Color-enhanced image of Pluto obtained from NASA’s New Horizons spacecraft in July 2015. (Credit: NASA / Johns Hopkins University Applied Physics Laboratory (JHUAPL) / Southwest Research Institute (SwRI))
What is the true definition of a planet, and could there be a more refined definition in the future? This is what a recent study published in The Planetary Science Journal hopes to address as a team of researchers from the United States and Canada investigated the potential for a new definition of a “planet”. This study holds the potential to challenge the longstanding definition outlined by the International Astronomical Union (IAU), which established IAU Resolution B5 in 2006, resulting in demoting Pluto from a “planet” to a “dwarf planet”.
The children’s poster of the Solar System that features Zoozve, Venus's quasi-moon. Credit: Alex Foster/Latif Nasser
Ask any astronomer, and they will tell you that all of the planets in the Solar System (including those “dwarf planets”) have satellites, with the exception of Mercury and Venus. However, that is not entirely the case, as Venus has what is known as a “quasi-moon” – a large asteroid that orbits the planet but is not gravitationally bound to it. In 2002, astronomer Brian Skiff discovered this body using the Discovery Telescope at the Lowell Observatory (where Clyde Tombaugh discovered Pluto). Until recently, this object was known by its official designation, 2002VE68.
However, on February 5th, 2024, the International Astronomical Union (IAU) conferred a new name for the object: Zoozve. The name was announced in a bulletin (vol. 4, no. 5) issued by the IAU’s Working Group for Small Bodies Nomenclature (WGSBN). The IAU, which is responsible for naming celestial objects, traditionally prefers to assign names that come from mythological traditions to objects that cross Earth’s orbit. But in this case, the origins of Zoozve’s strange name are more of (to quote Bob Ross) a “happy accident,” where a children’s poster that showed the object led to a conversation and an official request.
Welcome to another edition of Constellation Friday! Today, in honor of the late and great Tammy Plotner, we take a look at “the Furnace” – the Fornax constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age. This list has since come to be expanded to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today.
Among the updated list is the constellations Fornax, a relatively obscure constellation in the southern sky that is noted for the many bright galaxies it is associated with (the Fornax Cluster). This constellation was added French astronomer Nicolas Louis de Lacaille in the mid-18th century and is therefore part of the Lacaille family, which includes with Antlia, Caelum, Circinus, Horologium, Mensa, Microscopium, Norma, Octans, Pictor, Reticulum, Sculptor, and Telescopium.
Within the framework of its 100th anniversary commemorations, the International Astronomical Union (IAU) is organising the IAU100 NameExoWorlds global competition that allows any country in the world to give a popular name to a selected exoplanet and its host star. Image Credit: IAU/L. Calçada
When it comes to naming all those exoplanets that astronomers keep finding, it’s up to the International Astronomical Union (IAU) to do the job. In an effort to reach out to the global community, they’re running a new contest. In honour of their 100 year anniversary, the IAU has organized the 100IAU NameExoWorlds event.
The heart-shaped region of Pluto's surface was formed at least in part by a cataclysmic "splat," scientists say. (Credit: NASA / JHUAPL / SwRI)
In 2006, during their 26th General Assembly, the International Astronomic Union (IAU) passed a resolution to adopt a formal definition for the term “planet”. According to this definition, bodies that orbit the Sun, are spherical, do not orbit other bodies, and have cleared their orbits were designated planets. Pluto, and other such bodies that did not meet all of these requirements, would thereafter be designated as “dwarf planets”.
However, according to a new study led by Philip T. Metzger – a planetary scientists from the Florida Space Institute (at the University of Central Florida) – the IAU’s standard for classifying planets is not supported by the research literature on Pluto, and is therefore invalid. For those people who have maintained that “Pluto is still planet” for the past twelve years, this is certainly good news!
