Open cluster Messier 29 in Cygnus, conventionally taken (as looking at the object on the southern horizon). Very broad reddish nebulosity is noticeable to the west.
M29 is well within the several degrees of the arms and bulge of the Milky Way. It is at least many hundreds of light years short of the yardstick distance to the Galactic Center, as is between 4,000[6] and 7,200 light years away.[7] A 1998 popular work gives a value within this range.[lower-alpha 1][8] Data from Gaia EDR3 gives a parallactic distance of about 5,240 light years.[2] The uncertainty is due to poorly known absorption of the cluster's light. Its extinction greatly is from faint surrounding nebulosity and other foreground interstellar matter of this cross-section of the spiral arms (see Orion–Cygnus Arm, which is our local arm).
According to the Sky Catalogue,[6] M29 is included in the Cygnus OB1 association, and the radial velocity component of three-dimensional motion, by default factoring in the solar system's current trajectory, is one of approaching at 28km/s (noted, thus, as negative). Its age is estimated at 10 million years, as its five hottest stars are all giants of spectral class B0. Kepple and his associates give the apparent brightness of the brightest star as eighth magnitude of in the mid-wavelength (and frequency) "visual" band.[8][lower-alpha 2]
The cluster's absolute magnitude is estimated at −8.2, a luminosity of 160,000 solar luminosities (L☉). The linear diameter was estimated at only 11 light years. Its Trumpler class is III,3,p,n (as it is associated with nebulosity), although Götz gives, differently, II,3,m, and Kepple gives I,2,m,n.[8] The Sky Catalogue lists it with 50 member stars;[6] earlier Becvar estimated 20 members.
North of 47 degrees north, the cluster is for part or all of the day above the horizon. It can be made out in binoculars in a good sky. In telescopes, lowest powers are best. The brightest of its stars form a "stubby dipper", per Mallas. The four brightest stars form a quadrilateral, and another set a small triangle just north of the northernmost of the four. It is often known as the "cooling tower" due to its resemblance to the hyperboloid-shaped structures. A few fainter stars are around them, but the cluster appears quite isolated, especially in smaller telescopes. In photographs, many faint Milky Way background stars appear.
Messier 29 can be found quite easily as it is about 1.7 degrees south[lower-alpha 3] of Gamma or 37 Cygni (Sadr). Angularly close, and almost certainly nearby in space, is diffuse nebulosity.
The especially hot binary Wolf–Rayet star WR 143 (WC4+Be) (HD 195177) can be found near this cluster.
1 2 3 Kenneth Glyn Jones (ed.) The Sky Catalogue 2000.0
↑ Preferred by most sources including Mallas/Kreimer and Burnham, and agreeing with early estimates or R.J. Trumpler 1930
1 2 3 Kepple, George Robert., Sanner, Glen W.. The Night Sky Observer's Guide: Spring & summer. United States: Willmann-Bell, 1998 at Chapter 42. Cygnus, The Swan
Cygnus is a northern constellation on the plane of the Milky Way, deriving its name from the Latinized Greek word for swan. Cygnus is one of the most recognizable constellations of the northern summer and autumn, and it features a prominent asterism known as the Northern Cross. Cygnus was among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.
Albireo is a double star designated Beta Cygni. The International Astronomical Union uses the name "Albireo" specifically for the brightest star in the system. Although designated 'beta', it is fainter than Gamma Cygni, Delta Cygni, and Epsilon Cygni and is the fifth-brightest point of light in the constellation of Cygnus. Appearing to the naked eye to be a single star of magnitude 3, viewing through even a low-magnification telescope resolves it into its two components. The brighter yellow star, itself a very close binary system, makes a striking colour contrast with its fainter blue companion.
Messier 73 is an asterism of four stars in the constellation Aquarius. It lies several arcminutes east of globular cluster M72. According to Gaia EDR3, the stars are 1030±9, 1249±10, 2170±22, and 2290±24 light-years from the Sun, with the second being a binary star.
The Wild Duck Cluster is an open cluster of stars in the constellation Scutum. It was discovered by Gottfried Kirch in 1681. Charles Messier included it in his catalogue of diffuse objects in 1764. Its popular name derives from the brighter stars forming a triangle which could resemble a flying flock of ducks. The cluster is located just to the east of the Scutum Star Cloud midpoint.
Messier 21 or M21, also designated NGC 6531 or Webb's Cross, is an open cluster of stars located to the north-east of Sagittarius in the night sky, close to the Messier objects M20 to M25. It was discovered and catalogued by Charles Messier on June 5, 1764. This cluster is relatively young and tightly packed. A few blue giant stars have been identified in the cluster, but Messier 21 is composed mainly of small dim stars. With a magnitude of 6.5, M21 is not visible to the naked eye; however, with the smallest binoculars it can be easily spotted on a dark night. The cluster is positioned near the Trifid nebula, but is not associated with that nebulosity. It forms part of the Sagittarius OB1 association.
Messier 26, also known as NGC 6694, is an open cluster of stars in the southern constellation of Scutum. It was discovered by Charles Messier in 1764. This 8th magnitude cluster is a challenge to find in ideal skies with typical binoculars, where it can be, with any modern minimum 3-inch (76 mm) aperture device. It is south-southwest of the open cluster Messier 11 and is 14′ across. About 25 stars are visible in a telescope with a 150–200 mm (6–8 in) aperture.
