Tag: chemical composition

Sea Salt Discovered on Jupiter’s Moon Europa

This image shows a view of the trailing hemisphere of Jupiter's ice-covered satellite, Europa, in approximate natural color. Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long.   Image via Galileo spacecraft in 1996.

Europa is thought to have a subsurface ocean. Salt from this hidden sea might be emerging in long fractures visible in the moon’s crust.



Excerpt earthsky.org


Laboratory experiments have lead to new information about the chemical composition of the mysterious dark material in the long, dark fractures on the surface of Europa, a large moon of Jupiter. Researchers at NASA’s Jet Propulsion Laboratory (JPL) mimicked conditions on Europa’s surface. They now say that the dark material is discolored salt, likely sea salt from below the moon’s icy crust. The journal Geological Research Letters published their study on May 15, 2015.

The scientists say this new insight is important in considering whether this icy moon might be hospitable for extraterrestrial life. The life question is a key one for Europa, since this world is believed to have a liquid ocean beneath its crust. The presence of sea salt on Europa’s surface suggests the ocean is interacting with its rocky seafloor.

Scientists have been intensely curious about Europa since Galileo discovered it in 1610. In recent years, they’ve puzzled over the dark material coating the long, linear fractures on Europa’s observable surface. The material was associated with young terrain on this moon of Jupiter, suggesting that it had erupted from within Europa.
However, the chemical composition of the dark material remained elusive, until now.
Planetary scientist Kevin Hand at JPL led the new study. He said in a statement:
If it’s just salt from the ocean below, that would be a simple and elegant solution for what the dark, mysterious material is.
Europa is immersed radiation from Jupiter’s powerful magnetic field, causing high-powered electrons to slam into the moon’s surface. Hand and his team created a laboratory test that mimicked the conditions of Europa’s temperature, pressure, and radiation exposure. They tested a variety of samples including common salt – sodium chloride – and salt water in a vacuum chamber at Europa’s chilly surface temperature of minus 280 degrees Fahrenheit (minus 173 Celsius). They also bombarded the samples with an electron beam to imitate Jupiter’s influence. 

After several hours – a time period corresponding to over a century on Europa, the researchers said – the salt samples were observed to go from white to a yellowish brown, the color similar to the features on the icy moon. Hand said:
This work tells us the chemical signature of radiation-baked sodium chloride is a compelling match to spacecraft data for Europa’s mystery material.
A
A “Europa-in-a-can” laboratory setup at NASA-JPL mimics conditions of temperature, near vacuum and heavy radiation on the surface of Jupiter’s icy moon. Image via NASA/JPL-Caltech


A close-up of salt grains discolored by radiation following exposure in a
Close-up of salt grains discolored by radiation following exposure in a “Europa-in-a-can” test setup at JPL. Image via NASA/JPL-Caltech


Until now, telescopic observations have only shown glimpses of irradiated salts. No telescope on Earth can observe Europa’s surface with enough resolution to identify them with certainty. Researchers suggest additional spacecraft observation to gather more evidence.
A visit to this icy world would help answer the most tantalizing questions about Europa. Long believed to have a liquid ocean of salt water below its icy surface, this moon continues to display promising conditions for extraterrestrial life. 

As Europa orbits Jupiter, it experiences strong tidal forces similar to Earth and the Moon. These forces from Jupiter and the other Jovian moons cause Europa to flex and stretch, which creates heat, and results in Europa having a warm internal temperature than it would with just the heat from the Sun alone. 

Recent observable geological activity also creates strong evidence that the subsurface ocean interacts directly with Europa’s rocky interior, making geothermal vents, like those in Earth’s oceans, a strong possibility as well. 

These hydrothermal vent ecosystems on Earth thrive with no energy from the sun. Bacteria, shrimp and crustaceans have all been observed in these extreme environments, surviving on what researchers have deemed chemosythesis.

With Europa’s enormous amount of liquid salt water, essential chemical elements and geological activity, this long discovered icy moon appears to be one of the solar systems most promising locations for habitable requirements for life. 