Welcome to the 575th Carnival of Space! The Carnival is a community of space science and astronomy writers and bloggers, who submit their best work each week for your benefit. We have a fantastic roundup today including news from the IAU, so now, on to this week’s worth of stories! Continue reading “Carnival of Space #575”
Map projection of Charon, the largest of Pluto’s five moons, annotated with its first set of official feature names. With a diameter of about 1215 km, the France-sized moon is one of largest known objects in the Kuiper Belt, the region of icy, rocky bodies beyond Neptune. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
In 2015, the New Horizons mission made history by being the first spacecraft to conduct a flyby of Pluto. In addition to revealing things about the planet’s atmosphere, its geology and system of moons, the probe also provided the first clear images of the surface of Pluto and its largest moon, Charon. Because of this, scientists are now able to study Pluto and Charon’s many curious surface features and learn more about their evolution.
Another interesting thing that has resulted from this surface imaging has been the ability to name these features. Recently, the IAU Working Group for Planetary System Nomenclatureofficially approved of a dozen names that had been proposed by NASA’s New Horizons team. These names honor legendary explorers and visionaries, both real and fictitious, and include science fiction authors Octavia Butler and Arthur C. Clarke.
Aside from being Pluto’s largest moon, Charon is also one of the larger bodies in the Kuiper Belt. Because of its immense size, Charon does not orbit Pluto in the strictest sense. In truth, the barycenter of the Pluto-Charon system is outside Pluto, meaning the two bodies almost orbit each other. The moon also has a wealth of features, which include valleys, crevices, and craters similar to what have been seen on other moons.
Artist’s impression of New Horizons’ close encounter with the Pluto–Charon system. Credit: NASA/JHU APL/SwRI/Steve Gribben
For some time, the New Horizons team has been using a series of informal names to describe Charon’s many features. The team gathered most of them during the online public naming campaign they hosted in 2015. Known as “Our Pluto“, this campaign consisted of people from all over the world contributed their suggestions for naming features on Pluto and Charon.
The New Horizons team also contributed their own suggestions and (according to the IAU) was instrumental in moving the new names through approval. As Dr. Alan Stern, the New Horizon team leader, told Universe Today via email: “We conduced a public feature name bank process in 2015 before flyby. Once flyby was complete our science team created a naming proposal for specific features and sent it to IAU.”
A similar process took place last year, where the IAU officially adopted 14 place names that were suggested by the New Horizons team – many of which were the result of the online naming campaign. Here too, the names were those that the team had been using informally to describe the many regions, mountain ranges, plains, valleys and craters that were discovered during the spacecraft’s flyby.
The names that were ultimately selected honored the spirit of epic exploration, which the New Horizons mission demonstrated by being the first probe to reach Pluto. As such, the names that were adopted honored travelers, explorers, scientists, pioneering journeys, and mysterious destinations. For example, Butler Mons honors Octavia E. Butler, a celebrated author and the first science fiction writer to win a MacArthur fellowship.
Global map of Pluto’s moon Charon pieced together from images taken at different resolutions. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Similarly, Clarke Montes honors Sir Arthur C. Clarke, the prolific writer and futurist who co-wrote the screenplay for 2001: A Space Odyssey (which he later turned into a series of novels). Stanley Kubrik, who produced and directed 2001: A Space Odyssey, was also honored with the feature Kubrik Mons. Meanwhile, several craters were named in honor of fictional characters from famous stories and folklore.
The Revati Crater is named after the main character in the Hindu epic narrative Mahabharata while the Nasreddin Crater is named for the protagonist in thousands of folktales told throughout the Middle East, southern Europe and parts of Asia. Nemo Crater honors the captain of the Nautilus in Jule’s Verne’s novels Twenty Thousand Leagues Under the Sea (1870) and The Mysterious Island (1874).
The Pirx Crater is name after the main character in a series of short stories by Polish sci-fi author Stanislaw Lem, while the Dorothy Crater takes its name from the protagonist in The Wizard of Oz, one of several children’s stories by L. Frank Baum that was set in this magical land.