Messier 18 or M18, also designated NGC 6613 and sometimes known as the Black Swan Cluster, is an open cluster of stars in the constellation Sagittarius. It was discovered by Charles Messier in 1764 and included in his list of comet-like objects. From the perspective of Earth, M18 is situated between the Omega Nebula (M17) and the Small Sagittarius Star Cloud (M24).
Messier 39 or M39, also known as NGC 7092, is an open cluster of stars in the constellation of Cygnus, sometimes referred to as the Pyramid Cluster. It is positioned two degrees south of the star Pi Cygni and around 9° east-northeast of Deneb. The cluster was discovered by Guillaume Le Gentil in 1749, then Charles Messier added it to his catalogue in 1764. When observed in a small telescope at low power the cluster shows around two dozen members but is best observed with binoculars. It has a total integrated magnitude (brightness) of 4.6 and spans an angular diameter of 29 arcminutes – about the size of the full Moon. It is centered about 1,010 light-years away.
Messier 52 or M52, also known as NGC 7654 or the Scorpion Cluster, is an open cluster of stars in the highly northern constellation of Cassiopeia. It was discovered by Charles Messier in 1774. It can be seen from Earth under a good night sky with binoculars. The brightness of the cluster is influenced by extinction, which is stronger in the southern half. Its metallicity is somewhat below that of the Sun, and is estimated to be [Fe/H] = −0.05 ± 0.01.
KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is approximately 4,700 light-years away.
NGC 6530 is a young open cluster of stars in the southern constellation of Sagittarius, located some 4,300 light years from the Sun. It exists within the H II region known as the Lagoon Nebula, or Messier 8, and spans an angular diameter of 14.0′. The nebulosity was first discovered by G. B. Hodierna prior to 1654, then re-discovered by J. Flamsteed circa 1680. It was P. Loys who classified it as a cluster in 1746, as he could only resolve stars. The following year, G. Le Gentil determined it was both a nebula and a cluster.
Cygnus OB2 #12 is an extremely luminous blue hypergiant with an absolute bolometric magnitude of −10.9, among the most luminous stars known in the galaxy. This makes the star nearly two million times more luminous than the Sun, although estimates were even higher when the star was first discovered. It is now known to be a binary, with the companion approximately a tenth as bright. A very approximate initial estimate of the orbit gives the total system mass as 120 M☉ and the period as 30 years.
NGC 2374 is an open cluster of stars in the Canis Major constellation. It was discovered on January 31, 1785 by the German-British astronomer William Herschel. This cluster is relatively rich in stars but is scattered across an angular diameter of 19.0′. It has an integrated visual magnitude of 8.0 and can be viewed with a modest amateur telescope. NGC 2374 is located at a distance of approximately 3,950 light-years (1,212 pc) from the Sun.
NGC 6834 is a young open cluster of stars located about 10,850 light years from the Sun in the constellation Cygnus. It was discovered on July 17, 1784, by Anglo-German astronomer William Herschel. The cluster has a visual magnitude of 7.8, which is dimmed by 2.1 magnitudes due to interstellar dust. Half the cluster members lie within an angular radius of 6′.
NGC 6281 is an open cluster of stars in the constellation Scorpius. It was not included in the Messier or Caldwell catalogues of nebulous objects, but it is the brightest such cluster in the constellation to be left out of both. It is readily observed with the naked eye; it is located about 2° to the east of Mu Scorpii. James Dunlop described the cluster as a "curiously curved line of pretty bright stars, with many stars mixt". John Herschel then described the cluster as both "pretty bright" and "pretty rich".
IC 2488 is an open cluster in the constellation Vela. It was discovered by Nicolas-Louis de Lacaille in 1752. It is located approximately 3,700 light years away from Earth.
IC 2714 is an open cluster in the constellation Carina. It was discovered by James Dunlop in 1826. It is located approximately 4,000 light years away from Earth, in the Carina–Sagittarius Arm.
NGC 6910 is an open cluster in the constellation Cygnus. It was discovered by William Herschel on October 17, 1786. The cluster was also observed by John Herschel on September 18, 1828. It is a poor cluster with prominent central concentration and Trumpler class I2p. NGC 6910 is the core cluster of the stellar association Cygnus OB9.
V1794 Cygni is a single variable star in the northern constellation Cygnus. It has the identifier HD 199178 from the Henry Draper Catalogue; V1794 Cygni is its variable star designation. With an apparent visual magnitude of 7.24, it's too dim to be visible with the naked eye but can be seen with binoculars. V1794 is located at a distance of 367 light-years (113 pc) based on parallax measurements, but is drifting closer to the Sun with a radial velocity of −31 km/s. It lies superimposed over a region of faint nebulosity to the west of the North American Nebula.
X Cygni is a variable star in the northern constellation of Cygnus, abbreviated X Cyg. This is a Delta Cephei variable that ranges in brightness from an apparent visual magnitude of 5.85 down to 6.91 with a period of 16.386332 days. At it brightest, this star is dimly visible to the naked eye. The distance to this star is approximately 628 light years based on parallax measurements. It is drifting further away with a radial velocity of 8.1 km/s. This star is a likely member of the open cluster Ruprecht 173.
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