However, until a devoted spacecraft visit’s, nothing beyond hopeful speculation can be proven, the researchers say.

Bottom line: Researchers at NASA’s Jet Propulsion Laboratory created laboratory conditions that mimicked those on Jupiter’s large moon Europa, to learn the chemical compositions of the material in long, dark fractures in the moon’s surface. They now believe this material is sea salt, which has emerged to Europa’s surface from its liquid ocean below.

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Sea Salt Discovered on Jupiter’s Moon Europa

This image shows a view of the trailing hemisphere of Jupiter's ice-covered satellite, Europa, in approximate natural color. Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long.   Image via Galileo spacecraft in 1996.

Europa is thought to have a subsurface ocean. Salt from this hidden sea might be emerging in long fractures visible in the moon’s crust.



Excerpt earthsky.org


Laboratory experiments have lead to new information about the chemical composition of the mysterious dark material in the long, dark fractures on the surface of Europa, a large moon of Jupiter. Researchers at NASA’s Jet Propulsion Laboratory (JPL) mimicked conditions on Europa’s surface. They now say that the dark material is discolored salt, likely sea salt from below the moon’s icy crust. The journal Geological Research Letters published their study on May 15, 2015.

The scientists say this new insight is important in considering whether this icy moon might be hospitable for extraterrestrial life. The life question is a key one for Europa, since this world is believed to have a liquid ocean beneath its crust. The presence of sea salt on Europa’s surface suggests the ocean is interacting with its rocky seafloor.

Scientists have been intensely curious about Europa since Galileo discovered it in 1610. In recent years, they’ve puzzled over the dark material coating the long, linear fractures on Europa’s observable surface. The material was associated with young terrain on this moon of Jupiter, suggesting that it had erupted from within Europa.
However, the chemical composition of the dark material remained elusive, until now.
Planetary scientist Kevin Hand at JPL led the new study. He said in a statement:
If it’s just salt from the ocean below, that would be a simple and elegant solution for what the dark, mysterious material is.
Europa is immersed radiation from Jupiter’s powerful magnetic field, causing high-powered electrons to slam into the moon’s surface. Hand and his team created a laboratory test that mimicked the conditions of Europa’s temperature, pressure, and radiation exposure. They tested a variety of samples including common salt – sodium chloride – and salt water in a vacuum chamber at Europa’s chilly surface temperature of minus 280 degrees Fahrenheit (minus 173 Celsius). They also bombarded the samples with an electron beam to imitate Jupiter’s influence. 

After several hours – a time period corresponding to over a century on Europa, the researchers said – the salt samples were observed to go from white to a yellowish brown, the color similar to the features on the icy moon. Hand said:
This work tells us the chemical signature of radiation-baked sodium chloride is a compelling match to spacecraft data for Europa’s mystery material.
A
A “Europa-in-a-can” laboratory setup at NASA-JPL mimics conditions of temperature, near vacuum and heavy radiation on the surface of Jupiter’s icy moon. Image via NASA/JPL-Caltech


A close-up of salt grains discolored by radiation following exposure in a
Close-up of salt grains discolored by radiation following exposure in a “Europa-in-a-can” test setup at JPL. Image via NASA/JPL-Caltech


Until now, telescopic observations have only shown glimpses of irradiated salts. No telescope on Earth can observe Europa’s surface with enough resolution to identify them with certainty. Researchers suggest additional spacecraft observation to gather more evidence.
A visit to this icy world would help answer the most tantalizing questions about Europa. Long believed to have a liquid ocean of salt water below its icy surface, this moon continues to display promising conditions for extraterrestrial life. 

As Europa orbits Jupiter, it experiences strong tidal forces similar to Earth and the Moon. These forces from Jupiter and the other Jovian moons cause Europa to flex and stretch, which creates heat, and results in Europa having a warm internal temperature than it would with just the heat from the Sun alone. 

Recent observable geological activity also creates strong evidence that the subsurface ocean interacts directly with Europa’s rocky interior, making geothermal vents, like those in Earth’s oceans, a strong possibility as well. 

