Palomar globular clusters

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Hale Telescope at Palomar Observatory Hale Telescope, Palomar Observatory 005.jpg
Hale Telescope at Palomar Observatory
Photo of Palomar 6 taken by the Hubble Space Telescope Palomar6 - HST - Potw2138a.jpg
Photo of Palomar 6 taken by the Hubble Space Telescope
Palomar 5 located between the two bright stars in the bottom left and top right corners. Pal5 - SDSS DR14 (panorama).jpg
Palomar 5 located between the two bright stars in the bottom left and top right corners.

The Palomar globular clusters are some of the faintest of all globular clusters in the Milky Way galaxy, and been discovered in the 1950s on the survey plates of the first Palomar Observatory Sky Survey (POSS). [1] In total there are 15 Palomar globular clusters, which include Palomar 1, [2] Palomar 2, [3] Palomar 3, [4] Palomar 4, [5] Palomar 5, [6] Palomar 6, [7] Palomar 7, [8] Palomar 8, [9] Palomar 9, [10] Palomar 10, [11] Palomar 11, [12] Palomar 12, [13] Palomar 13, [14] Palomar 14, [15] and Palomar 15. [16] Some Palomar Globulars, like Palomar 6, Palomar 7, Palomar 9, Palomar 10 and Palomar 11 are clusters of average size located nearby, yet obscured in our line of sight by dust. Other Palomar globulars, like Palomar 3, Palomar 4 and Palomar 14 are giants located in the far outer halo of the Milky Way. Some even originated from a different galaxy, such as Palomar 12 from the Sagittarius Dwarf Spheroidal Galaxy, which is now known as a satellite of the Milky Way. Observation of different Palomar globulars greatly varies in the degree of difficulty depending on the cluster. Some are small and compact, others are very sparse, to the point where they may be hard to distinguish from foreground stars.

Contents

History

The Palomar globulars have been discovered fairly late due to them being very faint, heavily obscured, remotely located or having few member stars. For this reason, these were discovered only with the enormous 48-inch Schmidt camera at Palomar. Some of the astronomers who identified these objects as globular clusters include George Abell, Fritz Zwicky, Edwin Hubble, Halton Arp and Walter Baade. All Palomar globulars except two, Palomar 7 (IC1276) and Palomar 9 (NGC6717), have never been seen before. Palomar 9 was observed by William Herschel back on August 7, 1784. Palomar 7 was first discovered by an American astronomer Lewis Swift in 1889, and was independently rediscovered by George Abell as part of the survey in 1952. [17]

Palomar Globular catalogue

Catalogue of Palomar globular clusters [18]
Palomar Constellation RA DEC Size (arcmin) Magnitude Distance from sun (kly)Distance from Galactic Centre (kly)
1 Cepheus 03h 33m 23.0s+79d:34m:50s2.813.1835.655.4
2 Auriga 04h:46m:05.9s+31d:22m:51s2.213.0490.0115.5
3 Sextans 10h:05m:31.4s+00d:04m:17s1.614.26302.3312.8
4 Ursa Major 11h:29m:16.8s+28d:58m:25s1.314.20356.2364.6
5 Serpens 15h:16m:05.3s-00d:06m:41s8.011.7575.760.7
6 Ophiuchus 17h:43m:42.2s-26d:13m:21s1.211.5519.27.2
7 (IC 1276) Serpens 18h:10m:44.2s-07d:12m:27s8.010.3417.612.1
8 Sagittarius 18h:41m:29.9s-19d:49m:33s5.211.0242.118.3
9 (NGC 6717) Sagittarius 18h:55m:06.2s-22d:42m:03s5.49.2823.17.8
10 Sagitta 19h:18m:02.1s+18d:34m:18s4.013.2219.220.9
11 Aquila 19h:45m:14.4s-0.8d:00m:26s109.8042.425.8
12 Capricornus 21h:46m:38.8s-21d:15m:03s2.911.9962.351.9
13 Pegasus 23h:06m:44.4s+12d:46m:19s0.713.8084.187.0
14 Hercules 16h:11m:04.9s+14d:57m:29s2.214.74241.0225.0
15 Ophiuchus 17h:00m:02.4s-00d:32m:31s3.014.00145.5123.6

