere of 120 Mpc, we extract 60,130 galaxies with known positions. In our simulations we assign a halo dipole magnetic field (HDMF) to each galaxy. The code developed is able to retro-propagate a charged particle from the arrival points of UHECR data across our galaxy sample. We present simulations in the case of the Virgo Cluster and show that there is a nonnegligible deviation in the case of protons of 7 × 1019 eV, even if the B value is conservative. Then special attention is devoted to the AGASA triplet, where we find that NGC 3998 and NGC 3992 could be possible source candidates.”

But things aren’t sitting still inside Messier 109 while the action goes on. The central bar is rotating rather unusually, too. “The pattern speed is one of the fundamental parameters that determines the structure of barred galaxies. This quantity is usually derived from indirect methods or by employing model assumptions. The number of bar pattern speeds derived using the model-independent Tremaine & Weinberg technique is still very limited. We present the results of model-independent measurements of the bar pattern speed in four galaxies ranging in Hubble type from SB0 to SBbc.” says Joris Gerssen (et al). “Three of the four galaxies in our sample are consistent with bars being fast rotators. The lack of slow bars is consistent with previous observations and suggests that barred galaxies do not have centrally concentrated dark matter haloes. This contradicts simulations of cosmological structure formation and observations of the central mass concentration in nonbarred galaxies.”

When it comes to galaxy dynamics, it is this speed that determines the bulge in the center. Says E. M. Corsini: “The dynamics of a barred galaxy depends on the pattern speed of its bar. The only direct method for measuring the pattern speed of a bar is the Tremaine-Weinberg technique. This method is best suited to the analysis of the distribution and dynamics of the stellar component. Therefore it has been mostly used for early-type barred galaxies. Most of them host a classical bulge. On the other hand, a variety of indirect methods, which are based on the analysis of the distribution and dynamics of the gaseous component, has been used to measure the bar pattern speed in late-type barred galaxies. Nearly all the measured bars are as rapidly rotating as they can be. By comparing this result with high-resolution numerical simulations of bars in dark matter halos, it is possible to conclude that these bars reside in maximal disks.”

History: This interesting spiral galaxy was first turned up by Pierre Mechain on the night of March 12, 1781. It was later confirmed by Charles Messier on March 24, 1781, along with M108 while doing the computations for M97. Originally Messier included this finding as object #99 is his rough draft, but did not give it a position. From Mechain’s letter to Bernoulli of May 6, 1783: “A nebula near Beta in the Great Bear. Mr. Messier mentions, when indicating its position, two others, which I also have discovered and of which one is close to this one [M108], the other is situated close to Gamma in the Great Bear [this is M109], but I could not yet determine their positions.”

Because it wasn’t included in the catalog, Sir William Herschel independently recovered it on on April 12, 1789, gave it his own catalog number and writes: “Considerably bright. Irregularly formed. Extended meridionally [along the Meridian, i.e. North-South]. Little brighter Nucleus. With faint brances 7 or 8′ long, and 5 or 6′ broad.” His son John would also go on to add it to his catalog on February 17, 1831 when he writes: “Bright; Large; very suddenly brighter to the Middle; round; 3′ diameter. Fine object.”

Because M109 wasn’t added to the published Messier catalog of the time, poetic stargazer – Admiral Smyth – would attribute its discovery to Herschel and write in his own notes: “A large pale-white nebula, on the Bear’s right haunch, about 1d 1/4 south of Gamma; discovered in April, 1789. It has a peculiar appearance in the field, from there being a coarse small double star north of it, and from its being followed by a vertical line of five equidistant telescopic stellar attendants. This object is fine, but, in my instrument, faintish; it brightens towards the middle; and WH says there is, in that part, an unconnected star, the which I cannot make out. From every inference this nebula is a vast and remote globular cluster of worlds, for JH assures us it is actually resolvable. By its blazing towards the centre, proof is afforded that the stars are more condensed there than around its margin, an obvious indication of a clustering power directed from all parts towards the middle of the spherical group. In other words, the whole appearance affords presumptive evidence of a wonderful physical fact, — the actual existence of a central force.”

Although he didn’t know he was looking at a distant galaxy, Smyth definitely had some sort of clue as to what was going on. May your observations prove as interesting!

Top M109 image credit, Palomar Observatory courtesy of Caltech, M109 Images courtesy of SSDS, M109 courtesy of Hunter Wilson (Wikipedia), M109 IPAC Image, M109 Core Region courtesy of NASA/ESA Hubble Space Telescope, M109 2MASS Image and M109 image courtesy of NOAO/AURA/NSF.

Posted on by Tammy Plotner

Messier 108


Object Name: Messier 108
Alternative Designations: M108, NGC 3556
Object Type: Sc Spiral Galaxy
Constellation: Ursa Major
Right Ascension: 11 : 11.5 (h:m)
Declination: +55 : 40 (deg:m)
Distance: 45000 (kly)
Visual Brightness: 10.0 (mag)
Apparent Dimension: 8×1 (arc min)


Locating Messier 108: M108 is easily located about one quarter the distance between Beta Ursa Majoris and Gamma Ursa Majoris… but locating doesn’t mean it’s always easily seen! At nearly edge-on in presentation, this mottled streak of light is a rather difficult catch for smaller telescopes and requires good, dark sky to see any details. Larger instruments will make out both faint and bright patches in structure.