These hydrothermal vent ecosystems on Earth thrive with no energy from the sun. Bacteria, shrimp and crustaceans have all been observed in these extreme environments, surviving on what researchers have deemed chemosythesis.

With Europa’s enormous amount of liquid salt water, essential chemical elements and geological activity, this long discovered icy moon appears to be one of the solar systems most promising locations for habitable requirements for life. 

However, until a devoted spacecraft visit’s, nothing beyond hopeful speculation can be proven, the researchers say.

Bottom line: Researchers at NASA’s Jet Propulsion Laboratory created laboratory conditions that mimicked those on Jupiter’s large moon Europa, to learn the chemical compositions of the material in long, dark fractures in the moon’s surface. They now believe this material is sea salt, which has emerged to Europa’s surface from its liquid ocean below.

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Mystery space explosion in 1670 solved


Nova Vulpeculae 1670


By Kathy Fey

A mystery explosion in the night sky turns out to have been caused by colliding stars.




One of history’s mysteries revolved around a strange explosion observed in the sky in 1670, long thought to have been the first nova on record. Recent research suggests that this enigmatic event was actually a rare stellar collision.

According to a report by Astronomy Magazine, the so-called Nova Vulpeculae of 1670 was more likely the collision of two stars, which shines brighter than a nova but not as brightly as a supernova.

Observations made with various telescopes including the Submillimeter Array, the Effelsburg radio telescope and APEX have revealed the more unusual nature of the light source – a violent collision.

When the event first occurred, it would have been visible from Earth with the naked eye. Now, submillimeter telescopes are needed to detect the traces left in the aftermath of the event.

When first observed, 17th century astronomers described what they saw as a new star appearing in the head of Cygnus, the swan constellation.

“For many years, this object was thought to be a nova, but the more it was studied, the less it looked like an ordinary nova, or indeed any other kind of exploding star,” said Tomasz Kaminski of the European Southern Observatory.

Having observed the area of the supposed nova with both submillimeter and radio wavelengths, scientists “have found that the surroundings of the remnant are bathed in a cool gas rich in molecules with a very unusual chemical composition,” said Kaminski.

Researchers concluded that the amount of cool material they observed was too much to have been produced by a nova. The nature of the gas debris best fit with the rare scenario of two stars merging in an explosive collision.

The team’s report was published in the journal Nature.

Karl Menten of the Max Planck Institute called the discovery “the most fun – something that is completely unexpected.”

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Andromeda, feels like home to me…..

Andromeda Galaxy

The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224; often referred to as the Great Andromeda Nebula in older texts, is a spiral galaxy approximately 2,500,000 light-years away in the constellation Andromeda.

It is the nearest spiral galaxy to our own, the Milky Way. As it is visible as a faint smudge on a moonless night, it is one of the farthest objects visible to the naked eye, and can be seen even from urban areas with binoculars. It is named after the princess Andromeda in Greek mythology.

Andromeda is the largest galaxy of the Local Group, which consists of the Andromeda Galaxy, the Milky Way Galaxy, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and may be the most massive in the grouping.

The 2006 observations by the Spitzer Space Telescope revealed that M31 contains one trillion (1012) stars, several times more than the number of stars in our own galaxy, which is estimated to be c. 200-400 billion.

While the 2006 estimates put the mass of the Milky Way to be ~80% of the mass of Andromeda, which is estimated to be 7.1 X 1011 solar masses, a 2009 study concluded that Andromeda and the Milky Way are about equal in mass.

At an apparent magnitude of 3.4, the Andromeda Galaxy is notable for being one of the brightest Messier objects, making it easily visible to the naked eye even when viewed from areas with moderate light pollution. Although it appears more than six times as wide as the full moon when photographed through a larger telescope, only the brighter central region is visible with the naked eye.

Observation History

The earliest recorded observation of the Andromeda Galaxy was in 964 CE by the Persian astronomer, Abd al-Rahman al-Sufi (Azophi), who described it as a "small cloud" in his Book of Fixed Stars. Other star charts of that period have it labeled as the Little Cloud.

