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Lowenthal -full books. Pfeiffer -Full Audiobook. Gallant -Full Audiobook. Holechek -full books. Arden B. Andersen -full books. Silverstein -Full Online. Zeta Sagittarii is another binary star in Sagittarius. It is the third brightest star in the constellation, after Epsilon and Sigma Sagittarii. The star is approximately Zeta Sagittarii consists of a class A2 giant star with an apparent magnitude of 3.

The binary system has a combined apparent magnitude of 2. The two stars are separated by Ascella also has a dim companion 75 arc seconds away. It is a 10th magnitude star. Phi Sagittarii is a B8 class giant approximately light years from Earth. It is one of the stars that form the Teapot asterism ; it marks the junction of the handle and the lid of the Teapot. Pi Sagittarii is a triple star system approximately light years distant, with an apparent magnitude of 2. It belongs to the spectral class F2II. The primary star has two companions; Pi Sagittarii B 0.

Like several other stars in Sagittarius, Albaldah is near the ecliptic and can occasionally be occulted by the Moon and planets. The next occultation by a planet Venus will take place in our lifetime: on February 17, The Gamma designation used to be shared by two star systems in Sagittarius, Gamma-1 and Gamma-2, which were separated by 0. Gamma Sagittarii is also known by its traditional names, Alnasl and Nushaba.

Tau Sagittarii is an orange giant star belonging to the spectral type K1 or K2, approximately light years distant. It is one of the stars that mark the handle of the Teapot asterism. It is located between Zeta and Sigma Sagittarii. It is a suspected binary star, even though a companion has never been confirmed.

Tau Sagittarii is well known to astronomers as the closest visible star to the origin of the Wow! Jerry R. Ehman on August 15, at the Ohio State University. It lasted for full 72 seconds, but has never been detected since. Eta Sagittarii is another multiple star system in Sagittarius. It is approximately light years distant. Before being assigned to Sagittarius, the star system was known as Beta Telescopii. Around the year , the system will have moved from Sagittarius to the Corona Australis constellation.

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The primary component in the Eta Sagittarii system is a type M3. The brightest companion star is an F class dwarf with an apparent magnitude of 7. The companion can be found 3. Another companion star is only 13th magnitude and can be seen 33 arc seconds away from the primary, while the faintest star in the system is 10th magnitude and is separated from the brightest star by 93 arc seconds. The Pistol Star is one of the most luminous stars known. It is a blue variable star that is about four million times as luminous as our Sun and times as massive. It has about a third of the luminosity of the Eta Carinae binary system in the constellation Carina and is believed to radiate as much energy in 20 seconds as the Sun does in a year.

Pistol Star and Nebula false colour composite image , photo: Don F. Located in the Galactic centre region, the Pistol Star lies approximately 25, light years from our solar system. Without the interstellar dust in the way, despite its distance it would be a fourth magnitude star, visible to the naked eye. The star was named after the shape of the nebula it illuminates, the Pistol Nebula. Peony Star, or WR ka, is one of the most luminous stars known in our galaxy. Named after the nebula that surrounds it — the Peony Nebula — the Peony Star is a Wolf-Rayet star with an absolute magnitude of It lies at a distance of 26, light years from Earth.

It must be observed in infrared wavelengths. Peony Star has an estimated mass of about solar masses and a radius 92 times solar. It is less that 3 million years old, but it has shed a lot of its initial mass and is expected to end its life in a supernova or hypernova explosion in the next few million years. VX Sagittarii, currently as of one of the five largest known stars in the Milky Way, is an evolved red supergiant or hypergiant M4eIa — M10eIa with a radius between 1, and 1, times that of the Sun and a mass 12 times solar. The star is classified as a semiregular variable of the SRc type.

It has an apparent magnitude that varies from 6. VX Sagittarii lies at an approximate distance of 5, light years from Earth. Its final helium flash is expected to occur in the next few decades. The bright star in the centre of this image is not the star of this show. At the bottom centre is a rather unremarkable smudge of red which is in fact a rare and valuable object.

