Cygnus OB2

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Cygnus OB2
CygOB2 med.jpg
Cygnus OB2 in the light of H-Alpha; 3.5° view
Credit: IPHAS
Observation data (J2000.0 epoch)
Right ascension 20h 33m 12s [1]
Declination 41° 19′ 00″
Distance 5.12 kly (1,570+80
−70  pc [2] )
Apparent magnitude  (V)6.1
Apparent dimensions (V)60.0′
Physical characteristics
Estimated age1 to 7 million years
–
Associations
Constellation Cygnus
See also: Open cluster, List of open clusters
Short narrated video about Cygnus OB2 #9

Cygnus OB2 is an OB association that is home to some of the most massive and most luminous stars known, including suspected Luminous blue variable Cyg OB2 #12. It also includes one of the largest known stars, NML Cygni. [3] The region is embedded within a wider one of star formation known as Cygnus X, which is one of the most luminous objects in the sky at radio wavelengths. The region is approximately 1,570 parsecs from Earth in the constellation of Cygnus. [4]

The young cluster is one of the largest known and the largest in the northern hemisphere with some authors formerly classifying it as a young globular cluster similar to those in the Large Magellanic Cloud. [5] Today, however, it is considered a massive, low-density stellar association. [6]

Although it is over ten times more massive than the Orion Nebula, which is easily seen with the naked eye, Cygnus OB2 is hidden behind a massive dust cloud known as the Cygnus Rift, which obscures many of the stars in it. This means that despite its large size, it is hard to determine its actual properties. The estimated number of massive stars range from 50 [7] to 100 [5] of spectral type O and its total mass having been calculated as (4–10)×104 [5] or 3×104 solar masses according to other investigations. [7]

Despite this, recent surveys ranging from radio to X-ray wavelengths have observed the region to great depths to gain a better understanding of how the processes of star and planet formation occur on such a large scale. These studies include observations with the Chandra X-ray Observatory, Spitzer Space Telescope, the Herschel Space Observatory and the Gran Telescopio Canarias. As for recent observations, the final stages of the process of photoablation is taking place, where the biggest stars formed and cleared the ambient material from the region. [8]

Prominent stars
Schulte number [9] MT number [9] Other name/CPR number [10] Spectral type [10] [11] Luminosity [10]
(L☉)		Mass [10] [11]
(M☉)
HD 195213 [12] O7180,30043.3
WR 144WC4158,5009.9
WR 145WN7o/CE+O7V((f))371,00018.3
WR 146WC6+O8III115,0008?+?
WR 147 [13] WN8h+B0.5V2,000,00051
NML Cyg [14] [15] [16] M4.5–M7.9Ia–III229,00050
V1827 Cyg/B17 [12] Ofpe242,10057
BD+40°4210 [12] [17] B1III:e630,00054
BD+40 4223 [12] B0Ia539,50048.3
#159O8.5V120,00026
#283 [18] B1I40,00014
#3O6IV+O9III346,000>17 + >8
#4217O7III((f))158,00029
#5V729 [19] [20] O7I+O6I+O9V158400031 + 27 + 9
#6317O8V109,00025
#7457O3If426,00047
#8A 465 [21] O6If+O5.5III(f)501,00044 + 37
#8B462O6.5III(f)301,00035
#8C483O5If371,00042
#8D473 [22] O8.5V48,00020
#9431 [20] [23] O5–5.5I+O3–4III707,000>34 + >30
#10632O9.5I478,00037
#11734 [18] O5If537,00044
#12 304 [24] B3-4Ia+1,230,000110
#14227O9V45,00019
#15258O8V61,00022
#16299O8V83,00023
#17339O8.5V61,00021
#18556B1Ib338,00029
#19601B0Iab186,00026
#20145O9III26,00017
#21259B0.5V15,00013
#22417O3If+O6V(f)660,00050
#23470O9.5V26,00017
#24480O7.5V104,00025
#25531O8.5V97,00024
#26642B1III69,00016
#27696O9.5V+B0V30,00017
#29745O7V87,00025
#30793B1.5III33,00013
#37358B3V3,0007
#41378B0V44,00018
#51425B0V27,00016
#54395B1V7,00010
#64488B2Ve23,00012
#66515B1V10,00011
#70588B0V48,00018
#71646B1.5V6,0009
#73O8III+O8III41,00020
#74555O8V109,00025
#75736O9V31,00018
138 [12] O8I88,70026
267A11 [12] O7.5III323,00035
448O6V107,00029
516 [18] O5.5V((f))707,00052
716O9V28,00018
771O7V151,00029
A12 [12] B0Ia373,30036
A15O7I263,00032
A20O8II380,00035
A23B0.7Ib263,00026
A24O6.5III154,00030
A25 [12] O8III88,70028
A27B0Ia426,00035
A29 [12] O9.7Iab167,50029.1
A32 [12] O9.5IV106,70026.1
A36B0Ib+B0III173,00026
A37 [12] O5V((f))66,10034.8
A46 [12] O7V((f))46,60025.6
E47B0Ia676,00042
IRAS 20321+4009 [12] O9278,00032
TYC 3156-998-1 [12] OC9.7Ia516,00034.2