Visual observation

The Palomar globulars can be observed and identified by amateur astronomers, however dark skies and high power are required. Astronomers have made reports on visual observations using 17.5 inch and larger telescopes, while others have identified the brightest Palomar globulars with more modest sizes of 10 inch telescopes or less. [19] [20] Overall, there is great variability in the level of difficulty to observe these objects, yet, for successful observation, skies with no light-pollution and excellent seeing conditions coupled with high power (at least 200 power magnification) are necessary. Many Palomars are small objects and require the observer to know how to navigate the sky precisely, and rely on averted vision when needed. In some Palomars, visual observers can resolve individual stars, while others look hazy. Palomar 9 (NGC 6717) is the easiest object to observe of the Palomar globulars, while Palomar 15 is regarded as the most difficult.

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">Messier 2</span> Globular cluster in the constellation Aquarius

Messier 2 or M2 is a globular cluster in the constellation Aquarius, five degrees north of the star Beta Aquarii. It was discovered by Jean-Dominique Maraldi in 1746, and is one of the largest known globular clusters.

<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 54</span> Globular cluster in Sagittarius

Messier 54 is a globular cluster in the constellation Sagittarius. It was discovered by Charles Messier in 1778 and then included in his catalog of comet-like objects.

<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">NGC 1427</span> Galaxy in the constellation Fornax

NGC 1427 is a low-luminosity elliptical galaxy located approximately 71 million light-years away from Earth. It was discovered by John Frederick William Herschel on November 28, 1837. It is a member of the Fornax Cluster. The galaxy has a stellar mass of 7.9 × 1010M☉, and a total mass of 9.4 × 1010M☉. However, the mass of the dark matter halo surrounding the galaxy is around 4.3 × 1012M☉.

<span class="mw-page-title-main">Palomar 12</span> Globular cluster in the constellation Capricornus

Palomar 12 is a globular cluster in the constellation Capricornus, and is a member of the Palomar Globular Clusters group.

<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">NGC 1851</span> Globular cluster in the constellation Columba

NGC 1851 is a relatively massive globular cluster located in the southern constellation of Columba. Astronomer John Dreyer described it as not very bright but very large, round, well resolved, and clearly consisting of stars. It is located 39.5 kilolight-years from the Sun, and 54.1 kilolight-years from the Galactic Center. The cluster is following a highly eccentric orbit through the galaxy, with an eccentricity of about 0.7.

<span class="mw-page-title-main">Palomar 6</span>

Palomar 6 is a loose globular cluster in the constellation Ophiuchus that belongs to the Milky Way galaxy. It is a member of the Palomar Globular Clusters group. It is located about 25,000 light-years away from the Sun. It formed in what would become the bulge of the Milky Way. It is similar to other old-bulge globular clusters such as Messier 62, NGC 6522, NGC 6558, and Haute-Provence 1.

<span class="mw-page-title-main">NGC 6642</span> Globular cluster in the constellation Sagittarius

NGC 6642 is a globular cluster located 26,700 light-years from Earth, in the constellation Sagittarius. Many "blue stragglers" have been spotted in this globular, and it is known to be lacking in low-mass stars.

<span class="mw-page-title-main">NGC 6388</span> Globular cluster in the constellation Scorpius

NGC 6388 is a globular cluster of stars located in the southern constellation of Scorpius. The cluster was discovered by Scottish astronomer James Dunlop on May 13, 1826 using a 20 cm (9 in) reflector telescope. It was later determined to be a globular cluster by English astronomer John Herschel, who was able to resolve it into individual stars. NGC 6388 is located at a distance of approximately 35,600 light-years (10.90 kpc) from the Sun. Due to its apparent visual magnitude of +6.8, binoculars or a small telescope are required to view it.