The first description of the object based on telescopic observation was given by Simon Marius in 1612.

Charles Messier catalogued it as object M31 in 1764 and incorrectly credited Marius as the discoverer, unaware of Al Sufi's earlier work.

In 1785, the astronomer William Herschel noted a faint reddish hue in the core region of the M31. He believed it to be the nearest of all the "great nebulae" and, based on the color and magnitude of the nebula, he incorrectly guessed that it was no more than 2,000 times the distance of Sirius.

William Huggins in 1864 observed the spectrum of M31 and noted that it differed from a gaseous nebula. The spectra of M31 displayed a continuum of frequencies, superimposed with dark absorption lines that help identify the chemical composition of an object. The Andromeda nebula was very similar to the spectra of individual stars, and from this it was deduced that M31 had a stellar nature.

In 1885, a supernova (known as "S Andromedae") was seen in M31, the first and so far only one observed in that galaxy. At the time M31 was considered to be a nearby object, so the cause was thought to be a much less luminous and unrelated event called a nova, and was named accordingly "Nova 1885".

The first photographs of M31 were taken in 1887 by Isaac Roberts from his private observatory in Sussex, England. The long-duration exposure allowed the spiral structure of the galaxy to be seen for the first time. However, at the time this object was commonly believed to be a nebula within our galaxy, and Roberts mistakenly believed that M31 and similar spiral nebulae were actually solar systems being formed, with the satellites nascent planets.

The radial velocity of this object with respect to our solar system was measured in 1912 by Vesto Slipher at the Lowell Observatory, using spectroscopy. The result was the largest velocity recorded at that time, at 300 kilometres per second (190 mi/s), moving in the direction of the Sun.

Island Universe

In 1917, Heber Curtis observed a nova within M31. Searching the photographic record, 11 more novae were discovered. Curtis noticed that these novae were, on average, 10 magnitudes fainter than those that occurred within our Galaxy. As a result he was able to come up with a distance estimate of 500,000 light-years (3.2X1010 AU). He became a proponent of the so-called "island universes" hypothesis, which held that spiral nebulae were actually independent galaxies.

In 1920 the Great Debate between Harlow Shapley and Heber Curtis took place, concerning the nature of the Milky Way, spiral nebulae, and the dimensions of the universe. To support his claim that Great Andromeda Nebula (M31) was an external galaxy, Curtis also noted the appearance of dark lanes resembling the dust clouds in our own Galaxy, as well as the significant Doppler shift.

In 1922 Ernst Opik presented a very elegant and simple astrophysical method to estimate the distance of M31, his result (450 kpc (1,500 kly)) put Andromeda Nebula far outside our Galaxy.

Edwin Hubble settled the debate in 1925 when he identified extragalactic Cepheid variable stars for the first time on astronomical photos of M31. These were made using the 2.5 metres (98 in) Hooker telescope, and they enabled the distance of Great Andromeda Nebula to be determined. His measurement demonstrated conclusively that this feature was not a cluster of stars and gas within our Galaxy, but an entirely separate galaxy located a significant distance from our own.

Andromeda plays an important role in galactic studies, since it is the nearest spiral galaxy (although not the nearest galaxy).

In 1943, Walter Baade was the first person to resolve stars in the central region of the Andromeda Galaxy. Based on his observations of this galaxy, he was able to discern two distinct populations of stars based on their metallicity, naming the young, high velocity stars in the disk Type I and the older, red stars in the bulge Type II. This nomenclature was subsequently adopted for stars within the Milky Way, and elsewhere. (The existence of two distinct populations had been noted earlier by Jan Oort.) Dr. Baade also discovered that there were two types of Cepheid variables, which resulted in a doubling of the distance estimate to M31, as well as the remainder of the Universe.

Radio emission from the Andromeda Galaxy was first detected by Grote Reber in 1940. The first radio maps of the galaxy were made in the 1950s by John Baldwin and collaborators at the Cambridge Radio Astronomy Group. The core of the Andromeda Galaxy is called 2C 56 in the 2C radio astronomy catalogue.