The progenitor of BD+43°3654 might have been a member of Cygnus OB2. Two stars from two binaries would have collided and merged forming BD+43°3654, which would have then been ejected from the stellar association along with the two remaining stars. [25]

Prominent members of the association are often referred to by their Schulte numbers: for example Schulte 12, VI Cygni 12, or Cygnus OB2 #12. The numbers were first used in the 1953 discovery paper where 11 "blue giants" were numbered. [26] A 12th star (Cyg OB2 #12) was added in 1954, [27] and eight more shortly after. [28] Schulte himself maintained the already-published numbers and added many more when studying the association which he called VI Cygni. [9]

Cygnus OB2 contains embedded star clusters as well as two open clusters located in the center of Cygnus OB2. The open clusters are called Bica 1 and Bica 2. Both Bica 1 and Bica 2 contain several OB-stars, such as Cygnus OB2 #8A and Cygnus OB2 #22. [29]

Bica1 HST.jpg
Open cluster Bica 1
Bica2 HST.jpg
Part of open cluster Bica 2

Related Research Articles

<span class="mw-page-title-main">Cygnus (constellation)</span> Constellation in the northern celestial hemisphere

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.

<span class="mw-page-title-main">16 Cygni</span> Multiple star in the constellation Cygnus

16 Cygni or 16 Cyg is a triple star system approximately 69 light-years away from Earth in the constellation of Cygnus. It consists of two Sun-like yellow dwarf stars, 16 Cygni A and 16 Cygni B, together with a red dwarf, 16 Cygni C. In 1996 an extrasolar planet was discovered in an eccentric orbit around 16 Cygni B.

<span class="mw-page-title-main">KY Cygni</span> Star in the constellation Cygnus

KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is approximately 4,700 light-years away.

Pi2 Cygni, Latinized from π2 Cygni, is a triple star system in the northern constellation of Cygnus. It is visible to the naked eye about 2.5° east-northeast of the open cluster M39, having an apparent visual magnitude of 4.24. Based upon an annual parallax shift of 2.95 mas, it is located at a distance of roughly 1,100 light years from the Sun.

<span class="mw-page-title-main">Zeta Cygni</span> Star in the constellation Cygnus

Zeta Cygni is a binary star system in the northern constellation of Cygnus, the swan. It has an apparent visual magnitude of 3.26 and, based upon parallax measurements, is about 143 light-years away.

<span class="mw-page-title-main">Cygnus OB2-12</span> Blue hypergiant star

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.

<span class="mw-page-title-main">Cygnus OB2-8A</span> Spectroscopic binary star near the center of Cygnus OB2

Cygnus OB2 #8A is a double-lined spectroscopic binary located near the centre of the Cygnus OB2 association located 5,500 light years away.

<span class="mw-page-title-main">NML Cygni</span> Star in the constellation Cygnus

NML Cygni or V1489 Cygni is a red hypergiant or red supergiant (RSG) in the constellation Cygnus. It is possibly one of the largest known stars currently known, and is also possibly one of the most luminous and massive cool hypergiants, as well as one of the most luminous stars in the Milky Way.

Omega<sup>1</sup> Cygni B-type subgiant star in the constellation Cygnus

Omega1 Cygni, Latinized from ω1 Cygni, is the Bayer designation for a solitary star in the northern constellation of Cygnus. It is visible to the naked eye with an apparent visual magnitude of 4.94. Based upon an annual parallax shift of 2.59 mas, it is estimated to lie roughly 1,260 light years from the Sun. Relative to its neighbors, this star has a peculiar velocity of 25.7±2.2 km/s.

63 Cygni is a single star in the northern constellation of Cygnus, located around 1,030 light years away from Sun. It is visible to the naked eye as an orange-hued star with an apparent visual magnitude of 4.56. 63 Cyg is moving closer to the Earth with a heliocentric radial velocity of −26 km/s.

