Terzan 5

Last updated
Terzan 5
The unusual cluster Terzan.jpg
Hubble image of Terzan 5
Observation data (J2000 epoch)
Class G2 [1]
Constellation Sagittarius
Right ascension 17h 48m 05s [2]
Declination −24° 46′ 48″ [2]
Distance 18.8 ± 1.6 kly [note 1] (5.9 ± 0.5 kpc [4] )
Apparent magnitude (V)12.8 [1]
Apparent dimensions (V)1′02″ (half-mass diameter) [4]
Physical characteristics
Mass~2×106 [4]   M☉ (4 × 1036 kg)
Radius2.7 ly [note 2]
VHB22.5 [3]
Metallicity  = −0.21 dex
Estimated age 12 Gyr [6]
Notable featuresPossibly the core of a disrupted dwarf galaxy
Other designationsTer 5, IRC–20385
See also: Globular cluster, List of globular clusters

Terzan 5 is a heavily obscured globular cluster belonging to the bulge (the central star concentration) of the Milky Way galaxy. [3] It was one of six globulars discovered by French [7] astronomer Agop Terzan in 1968 [8] and was initially labeled Terzan 11. The cluster was cataloged by the Two-Micron Sky Survey as IRC–20385. [9] It is situated in the Sagittarius constellation in the direction of the Milky Way's center. Terzan 5 probably follows an unknown complicated orbit around the center of the galaxy, but currently it is moving towards the Sun with a speed of around 90 km/s. [6]

Contents

Physical properties

The absolute magnitude of Terzan 5 is at least MV=−7.5. [1] Its bolometric luminosity is about 800,000 times that of the Sun, while its mass is about 2 million solar masses. [4] The small core of Terzan 5—about 0.5 pc in size [4] —has one of the highest star densities in the galaxy. Its volume mass density exceeds 106M☉/pc3, [10] while its volume luminosity density exceeds 105.5L☉/pc3, where M☉ and L☉ are the Sun's mass and luminosity, respectively. The cluster also has one of the highest metallicities among the Milky Way's globular clusters—[Fe/H]=−0.21. [5]

In 2009 it was discovered that Terzan 5 consists of at least two generations of stars with ages of 12 and 4.5 billion years and slightly different metallicities, possibly indicating that it is the core of a disrupted dwarf galaxy, not a true globular cluster. [6] There are only a few other globular clusters in the Milky Way that contain stars with different ages. Among them are M54, Omega Centauri and Liller 1. The latter, like Terzan 5, is thought to be a fossil fragment from the assembly of the galactic bulge. [11] The cluster also contains around 1300 core helium burning horizontal branch (HB) stars, [6] including at least one RR Lyrae variable star. [10]

Pulsars and X-ray sources

Terzan 5 is known to contain 49 millisecond radio pulsars as of December 2023, [12] the largest MSP population among all globular clusters in the Galaxy; their true number may be as high as 200. [13] The first such object, PSR B1744-24A, discovered in 1990, has the period of 11.56  ms. The population of pulsars inside Terzan 5 includes PSR J1748–2446ad, the fastest known millisecond pulsar, which is spinning at 716 Hz (the rotation period is 1.40 ms). [14]

Terzan 5 also contains an X-ray burster, discovered in 1980, known as Terzan 5 or XB 1745-25. [15] It also contains around 50 weaker X-ray sources, many of which are likely Low-mass X-ray binaries (LMXB) or cataclysmic variables. [16]

The large number of X-ray sources and millisecond pulsars may be a direct consequence of the high density of the cluster's core, which leads to a high rate of star collisions, and to formation of close binaries, including binary systems which contain a neutron star. [16]

In addition to discrete X-ray sources Terzan 5 produces a diffuse non-thermal X-ray emission and high (a few GeV) and ultra-high (0.5–24 TeV) energy gamma-rays. The high energy gamma rays probably originate in the magnetosphere of abundant millisecond pulsars, while ultra-high energy gamma rays likely result from the inverse Compton scattering by the relativistic electron emitted by the pulsars off the cosmic microwave background radiation. [13]