In 2009, the first planet may have been discovered in the Andromeda Galaxy. This candidate was detected using a technique called microlensing, which is caused by the deflection of light by a massive object.

Structure

Based on its appearance in visible light, the Andromeda galaxy is classified as an SA(s)b galaxy in the de Vaucouleurs-Sandage extended classification system of spiral galaxies. However, data from the 2MASS survey showed that the bulge of M31 has a box-like appearance, which implies that the galaxy is actually a barred galaxy with the bar viewed almost directly along its long axis.

In 2005, astronomers used the Keck telescopes to show that the tenuous sprinkle of stars extending outward from the galaxy is actually part of the main disk itself. This means that the spiral disk of stars in Andromeda is three times larger in diameter than previously estimated. This constitutes evidence that there is a vast, extended stellar disk that makes the galaxy more than 220,000 light-years (67,000 pc) in diameter. Previously, estimates of Andromeda's size ranged from 70,000 to 120,000 light-years (21,000 to 37,000 pc) across.

The galaxy is inclined an estimated 77° relative to the Earth (where an angle of 90° would be viewed directly from the side). Analysis of the cross-sectional shape of the galaxy appears to demonstrate a pronounced, S-shaped warp, rather than just a flat disk. A possible cause of such a warp could be gravitational interaction with the satellite galaxies near M31. The galaxy M33 could be responsible for some warp in M31's arms, though more precise distances and radial velocities are required.

Spectroscopic studies have provided detailed measurements of the rotational velocity of M31 at various radii from the core. In the vicinity of the core, the rotational velocity climbs to a peak of 225 kilometres per second (140 mi/s) at a radius of 1,300 light-years (82,000,000 AU) light-years, then descends to a minimum at 7,000 light-years (440,000,000 AU) where the rotation velocity may be as low as 50 kilometres per second (31 mi/s).

Thereafter the velocity steadily climbs again out to a radius of 33,000 light-years (2.1x109 AU), where it reaches a peak of 250 kilometres per second (160 mi/s). The velocities slowly decline beyond that distance, dropping to around 200 kilometres per second (120 mi/s) at 80,000 light-years (5.1x109 AU). These velocity measurements imply a concentrated mass of about 6 x 109 M in the nucleus. The total mass of the galaxy increases linearly out to 45,000 light-years (2.8 x109 AU), then more slowly beyond that radius.

The spiral arms of Andromeda are outlined by a series of H II regions that Baade described as resembling "beads on a string". They appear to be tightly wound, although they are more widely spaced than in our galaxy.

Rectified images of the galaxy show a fairly normal spiral galaxy with the arms wound up in a clockwise direction. There are two continuous trailing arms that are separated from each other by a minimum of about 13,000 light-years (8.2E+8 AU). These can be followed outward from a distance of roughly 1,600 light-years (100,000,000 AU) from the core. The most likely cause of the spiral pattern is thought to be interaction with M32. This can be seen by the displacement of the neutral hydrogen clouds from the stars.

In 1998, images from the European Space Agency's Infrared Space Observatory demonstrated that the overall form of the Andromeda galaxy may be transitioning into a ring galaxy. The gas and dust within Andromeda is generally formed into several overlapping rings, with a particularly prominent ring formed at a radius of 32,000 light-years (2.0x109 AU) from the core. This ring is hidden from visible light images of the galaxy because it is composed primarily of cold dust.

Close examination of the inner region of Andromeda showed a smaller dust ring that is believed to have been caused by the interaction with M32 more than 200 million years ago. Simulations show that the smaller galaxy passed through the disk of Andromeda along the latter's polar axis. This collision stripped more than half the mass from the smaller M32 and created the ring structures in Andromeda.

Studies of the extended halo of M31 show that it is roughly comparable to that of the Milky Way, with stars in the halo being generally "metal-poor", and increasingly so with greater distance. This evidence indicates that the two galaxies have followed similar evolutionary paths. They are likely to have accreted and assimilated about 1-200 low-mass galaxies during the past 12 billion years. The stars in the extended halos of M31 and the Milky Way may extend nearly one third the distance separating the two galaxies.