57 Cygni is a close binary star system in the constellation Cygnus, located about 530 light years from Earth. It is visible to the naked eye as a blue-white hued star with a baseline apparent visual magnitude of 4.80. The pair have a magnitude difference of 0.34. This system is moving closer to the Earth with a heliocentric radial velocity of −21 km/s.

<span class="mw-page-title-main">55 Cygni</span> Star in the constellation Cygnus

55 Cygni is a blue supergiant star in the constellation Cygnus. It is thought to be a member of the Cygnus OB7 stellar association at about 2,700 light years.

<span class="mw-page-title-main">29 Cygni</span> A-type main sequence star in the constellation Cygnus

29 Cygni is a single star in the northern constellation of Cygnus. It is dimly visible to the naked eye as a white-hued star with an apparent visual magnitude of 4.93. The distance to 29 Cyg, as estimated from an annual parallax shift of 24.5 mas, is 133 light years. The star is moving closer to the Earth with a heliocentric radial velocity of −17 km/s. It is a member of the 30–50 million year old Argus Association of co-moving stars.

<span class="mw-page-title-main">Westerlund 1 W26</span> Star in the constellation Ara

Westerlund 1 W26 or Westerlund 1 BKS AS is a red supergiant located at the outskirts of the Westerlund 1 super star cluster. It is one of the largest known stars and the most luminous supergiant stars discovered so far with radius calculated to be in excess of a thousand times the solar radius, and a luminosity of over 200,000 times the solar luminosity. If placed at the center of the Solar System, its photosphere would engulf the orbit of Jupiter.

<span class="mw-page-title-main">BC Cygni</span> Star in the constellation Cygnus

BC Cygni is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus.

<span class="mw-page-title-main">RW Cygni</span> Star in the constellation Cygnus

RW Cygni is a semiregular variable star in the constellation Cygnus, about a degree east of 2nd magnitude γ Cygni. Its apparent magnitude varies between 8.05 and 9.70 and its spectral type between M3 and M4.

9 Cygni is a binary star system in the northern constellation of Cygnus. 9 Cygni is its Flamsteed designation. The two stars have a combined magnitude of 5.39, so it can be seen with the naked eye under good viewing conditions. Parallax measurements made by Gaia put the star at a distance of around 590 light-years away.

<span class="mw-page-title-main">X Cygni</span> Variable star in the constellation Cygnus

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.

<span class="mw-page-title-main">SU Cygni</span> Variable star system in the constellation Cygnus

SU Cygni is a triple star system in the northern constellation of Cygnus, abbreviated SU Cyg. The primary component of the system is a classical Cepheid variable with a period of 3.8455473 days. The changing luminosity of this star causes the system to vary in brightness from a peak apparent visual magnitude of 6.44 down to magnitude 7.22 over the course of its cycle. The distance to this system is approximately 3,200 light years based on parallax measurements. It is a member of the Turner 9 open cluster of stars.