Notes

  1. ↑ The distance estimates have historically varied from as close as 2.3 kpc [1] to as far as 14.6 kpc. [3] The recent estimates generally range from 5.5 to 8.7 kpc. [4] [5]
  2. ↑ Based on the half-mass radius of 31″ [4] and the known distance of 5.9 kpc. The dense core of the cluster has the radius of 9.0″. [4]

Related Research Articles

<span class="mw-page-title-main">Globular cluster</span> Spherical collection of stars

A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars, all orbiting in a stable, compact formation. Globular clusters are similar in form to dwarf spheroidal galaxies, and the distinction between the two is not always clear. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".

<span class="mw-page-title-main">Andromeda Galaxy</span> Barred spiral galaxy in the Local Group

The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a D25 isophotal diameter of about 46.56 kiloparsecs (152,000 light-years) and is approximately 765 kpc (2.5 million light-years) from Earth. The galaxy's name stems from the area of Earth's sky in which it appears, the constellation of Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology.

<span class="mw-page-title-main">Sagittarius Dwarf Spheroidal Galaxy</span> Satellite galaxy of the Milky Way

The Sagittarius Dwarf Spheroidal Galaxy (Sgr dSph), also known as the Sagittarius Dwarf Elliptical Galaxy, is an elliptical loop-shaped satellite galaxy of the Milky Way. It contains four globular clusters in its main body, with the brightest of them—NGC 6715 (M54)—being known well before the discovery of the galaxy itself in 1994. Sgr dSph is roughly 10,000 light-years in diameter, and is currently about 70,000 light-years from Earth, travelling in a polar orbit at a distance of about 50,000 light-years from the core of the Milky Way. In its looping, spiraling path, it has passed through the plane of the Milky Way several times in the past. In 2018 the Gaia project of the European Space Agency showed that Sgr dSph had caused perturbations in a set of stars near the Milky Way's core, causing unexpected rippling movements of the stars triggered when it moved past the Milky Way between 300 and 900 million years ago.

<span class="mw-page-title-main">Intermediate-mass black hole</span> Class of black holes with a mass range of 100 to 100000 solar masses

An intermediate-mass black hole (IMBH) is a class of black hole with mass in the range 102–105 solar masses: significantly more than stellar black holes but less than the 105–109 solar mass supermassive black holes. Several IMBH candidate objects have been discovered in the Milky Way galaxy and others nearby, based on indirect gas cloud velocity and accretion disk spectra observations of various evidentiary strength.

<span class="mw-page-title-main">Messier 28</span> Globular cluster in the constellation of Sagittarius

Messier 28 or M28, also known as NGC 6626, is a globular cluster of stars in the center-west of Sagittarius. It was discovered by French astronomer Charles Messier in 1764. He briefly described it as a "nebula containing no star... round, seen with difficulty in 31⁄2-foot telescope; Diam 2′."

<span class="mw-page-title-main">Messier 30</span> Globular cluster in the constellation Capricornus

Messier 30 is a globular cluster of stars in the southeast of the southern constellation of Capricornus, at about the declination of the Sun when the latter is at December solstice. It was discovered by the French astronomer Charles Messier in 1764, who described it as a circular nebula without a star. In the New General Catalogue, compiled during the 1880s, it was described as a "remarkable globular, bright, large, slightly oval." It can be easily viewed with a pair of 10×50 binoculars, forming a patch of hazy light some 4 arcminutes wide that is slightly elongated along the east–west axis. With a larger instrument, individual stars can be resolved and the cluster will cover an angle of up to 12 arcminutes across graduating into a compressed core about one arcminute wide that has further star density within.

<span class="mw-page-title-main">Messier 53</span> Globular cluster in the constellation Coma Berenices

Messier 53 is a globular cluster in the Coma Berenices constellation. It was discovered by Johann Elert Bode in 1775. M53 is one of the more outlying globular clusters, being about 60,000 light-years (18.4 kpc) light-years away from the Galactic Center, and almost the same distance from the Solar System. The cluster has a core radius (rc) of 2.18 pc, a half-light radius (rh) of 5.84 pc, and a tidal radius (rtr) of 239.9 pc.

