Chamaeleon is a very small constellation located near the South Pole. The constellation was named after the chameleon, a type of lizard. Australians sometimes call it the ‘Frying Pan.’ Chamaeleon is among the smallest constellations in the sky, 79th in size. It occupies an area of 132 square degrees. It lies in the second quadrant of the southern hemisphere (SQ2) and can be seen at latitudes between +0° and -90° and is best visible at 9 p.m. during the month of April. Constellations directly bordering Chamaeleon are Musca, Carina, Volans, Mensa, Octans and Apus.
[http://www.constellation-guide.com/constellation-list/chamaeleon-constellation/]
Chamaeleon as depicted on Chart XX of the Uranographia of Johann Bode (1801). Unlike in some representations it is ignoring the fly, Musca, which lies above its head, off the top of this illustration. Bode named and depicted Musca not as a fly but as Apis, the bee, as had Bayer before him.
The celestial chameleon, named after the lizard that can change its skin colour to match its mood, is one of the constellations representing exotic animals introduced by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman when they charted the southern skies in 1595–97. These new southern constellations were first shown on a globe by their fellow Dutchman Petrus Plancius in 1598 and were rapidly adopted by other map makers such as Johann Bayer, for no other observations of the far southern skies were then available. Chameleons are particularly common in Madagascar, where the Dutch fleet stopped to rest and resupply in 1595 on its way to the East Indies, so they probably saw plenty of them there.
Chamaeleon lies near the south celestial pole, next to Musca, the fly. On a globe of 1600, the Dutch cartographer Jodocus Hondius depicted the chameleon sticking out its tongue to catch the fly. Three years later, Johann Bayer in his Uranometria showed the chameleon in the same pose yet evidently failed to appreciate what the insect, then still unnamed, was supposed to be – he depicted it not as a fly but a bee and named it Apis, as did Bode nearly 200 years later.
[http://www.ianridpath.com/startales/chamaeleon.htm]
The modern constellation Chamaeleon is not included in the Three Enclosures and Twenty-Eight Mansions system of traditional Chinese uranography because its stars are too far south for observers in China to know about them prior to the introduction of Western star charts. Based on the work of Xu Guangqi and the German Jesuit missionary Johann Adam Schall von Bell in the late Ming Dynasty, this constellation has been classified as one of the 23 Southern Asterisms (Jìnnánjíxīngōu) under the name Little Dipper (Xiǎodǒu). The name of the western constellation in modern Chinese is (yǎn tíng zuò), meaning ‘the flying gecko constellation.’
[https://en.wikipedia.org/wiki/Chamaeleon_(Chinese_astronomy)]
[http://astropixels.com/constellations/charts/Cha.html]
[http://www.southernskyphoto.com/constellations/south_celestial_pole.htm]
There are four bright stars in Chamaeleon. Alpha Chamaeleontis is a white-hued star of magnitude 4.1, 63 light-years from Earth. Beta Chamaeleontis is a blue-white hued star of magnitude 4.2, 27 light-years from Earth. Gamma Chamaeleontis is a red-hued giant star of magnitude 4.1, 413 light-years from Earth. The other bright star in Chamaeleon is Delta Chamaeleontis, a wide double star. The brighter star is Delta2 Chamaeleontis, a blue-hued star of magnitude 4.4, 364 light-years from Earth. Delta1 Chamaeleontis, the dimmer component, is an orange-hued giant star of magnitude 5.5, 354 light-years away.
[http://exoplanets.seti.org/hd-63454/]
HD 63454 is a ninth magnitude K-type main sequence star located approximately 117 light-years away in the constellation of Chamaeleon. It is somewhat cooler and less luminous than our Sun. To see the star one needs a small telescope. It is located near the south celestial pole and is never visible north of latitude 12°N. On Valentine’s Day 2005, a hot Jupiter, HD 63454 b was found. The planet has 0.38 times the mass of Jupiter, and an orbital period of 2.8 days.
[https://en.wikipedia.org/wiki/HD_63454]
A size comparison between the colossal planet CT Chamaeleontis b and Jupiter.