As Rita Schulz, chair of the IAU Working Group for Planetary System Nomenclature, commented, “I am pleased that the features on Charon have been named with international spirit.” Dr. Alan Stern expressed similar sentiments. When asked if he was happy with the new names that have been approved, he said simply, “Very.”
Artist’s impression of NASA’s New Horizons spacecraft encountering 2014 MU69 (Ultima Thule), a Kuiper Belt object that orbits 1.6 billion km (1 billion mi) beyond Pluto, on Jan. 1st, 2019. Credits: NASA/JHUAPL/SwRI/Steve Gribben
Even though the encounter with the Pluto system happened almost three years ago, scientists are still busy studying all the information gathered during the historic flyby. In addition, the New Horizons spacecraft will be making history again in the not-too-distant future. At present, the spacecraft is making its way farther into the outer Solar System with the intention of rendezvousing with two Kuiper Belt Objects.
On Jan. 1st, 2019, it will rendezvous with its first destination, the KBO known as 2014 MU69 (aka. “Ultima Thule“). This object will be the most primitive object ever observed by a spacecraft, and the encounter will the farthest ever achieved in space exploration. Before this intrepid exploration mission is complete, we can expect that a lot more of the outer Solar System will be mapped and named.
The two brightest stars of the Centaurus constellation - (left) Alpha Centauri and (right) Beta Centauri. The faint red star in the center of the red circle is Proxima Centauri. Credit: Wikipedia Commons/Skatebiker
What springs to mind when we think of the most commonly-known stars in the night sky? Chances are, it would be stars like Sirius, Vega, Deneb, Rigel, Betelgeuse, Polaris, and Arcturus – all of which derive their names from Arabic, Greek or Latin origins. Much like the constellations, these names have been passed down from one astronomical tradition to another and were eventually adopted by the International Astronomical Union (IAU).
But what about the astronomical traditions of Earth’s many, many other cultures? Don’t the names they applied to heavens also deserve mention? According to the IAU, they do indeed! After a recent meeting by the Working Group on Star Names (WGSN), the IAU formally adopted 86 new names for stars drawn largely from the Australian Aboriginal, Chinese, Coptic, Hindu, Mayan, Polynesian, and South African peoples.
The WGSN is an international group of astronomers tasked with cataloging and standardizing the star names used by the international astronomical community. This job entails establishing IAU guidelines for the proposals and adoption of names, searching through international historical and literary sources for star names, adopting names of unique historical and cultural value, and maintaining and disseminating the official IAU star catalog.
Star map painting by Senior Wardaman Elder Bill Yidumduma Harney, featuring the Milky Way, the Moon, and ancestor spirits. Credit: IAU
Last year, the WGSN approved the names for 227 stars. With these latest additions, the catalog now contains the names of 313 stars. Unlike standard star catalogs containing millions or billions of stars designated using strings of letters and numbers, the IAU star catalog consists of bright stars with proper names derived from historical and cultural sources. As Eric Mamajek, chair and organizer of the WGSN, indicated in an IAU press release:
“The IAU Working Group on Star Names is researching traditional star names from cultures around the world and adopting unique names and spellings to avoid confusion in astronomical catalogues and star atlases. These names help ensure that intangible astronomical heritage from skywatchers around the world, and across the centuries, are preserved for use in an era of exoplanetary systems.”
A total of eleven Chinese star names were incorporated into the catalog, three of which are derived from the “lunar mansions” of traditional Chinese astronomy. This refers to vertical strips of the sky that act as markers for the progress of the Moon across the sky in the course of a year. In this sense, they provide a basis for the lunar calendar in the same way that the zodiac worked for Western calendars.
Two names were derived from the ancient Hindu lunar mansions as well. These stars are Revati and Bharani, which designate Zeta Piscium and 41 Arietis, respectively. In addition to being a lunar mansion, Revati was also the daughter of King Kakudmi in Hindu mythology and the consort of the God Balarama – the elder brother of Krishna. On the other hand, Bharani is the name for the second lunar mansion in Hindu astronomy and is ruled by Shurka (Venus).
