Messier 5

Messier 5 or M5 (also designated NGC 5904) is a globular cluster in the constellation Serpens. It was discovered by Gottfried Kirch in 1702.

Messier 5
Messier 5 - HST
Messier 5 by Hubble Space Telescope. 2.85′ view
Credit: NASA/STScI/WikiSky
Observation data (J2000 epoch)
ClassV[1]
ConstellationSerpens
Right ascension 15h 18m 33.22s[2]
Declination+02° 04′ 51.7″[2]
Distance24.5 kly (7.5 kpc)[3]
Apparent magnitude (V)+5.95[4]
Apparent dimensions (V)23′.0
Physical characteristics
Mass8.57×105[5] M
Radius80 ly
Metallicity = –1.12[6] dex
Estimated age10.62 Gyr[6]
Other designationsNGC 5904, GCl 34[4]

Discovery and visibility

M5 is, under extremely good conditions, just visible to the naked eye as a faint "star" near the star 5 Serpentis. Binoculars or small telescopes will identify the object as non-stellar while larger telescopes will show some individual stars, of which the brightest are of apparent magnitude 12.2.

M5 was discovered by German astronomer Gottfried Kirch in 1702 when he was observing a comet. Charles Messier also noted it in 1764, but thought it was a nebula without any stars associated with it. William Herschel was the first to resolve individual stars in the cluster in 1791, counting roughly 200.

Characteristics

M5--LRGB2 898x688
M5 wide angle by Robert J. Vanderbei
Messier 5 (Globular Cluster)
M5 photographed with a DSLR camera.

Spanning 165 light-years in diameter, M5 is one of the largest known globular clusters. The gravitational sphere of influence of M5, (i.e. the volume of space in which stars are gravitationally bound to it rather than being torn away by the Milky Way's gravitational pull) has a radius of some 200 light-years.

At 13 billion years old, M5 is also one of the eldest globular clusters in the Milky Way Galaxy. Its distance is about 24,500 light-years from Earth, and it contains more than 100,000 stars, as many as 500,000 according to some estimates.

Notable stars

105 stars in M5 are known to be variable in brightness, 97 of them belonging to the RR Lyrae type. RR Lyrae stars, sometimes referred to as "Cluster Variables", are somewhat similar to Cepheid type variables and as such can be used as a tool to measure distances in outer space since the relation between their luminosities and periods are well known. The brightest and most easily observed variable in M5 varies from magnitude 10.6 to 12.1 in a period of just under 26.5 days.

A dwarf nova has also been observed in this cluster.

References

  1. ^ Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin, 849 (849): 11–14, Bibcode:1927BHarO.849...11S.
  2. ^ a b Goldsbury, Ryan; et al. (December 2010), "The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters", The Astronomical Journal, 140 (6): 1830–1837, arXiv:1008.2755, Bibcode:2010AJ....140.1830G, doi:10.1088/0004-6256/140/6/1830.
  3. ^ Paust, Nathaniel E. Q.; et al. (February 2010), "The ACS Survey of Galactic Globular Clusters. VIII. Effects of Environment on Globular Cluster Global Mass Functions", The Astronomical Journal, 139 (2): 476–491, Bibcode:2010AJ....139..476P, doi:10.1088/0004-6256/139/2/476.
  4. ^ a b "M 5". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-11-15.
  5. ^ Boyles, J.; et al. (November 2011), "Young Radio Pulsars in Galactic Globular Clusters", The Astrophysical Journal, 742 (1): 51, arXiv:1108.4402, Bibcode:2011ApJ...742...51B, doi:10.1088/0004-637X/742/1/51.
  6. ^ a b Forbes, Duncan A.; Bridges, Terry (May 2010), "Accreted versus in situ Milky Way globular clusters", Monthly Notices of the Royal Astronomical Society, 404 (3): 1203–1214, arXiv:1001.4289, Bibcode:2010MNRAS.404.1203F, doi:10.1111/j.1365-2966.2010.16373.x.

External links

Coordinates: Sky map 15h 18m 33.75s, 02° 04′ 57.7″

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Beta Serpentis

Beta Serpentis, Latinized from β Serpentis, is a binary star system in the constellation Serpens, in its head (Serpens Caput). It is visible to the naked eye with a combined apparent visual magnitude of +3.65. Based upon an annual parallax shift of 21.03 mas as seen from Earth, it is located around 155 light years from the Sun. The system is a member of the Ursa Major Moving Group.