What You Are Looking At: Located about 45 million light years away from Earth and running away from us at 772 kilometers per second, this disturbed looking galaxy is rich in dark dust, star forming regions and a supershell. “We present the first high resolution HI maps of the nearby edge-on galaxy, M 108 (NGC 3556). This galaxy is known to have a radio continuum thick disk and we have now found HI arcs and extensions protruding from the plane on kpc scales. Two HI arcs, positioned at either end of the optical major axis have the signature of expanding shells and, in the context of energy input from supernovae and stellar winds, the required input energy for the eastern shell is > 2.6 times 10^56 erg, making this the most energetic HI supershell yet detected.” says D. L. Giguere and J. Irwin.

“Since this galaxy is isolated, the supershells are unlikely to have been created through impacting external clouds, yet the required input energy is also greater than that available from the observed internal star formation rate. Thus it would appear that some form of energy enhancement (such as magnetic fields) must also be important in creating these features. The supershells are so dominant that they distort the outer major axis. Without a knowledge of the resolved structure of these features, the galaxy would mistakenly be considered warped. We have also modeled the underlying smooth density and velocity distributions of this galaxy by reproducing the line profiles in the HI cube.”

What else is unusual about Messier 108? Try a water maser that disappeared. “NGC 3556: is a nearby spiral galaxy located at a distance of 12Mpc. Its FIR luminosity, LFIR 1010 L?, is similar to that of the Milky Way. The detected H2O maser line initially had a central velocity of 738 kms?1. With a peak flux of 20–40mJy, the maser had an isotropic luminosity of 1 L. More recently, the maser feature disappeared and another weaker component, at 708 kms?1, was detected.” says A. Tarchi (et al). “The high rate of maser detections in our sample of galaxies strongly suggests that a relationship between FIR flux density and maser phenomena exists.”

What else is hiding? Perhaps an intermediate mass black hole, you say? “We present a 60 ks Chandra ACIS-S observation of the isolated edge-on spiral galaxy NGC 3556, together with a multiwavelength analysis of various discrete X-ray sources and diffuse X-ray features. Among 33 discrete X-ray sources detected within the IB = 25 mag arcsec-2 isophote ellipse of the galaxy, we identify a candidate for the galactic nucleus, an ultraluminous X-ray source that might be an accreting intermediate-mass black hole, a possible X-ray binary with a radio counterpart, and two radio-bright giant H II regions.” says Q. Daniel Wang (et al). “The diffuse X-ray emission exhibits significant substructures, possibly representing various blown-out superbubbles or chimneys of hot gas heated in massive star-forming regions. This X-ray-emitting gas has temperatures in the range of ~(2-7) × 106 K and has a total cooling rate of ~2 × 1040 ergs s-1. The energy can be easily supplied by supernova blast waves in the galaxy. These results show NGC 3556 to be a galaxy undergoing vigorous disk-halo interaction. The halo in NGC 3556 is considerably less extended, however, than that of NGC 4631, in spite of many similarities between the two galaxies. This may be due to the fact that NGC 3556 is isolated, whereas NGC 4631 is interacting. Thus, NGC 3556 presents a more pristine environment for studying the disk-halo interaction.”

History: According to SEDS, Charles Messier’s hand-written preliminary and unpublished version of his catalog, M108, similar to M109, was discovered by Pierre Méchain shortly after M97 (which he had found February 16, 1781): Méchain discovered M108 3 days after M97 on February 19, 1781, and M109 on March 12, 1781. Both objects were apparently also observed by Charles Messier when he measured the position of M97 (March 24, 1781), but apparently he didn’t find occasion to obtain positions for these objects at that time. Messier listed this object, M108, under number “98” in his preliminary manuscript version of his catalog, without giving a position.

M108 was catalog again by William Hershel in 1789, but best described by Admiral Smyth who said: “A large milky-white nebula, on the body of the Great Bear, with a small star at its sp [South Preceding, SW] apex, and an 8th-magnitude preceding [W] it at double the distance; there is also a brightish group in the np [North Preceding, NW] quadrant. It is easily found, since it lies only about 1 deg south-east of Beta, Merak. This object was discovered by H. [William Herschel] in April, 1789; and is No. 831 of his son’s Catalogue. It is faint but well defined, being much elongated with an axis-major trending sp [South Preceding, SW] and nf [north following, NE] across the parallel, and a small star, like a nucleus, in its center. As H. [WH] considers this star to be unconnected with the nebula, it follows that it is between us and it, and therefore strengthens to confirmation our belief in the inconceivable remoteness of those mysterious bodies.”

Enjoy every inch of this mysterious body!

Top M108 image credit, Palomar Observatory courtesy of Caltech, M108 Hubble Image, M108 courtesy of Ole Nielsen (Wikipedia), M108 GALEX image and M108 image courtesy of NOAO/AURA/NSF.