CT Chamaeleontis (CT Cha) is a T Tauri star in the constellation of Chamaeleon, with an apparent visual magnitude which varies between 12.31 and 12.43.
In 2006 and 2007, a faint companion was observed 2.7 arcseconds away from CT Chamaeleontis, using the Very Large Telescope at the European Southern Observatory. Since the object shares common proper motion with CT Chamaleontis, it is believed to be physically close to the star, with a projected separation of approximately 440 astronomical units. It is estimated to have a mass of approximately 17 Jupiter masses and is probably a brown dwarf or a planet. The companion has been designated CT Chamaeleontis b.
[https://en.wikipedia.org/wiki/CT_Chamaeleontis]
HD 97048 or CU Chamaeleontis is a young star, in the constellation Chamaeleon, which has a substantial dust disk:
Artist’s impression of a flared proto-planetary disc, similar to what has been deduced from VISIR observations on ESO’s Very Large Telescope around the 2.5 solar mass star HD 97048.
[https://www.eso.org/public/images/eso0636a/]
The disks of gas, dust and debris that surround young stars are breeding grounds for planets, a premise that every new exoplanet detection seems to confirm. But we know little about the disks themselves, and a key area of uncertainty continues to be the nature of disks around stars more massive than the Sun. What effect, for example, does their luminosity have on the disk, and how do the processes of large star formation affect planetary systems?
The European Southern Observatory’s Very Large Telescope is providing data that will shape a more refined view of these disks. At the heart of these new studies is HD 97048, a star some 600 light years away in the stellar spawning ground known as the Chameleon 1 dark cloud. HD 97048 is two and a half times as massive as the Sun, and fully forty times more luminous, making it ideal for such study.
Infrared mapping of this star’s disk with ESO’s VISIR (VLT Imager and Spectrometer for the InfraRed) instrument shows a huge, flared disk, reaching twelve times further than the orbit of Neptune. “This is,” says Pierre-Olivier Lagage, leader of the team that carried out the observations, “the first time such a structure, predicted by some theoretical models, is imaged around a massive star.”
Unclear of the meaning of the word ‘flared’ in this context, I checked with Dr. Lagage. His answer: “A flared disk is a disk whose thickness increases rapidly when going further away from the star, so that any point at the surface from the disk is in direct view from the star.”
Astronomers on Lagage’s team estimate the disk must contain a large amount of gas, amounting to ten times the mass of Jupiter, and perhaps 50 Earth masses worth of dust. That would make for a dust mass about a thousand times larger than what we’ve yet seen around older stars like Beta Pictoris, Fomalhaut and Vega. Lagage again: “From the structure of the disc, we infer that planetary embryos may be present in the inner part of the disc.”
In other words, the older stars mentioned contain dusty disks filled with debris thought to be the result of larger bodies colliding. We can do measurements on the dust but we have yet to detect the parent bodies that spawned it. Add up the mass of the dust and the presumed bodies that produced it and you get a mass similar to what is being seen around HD 97048. The young star’s disk, then, is simply much less evolved, a precursor for later planet formation.
[http://www.centauri-dreams.org/?p=839]
Chamaeleon is also the location of Cha 110913, a unique dwarf star or proto solar system:
This artist’s concept compares a hypothetical solar system centered around a tiny ‘sun’ (top) to a known solar system centered around a star, called 55 Cancri, which is about the same size as our sun.
A Planet With Planets? Spitzer Finds Cosmic Oddball
Planets are everywhere these days. They have been spotted around more than 150 stars, and evidence is growing that they also circle ‘failed,’ or miniature, stars called brown dwarfs. Now, astronomers using NASA’s Spitzer Space Telescope say they have found what may be planets-in-the-making in the strangest of places - around a brown dwarf that itself is the size of a planet.
The little brown dwarf, called Cha 110913-773444, is one of the smallest known. At eight times the mass of Jupiter, it is even smaller than several planets around other stars.