Chi Serpentis

Chi Serpentis (χ Ser, χ Serpentis) is a solitary star in the Serpens Caput section of the equatorial constellation Serpens. Based upon an annual parallax shift of 14.84 mas as seen from Earth, it is located around 220 light years from the Sun. The star is bright enough to be faintly visible to the naked eye, having an apparent visual magnitude of +5.30.In 1966 it was listed as a suspected spectroscopic binary, but it is believed to be single. This is a chemically peculiar star Ap star with a stellar classification of A2 Vp MnEu(Sr), indicating the spectrum shows abnormal excesses of manganese and europium. The star has 2.11 times the mass of the Sun and about 1.9 times the Sun's radius. It is radiating 26 times the solar luminosity from its photosphere at an effective temperature of 9,557 K. At the age of 212 million years, it is spinning with a rotation period of 1.6 days.Chi Serpentis is classified as an Alpha2 Canum Venaticorum type variable star, and its magnitude varies by 0.03 with a period of 1.5948 days. The pattern of variation in the spectrum suggest there are regions of enhanced strontium, chromium, iron, titanium, and magnesium on the surface of the star. The averaged quadratic field strength of the surface magnetic field is (859.1±712.3)×10−4 T.

Globular cluster

A globular cluster is a spherical collection of stars that orbit a galactic core, as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes, and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin, globulus—a small sphere. A globular cluster is sometimes known, more simply, as a globular.

Globular clusters are found in the halo of a galaxy and contain considerably more stars, and are much older, than the less dense, open clusters which are found in the disk of a galaxy. Globular clusters are fairly common; there are about 150 to 158, currently known globular clusters in the Milky Way, with, perhaps, 10 to 20 more, still undiscovered. Larger galaxies can have more: The Andromeda Galaxy, for instance, may have as many as 500. Some giant elliptical galaxies (particularly those at the centers of galaxy clusters), such as M87, have as many as 13,000 globular clusters.

Every galaxy of sufficient mass in the Local Group has an associated group of globular clusters, and almost every large galaxy surveyed, has been found to possess a system of globular clusters. The Sagittarius Dwarf galaxy, and the disputed Canis Major Dwarf galaxy appear to be in the process of donating their associated globular clusters (such as Palomar 12) to the Milky Way. This demonstrates how many of this galaxy's globular clusters might have been acquired in the past.

Although it appears that globular clusters contain some of the first stars to be produced in the galaxy, their origins and their role in galactic evolution are still unclear. It does appear clear that globular clusters are significantly different from dwarf elliptical galaxies and were formed as part of the star formation of the parent galaxy, rather than as a separate galaxy.

List of NGC objects (5001–6000)

This is a list of NGC objects 5001–6000 from the New General Catalogue (NGC). The astronomical catalogue is composed mainly of star clusters, nebulae, and galaxies. Other objects in the catalogue can be found in the other subpages of the list of NGC objects.

The constellation information in these tables is taken from The Complete New General Catalogue and Index Catalogue of Nebulae and Star Clusters by J. L. E. Dreyer, which was accessed using the "VizieR Service". Galaxy types are identified using the NASA/IPAC Extragalactic Database. The other data of these tables are from the SIMBAD Astronomical Database unless otherwise stated.

Messier object

The Messier objects are a set of 110 astronomical objects cataloged by the French astronomer Charles Messier in his Catalogue des Nébuleuses et des Amas d'Étoiles ("Catalogue of Nebulae and Star Clusters").

Because Messier was interested in finding only comets, he created a list of non-comet objects that frustrated his hunt for them. The compilation of this list, in collaboration with his assistant Pierre Méchain, is known as the Messier catalogue. This catalogue of objects is one of the most famous lists of astronomical objects, and many Messier objects are still referenced by their Messier number.

The catalogue includes some astronomical objects that can be observed from Earth's Northern Hemisphere such as deep-sky objects, a characteristic which makes the Messier objects extremely popular targets for amateur astronomers.A preliminary version first appeared in the Memoirs of the French Academy of Sciences in 1771,

and the last item was added in 1966 by Kenneth Glyn Jones, based on Messier's observations.

The first version of Messier's catalogue contained 45 objects and was published in 1774 in the journal of the French Academy of Sciences in Paris. In addition to his own discoveries, this version included objects previously observed by other astronomers, with only 17 of the 45 objects being Messier's.