Position of the Hindu Nakshatra Mandala, the “lunar mansions” in Hindu mythology. Credit: Wikipedia Commons/ Kishorekumar 62
Beyond the astronomical traditions of India and China, there are also two names adopted from the Khoikhoi people of South Africa and the people of Tahiti – Xamidimura and Pipirima. These names were approved for Mu¹ and Mu² Scorpii, the stars that make up a binary system located in the constellation of Scorpius. Xamidimura is derived from the Khoikhoi name for the star xami di mura – literally “eyes of the lion.”
Pipirima refers to the inseparable twins from Tahitian mythology, a boy and a girl who ran away from their parents and became stars in the night sky. Then you have the Yucatec Mayan name Chamukuy, a small bird that now designates the star Theta-2 Tauri, which is located in the Hyades star cluster in Taurus.
Four Aboriginal Australian star names were also added to the catalog, including the Wardaman names Larawag, Ginan, and Wurren and the Boorong name Unurgunite. These names now designate Epsilon Scorpii, Epsilon Crucis, Zeta Pheonicis, and Sigma Canis Majoris, respectively. Given that Aboriginal Australians have traditions that go back as far as 65,000 years, these names are some of the oldest in existence.
The brightest star to receive a new name was Alsephina, which was given to the star previously designated as Delta Velorum. The name stems from the Arabic name al-safinah (“the ship”), which refers to the ancient Greek constellation Argo Navis (the ship of the Argonauts). This name goes back to the 10th-century Arabic translation of the Almagest, which was compiled by Ptolemy in the 2nd century CE.
Artist’s concept of exoplanets orbiting a red dwarf star. Credit: NASA/JPL-Caltech
The new catalog also includes Barnard’s Star, a name that has been in common usage for about a century but was never an official designation. This red dwarf star, which is less than six light-years from Earth, is named after the astronomer who discovered it – Edward Emerson Barnard – in 1916. It now joins Alsafi (Sigma Draconis), Achird (Eta Cassiopeiae), and Tabit (Pi-3 Orionis) as being one of four nearby stars whose proper names were approved in 2017.
One of the hallmarks of modern astronomy is how naming conventions are moving away from traditional Western and Classical sources and broadening to become more worldly. In addition to being a more inclusive, multicultural approach, it reflects the spirit of modern astronomical research and space exploration, which is characterized by international cooperation.
Someday, assuming our progeny ever go forth and begin to colonize distant star systems, we can expect that the stars and planets they come to know will have names that reflect the diverse astronomical traditions of Earth’s many cultures.
The Crater Constellation relative to others in the south sky. Credit: go-astronomy.com
Welcome to another edition of Constellation Friday! Today, in honor of the late and great Tammy Plotner, we take a look at “The Cup” – the Crater constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age
One of these constellation is Crater (aka. “The Cup”), an asterism located in the Southern Hemisphere. This small constellation is located south of the ecliptic plane, with no bright marker stars. As part of the Hercules family, it is bordered by the constellations of Leo, Sextans, Hydra, Corvus and Virgo. Today, it is one of the 88 modern constellations recognized by the International Astronomical Union.
Name and Meaning:
In Greek mythology, Crater represents the Cup of Apollo – the god of the skies – which is due to its chalice-like configuration. The cup is being held up by the Raven – Corvus – another figure in Greek mythology. The tale, much like many mythological stories, is a sad one, and begins with the Raven being sent to fetch water for his master, Apollo.
Unfortunately, Corvus (the Raven) was distracted as he became tempted by a fig, and then waited too long for it to ripen. When he realized his mistake, he returned sorrowfully to Apollo with his cup (Crater) and brought along the serpent Hydra in his claws as well. Angry, Apollo tossed all three into the sky for all eternity, where they became part of the starry firmament.
