Tammy was a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.
(Tammy passed away in early 2015... she will be missed)
The Lagoon Nebula, as imaged by the VLT Survey Telescope (VST) at ESO's Paranal Observatory in Chile. Credit: ESO/VPHAS
Welcome to another Messier Monday. In our ongoing tribute to the great Tammy Plotner, we bring you another item from the Messier Catalog!
In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. In time, he would come to compile a list of approximately 100 of these objects, with the purpose of making sure that astronomers did not mistake them for comets. However, this list – known as the Messier Catalog – would go on to serve a more important function, acting as a milestone in the history of the study of Deep Sky Objects.
However, not all objects in the catalog were first discovered by Charles Messier himself. Some, like the Lagoon Nebula, were observed sooner, owing to the fact that they are visible to the naked eye. This interstellar cloud, which is located in the Sagittarius constellation, has been known of since the late 17th century, and is one of only two star-forming nebulae that is visible to the naked eye from mid-northern latitudes.
The Aquila Constellation, aka "The Eagle". Credit: eaae-astronomy.org
Welcome to another edition of Constellation Friday! Today, we honor our dear friend and honored colleague, Tammy Plotner, by taking a look at the Aquila Constellation. Enjoy!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) released one of the most influential books in the history of astronomy. Known as the Almagest, this book included the 48 then-known constellation into a system of cosmology that would remain influential for over a thousand years. Among the 48 constellations listed in this book was Aquila, a constellation in the northern sky that extends across the celestial equator.
Messier 7, open cluster in Scorpius. Image taken from Stellarium. Credit: Roberto Mura
Welcome to another Messier Monday. In our ongoing tribute to the great Tammy Plotner, we bring you another item from the Messier Catalog!
In the 18th century, while searching the night sky for comets, French astronomer Charles Messier kept noting the presence of fixed, diffuse objects in the night sky. In time, he would come to compile a list of approximately 100 of these objects, with the purpose of making sure that astronomers did not mistake them for comets. However, this list – known as the Messier Catalog – would go on to serve a more important function.
However, not all of the Messier Objects were first observed in the 18th century. Some, like Messier 7 cluster (aka. NGC 6475 or the Ptolemy Cluster) have been known about since classical antiquity. As the name would suggest, this open star cluster was first observed in the 2nd century CE by Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy), who described it as a nebula in 130 CE.
Welcome back to Messier Monday! We continue our tribute to our dear friend, Tammy Plotner, by looking at Messier 6, otherwise known as NGC 6405 and the Butterfly Cluster. Enjoy!
In the late 18th century, Charles Messier was busy hunting for comets in the night sky, and noticed several “nebulous” objects. After initially mistaking them for the comets he was seeking, he began to compile a list of these objects so other astronomers would not make the same mistake. Known as the Messier Catalog, this list consists of 100 objects, consisting of distant galaxies, nebulae, and star clusters.
This Catalog would go on to become a major milestone in the history of astronomy, as well as the study of Deep Sky Objects. Among the many famous objects in this catalog is M6 (aka. NGC 6405), an open cluster of stars in the constellation of Scorpius. Because of its vague resemblance to a butterfly, it is known as the Butterfly Cluster.
Aquarius the "Water Bearer" is a large but faint constellation in the Southern sky. Credit: Stellarium
Welcome back to Constellation Friday! Today, we will be dealing with one of the best-known constellations, that “watery” asterism and section of the sky known as Aquarius. Cue the soundtrack from Hair!
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of all the-then known constellations. This work (known as the Almagest) would remain the definitive guide to astronomy and astrology for over a thousand years. Among the 48 constellations listed in this book was Aquarius, a constellation of the zodiac that stretches from the celestial equator to the southern hemisphere.
The globular cluster Messier 5, one of the oldest belonging to the Milky Way. Credit: NASA/ESA/HST
In the late 18th century, Charles Messier was busy hunting for comets in the night sky, and noticed several “nebulous” objects. After initially mistaking them for the comets he was seeking, he began to compile a list of these objects so other astronomers would not make the same mistake. Known as the Messier Catalog, this list consists of 100 objects, consisting of distant galaxies, nebulae, and star clusters.