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

NGC 6441, sometimes also known as the Silver Nugget Cluster, 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 3311</span> Galaxy in the constellation Hydra

NGC 3311 is a super-giant elliptical galaxy located about 190 million light-years away in the constellation Hydra. The galaxy was discovered by astronomer John Herschel on March 30, 1835. NGC 3311 is the brightest member of the Hydra Cluster and forms a pair with NGC 3309 which along with NGC 3311, dominate the central region of the Hydra Cluster.

<span class="mw-page-title-main">NGC 708</span> Galaxy in the constellation Andromeda

NGC 708 is an elliptical galaxy located 240 million light-years away in the constellation Andromeda and was discovered by astronomer William Herschel on September 21, 1786. It is classified as a cD galaxy and is the brightest member of Abell 262. NGC 708 is a weak FR I radio galaxy and is also classified as a type 2 Seyfert galaxy.

<span class="mw-page-title-main">NGC 1395</span> Galaxy in the constellation Eridanus

NGC 1395 is an elliptical galaxy located in the constellation Eridanus. It is located at a distance of circa 75 million light years from Earth, which, given its apparent dimensions, means that NGC 1395 is about 130,000 light years across. It was discovered by William Herschel on November 17, 1784. It is a member of the Eridanus Cluster.

<span class="mw-page-title-main">NGC 753</span> Galaxy in the constellation Andromeda

NGC 753 is a spiral galaxy located 220 million light-years away in the constellation Andromeda. The galaxy was discovered by astronomer by Heinrich d'Arrest on September 16, 1865 and is a member of Abell 262.

<span class="mw-page-title-main">NGC 7492</span> Globular cluster in the constellation Aquarius

NGC 7492 is a globular cluster in the constellation Aquarius. It was discovered by the astronomer William Herschel on September 20, 1786. It resides in the outskirts of the Milky Way, about 80,000 light-years away, more than twice the distance between the Sun and the center of the galaxy, and is a benchmark member of the outer galactic halo. The cluster is immersed in, but does not kinematically belong to, the Sagittarius Stream.