Corvus, Crater and other constellations seen around Hydra. From Urania’s Mirror (1825). Credit: US Library of Congress
History of Observation:
The Crater constellation comes to us from Classical Antiquity and was recorded by Ptolemy in his 2nd-century CE tract the Almagest. However, it was also recognized by Chinese astronomers, where the stars associated with it were viewed as being part the Vermillion Bird of the South (Nan Fang Zhu Que). Along with the some of the stars from Hydra, they depict the Red Bird’s wings.
Notable Objects:
Crater has only a few bright stars associated with it and no Messier Objects. The brightest, Delta Crateris, is an orange giant located approximately 196 light yeas from Earth. The star is also known as Labrum (Latin for “the lip”), due to the fact that it was sometimes associated with the story of the Holy Grail.
Next is Alpha Crateris, an orange giant located approximately 174 light-years from Earth which is 80 times more luminous than our Sun. It is also known as Alkes, derived from the Arabic word alkas, which means “the cup”. Then there’s Beta Crateris, a white sub-giant that is located approximately 266 light years from Earth. This star is also known by the name Al Sharasif, which means “the ribs” in Arabic.
In terms of Deep Sky Objects, Crater has no associated Messier Objects, but a few galaxies can be found in its region of the night sky. These include the Crater 2 dwarf galaxy, a satellite galaxy of the Milky Way that is located approximately 380,000 light years from Earth. There’s also the spiral galaxy known as NGC 3511, which has a slight bar and is seen from Earth nearly edge-on.
The spiral galaxy NGC 3887, located in the constellation Crater. Credit: NASA (Wikisky)
There’s also the NGC 3887 and NGC 2981 spiral galaxies, and the RX J1131 quasar, which is located 6 billion light years away from Earth. Interestingly, the black hole at the center of this quasar was the first to have its spin directly measured by astronomers.
Finding Crater:
Crater is visible at latitudes between +65° and -90° and is best seen at culmination during the month of April. It is comprised of only 4 main stars, and 12 stars with Bayer/Flamsteed designations. In order to spot these stars, observers should begin by looking for the Alpha star (the “a” shape on their star map) with binoculars.
Situated some 174 light-years from Earth, Alpha Crateris (the star’s official designation) is a spectral class K1 star – an orange giant that’s a little different from the rest. This is because Alkes is a “high velocity” star, which means it moves far faster than the stars around it. Another thing that sets it apart is its high metal content, which according to some researchers, it may have picked up when it came from the inner, metal-rich part of the Galaxy.
Artist’s impression of Alkes – aka. Alpha Crateris – a K1 orange giant star in the Crater constellation. Credit: constellation-guide.com
Next, observers should look to Beta Crateris (the “B” shape on the map) which also goes by the name of Al Sharasif. This star is not an ordinary one either. For starters, Al Sharasif is about 265 light-years from our solar system, and it’s a white sub-giant star. To boot, it also has a low mass, white dwarf companion – which is why astronomers classify it as a Sirius-like system.
Next up is Delta Crateris – the “8” symbol on the map – which is an orange giant, spectral class K0III star with an apparent magnitude of 3.56. In time, this star will become an even larger giant, eventually turning into a Mira-type variable star before ending its life as a white dwarf. Oddly enough, Labrum has a very low metal content compared to its Crater-neighbors, containing about 40% as much iron as our own Sun.
At this point, observers with telescopes and have a look at Gamma Crateris – the “Y” shape on the map. Gamma Crateris is a fixed binary white dwarf star with an easy separation of 5.2″. Gamma itself is 89 light-years for Earth, which is rather hard to believe when you try to seek out the 9.5 stellar magnitude companion that accompanies it.
Although this is a disparate double star, it is still quite fun and easy to spot with a small telescope. For a challenge, try Iota Crateris – a close binary star with an 11th magnitude companion that’s only separated by 1.4″. Psi Crateris is an even closer binary. Both stars are within a half magnitude of each other, but the separation is only 0.2″.
Artist’s impression of white dwarf binary pair, a type of star system that describes Gamma Crateris. Credit: Andrew Taylor.