The object is actually a small white dwarf star undergoing a helium flash — one of only a handful of examples of such an event ever witnessed by astronomers.

Normally, the white dwarf stage is the last in the life cycle of a low-mass star. In some cases, however, the star reignites in a helium flash and expands to return to a red giant state, ejecting huge amounts of gas and dust in the process, before once again shrinking to become a white dwarf. The white dwarf emits sufficient ultraviolet radiation to illuminate the gas it has expelled, which can just be seen in this image as the ring of red material.

Image: ESO. The star was discovered in February by Yukio Sakurai, an amateur astronomer. At the time, it was believed to be a magnitude By , the star became invisible in optical wavelengths as a result of being obscured by a very thick shell of dust. KW Sagittarii is one of the largest known stars. It is a red supergiant located about 10, light years from Earth, with an apparent magnitude varying between 8.

Mu Sagittarii is a multiple star system in Sagittarius, with individual components designated Polis A through Polis E. Polis is about 3, light years distant from Earth. The primary component in the star system is a class B giant 23 times as massive as the Sun, and , times more luminous. It is an eclipsing binary star, with a B8 supergiant star for a primary component and a B2 type giant as the companion star. The apparent magnitude of Polis A ranges from 3. Rho Sagittarii is a binary star with a subgiant belonging to the spectral class F0 as the primary component and a K0 type giant as the companion, separated by 0.

The subgiant has an apparent magnitude of 3. The companion star has an apparent magnitude of 5. Upsilon Sagittarii is a spectroscopic binary star. It is one of only four star systems known to be hydrogen-deficient, which makes it difficult to classify U Sgr. Most likely, the primary component is an A type supergiant. It is classified as an irregular variable star, with an apparent magnitude varying from 4.

The companion star is more massive than the primary, but so faint that optical telescopes cannot detect it. The Upsilon Sagittarii system is about 1, light years distant and has an orbital period of Ross is a red dwarf only 9. It is one of the closest stars to the Sun and the nearest star in Sagittarius constellation. It is located only 5. The star is a relatively young one, with an estimated age of less than a billion years. It is a known X-ray source. It will make its closest approach to the Sun in about , years, when it comes within 6.

Ross was originally catalogued by the American astronomer and physicist Frank Elmore Ross in It is classified as a UV Ceti-type flare star, one undergoing sudden dramatic increases in brightness for a few minutes. Flare stars are typically dim red dwarfs or less massive brown dwarfs. V Sagittarii is the fourth known microquasar, discovered after four of the fastest X-ray intensity changes ever seen from a star. First detected in , V Sgr is a variable X-ray binary system once considered to be the closest black hole to Earth, at a distance of about 1, light years.

Constellations by Sinéad Gleeson

It is now believed to be located at least 15 times farther away. The system is notable for being the source of one of the most rapid superluminal faster than light jets in our galaxy. The Terebellum is a quadrilateral formed by four fourth magnitude stars in Sagittarius, all within two degrees of each other: Omega Sagittarii, 59 Sagittarii, 60 Sagittarii and 62 Sagittarii. Omega Sagittarii is a G-type subgiant marking the northeast corner of the Terebellum, about 78 light years distant from Earth.

The star is classified as an irregular variable. The stars are located at different distances from the solar system and are not gravitationally bound. Sagittarius A is a radio source located at the centre of the Milky Way, in the direction of the Sagittarius constellation. The supernova remnant Sagittarius A East is about 25 light years wide and appears to have originated in an explosion that occurred between 35, and , years ago. Because it has an imposing size and energy, Sagittarius A East is believed to be a remnant of the explosion of a star that came close to the central black hole and was gravitationally compressed.