<span class="mw-page-title-main">Messier 62</span> Globular cluster in the constellation Ophiuchus

Messier 62 or M62, also known as NGC 6266 or the Flickering Globular Cluster, is a globular cluster of stars in the south of the equatorial constellation of Ophiuchus. It was discovered in 1771 by Charles Messier, then added to his catalogue eight years later.

<span class="mw-page-title-main">47 Tucanae</span> Globular cluster in the constellation Tucana

47 Tucanae or 47 Tuc is a globular cluster located in the constellation Tucana. It is about 4.45 ± 0.01 kpc (15,000 ± 33 ly) away from Earth, and 120 light years in diameter. 47 Tuc can be seen with the naked eye, with an apparent magnitude of 4.1. It appears about 44 arcminutes across including its far outreaches. Due to its far southern location, 18° from the south celestial pole, it was not catalogued by European astronomers until the 1750s, when the cluster was first identified by Nicolas-Louis de Lacaille from South Africa.

<span class="mw-page-title-main">Milky Way</span> Galaxy containing the Solar System

The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.

<span class="mw-page-title-main">NGC 5986</span> Globular cluster in the constellation Lupus

NGC 5986 is a globular cluster of stars in the southern constellation of Lupus, located at a distance of approximately 34 kilolight-years from the Sun. It was discovered by Scottish astronomer James Dunlop on May 10, 1826. John L. E. Dreyer described it as, "a remarkable object, a globular cluster, very bright, large, round, very gradually brighter middle, stars of 13th to 15th magnitude". Its prograde–retrograde orbit through the Milky Way galaxy is considered irregular and highly eccentric. It has a mean heliocentric radial velocity of +100 km/s. The galacto-centric distance is 17 kly (5.2 kpc), which puts it in the galaxy's inner halo.

<span class="mw-page-title-main">Terzan 7</span>

Terzan 7 is a sparse and young globular cluster that is believed to have originated in the Sagittarius Dwarf Spheroidal Galaxy and is physically associated with it. It is relatively metal rich with [Fe/H] = -0.6 and an estimated age of 7.5 Gyr. Terzan 7 has low levels of nickel which supports its membership in the Sag DEG system since it has a similar chemical signature. It has a rich population of blue stragglers that are strongly concentrated toward the center of Terzan 7. It has an average luminosity distribution of Mv = -5.05. It has a half-light radius (Rh) of 6.5pc.

<span class="mw-page-title-main">NGC 6539</span> Globular cluster in the constellation Serpens

NGC 6539, or GCL 85, is a globular cluster of stars in the constellation Serpens. It was discovered by Danish astronomer Theodor Brorsen in 1856. This cluster is visible with a small amateur telescope, having an apparent visual magnitude of 9.6 and an angular size of 6.9″. It is located at a distance of 26.63 kly (8.165 kpc) from the Sun, and 10 kly (3.1 kpc) from the galactic center.

<span class="mw-page-title-main">NGC 6352</span> Globular cluster in the constellation Ara

NGC 6352 is a globular cluster of stars in the southern constellation of Ara, located approximately 18.3 kly from the Sun. It was discovered by Scottish astronomer James Dunlop on May 14, 1826. The cluster has a Shapley–Sawyer Concentration Class of XI:. A telescope with a 15 cm (5.9 in) aperture is required to resolve the stars within this loose cluster.

<span class="mw-page-title-main">Liller 1</span>

Liller 1 is a globular cluster in the constellation Scorpius, discovered by the American astronomer William Liller in 1977. It is close to the centre of the Milky Way in its galactic bulge, only 2,600 light-years from the centre. Liller 1 is just under 30,000 light years from Earth.

<span class="mw-page-title-main">NGC 6441</span> Globular cluster in Scorpius

NGC 6441 is a globular cluster in the southern constellation of Scorpius. It was discovered by the Scottish astronomer James Dunlop on May 13, 1826, who described it as "a small, well-defined rather bright nebula, about 20″ in diameter". The cluster is located 5 arc minutes east-northeast of the star G Scorpii, and is some 43,000 light-years from the Sun.