Yet, this tiny orb might eventually host a tiny solar system. Spitzer’s infrared eyes found, swirling around it, a flat disk made up of dust that is thought to gradually clump together to form planets. Spitzer has previously uncovered similar planet-forming disks around other brown dwarfs, but Cha 110913-773444 is the true dwarf of the bunch.
“Our goal is to determine the smallest ‘sun’ with evidence for planet formation,” said Dr. Kevin Luhman, lead author of a new paper describing the findings. “Here, we have a sun that is so small it is the size of a planet.”
Brown dwarfs are born like stars, condensing out of thick clouds of gas and dust. But unlike stars, brown dwarfs do not grow large enough to trigger nuclear fusion. They remain relatively cool spheres of gas and dust.
Astronomers have become more confident in recent years that brown dwarfs share another trait in common with stars- planets. The evidence is in the planet-forming disks. Such disks are well-documented around stars, but only recently have they been located in increasing numbers around brown dwarfs. So far, Spitzer has found dozens of disk-sporting brown dwarfs, five of which show the initial stages of the planet-building process. The dust in these five disks is beginning to stick together into what may be the ‘seeds’ of planets.
Last year, Luhman and his colleagues used Spitzer to uncover what was then the smallest of brown dwarfs hugged by a disk. At only 15 times the mass of Jupiter, the brown dwarf, called OTS 44, is comparable to the most massive extrasolar planets.
Now, the team has again used Spitzer, this time to detect a disk around Cha 110913-773444, which has only about half the mass of OTS 44. The object itself was discovered by Spitzer with the help of NASA’s Hubble Space Telescope, the 4-meter Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile and the Gemini South Observatory, also in Chile. Its cool and dusty disk, however, could be seen by only Spitzer’s infrared eyes. The teeny brown dwarf is young at 2 million years old, and lives 500 light-years away in the Chamaeleon constellation.
So, what makes this oddball a brown dwarf and not a planet? “There are two camps when it comes to defining planets versus brown dwarfs,” said Dr. Giovanni Fazio, co-author of the new paper. “Some go by size and others go by how the object formed. For instance, this new object would be called a planet based on its size, but a brown dwarf based on how it formed. The question then becomes what do we call any little bodies that might be born from this disk- planets or moons?”
If one were to call the object a planet, then it would seem Spitzer has discovered its first ‘moon-forming’ disk. But, no matter what the final label may be, one thing is clear: the universe produces some strange solar systems very different from our own.
[http://www.nasa.gov/vision/universe/starsgalaxies/spitzerf-20051129.html]
In 1999, a nearby open cluster was discovered centered on the star η Chamaeleontis. The cluster, known as either the Eta Chamaeleontis cluster or Mamajek 1, is 8 million years old, and lies 316 light years from Earth:
Eta Chamaeleontis
[https://it.wikipedia.org/wiki/Associazione_di_Eta_Chamaeleontis]
This unique star cluster was discovered in 1999 by Eric Mamajek, Warick Lawson, and Eric Feigleson. The researchers have determined that the Eta Chamaeleontis Cluster is about 8 million years old! This is an open cluster meaning that all of the stars were formed by the same molecular cloud. This cluster is 316 light years away. There are 20 stars that reside in this 40arc minutes long cluster. This cluster is located at right ascension 8hours 42 minutes 6 second and declination -79 degrees 1arc minutes and 38 arc seconds. This cluster has proven to be extremely important for future research with PMS stars. This means pre- main- sequence stars which can be described as stars that have not reached main sequence. Main sequence is how we plot stars based on mass, and chemical composition.
[http://www.barransclass.com/astr1070/const/Chamaeleon/Chamaeleon.html]
Chamaeleon contains one planetary nebula, NGC 3195, which is fairly faint. It appears in a telescope at about the same apparent size as Jupiter:
A Hubble Space Telescope (HST) image of NGC 3195
NGC 3195 is the most southern of all the bright sizable planetary nebula in the sky, and remains invisible to all northern observers. Discovered by Sir John Herschel in 1835, this 11.6 apparent magnitude planetary nebula is slightly oval in shape, with dimensions of 40×35 arc seconds, and can be seen visually in telescopic apertures of 10.5 centimeters (4.1 in) at low magnifications. Distance is estimated at about 1.7 kpc.