Next up is R Crateris, a variable star that can be observed with binoculars, and which is located at RA 10 56 Dec -17 47. You will notice it by its lovely red color and its nice change of magnitude, which goes from 8 to 9.5 in a period of about 160 days. And then there’s SZ Crateris, a magnitude 8.1 variable star. It is a nearby star system located about 44 light years from the Sun and is known as Gliese 425 – which in the past was known as Abt’s Star.
While there’s no brighter deep sky objects for binoculars or small telescopes, there are a couple of challenging galaxies in the Crater constellation that are well suited to a large aperture. Let’s start with the brightest – elliptical galaxy NGC 3962 – which is easy to spot (like all elliptical galaxies), though there’s not much detail to be seen. Even if it is not terribly exciting to behold, it is on the Herschel 400 observing list.
And then there’s NGC 3887 (11h47.1 -16 51), a nice spiral galaxy that’s only slightly fainter. It has two faint stars which accompany it and a stellar nucleus which occasionally makes an appearance and provides an opportunity for some very interesting viewing. Both of these galaxies are in the slightly fainter range, both being just under magnitude 11.
List of the stars that appear in the Crater constellation. Credit: IAU and Sky & Telescope magazine/Roger Sinnott & Rick Fienberg
Observers who are skilled with telescopes should also keep and eye out for NGC 3511 (11h03.4 -23 05), a spiral galaxy of magnitude 11.5. It is joined in the same field of view by NGC 3513, a barred spiral galaxy that is a full magnitude dimmer. People with larger telescopes should also take a crack at spotting NGC 3672 (11h25.0 -09 48), a faint spiral galaxy that nevertheless has nice halo and a bright, apparent nucleus.
And last, but not least, there is NGC 3981 (11h56.1 -19 54), a beautifully inclined, magnitude 12 spiral galaxy that has a bright nucleus, and which sometimes shows some spiral galaxy structure when observing conditions are right.
The Constellation Chamaeleon. Credit: Till Credner/AlltheSky.com
Welcome back to Constellation Friday! Today, in honor of the late and great Tammy Plotner, we will be dealing with that famous lizard that specializes at blending in – the Chamaeleon constellation!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the then-known 48 constellations. This treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come, effectively becoming astrological and astronomical canon until the early Modern Age.
In time, this list would come to be expanded as astronomers became aware of more asterisms in the night sky. One of these is Chamaeleon, a small constellation located in the southern sky that was first defined in the 16th century. This constellation was appropriately named, given its ability to blend into the background! Today, it is one of the 88 constellations recognized by the IAU.
Name and Meaning:
Since Chamaeleon was unknown to the ancient Greeks and Romans, it has no mythology associated with it, but it’s not hard to understand how it came about its fanciful name. As exploration of the southern hemisphere began, what biological wonders were discovered! Can you imagine how odd a creature that could change its skin color to match its surroundings would be to someone who wasn’t familiar with lizards?
Map of the dark molecular clouds associated with the Chamaeleon constellation. Credit: Roberto Mura
Small wonder that a constellation that blended right in with the background stars could be considered a “chamaeleon” or that it might be pictured sticking its long tongue out to capture its insectile constellation neighbor – Musca the “fly”!
History of Observation:
Chamaeleon was one of twelve constellations created by Pieter Dirkszoon Keyser and Frederick de Houtman between 1595 and 1597. Both were Dutch navigators and early astronomical explorers who made attempts to chart southern hemisphere skies. Their work was added to Johann Bayer’s “Uranometeria” catalog in 1603, where Chamaeleon was first introduced as one of the 12 new southern constellations and its stars given Bayer designations.
To this day, Chamaeleon remain as one of the 88 modern constellations recognized by the IAU and it is bordered by Musca, Carina, Volans, Mensa, Octans and Apus. It contains only 3 main stars, the brightest of which is 4th magnitude Alpha – but it also has 16 Bayer/Flamsteed designated stars within its boundaries.