By 1780 the catalogue had increased to 80 objects. The final version of the catalogue containing 103 objects was published in 1781 in the Connaissance des Temps for the year 1784.

However, due to what was thought for a long time to be the incorrect addition of Messier 102, the total number remained 102. Other astronomers, using side notes in Messier's texts, eventually filled out the list up to 110 objects.The catalogue consists of a diverse range of astronomical objects, ranging from star clusters and nebulae to galaxies. For example, Messier 1 is a supernova remnant, known as the Crab Nebula, and the great spiral Andromeda Galaxy is M31. Many further inclusions followed in the next century when the first addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding Messier's side note in his 1781 edition exemplar of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.

Mu Serpentis

Mu Serpentis, Latinized from μ Serpentis, is a binary star in the Serpens Caput (head) section of the equatorial constellation Serpens. It is visible to the naked eye with an apparent visual magnitude of 3.543. Based upon an annual parallax shift of 19.23 mas as seen from Earth, it is located around 170 light years from the Sun.

This is an astrometric binary for which coarse orbital elements have been determined based on interferometric observations. The pair orbit each other with a period of around 36 years and an eccentricity of roughly 0.4. The primary member, component A, is a white-hued A-type main sequence star with a stellar classification of A0 V. The nature of the secondary, component B, is less certain – it may be a class A or F type star of unknown luminosity class.In Chinese astronomy, Mu Serpentis is called 天乳, Pinyin: Tiānrǔ, meaning Celestial Milk, because this star is marking itself and stand alone in Celestial Milk asterism, Root mansion (see : Chinese constellation).

Nu Serpentis

Nu Serpentis (ν Ser, ν Serpentis) is a solitary star in the constellation Serpens. Based upon an annual parallax shift of 16.05 mas as seen from Earth, it is about 203 light years from the Sun.

This is a white A-type main sequence dwarf with an apparent magnitude of +4.32. It has an optical companion, a magnitude +9.4 star at an angular separation of 46 arcseconds.

Omega Serpentis

Omega Serpentis (ω Ser, ω Serpentis) is a solitary star within the Serpens Caput part of the equatorial constellation of Serpens. It is visible to the naked eye with an apparent visual magnitude of +5.22. Based upon an annual parallax shift of 11.93 mas as seen from Earth, it is located about 273 light years from the Sun. At that distance, its visual magnitude is diminished by an extinction factor of 0.19 due to interstellar dust. It is a member of the Ursa Major Stream, lying among the outer parts, or corona, of this moving group of stars that roughly follow a common heading through space.With an estimated age of around four billion years, Omega Serpentis is an evolved G-type giant star with a stellar classification of G8 III. It is a red clump giant, which means that it is generating energy at its core through the nuclear fusion of helium. The star has an estimated 120% of the Sun's mass but has expanded to 10.48 times the radius of the Sun. It is radiating 69 times the solar luminosity from its photosphere at an effective temperature of 4,797 K.

Omicron Serpentis

Omicron Serpentis (ο Ser, ο Serpentis) is a solitary star in the Serpens Cauda (tail) section of the equatorial constellation Serpens. Based upon an annual parallax shift of 18.83 mas as seen from Earth, it is located around 173 light years from the Sun. The star is visible to the naked eye with a base apparent visual magnitude of +4.26.This is a white-hued A-type main sequence star with a stellar classification of A2 Va. It is located on the lower instability strip and is classified as a Delta Scuti type variable star. The apparent magnitude of the star varies in the range 4.26−4.27 with a period of 76 minutes, or 0.053 days.The star has an estimated 2.13 times the mass of the Sun and about 2.2 times the Sun's radius. It is about half a billion years old and is spinning with a projected rotational velocity of 112.6 km/s. Omicron Serpentis is radiating 42.6 times the solar luminosity from its photosphere at an effective temperature of 8,972 K.

Orders of magnitude (length)

The following are examples of orders of magnitude for different lengths.

Phi Serpentis

Phi Serpentis (φ Ser, φ Serpentis) is a solitary star in the Serpens Caput portion of the equatorial constellation Serpens. Based upon an annual parallax shift of 13.52 mas as seen from Earth, it is located about 241 light years distant. The star is faintly visible to the naked eye with an apparent visual magnitude of +5.55.At the estimated age of 3.42 billion years, this is an evolved K-type subgiant star with a stellar classification of K1 IV. It has about 1.19 times the mass of the Sun and around 4.2 times the Sun's radius. The star radiates 41.7 times the solar luminosity from its photosphere at an effective temperature of 4,493 K.