<span class="mw-page-title-main">NGC 5053</span> Globular cluster in the constellation Coma Berenices

NGC 5053 is the New General Catalogue designation for a globular cluster in the northern constellation of Coma Berenices. It was discovered by German-British astronomer William Herschel on March 14, 1784 and cataloged as VI-7. In his abbreviated notation, he described it as, "an extremely faint cluster of extremely small stars with resolvable nebula 8 or 10′ diameter, verified by a power of 240, beyond doubt". Danish-Irish astronomer John Louis Emil Dreyer reported in 1888 that the cluster appeared, "very faint, pretty large, irregular round shape, growing very gradually brighter at the middle".

<span class="mw-page-title-main">NGC 720</span> Galaxy in the constellation Cetus

NGC 720 is an elliptical galaxy located in the constellation Cetus. It is located at a distance of circa 80 million light years from Earth, which, given its apparent dimensions, means that NGC 720 is about 110,000 light years across. It was discovered by William Herschel on October 3, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies about three and a half degrees south and slightly east from zeta Ceti.

<span class="mw-page-title-main">NGC 1380</span> Galaxy in the constellation Fornax

NGC 1380 is a lenticular galaxy located in the constellation Fornax. It is located at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 1380 is about 85,000 light years across. It was discovered by James Dunlop on September 2, 1826. It is a member of the Fornax Cluster.

Robert Michael Rich is an American astrophysicist. He obtained his B.A. at Pomona College in 1979 and earned his Ph.D. from the California Institute of Technology in 1986 under thesis supervisor Jeremy R. Mould. He was a Carnegie Fellow at Carnegie/DTM until 1988 when he joined the faculty of Columbia University where he was the doctoral thesis adviser to Neil deGrasse Tyson, and is on the faculty of the University of California, Los Angeles.