Notable Features:
The Chamaeleon constellation is home to several notable stars. These include Alpha Chamaeleontis, a spectral type F5III star located approximately 63.5 light years from Earth. Beta Chamaeleontis is a main sequence star that is approximately 270 light years distant. This star is the third brightest in the constellation, after Alpha and Gamma Chamaeleontis.
Artist’s concept of “hot Jupiter”, a Jupiter-sized planet orbiting closely to its star. Credit: NASA/JPL-Caltech
And then there’s HD 63454, a K-type main sequence star located approximately 116.7 light years away. It lies near the south celestial pole and is slightly cooler and less luminous than the Sun. In February of 2005, a hot Jupiter-like planet (HD 63454 b) was discovered orbiting the star.
The “Chamaeleon” also disguises itself with a huge number of dark molecular clouds that are often referred to as the “Chamaeleon Cloud Complex”. Situation about 15 degrees below the galactic plane, it is accepted is one of the closest low mass star forming regions to the Sun with a distance of about 400 to 600 light years.
Within these clouds are pre-main sequence star candidates, and low-mass T Tauri stars. The southern region of the Chamaeleon Cloud is a complex pattern of dark knots connected by elongated, dark, wavy filaments, with a serpentine-like shape. Bright rims with finger-like extensions are apparent, and a web of very faint, extremely thin but very long and straight shining filaments.
These feeble structures, reflecting stellar light, extend over the entire Chamaeleon complex and are considered very young – not yet capable of the type of collapse needed to introduce major star formation. Thanks to Gemini Near Infrared Spectrograph (GNIRS) on Gemini South Telescope, a very faint infrared object confirmed – a very low-mass, newborn brown dwarf star and the lowest mass brown dwarf star found to date in the Chamaeleon I cloud complex.
A newly formed star lights up the surrounding cosmic clouds in this image from ESO’s La Silla Observatory in Chile. Credit: ESO
Chamaeleon is also home to the Eta Chamaeleontis Cluster (aka. Mamajek 1). This open star cluster, which is centered on the star Eta Chamaeleontis, is approximately 316 light years distant and believed to be around eight million years old. The cluster was discovered in 1999 and consists of 12 or so relatively young stars. It was also the first open cluster discovered because of its X-ray emissions its member stars emit.
Finding Chamaeleon:
Chamaeleon is visible at latitudes between +0° and -90° and is best seen at culmination during the month of April. Now take out your telescope and aim it towards Eta for a look at newly discovered galactic star cluster – the Eta Chamaeleontis cluster – Mamajek 1. In 1999, a cluster of young, X-ray-emitting stars was found in the vicinity of eta Chamaeleontis from a deep ROSAT high-resolution imager observation.
They are believed to be pre-main-sequence weak-lined T Tauri stars, with an age of up to 12 million years old. The cluster itself is far from any significant molecular cloud and thus it has mysterious origins – not sharing proper motions with other young stars in the Chamaeleon region. There’s every possibility it could be a moving star cluster that’s a part of the Scorpius/Centaurus OB star association!
For binoculars, take a look at fourth magnitude Alpha Chamaeleontis. It is a rare class F white giant star that is about 63.5 light years from Earth. It is estimated to be about 1.5 billion years old. Its spectrum shows it to be a older giant with a dead helium core, yet its luminosity and temperature show it to be a younger dwarf.
The location of the Chamaeleon Constellation. Credit: IAU /Sky&Telescope magazine
Now point your binoculars or telescope towards Delta Chamaeleontis. While these two stars aren’t physically connect to one another, the visual double star is exceptionally pleasing with one orange component and one blue.
Last, but not least, take a look at Gamma Chamaeleontis. Although the south celestial pole currently lacks a bright star like Polaris to mark its position, the precession of the equinoxes will change that. One day – in the next 7500 years – the south celestial pole will pass close to the stars Gamma Chamaeleontis. But don’t wait up…