Among the many famous objects in this catalog is the M5 globular star cluster (aka. NGC 5904). Located in the galactic halo within the Serpens Constellation, this cluster of stars is almost as old as the Universe itself (13 billion years)! Though very distant from Earth and hard to spot, it is a favorite amongst amateur astronomers who swear by its beauty.
The constellation Apus, located in the Southern Hemisphere. Credit: astropixels.com
Welcome back to Constellation Friday! Today, we will be dealing with the beautiful bird-of-paradise itself, the Apus constellation!
The Southern Hemisphere is replete with beautiful stars and constellations, enough to keep a stargazing enthusiast busy for a lifetime. For countless centuries, the indigenous peoples of South America, South Africa, Australia and the South Pacific have looked up at these stars and drawn inspiration. However, to European astronomers, they remained uncharted and unknown until the 16th century.
It was during this time that Flemish astronomer Petrus Plancius designated twelve constellations, using asterisms found in the southern skies. One such constellation was Apus, a faint constellation in the southern sky that is named for the bird-of-paradise – a beautiful bird that is indigenous to the South Pacific. Today, it is one of the 88 constellations defined by the International Astronomic Union (IAU).
Name and Meaning:
The name Apus is derived from Greek word apous, which literally means “no feet”. The name applies to a species of bird that is indigenous to Indonesia, Papua New Guinea, and Eastern Australia (which was believed at one time to have no feet). Its original name on Plancius’ charts was “Apis Indica” – the Latin term for “Indian Bee” (presumably an error for “avis”, which means bird).
This faint southern constellation of Apus was one of the original twelve created by Plancius, based on observations provided by Pieter Dirkszoon Keyser and Frederick de Houtman – two Dutch explorers/navigators who mapped the southern sky around Australia between 1595 and 1597.
It was included on a celestial globe published in 1597 or 1598 in Amsterdam by Plancius and his associate, Flemish cartographer and engraver Jodocus Hondius. After it’s introduction on Plancius’ globe, it also appeared in Uranometria, a star atlas published by Johann Bayer – a German celestial catrographer – in 1603.
Here, it appeared under the name “Apis Indica”. It also grouped with the other members of the “Johann Bayer family” of constellations, all of which appeared in Uranometria. These include Chamaeleon, Dorado, Grus, Hydrus, Indus, Musca, Pavo, Phoenix, Tucana, and Volans. The constellation also appears as part of the Chinese constellations, where it is known as the “Little Wonder Bird”.
In the 17th century, Ming Dynasty astronomer Xu Guangqi adapted the European southern hemisphere constellations when producing The Southern Asterisms. Combining Apus with some of the stars in Octans, he designated the stars in this area of the night sky into the constellation known as Yìquè (“Exotic Bird”). In 1922, Apus was included by the International Astronomical Union in the list of 88 constellations.
The southern constellation Apus and neighboring Deep Sky Objects. Credit: absoluteaxarquia.com
Notable Features:
Within the Apus constellation, there are 39 stars that are brighter than or equal to apparent magnitude 6.5. The most notable of these is Alpha Apodis. an orange giant star with a magnitude of 3.8, located roughly 411 light years away from Earth. Beta Apodis is also an orange giant, with a magnitude of 4.2. and located 158 light years from Earth. And Gamma Apodis , another orange giant, has a magnitude of 3.9 and is located 160 light years away.
Delta Apodis is a binary star system consisting of a red giant and an orange giant. Delta¹ has a magnitude of 4.7 and is located 765 light years away, while Delta² has a magnitude of 5.3 and is located 663 light years away. Then there is Theta Apodis, a variable red giant star with a maximum magnitude of 4.8 and a minimum of 6.1 that is located 328 light years away.
NO Apodis is a red giant that varies between magnitudes 5.71 and 5.95 and is located around 883 light-years away from Earth. This star shines with a luminosity that is approximately 2059 times greater than our Sun’s and has a surface temperature of 3568 K.