References

  1. ↑ Abell, G. O. (1955). "Globular Clusters and Planetary Nebulae Discovered on the National Geographic Society-Palomar Observatory Sky Survey". Publications of the Astronomical Society of the Pacific. 67 (397): 258–261. Bibcode:1955PASP...67..258A. doi: 10.1086/126815 . ISSN   0004-6280. JSTOR   40676260. S2CID   208869169.
  2. ↑ Rosenberg, A., Saviane, I., Piotto, G., Aparicio, A., & Zaggia, S. R. (1998). Palomar 1: Another Young Galactic Halo Globular Cluster?. The Astronomical Journal, 115(2), 648.
  3. ↑ Bonatto, Charles; Chies-Santos, Ana L (2020-04-01). "Lifting the dust veil from the globular cluster Palomar 2". Monthly Notices of the Royal Astronomical Society. 493 (2): 2688–2693. doi: 10.1093/mnras/staa510 . hdl: 10183/212352 . ISSN   0035-8711.
  4. ↑ Catelan, M.; Ferraro, F. R.; Rood, R. T. (2001-10-20). "Horizontal-Branch Models and the Second-Parameter Effect. IV. The Case of M3 and Palomar 3". The Astrophysical Journal. 560 (2): 970–985. arXiv: astro-ph/0106554 . Bibcode:2001ApJ...560..970C. doi:10.1086/323049. ISSN   0004-637X. S2CID   17178717.
  5. ↑ Zonoozi, Akram Hasani; Haghi, Hosein; Küpper, Andreas H. W.; Baumgardt, Holger; Frank, Matthias J.; Kroupa, Pavel (2014-06-01). "Direct N-body simulations of globular clusters – II. Palomar 4". Monthly Notices of the Royal Astronomical Society. 440 (4): 3172–3183. arXiv: 1404.5969 . doi: 10.1093/mnras/stu526 . ISSN   1365-2966.
  6. ↑ Bonaca, Ana; Pearson, Sarah; Price-Whelan, Adrian M.; Dey, Arjun; Geha, Marla; Kallivayalil, Nitya; Moustakas, John; Muñoz, Ricardo; Myers, Adam D.; Schlegel, David J.; Valdes, Francisco (2020-01-27). "Variations in the Width, Density, and Direction of the Palomar 5 Tidal Tails". The Astrophysical Journal. 889 (1): 70. arXiv: 1910.00592 . Bibcode:2020ApJ...889...70B. doi: 10.3847/1538-4357/ab5afe . ISSN   1538-4357. S2CID   203626938.
  7. ↑ Lee, J. W., & Carney, B. W. (2002). Near-Infrared Photometry of the Globular Cluster Palomar 6. The Astronomical Journal, 123(6), 3305.
  8. ↑ Barbuy, B., Ortolani, S., & Bica, E. (1998). Terzan 3 and IC 1276 (Palomar 7): Two metal-rich bulge globular clusters uncovered. Astronomy and Astrophysics Supplement Series, 132(3), 333-340.
  9. ↑ Astronomy and Astrophysics Supplement Series, Vol. 45, p. 53-60 (1981)
  10. ↑ Ortolani, S., Barbuy, B., & Bica, E. (1999). Colour-magnitude diagrams of the post-core collapse globular clusters NGC 6256 and NGC 6717 (Palomar 9). Astronomy and Astrophysics Supplement Series, 136(2), 237-243.
  11. ↑ Kaisler, D., Harris, W. E., & McLaughlin, D. E. (1997). Palomar 10 and NGC 6749: A Study in Contrasts. Publications of the Astronomical Society of the Pacific, 109(738), 920.
  12. ↑ Brian, Lewis, M. S. Liu, W. M. Paust, N. E. Q. Chaboyer (2006-01-13). A New Color-Magnitude Diagram for Palomar 11. OCLC   691210799.{{cite book}}: CS1 maint: multiple names: authors list (link)
  13. ↑ Cohen, J. (2003). Pal 12 As A Part of the Sgr Stream; the Evidence From Abundance Ratios. arXiv preprint astro-ph/0311187.
  14. ↑ M. H. Siegel et al 2001 AJ 121 935
  15. ↑ Sollima, A.; Martínez-Delgado, D.; Valls-Gabaud, D.; Peñarrubia, J. (2010-12-14). "Discovery of Tidal Tails Around the Distant Globular Cluster Palomar 14". The Astrophysical Journal. 726 (1): 47. arXiv: 1010.6303 . doi: 10.1088/0004-637x/726/1/47 . ISSN   0004-637X. S2CID   118471604.
  16. ↑ Myeong, G. C.; Jerjen, Helmut; Mackey, Dougal; Da Costa, Gary S. (2017-05-11). "Tidal Tails around the Outer Halo Globular Clusters Eridanus and Palomar 15". The Astrophysical Journal. 840 (2): L25. arXiv: 1704.07690 . Bibcode:2017ApJ...840L..25M. doi: 10.3847/2041-8213/aa6fb4 . ISSN   2041-8213. S2CID   118856686.
  17. ↑ "Palling Around With Palomar Globular Clusters". Sky & Telescope. 2016-08-17. Retrieved 2022-06-04.
  18. ↑ Harris, W. E. (1996). A Catalog of Parameters for Globular Clusters in the Milky Way. AJ 112, 1487.
  19. ↑ "The Palomar Globulars". www.astronomy-mall.com. Retrieved 2022-06-03.
  20. ↑ "The Palomar Globular Clusters". www.deep-sky.co.uk. Retrieved 2022-06-03.
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