The spiral structure Sagittarius A West appears like a three-arm spiral and is sometimes called the Minispiral. It does not really have the structure of a spiral. The clouds have an ionized surface. Stars orbit the object at speeds greater than those of any other stars found in the Milky Way. Sagittarius B2 is a very large molecular cloud of dust and gas approximately light years from the centre of the Milky Way. It has a mass three million times that of the Sun. The Lagoon Nebula is a large interstellar cloud classified as an emission nebula. It is one of the several notable H II regions in Sagittarius.

It has an apparent magnitude of 6. Messier 8 is one of only two nebulae that are star forming regions and can be seen by naked eye. It was first discovered by the French astronomer Guillaume Le Gentil in At the centre of the Lagoon Nebula, there is a structure known as the Hourglass Nebula not the same object as the famous Hourglass Nebula , which is located in the constellation Musca. The Hourglass Nebula contains several Herbig-Haro objects, small patches of nebulosity indicating that there are newly born stars in the vicinity, and providing direct evidence of star forming activity in the region.

NGC is an open cluster within the Lagoon Nebula. The brightest stars in the cluster are 7th magnitude. They are in fact located behind the nebula. The cluster has a diameter of 10 arc minutes and an apparent magnitude of 4. It was discovered by Italian astronomer Giovanni Battista Hodierna in The Omega Nebula is an emission nebula in Sagittarius. Hester ASU. Messier included it in his catalogue in The Omega Nebula has an apparent magnitude of 6.

It is about 15 light years in diameter. Messier 18 is an open star cluster in Sagittarius. It was originally discovered by Charles Messier in The cluster is nine light years in radius, has an apparent magnitude of 7. The nebula is in fact a combination of an emission nebula the lower part , a reflection nebula the upper part and an open cluster. It is an H II region, containing a stellar nursery full of embryonic stars.

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The Trifid Nebula is about 28 arc minutes across in size. It can be observed through a small telescope and is a popular deep sky object among amateur astronomers. The Trifid Nebula has an apparent magnitude of 6. Messier 21 is another open star cluster in Sagittarius. It is a relatively young cluster, only 4. The cluster was first observed by Charles Messier in June He later included it in his catalogue. M21 has an apparent magnitude of 6. It is elliptical in shape and about 32 arc minutes across in size.

It has an apparent magnitude of 5. It is one of the nearest globular star clusters to Earth. M22 was originally discovered by the German amateur astronomer Johann Abraham Ihle in Messier included the cluster in his catalogue in June The Sagittarius Cluster is located near the galactic bulge, the central group of stars in the Milky Way.

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It is also notable for being one of only four known globular clusters that contain a planetary nebula. The planetary nebula in the Sagittarius Cluster, designated GJJC1 is believed to be only 6, years old and has a blue star at the centre. The cluster has an apparent magnitude of 6. It is light years in radius and contains about stars. The brightest one has a magnitude of 9. The Sagittarius Star Cloud Messier 24 is, as the name says, a star cloud in the constellation Sagittarius.

It is the densest concentration of stars that can be seen using binoculars; about a thousand stars are visible within a single field of view. The cloud is about light years wide and approximately 10, light years distant.

It was discovered by Charles Messier in The Carina-Sagittarius Arm is particularly notable for containing a large number of H II regions, giant molecular clouds and young stars. Messier 25 is an open cluster with an apparent magnitude of 4. The cluster is about 19 light years across. Its estimated age is 90 million years. Messier 28 is a globular cluster located near Lambda Sagittarii Kaus Borealis. It is between 18, and 19, light years distant and has an apparent magnitude of 7.

The cluster contains 18 RR Lyrae type variable stars. Messier 28 was the first globular star cluster in which a milisecond pulsar a pulsar with a rotational period between 1 and 10 miliseconds was discovered in Messier 54 is a dense globular cluster with an apparent magnitude of 8. The cluster was discovered by Charles Messier in Messier later included it in his catalogue. M54 is believed to belong to the Sagittarius Dwarf Elliptical Galaxy. It lies close to the star Zeta Sagittarii. Messier 55 is another globular cluster in Sagittarius.