References

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  2. ↑ Parker, Richard J.; Crowther, Paul A.; Rate, Gemma (2020). "Unlocking Galactic Wolf–Rayet stars with Gaia DR2 – II. Cluster and association membership". Monthly Notices of the Royal Astronomical Society. 495 (1): 1209–1226. arXiv: 2005.02533 . Bibcode:2020MNRAS.495.1209R. doi: 10.1093/mnras/staa1290 . S2CID   218516882.
  3. ↑ Schuster, M. T.; Marengo, M.; Hora, J. L.; Fazio, G. G.; Humphreys, R. M.; Gehrz, R. D.; Hinz, P. M.; Kenworthy, M. A.; Hoffmann, W. F. (2009). "Imaging the Cool Hypergiant NML Cygni's Dusty Circumstellar Envelope with Adaptive Optics". The Astrophysical Journal. 699 (2): 1423–1432. arXiv: 0904.4690 . Bibcode:2009ApJ...699.1423S. doi:10.1088/0004-637X/699/2/1423. S2CID   17699562.
  4. ↑ Rygl, K.; Brunthaler, A.; Sanna, A.; Menten, K. M.; Reid, M. J.; van Langevelde, H. J.; Honma, M.; Torstensson, K. J. E.; Fujisawa, K. (March 2012). "Parallaxes and proper motions of interstellar masers toward the Cygnus X star-forming complex. I. Membership of the Cygnus X region". Astronomy and Astrophysics. 539: A79. arXiv: 1111.7023 . Bibcode:2012A&A...539A..79R. doi:10.1051/0004-6361/201118211. S2CID   54647474.
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  6. ↑ Wright, Nicholas J.; Parker, Richard J.; Goodwin, Simon P.; Drake, Jeremy J. (2014). "Constraints on massive star formation: Cygnus OB2 was always an association". Monthly Notices of the Royal Astronomical Society. 438 (1): 639–646. arXiv: 1311.4537 . Bibcode:2014MNRAS.438..639W. doi: 10.1093/mnras/stt2232 . S2CID   16957082.
  7. 1 2 Wright, N. J.; Drake, J. J.; Drew, J. E.; Vink, J. S. (2010). "The Massive Star-Forming Region Cygnus OB2. II. Integrated Stellar Properties and the Star Formation History". The Astrophysical Journal. 713 (2): 871–882. arXiv: 1003.2463 . Bibcode:2010ApJ...713..871W. doi:10.1088/0004-637X/713/2/871. S2CID   118590238.
  8. ↑ Hartigan, P.; Palmer, J.; Cleeves, L.I. (2012). "Irradiated interfaces in the Ara OB1, Carina, Eagle Nebula, and Cyg OB2 massive star formation regions". High Energy Density Physics. 8 (4): 313. arXiv: 1304.3930 . Bibcode:2012HEDP....8..313H. doi:10.1016/j.hedp.2012.08.002. S2CID   118863688.
  9. 1 2 3 Massey, P.; Thompson, A. B. (1991). "Massive stars in CYG OB2". The Astronomical Journal. 101: 1408. Bibcode:1991AJ....101.1408M. doi:10.1086/115774.
  10. 1 2 3 4 Wright, Nicholas J.; Drew, Janet E.; Mohr-Smith, Michael (2015). "The massive star population of Cygnus OB2". Monthly Notices of the Royal Astronomical Society. 449 (1): 741–760. arXiv: 1502.05718 . Bibcode:2015MNRAS.449..741W. doi: 10.1093/mnras/stv323 . S2CID   119268358.
  11. 1 2 Massey, P.; Degioia-Eastwood, K.; Waterhouse, E. (2001). "The Progenitor Masses of Wolf-Rayet Stars and Luminous Blue Variables Determined from Cluster Turnoffs. II. Results from 12 Galactic Clusters and OB Associations". The Astronomical Journal. 121 (2): 1050–1070. arXiv: astro-ph/0010654 . Bibcode:2001AJ....121.1050M. doi:10.1086/318769. S2CID   53345173.
  12. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Comerón, F.; Pasquali, A. (2012). "New members of the massive stellar population in Cygnus". Astronomy & Astrophysics. 110: 2715. Bibcode:2012A&A...543A.101C. doi: 10.1051/0004-6361/201219022 .
  13. ↑ Sota, A.; Maíz Apellániz, J.; Morrell, N. I.; Barbá, R. H.; Walborn, N. R.; Gamen, R. C.; Arias, J. I.; Alfaro, E. J.; Oskinova, L. M. (2019). "The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters". Astronomy & Astrophysics. A57: 625. arXiv: 1904.04687 . Bibcode:2019A&A...625A..57H. doi:10.1051/0004-6361/201834850. S2CID   104292503.
  14. ↑ "GCVS Query=V1489 Cyg". Sternberg Astronomical Institute. General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia . Retrieved 2018-09-21.
  15. ↑ Davies, Ben; Beasor, Emma R. (March 2020). "The 'red supergiant problem': the upper luminosity boundary of Type II supernova progenitors". MNRAS . 493 (1): 468–476. arXiv: 2001.06020 . Bibcode:2020MNRAS.493..468D. doi: 10.1093/mnras/staa174 . S2CID   210714093.