Pi Serpentis

Pi Serpentis, Latinized from π Serpentis, is a solitary white-hued star in the constellation Serpens, located in its head, Serpens Caput. Based upon an annual parallax shift of 18.22 mas as seen from Earth, it is located around 179 light years from the Sun. It is visible to the naked eye with an apparent visual magnitude of 4.82.This is a A-type main sequence star with a stellar classification of A3 V. It is about 320 million years old with a high rate of spin, measured at a 128 km/s projected rotational velocity. The star has an estimated 2.50 times the mass of the Sun and 2.27 times the Sun's radius. It is radiating 27 times the solar luminosity from its photosphere at an effective temperature of 7,566 K.In 1992, an infrared excess was detected from this system at a wavelength of 60μm. The data suggests a dusty debris disk with a temperature of 45 K is orbiting 211 AU from the host star.

Serpens

Serpens ("the Serpent", Greek Ὄφις) is a constellation of the northern hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations defined by the International Astronomical Union. It is unique among the modern constellations in being split into two non-contiguous parts, Serpens Caput (Serpent Head) to the west and Serpens Cauda (Serpent Tail) to the east. Between these two halves lies the constellation of Ophiuchus, the "Serpent-Bearer". In figurative representations, the body of the serpent is represented as passing behind Ophiuchus between Mu Serpentis in Serpens Caput and Nu Serpentis in Serpens Cauda.

The brightest star in Serpens is the red giant star Alpha Serpentis, or Unukalhai, in Serpens Caput, with an apparent magnitude of 2.63. Also located in Serpens Caput are the naked-eye globular cluster Messier 5 and the naked-eye variables R Serpentis and Tau4 Serpentis. Notable extragalactic objects include Seyfert's Sextet, one of the densest galaxy clusters known; Arp 220, the prototypical ultraluminous infrared galaxy; and Hoag's Object, the most famous of the very rare class of galaxies known as ring galaxies.

Part of the Milky Way's galactic plane passes through Serpens Cauda, which is therefore rich in galactic deep-sky objects, such as the Eagle Nebula (IC 4703) and its associated star cluster Messier 16. The nebula measures 70 light-years by 50 light-years and contains the Pillars of Creation, three dust clouds that became famous for the image taken by the Hubble Space Telescope. Other striking objects include the Red Square Nebula, one of the few objects in astronomy to take on a square shape; and Westerhout 40, a massive nearby star-forming region consisting of a molecular cloud and an H II region.

Sigma Serpentis

Sigma Serpentis, Latinized from σ Serpentis, is a star in the equatorial constellation Serpens. It is faintly visible to the naked eye with an apparent visual magnitude of +4.82. Based upon an annual parallax shift of 36.67 mas as seen from Earth, it is located 89 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −49 km/s.Barry (1970) assigned this star a stellar classification of F3 V, indicating an ordinary F-type main-sequence star. However, Houk and Swift (1999) classified it as A9 Ib/II, suggesting instead that this is a evolved F-type bright giant/supergiant. It is about one billion years old and is spinning with a projected rotational velocity of 77.7 km/s. The star has an estimated 1.58 times the mass of the Sun and is radiating 7.7 times the Sun's luminosity from its photosphere at an effective temperature of 6,952 K.

Upsilon Serpentis

Upsilon Serpentis, Latinized from υ Serpentis, is a star in the Serpens Caput section of the constellation Serpens. Based upon an annual parallax shift of 13.04 mas as seen from Earth, it is located around 250 light years from the Sun. The star is bright enough to be faintly visible to the naked eye, having an apparent visual magnitude of +5.70. It is a member of the Hyades group, a stream of stars that share a similar trajectory to the Hyades cluster.This is an A-type main sequence star with a stellar classification of A3 V. It has an estimated 2.9 times the mass of the Sun and around 2.2 times the Sun's radius. With an age of 403 million years, it has a high rate of spin with a projected rotational velocity of 133 km/s. It is radiating 23 times the solar luminosity from its photosphere at an effective temperature of 8,917 K.Upsilon Serpentis is a suspected astrometric binary, which means an undetected companion is perturbing the motion of the visible star. An X-ray emission has been detected from this system with a luminosity of 247.8×1020 W. This may be coming from the companion, since A-type stars are not expected to emit X-rays.

List
See also

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