Microscopium is a minor constellation in the Southern Celestial Hemisphere, one of twelve created in the 18th century by French astronomer Nicolas Louis de Lacaille and one of several depicting scientific instruments. Its name is a Latinized form of the Greek word for microscope. Its stars are faint and hardly visible from most of the non-tropical Northern Hemisphere. It is bordered by Capricornus to the north, Piscis Austrinus and Grus to the west, Sagittarius to the east, and Indus to the south, touching on Telescopium to the southeast. In the equatorial coordinate system, the right ascension coordinates of the constellation lie between 20h 27.3m and 21h 28.4m, while the declination coordinates are between −27.45° and −45.09°. The whole constellation is visible to observers south of latitude 45°N. Given that its brightest stars are of fifth magnitude, the constellation is invisible to the naked eye in areas with polluted skies.
Microscopium shown on Chart XVI of the Uranographia of Johann Bode (1801). For Lacaille’s original depiction of the constellation, click here. Next to it on this chart lies the obsolete constellation Globus Aerostaticus, the hot-air balloon.
[http://www.ianridpath.com/startales/microscopium.htm]
The stars that comprise Microscopium are in a region previously considered the hind feet of Sagittarius, a neighboring constellation. John Ellard Gore wrote that al-Sufi seems to have reported that Ptolemy had seen the stars but he (Al Sufi) did not pinpoint their positions. Microscopium itself was introduced in 1751-52 by Lacaille with the French name le Microscope, after he had observed and catalogued 10,000 southern stars during a two-year stay at the Cape of Good Hope. He devised fourteen new constellations in uncharted regions of the Southern Celestial Hemisphere not visible from Europe. All but one honored instruments that symbolized the Age of Enlightenment. Commemorating the compound microscope, the Microscope’s name had been Latinized by Lacaille to Microscopium by 1763.
[http://www.dibonsmith.com/mic_con.htm]
[http://www.davidmalin.com/fujii/source/Mic.html]
Gamma Microscopii is the brightest star in Microscopium. It has an apparent visual magnitude of 4.68 and is approximately 229 light years distant from Earth. It is a yellow giant star with the stellar classification of G6 III. It has a visual companion with an apparent magnitude of 13.7 at an angular separation of 26 arcseconds. Gamma Microscopii has 2.5 times the Sun’s mass, 10 times the solar radius, and is about 64 times more luminous than the Sun.
Epsilon Microscopii is the second brightest star in Microscopium. It has a visual magnitude of 4.72 and is approximately 165 light years distant from the solar system. It is a white main sequence dwarf with the stellar classification A1V.
Theta Microscopii consists of a wide double star, Theta-1 Microscopii and Theta-2 Microscopii, which can both be seen without binoculars. Both components belong to the spectral class A and are white magnetic spectrum variable stars that have strong metallic lines. Theta Microscopii is the third brightest star in the constellation and marks the microscope’s specimen slide. It has an apparent visual magnitude of 4.81 and is approximately 186 light years distant from the Sun. Theta-1 Microscopii is classified as an Alpha-2 Canum Venaticorum type variable.
Alpha Microscopii is only the fourth brightest star in the constellation. It is a variable star with an apparent magnitude that ranges from 4.88 to 4.94. The star is approximately 380 light years distant from Earth. Alpha Microscopii is a yellow giant belonging to the stellar class G7III. It has a visual companion with an apparent magnitude of 10 at a separation of 20.4 seconds of arc. The companion can be seen in a small telescope.
[http://www.constellation-guide.com/constellation-list/microscopium-constellation/]
AU Microscopii (AU Mic) is a small star located 32.3 light-years (9.9 parsecs) away- about 8 times as far as the closest star after the Sun. The apparent visual magnitude of AU Microscopii is 8.73, which is too dim to be seen with the naked eye. It was given this designation because it is in the southern constellation Microscopium and is a variable star. Like β Pictoris, AU Microscopii has a circumstellar disk of dust known as a debris disk:
[https://en.wikipedia.org/wiki/AU_Microscopii]
This image shows the sky around AU Microscopii. It was created from images forming part of the Digitized Sky Survey 2. AU Microscopii is an orangish star of moderate brightness in the center of the image.
Using images from ESO’s Very Large Telescope (VLT) in Chile and the NASA/ESA Hubble Space Telescope, a team of astronomers has discovered unique structures within the dusty disc around the nearby star AU Microscopii. According to the team, these fast-moving wave-like structures are unlike anything ever observed, or even predicted, before now.
AU Microscopii lies in the southern constellation Microscopium and is about 29 light-years away. It is a young star surrounded by a large disc of dust. The disc essentially comprises asteroids that have collided with such vigor that they have been ground to dust. The star is an optimal object to observe because the disk is tilted edge-on to our view from Earth. This allow for certain details in the disk to be better seen.
Astronomers have been searching AU Microscopii’s disc for any signs of clumpy or warped features, as such signs might give away the location of possible planets. And in 2014 they used imaging capabilities of VLT’s SPHERE instrument for their search- and discovered something very unusual.
Top and middle rows show Hubble images of the AU Microscopii disc from 2010 and 2011, the bottom row is an image taken with VLT’s SPHERE instrument in 2014. The black central circles show where the brilliant light of the central star has been blocked off to reveal the much fainter disc, and the position of the star is indicated schematically. The scale bar at the top of the picture indicates the diameter of the orbit of the planet Neptune in the Solar System (60 AU).