References

  1. 1 2 3 4 Racine, René (1975). "UBV photometry of faint globular clusters". The Astronomical Journal. 80 (12): 1031–36. Bibcode:1975AJ.....80.1031R. doi:10.1086/111835.
  2. 1 2 "Cl Terzan 5". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2009-12-04.
  3. 1 2 3 Ortolani, S.; Barbuy, B.; Bica, E. (1996). "NTT VI photometry of the metal rich and obscured bulge globular cluster Terzan 5". Astronomy and Astrophysics. 308: 733–37. Bibcode:1996A&A...308..733O.
  4. 1 2 3 4 5 6 7 8 Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.; Mucciarelli, A.; Beccari, G.; Miocchi, P.; Bellazzini, M.; Rich, R. M.; Origlia, L.; Valenti, E.; Rood, R. T.; Ransom, S. M. (2010). "New Density Profile and Structural Parameters of the Complex Stellar System Terzan 5". The Astrophysical Journal. 717 (2): 653. arXiv: 1005.2847 . Bibcode:2010ApJ...717..653L. doi:10.1088/0004-637X/717/2/653. S2CID   118665166.
  5. 1 2 Ortolani, S.; Barbuy, B.; Zoccali, M.; Renzini, A.; Renzini, A. (2007). "Distances of the bulge globular clusters Terzan 5, Liller 1, UKS 1 and Terzan 4 based on HST NICMOS photometry". Astronomy and Astrophysics. 470 (3): 1043–49. arXiv: 0705.4030 . Bibcode:2007A&A...470.1043O. doi:10.1051/0004-6361:20066628. S2CID   18360940.
  6. 1 2 3 4 Ferraro, F.R.; Dalessandro, E.; Mucciarelli, A.; Beccari, G; Rich, RM; Origlia, L; Lanzoni, B; Rood, RT; et al. (2009). "The cluster Terzan 5 as a remnant of a primordial building block of the Galactic bulge". Nature. 462 (7272): 483–486. arXiv: 0912.0192 . Bibcode:2009Natur.462..483F. doi:10.1038/nature08581. PMID   19940920. S2CID   35131.
  7. ↑ Gottlieb, Steve (August 1, 2000). "Deep-Sky Notebook: A Tour of Obscure Summer Globular Clusters". Sky and Telescope. 100 (2): 112. ISSN   0037-6604.
  8. ↑ Terzan, Agop (1968). "Six nouveaux amas stellaires (Terzan 3-8) dans la region DU centre de la Voie lactee et les constellations DU Scorpion et DU Sagittaire". C. R. Acad. Sci. 267 (Ser. B): 1245–1248. Bibcode:1968CRASB.267.1245T.
  9. ↑ King, I.R. (1972). "The identity and aliases of the stellar system Terzan 5". Astronomy and Astrophysics. 19: 166. Bibcode:1972A&A....19..166K.
  10. 1 2 Cohn, Haldan N.; Lugger, Phyllis M.; Grindlay, Jonathan E.; Edmonds, Peter D. (2002). "Hubble Space Telescope/NICMOS observations of Terzan 5: stellar content and structure of the core". The Astrophysical Journal. 571 (2): 818–29. arXiv: astro-ph/0202059 . Bibcode:2002ApJ...571..818C. doi:10.1086/339874. S2CID   18698604.
  11. ↑ Ferraro, F. R.; Pallanca, C.; Lanzoni, B.; Crociati, C.; Dalessandro, E.; Origlia, L.; Rich, R. M.; Saracino, S.; Mucciarelli, A.; Valenti, E.; Geisler, D.; Mauro, F.; Villanova, S.; Moni Bidin, C.; Beccari, G. (2021). "A new class of fossil fragments from the hierarchical assembly of the Galactic bulge". Nature Astronomy. 5 (3): 311–318. arXiv: 2011.09966 . Bibcode:2021NatAs...5..311F. doi:10.1038/s41550-020-01267-y. S2CID   227054148.
  12. ↑ "Pulsars in Globular Clusters". www3.mpifr-bonn.mpg.de. Retrieved 2023-12-20.
  13. 1 2 Abramowski, A.; et al. (2011). "Very-high-energy gamma-ray emission from the direction of the Galactic globular cluster Terzan 5". Astronomy & Astrophysics. 531: L18. arXiv: 1106.4069 . Bibcode:2011A&A...531L..18H. doi:10.1051/0004-6361/201117171. S2CID   59036124.
  14. ↑ Hessels, J. W. T.; Ransom, S. M.; Stairs, I. H.; Freire, P. C.; Kaspi, V. M.; Camilo, F. (2006). "A Radio Pulsar Spinning at 716 Hz". Science. 311 (5769): 1901–1904. arXiv: astro-ph/0601337 . Bibcode:2006Sci...311.1901H. doi:10.1126/science.1123430. PMID   16410486. S2CID   14945340.
  15. ↑ Makishima, K.; Ohashi, T.; Inoue, H.; Koyama, K.; Matsuoka, M.; Murakami, T.; Oda, M.; Ogawara, Y.; Shibazaki, N.; Tanaka, Y.; Kondo, I.; Hayakawa, S.; Kunieda, H.; Makino, F.; Masai, K.; Nagase, F.; Tawara, Y.; Miyamoto, S.; Tsunemi, H.; Da Yamashita, K. (1981). "Discovery of two new burst sources in the globular clusters Terzan 1 and Terzan 5". The Astrophysical Journal. 247: L23–25. Bibcode:1981ApJ...247L..23M. doi: 10.1086/183581 .
  16. 1 2 Heinke, C.O.; Wijnands, R.; Cohn, H.N.; Lugger, P. M.; Grindlay, J. E.; Pooley, D.; Lewin, W. H. G. (2006). "Faint X-ray sources in the globular cluster Terzan 5". The Astrophysical Journal. 651 (2): 1098–1111. arXiv: astro-ph/0606253 . Bibcode:2006ApJ...651.1098H. doi:10.1086/507884. S2CID   15975974.
  17. ↑ "The unusual cluster Terzan 5". www.eso.org. Retrieved 9 September 2016.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.