Apus is also home to a few Deep Sky Objects. These include the IC 4499 loose globular cluster (shown below), which is located in the medium-far galactic halo and has an apparent magnitude of 10.6. This object is rather unique in that its metallicity readings indicate that it is younger than most other globular clusters in the region.
NASA/ESA Hubble Space Telescope image of the globular cluster IC 4499, located in the Apus constellation. Credit: ESA/NASA/HST
Then there’s NGC 6101, a 14th mangitude globular cluster located seven degree north of Gamma Apodis. Last, there is the spiral galaxy IC 4633, which is very faint due to its location well within the Milky Way’s nebulous disc.
Finding Apus:
For binoculars, take a look at Alpha Apodis. This 3.8 magnitude star is located 411 light years away from Earth. Now move on to Delta. It is a wide double star which is two orange 5th-magnitude members separated by 103 arc seconds and an easy split. Or try observing Theta – its a variable star whose brightness ranges from magnitude 4.8 to 6.1 in a period of 109 days.
For telescopes, take a look at more difficult binary star Kappa-1 Apodis. The brightest component of this disparate pair has a magnitude of 5.4 and the companion is 12th magnitude, 27 arcseconds away. Need more? Then turn your gaze towards Kappa-2 only 0.63 degrees from Kappa-1. Kappa-1 Apodis is a binary star approximately 1020 light years from Earth. The primary component, Kappa-1 Apodis A, is a blue-white B-type subgiant with a mean apparent magnitude of +5.40. It is classified as a Gamma Cassiopeiae type variable star and its brightness varies from magnitude +5.43 to +5.61. The companion star, Kappa-1 Apodis B, is a 12th magnitude orange K-type subgiant. It is 27 arc seconds from the primary.
For larger telescopes, wander off and look at NGC 6101 located about seven degrees north of Gamma. Here we have a small, 14th magnitude globular cluster! If you’re really good you can try for spiral galaxy IC 4633. It’s so faint it doesn’t even have a magnitude listing!
This M4 globular cluster, as imaged by the Wide Field Imager at ESO’s La Silla Observatory. Credit: ESO
During the late 18th century, Charles Messier began to notice that a series of “nebulous” objects in the night sky that he originally mistook for comets. In time, he would notice that they were in fact something significantly different. With the hope of preventing other astronomers from making the same mistake, he began compiling a list of these in what would come to be known as the Messier Catalog.
Consisting of 100 objects, the catalog became an important milestone in both astronomy and the research of Deep Sky objects. Among the many famous objects in this catalog is the M4 loose globular cluster (aka. NGC 6121). Located in the Scorpius (Scorpio) Constellation, this great cluster of ancient stars is one of the closest Messier Objects of its kind to Earth.
In the 2nd century CE, Greek-Egyptian astronomer Claudius Ptolemaeus (aka. Ptolemy) compiled a list of the then-known 48 constellations. His treatise, known as the Almagest, would be used by medieval European and Islamic scholars for over a thousand years to come. Thanks to the development of modern telescopes and astronomy, this list was amended by the early 20th century to include the 88 constellation that are recognized by the International Astronomical Union (IAU) today.
One such constellation is Antlia, who’s name means “the Pump”. Discovered by French astronomer Nicolas Louis de Lacaille in the mid-eighteenth century, Antlia is located in a rather remote and open section of the southern skies, and was used to chart the southern hemisphere. Today, it is one of the 88 constellations recognized by the IAU.
Messier Object 3, as imaged by Adam Block at Mount Lemmon SkyCenter, University of Arizona. Credit: caelumobservatory.com
During the late 18th century, Charles Messier began to notice a series of “nebulous” objects in the night sky which he originally mistook for comets. With the hope of preventing other astronomers from making the same mistake, he began compiling a list of these in what would come to be known as the Messier Catalog. Consisting of 100 objects, the catalog became an important milestone in the discovery and research of Deep Sky objects.
One such object is Messier Object 3 (aka. M3 or NGC 5272) globular cluster that is located in the northern constellation of Canes Venatici. Since it was first observed, this globular star cluster has gone on to become one of the best-studied objects in the night sky, and is considered by many amateur astronomers to be one of the finest visible clusters.