Five wave-like arches at different distances from the star show up in the SPHERE images, reminiscent of ripples in water:
“Our observations have shown something unexpected. The images from SPHERE show a set of unexplained features in the disc which have an arch-like, or wave-like, structure, unlike anything that has ever been observed before,” said Dr Anthony Boccaletti of the Paris Observatory.
After spotting the features in the SPHERE data Dr Boccaletti and his colleagues turned to earlier Hubble images of the disk, taken in 2010 and 2011. The astronomers were not only able to identify the features on the earlier Hubble images, but the team also discovered that the features had changed over time. They report that these ripples are moving, and they are moving very fast.
“We reprocessed images from the Hubble data and ended up with enough information to track the movement of these strange features over a four-year period. By doing this, we found that the arches are racing away from the star at speeds of up to about 22,000 miles per hour (10 km per second),” said co-author Dr Christian Thalmann of the Swiss Federal Institute of Technology in Zurich, Switzerland.
“Because nothing like this has been observed or predicted in theory we can only hypothesize when it comes to what we are seeing and how it came about,” said co-author Dr Carol Grady of Eureka Scientific in Oakland, California.
The features further away from the star seem to be moving faster than those closer to it. At least three of the features are moving so fast that they could well be escaping from the gravitational attraction of the star. Such high speeds rule out the possibility that these are conventional disc features caused by objects- like exoplanets- disturbing material in the disc while orbiting the star. There must have been something else involved to speed up the ripples and make them move so quickly, meaning that they are a sign of something truly unusual.
This set of images of a 40 billion-mile diameter edge-on disk encircling AU Microscopii reveals a string of wave-like features.
Dr Boccaletti and co-authors have also ruled out a series of phenomena as explanations, including the collision of two massive and rare asteroid-like objects releasing large quantities of dust and spiral waves triggered by instabilities in the system’s gravity. But other ideas that they have considered look more promising.
“One explanation for the strange structure links them to the star’s flares,” said co-author Dr Glenn Schneider of Steward Observatory. “AU Microscopii is a star with high flaring activity- it often lets off huge and sudden bursts of energy from on or near its surface. One of these flares could perhaps have triggered something on one of the planets- if there are planets- like a violent stripping of material which could now be propagating through the disc, propelled by the flare’s force,” he said.
The astronomers plan to continue to observe the AU Microscopii system with SPHERE and other facilities to try to understand what is happening. But, for now, these curious features remain an unsolved mystery.
[http://www.sci-news.com/astronomy/science-fast-moving-structures-au-microscopii-03318.html]
Lacaille 8760 (AX Microscopii) is a red dwarf star in the constellation Microscopium. Although it is generally too faint to be seen without a telescope, it is one of the nearest stars to the Sun at about 12.9 light-years’ distance. At an apparent magnitude of +6.7, it may only be visible to the unaided eye under exceptionally good viewing conditions, under dark skies. It was originally listed in a 1763 catalog that was published posthumously by the French Abbé Nicolas Louis de Lacaille. He observed it in the southern sky while working from an observatory at the Cape of Good Hope.
In the past Lacaille 8760 has been classified anywhere from spectral class K7 down to M2. In 1979 the Irish astronomer Patrick Byrne discovered that it is a flare star, and it was given the variable star designation AX Microscopii. As a flare star it is relatively quiet, only erupting on average less than once per day.
Lacaille 8760 orbits around the galaxy with a relatively high ellipticity of 0.23. Its closest approach to the Sun occurred about 20,000 years ago when it came within 12 light-years (3.7 parsecs). Due to its low mass (60% of the Sun), it has an expected lifespan of about 7.5 × 10^10 years, seven times longer than the Sun’s.
Despite efforts by astronomers, as of 2011 no planets have been detected in orbit around this star.
Lacaille 8760 is one of the largest and brightest red dwarfs known, with about 60% the mass and 51% the radius of the Sun.
[https://en.wikipedia.org/wiki/Lacaille_8760]
WASP-7, also identified as HD 197286, is a type F star located about 456 light years away in the constellation Microscopium. This star is a little larger and about 28% more massive than the Sun and is also brighter and hotter. At magnitude 9 the star cannot be seen by the naked eye but is visible through a small telescope.
The SuperWASP project announced an extrasolar planet, WASP-7b, orbiting this star in 2008. The planet appears to be another hot Jupiter, a dense planet with Jupiter’s mass orbiting very close to a hot star and thus emitting enough heat to shine.
[https://en.wikipedia.org/wiki/WASP-7]
[https://cgs.obs.carnegiescience.edu/CGS/object_html_pages/NGC6925.html]
NGC 6925 is an unbarred spiral galaxy in the constellation Microscopium of apparent magnitude 11.3. In the Catalogue of Named Galaxies, it is called Solitarius Microscopii, or the lonely galaxy. It is lens-shaped, as it lies almost edge on to observers on Earth. It lies 3.7 degrees west-northwest of Alpha Microscopii.
SN 2011ei, a Type II supernova in NGC 6925, was discovered by Stu Parker in New Zealand in July 2011:
[https://en.wikipedia.org/wiki/NGC_6925]
[http://www.bosssupernova.com/publishedwork.htm]
The Microscopium Supercluster is an overdensity of galaxy clusters that was first noticed in the early 1990s. The component Abell clusters 3695 and 3696 are likely to be gravitationally bound, while the relations of Abell clusters 3693 and 3705 in the same field are unclear.
The Microscopium Void is a roughly rectangular region of relatively empty space, bounded by incomplete sheets of galaxies from other voids.
The Microscopids are a minor meteor shower that appear from June to mid-July.
[https://en.wikipedia.org/wiki/Microscopium]
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