Nucleus

M31 is known to harbor a dense and compact star cluster at its very center. In a large telescope it creates a visual impression of a star embedded in the more diffuse surrounding bulge. The luminosity of the nucleus is in excess of the most luminous globular clusters.

In 1991 Tod R. Lauer used WFPC, then on board the Hubble Space Telescope, to image Andromeda's inner nucleus. The nucleus consists of two concentrations separated by 1.5 parsecs (4.9 ly). The brighter concentration, designated as P1, is offset from the center of the galaxy. The dimmer concentration, P2, falls at the true center of the galaxy and contains a 3-5x107 M black hole.

Scott Tremaine has proposed that the observed double nucleus could be explained if P1 is the projection of a disk of stars in an eccentric orbit around the central black hole. The eccentricity is such that stars linger at the orbital apocenter, creating a concentration of stars. P2 also contains a compact disk of hot, spectral class A stars. The A stars are not evident in redder filters, but in blue and ultraviolet light they dominate the nucleus, causing P2 to appear more prominent than P1.

While at the initial time of its discovery it was hypothesized that the brighter portion of the double nucleus was the remnant of a small galaxy "cannibalized" by Andromeda, this is no longer considered to be a viable explanation. The primary reason is that such a nucleus would have an exceedingly short lifetime due to tidal disruption by the central black hole. While this could be partially resolved if P1 had its own black hole to stabilize it, the distribution of stars in P1 does not suggest that there is a black hole at its center.

Artist's concept of Andromeda galaxy core showing a view across a

mysterious disk of young, blue stars encircling a supermassive black hole.

Discrete Sources

Multiple X-ray sources have been detected in the Andromeda Galaxy, using observations from the ESA's XMM-Newton orbiting observatory. Robin Barnard et al. hypothesized that these are candidate black holes or neutron stars, which are heating incoming gas to millions of kelvins and emitting X-rays. The spectrum of the neutron stars is the same as the hypothesized black holes, but can be distinguished by their masses.

There are approximately 460 globular clusters associated with the Andromeda galaxy. The most massive of these clusters, identified as Mayall II, nicknamed Globular One, has a greater luminosity than any other known globular cluster in the local group of galaxies.

It contains several million stars, and is about twice as luminous as Omega Centauri, the brightest known globular cluster in the Milky Way. Globular One (or G1) has several stellar populations and a structure too massive for an ordinary globular. As a result, some consider G1 to be the remnant core of a dwarf galaxy that was consumed by M31 in the distant past. The globular with the greatest apparent brightness is G76 which is located in the south-west arm's eastern half.

In 2005, astronomers discovered a completely new type of star cluster in M31. The new-found clusters contain hundreds of thousands of stars, a similar number of stars that can be found in globular clusters. What distinguishes them from the globular clusters is that they are much larger ­ several hundred light-years across ­ and hundreds of times less dense. The distances between the stars are, therefore, much greater within the newly discovered extended clusters.

Future Collision of the Milky Way with Andromeda

The Andromeda Galaxy is approaching the Sun at about 100 to 140 kilometres per second (62 to 87 mi/s),[56] so it is one of the few blue shifted galaxies. The Andromeda Galaxy and the Milky Way are thus expected to collide in perhaps 2.5 billion years, although the details are uncertain since Andromeda's tangential velocity with respect to the Milky Way is only known to within about a factor of two.

A likely outcome of the collision is that the galaxies will merge to form a giant elliptical galaxy. Such events are frequent among the galaxies in galaxy groups. The fate of the Earth and the Solar System in the event of a collision are presently unknown. If the galaxies do not merge, there is a small chance that the Solar System could be ejected from the Milky Way or join Andromeda.

Andromeda's Satellite Galaxies  Wikipedia
Like the Milky Way, Andromeda Galaxy has satellite galaxies, consisting of 14 known dwarf galaxies.

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