Cygnus OB2
| Cygnus OB2 | |
|---|---|
 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 age | 1 to 7 million years |
| – | |
| Associations | |
| Constellation | Cygnus |
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]
| 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] | O7 | 180300 | 43.3 | ||
| WR 144 | WC4 | 97000 | >20 | ||
| WR 145 | WN7o/CE+O7V((f)) | 371000 | >25 | ||
| WR 146 | WC6+O8III | 114000 | >25 | ||
| WR 147[13] | WN8h+B0.5V | 2000000 | 51 | ||
| NML Cyg[14][15][16] | M4.5–M7.9Ia–III | 229000 | 50 | ||
| V1827 Cyg/B17[12] | Ofpe | 242100 | 57 | ||
| BD+40°4210[12][17] | B1III:e | 630000 | 54 | ||
| BD+40 4223[12] | B0Ia | 539500 | 48.3 | ||
| #1 | 59 | O8.5V | 120000 | 26 | |
| #2 | 83[18] | B1I | 40000 | 14 | |
| #3 | O6IV+O9III | 346000 | >17 + >8 | ||
| #4 | 217 | O7III((f)) | 158000 | 29 | |
| #5 | V729[19][20] | O7I+O6I+O9V | 1584000 | 31 + 27 + 9 | |
| #6 | 317 | O8V | 109000 | 25 | |
| #7 | 457 | O3If | 426000 | 47 | |
| #8A | 465[21] | O6If+O5.5III(f) | 501000 | 44 + 37 | |
| #8B | 462 | O6.5III(f) | 301000 | 35 | |
| #8C | 483 | O5If | 371000 | 42 | |
| #8D | 473[22] | O8.5V | 48000 | 20 | |
| #9 | 431[20][23] | O5–5.5I+O3–4III | 707000 | >34 + >30 | |
| #10 | 632 | O9.5I | 478000 | 37 | |
| #11 | 734[18] | O5If | 537000 | 44 | |
| #12 | 304[24] | B3-4Ia+ | 1230000 | 110 | |
| #14 | 227 | O9V | 45000 | 19 | |
| #15 | 258 | O8V | 61000 | 22 | |
| #16 | 299 | O8V | 83000 | 23 | |
| #17 | 339 | O8.5V | 61000 | 21 | |
| #18 | 556 | B1Ib | 338000 | 29 | |
| #19 | 601 | B0Iab | 186000 | 26 | |
| #20 | 145 | O9III | 26000 | 17 | |
| #21 | 259 | B0.5V | 15000 | 13 | |
| #22 | 417 | O3If+O6V(f) | 660000 | 50 | |
| #23 | 470 | O9.5V | 26000 | 17 | |
| #24 | 480 | O7.5V | 104000 | 25 | |
| #25 | 531 | O8.5V | 97000 | 24 | |
| #26 | 642 | B1III | 69000 | 16 | |
| #27 | 696 | O9.5V+B0V | 30000 | 17 | |
| #29 | 745 | O7V | 87000 | 25 | |
| #30 | 793 | B1.5III | 33000 | 13 | |
| #37 | 358 | B3V | 3000 | 7 | |
| #41 | 378 | B0V | 44000 | 18 | |
| #51 | 425 | B0V | 27000 | 16 | |
| #54 | 395 | B1V | 7000 | 10 | |
| #64 | 488 | B2Ve | 23000 | 12 | |
| #66 | 515 | B1V | 10000 | 11 | |
| #70 | 588 | B0V | 48000 | 18 | |
| #71 | 646 | B1.5V | 6000 | 9 | |
| #73 | O8III+O8III | 41000 | 20 | ||
| #74 | 555 | O8V | 109000 | 25 | |
| #75 | 736 | O9V | 31000 | 18 | |
| 138[12] | O8I | 88700 | 26 | ||
| 267 | A11[12] | O7.5III | 323000 | 35 | |
| 448 | O6V | 107000 | 29 | ||
| 516[18] | O5.5V((f)) | 707000 | 52 | ||
| 716 | O9V | 28000 | 18 | ||
| 771 | O7V | 151000 | 29 | ||
| A12[12] | B0Ia | 373300 | 36 | ||
| A15 | O7I | 263000 | 32 | ||
| A20 | O8II | 380000 | 35 | ||
| A23 | B0.7Ib | 263000 | 26 | ||
| A24 | O6.5III | 154000 | 30 | ||
| A25[12] | O8III | 88700 | 28 | ||
| A27 | B0Ia | 426000 | 35 | ||
| A29[12] | O9.7Iab | 167500 | 29.1 | ||
| A32[12] | O9.5IV | 106700 | 26.1 | ||
| A36 | B0Ib+B0III | 173000 | 26 | ||
| A37[12] | O5V((f)) | 66100 | 34.8 | ||
| A46[12] | O7V((f)) | 46600 | 25.6 | ||
| E47 | B0Ia | 676000 | 42 | ||
| IRAS 20321+4009[12] | O9 | 278000 | 32 | ||
| TYC 3156-998-1[12] | OC9.7Ia | 516000 | 34.2 |
The progenitor of BD+43°3654 might be a member in Cygnus OB2 before. Two stars of each binary would collide and merge forming BD+43°3654, that would be ejected from the stellar association along with two other stars. 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.[25] A 12th star (Cyg OB2 #12) was added in 1954,[26] and eight more shortly after.[27] Schulte himself maintained the already-published numbers and added many more when studying the association which he called VI Cygni.[9]
References
- ^ "Ass Cyg OB 2". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2009-12-06.
- ^ 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.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ 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.
- ^ 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.
- ^ a b c Knödlseder, J. (2000). "Cygnus OB2—a young globular cluster in the Milky Way". Astronomy and Astrophysics. 360: 539. arXiv:astro-ph/0007442. Bibcode:2000A&A...360..539K.
- ^ 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.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b 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.
- ^ 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.
- ^ a b c Massey, P.; Thompson, A. B. (1991). "Massive stars in CYG OB2". The Astronomical Journal. 101: 1408. Bibcode:1991AJ....101.1408M. doi:10.1086/115774.
- ^ a b c d 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.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b 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.
- ^ a b c d e f g h i j k l m n 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.
- ^ 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.
- ^ "GCVS Query=V1489 Cyg". Sternberg Astronomical Institute. General Catalogue of Variable Stars @ Sternberg Astronomical Institute, Moscow, Russia. Retrieved 2018-09-21.
- ^ 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.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ Morris, M.; Jura, M. (1983). "The nature of NML Cygnus". Astrophysical Journal. 267: 179. Bibcode:1983ApJ...267..179M. doi:10.1086/160856.
- ^ 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
- ^ a b c 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.
- ^ 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.
- ^ a b 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.
- ^ 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.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.