It was discovered by the French astronomer Nicolas Louis de Lacaille in and included by Messier in his catalogue in The cluster is a relatively large and bright one, with an apparent magnitude of 7. It is located approximately 17, light years from Earth. Messier 69 is a globular cluster. It was discovered by Charles Messier on August 31, , along with another globular cluster, Messier M69 has a radius of 42 light years and an apparent magnitude of 8. It contains very few variable stars.

M69 is only 1, light years away from M70 and located near the Galactic centre. It is approximately 29, light years distant from Earth. Messier 70 is a globular cluster in Sagittarius, located close to the Galactic centre. Charles Messier discovered it in and subsequently included it in his catalogue. The cluster is about 34 light years in radius, has an apparent magnitude of 9. Messier 75 is a globular star cluster about 67, light years from Earth.

The cluster is about 67 light years in radius and has an apparent magnitude of 9. It is a densely populated cluster, classified as class I. It is a satellite galaxy of the Milky Way and headed for a collision with our galaxy.

The Sagittarius Dwarf is believed to already have orbited the Milky Way about 10 times in the last billion years or so, and it still appears to have coherence as an elongated ellipse despite being torn apart by enormous tidal forces as a result of the interaction. The Sagittarius Dwarf Elliptical Galaxy has an apparent magnitude of 4. It is located about 50, light years from the centre of the Milky Way. The galaxy is about 10, light years in diameter and it consists of four globular star clusters, the main one of which was discovered in In , the Canis Major Dwarf Galaxy was discovered and recognized as the nearest neighbour.

The globular cluster Messier 54 lies at the core of the galaxy. NGC is a planetary nebula, a cloud of gas expelled by a dying central star, located about 14, light years away in Sagittarius. The nebula has an apparent size of only 10 by 8 arc seconds and an apparent magnitude of It is also catalogued as ESO The nebula was discovered by Edward Charles Pickering on July 14, These same colours can be seen in the famous and impressive Ring Nebula heic , a prominent example of a nebula like this one.

The Arches Cluster is the densest open cluster known in the Milky Way. Located 25, light years from Earth, the cluster lies only about light years from the Galactic centre. Obscured by clouds of dust, it cannot be observed in the visual bands, but is visible in radio, infrared and X-ray wavelengths. The cluster contains some of the brightest, most massive stars in our galaxy. The most prominent members are Wolf-Rayet stars and O-type supergiants. The cluster is believed to be only 2. With a mass of 10, solar masses, it is about 10 times more massive than typical open clusters in the Milky Way.

The clusters, Arches upper right , Quintuplet upper center , and the GC cluster bottom center , contain massive stars that appear as very bright, point-like X-ray sources when winds from their surfaces collide with those from an orbiting companion. Vast amounts of energy are also released when these stars explode as supernovas, heating the surrounding material.

Stellar corpses in this image also emit X-rays as either neutron stars or black holes in binary systems.

Collisions between the clusters themselves and cooler molecular clouds of gas contribute to the diffuse X-rays seen in this image. Image: Chandra X-ray Observatory. Wang et al. Smithsonian Institution Flickr Commons. The Quintuplet Cluster is another dense open cluster located in same region as the Arches Cluster , about 26, light years from Earth and light years from the centre of the Milky Way.

Named for its most prominent five stars, the cluster was only discovered in It cannot be seen visually, but must be observed in radio, X-ray and infrared bands. The Quintuplet Cluster contains more Wolf-Rayet stars than any other cluster known and several notable luminous blue variables, including the Pistol Star, V Sagittarii and the runaway star V Sagittarii. It has an apparent magnitude of The Sagittarius Dwarf Irregular Galaxy contains mainly intermediate-age stars as a result of a prolonged period of star formation.

It is one of the most metal-poor galaxies known.