  16. ↑ Morris, M.; Jura, M. (1983). "The nature of NML Cygnus". Astrophysical Journal. 267: 179. Bibcode:1983ApJ...267..179M. doi: 10.1086/160856 .
  17. ↑ http://www.sciops.esa.int/SD/ESACFACULTY/docs/seminars/160212_Comeron.pdf Archived 2016-03-03 at the Wayback Machine In and around the rich association Cygnus OB2
  18. 1 2 3 Herrero, A.; Puls, J.; Najarro, F. (2002). "Fundamental parameters of Galactic luminous OB stars VI. Temperatures, masses and WLR of Cyg OB2 supergiants". Astronomy and Astrophysics. 396 (3): 949–966. arXiv: astro-ph/0210469 . Bibcode:2002A&A...396..949H. doi:10.1051/0004-6361:20021432. S2CID   16917437.
  19. ↑ Rauw, G.; Vreux, J. -M.; Bohannan, B. (1999). "The Interacting Early-Type Binary BD +40°4220 (V729 Cyg): Modeling the Colliding Winds Region". The Astrophysical Journal. 517 (1): 416–430. Bibcode:1999ApJ...517..416R. doi: 10.1086/307185 .
  20. 1 2 Kiminki, D. C.; Kobulnicky, H. A.; Ewing, I.; Bagley Kiminki, M. M.; Lundquist, M.; Alexander, M.; Vargas-Alvarez, C.; Choi, H.; Henderson, C. B. (2012). "Additional Massive Binaries in the Cygnus OB2 Association". The Astrophysical Journal. 747 (1): 41. arXiv: 1112.3383 . Bibcode:2012ApJ...747...41K. doi:10.1088/0004-637X/747/1/41. S2CID   119203797.
  21. ↑ De Becker, M.; Rauw, G.; Sana, H.; Pollock, A. M. T.; Pittard, J. M.; Blomme, R.; Stevens, I. R.; Van Loo, S. (2006). "XMM-Newton observations of the massive colliding wind binary and non-thermal radio emitter CygOB2#8A [O6If + O5.5III(f)]" (PDF). Monthly Notices of the Royal Astronomical Society. 371 (3): 1280–1294. Bibcode:2006MNRAS.371.1280D. doi: 10.1111/j.1365-2966.2006.10746.x .
  22. ↑ Kobulnicky, Henry A.; Kiminki, Daniel C.; Lundquist, Michael J.; Burke, Jamison; Chapman, James; Keller, Erica; Lester, Kathryn; Rolen, Emily K.; Topel, Eric; Bhattacharjee, Anirban; Smullen, Rachel A.; Vargas Alvarez, Carlos A.; Runnoe, Jessie C.; Dale, Daniel A.; Brotherton, Michael M. (2014). "Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey". The Astrophysical Journal Supplement Series. 213 (2): 34. arXiv: 1406.6655 . Bibcode:2014ApJS..213...34K. doi:10.1088/0067-0049/213/2/34. S2CID   118543368.
  23. ↑ Nazé, Y.; Mahy, L.; Damerdji, Y.; Kobulnicky, H. A.; Pittard, J. M.; Parkin, E. R.; Absil, O.; Blomme, R. (2012). "The 2.35 year itch of Cygnus OB2 #9". Astronomy & Astrophysics. 546: A37. arXiv: 1209.5622 . Bibcode:2012A&A...546A..37N. doi:10.1051/0004-6361/201219442. S2CID   119187102.
  24. ↑ Clark, J. S.; Najarro, F.; Negueruela, I.; Ritchie, B. W.; Urbaneja, M. A.; Howarth, I. D. (2012). "On the nature of the galactic early-B hypergiants". Astronomy & Astrophysics. 541: A145. arXiv: 1202.3991 . Bibcode:2012A&A...541A.145C. doi:10.1051/0004-6361/201117472. S2CID   11978733.
  25. ↑ Gvaramadze, V. V.; Bomans, D. J. (2008). "BD+43 3654 - a blue straggler?". Astronomy & Astrophysics. 485 (3): L29–L32. arXiv: 0805.3893 . Bibcode:2008A&A...485L..29G. doi:10.1051/0004-6361:200809860. S2CID   18755032.
  26. ↑ Münch, Luis; Morgan, W. W. (1953). "Notes: A Probable Clustering of Blue Giants in Cygnus". Astrophysical Journal. 118: 161. Bibcode:1953ApJ...118..161M. doi: 10.1086/145737 .
  27. ↑ Morgan, W. W.; Johnson, H. L.; Roman, Nancy G. (1954). "A Very Red Star of Early Type in Cygnus". Publications of the Astronomical Society of the Pacific. 66 (389): 85. Bibcode:1954PASP...66...85M. doi: 10.1086/126660 .
  28. ↑ Morgan, W. W.; Meinel, A. B.; Johnson, Hugh M. (1954). "Spectral Classification with Exceedingly Low Dispersion". Astrophysical Journal. 120: 506. Bibcode:1954ApJ...120..506M. doi:10.1086/145938.
  29. ↑ Bica, E.; Bonatto, Ch.; Dutra, C. M. (2003-07-01). "Does Cyg OB2 harbour any open cluster?". Astronomy and Astrophysics. 405 (3): 991–998. Bibcode:2003A&A...405..991B. doi:10.1051/0004-6361:20030700. hdl: 10183/108028 . ISSN   0004-6361.
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