[https://en.wikipedia.org/wiki/NGC_3195]
The constellation contains a number of molecular clouds (the Chamaeleon dark clouds) that are forming low-mass T Tauri stars. The cloud complex lies some 400 to 600 light years from Earth, and contains tens of thousands of solar masses of gas and dust. The most prominent cluster of T Tauri stars and young B-type stars are in the Chamaeleon I cloud, and are associated with the reflection nebula IC 2631:
A Chamaeleon Sky
A photogenic group of nebulae can be found toward Chamaeleon, a constellation visible predominantly in skies south of the Earth’s equator. Celestial objects visible there include the blue reflection nebulas highlighted by thin dust surrounding the bright stars in the above image center. Toward the top and lower right, dark molecular clouds laced with thick dust block light from stars in the background. The parent molecular cloud Chamaeleon I is located about 450 light years from Earth.
[http://apod.nasa.gov/apod/ap020609.html]
Hubble Looks in on a Nursery for Unruly Young Stars
This striking new image, captured by the NASA/ESA Hubble Space Telescope, reveals a star in the process of forming within the Chameleon cloud. This young star is throwing off narrow streams of gas from its poles- creating this ethereal object known as HH 909A. These speedy outflows collide with the slower surrounding gas, lighting up the region.
When new stars form, they gather material hungrily from the space around them. A young star will continue to feed its huge appetite until it becomes massive enough to trigger nuclear fusion reactions in its core, which light the star up brightly.
Before this happens, new stars undergo a phase during which they violently throw bursts of material out into space. This material is ejected as narrow jets that streak away into space at breakneck speeds of hundreds of miles/kilometers per second, colliding with nearby gas and dust and lighting up the region. The resulting narrow, patchy regions of faintly glowing nebulosity are known as Herbig-Haro objects. They are very short-lived structures, and can be seen to visibly change and evolve over a matter of years- just the blink of an eye on astronomical timescales.
These structures are very common within star-forming regions like the Orion Nebula, or the Chameleon I molecular cloud- home to the subject of this image. The Chameleon cloud is located in the southern constellation of Chameleon, just over 500 light-years from Earth. Astronomers have found numerous Herbig-Haro objects embedded in this stellar nursery, most of them emanating from stars with masses similar to that of the sun. A few are thought to be tied to less massive objects such as brown dwarfs, which are ‘failed’ stars that did not hit the critical mass to spark reactions in their centers.
[http://www.nasa.gov/content/goddard/hubble-looks-in-on-a-nursery-for-unruly-young-stars/#.V6PBFDUrSXc]
An infant star lights up the nebula IC 2631 in this remarkable new image from the MPG/ESO 2.2-m telescope at ESO’s La Silla Observatory, Chile.
IC 2631, also known as Ced 112 and BRAN 341C, is a so-called reflection nebula, a dust cloud that reflects light from a nearby star into space, creating a stunning light show. This object is the brightest nebula in the Chamaeleon Complex, a large region of gas and dust clouds that harbors numerous newborn and still-forming stars. The complex is located in the southern constellation Chamaeleon, approximately 500 light-years away.
IC 2631 is illuminated by a very young star known as HD 97300. Despite its dominating presence, the heft of HD 97300 should be kept in perspective. It is a T Tauri star, the youngest visible stage for relatively small stars. As these stars mature and reach adulthood they will lose mass and shrink. But during the T Tauri phase these stars have not yet contracted to the more modest size that they will maintain for billions of years as main sequence stars.
Reflection nebula, like the one spawned by HD 97300, merely scatter starlight back out into space. Starlight that is more energetic, such as UV radiation pouring forth from very hot new stars, can ionize nearby gas, making it emit light of its own. These emission nebulae indicate the presence of hotter and more powerful stars, which in their maturity can be observed across thousands of light-years.
[http://www.sci-news.com/astronomy/reflection-nebula-ic2631-photo-03624.html]
[https://en.wikipedia.org/wiki/Chamaeleon]
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