NGC 6951

NGC 6951 imaged by the Hubble Space Telescope

Observation data (J2000 epoch)
Constellation| Cepheus
Right ascension|  20h 37m 14.1192s[1]
Declination| +66° 06′ 20.153″[1]
Redshift| 0.004750 ± 0.000005 [1]
Helio radial velocity| 1,424 ± 1 km/s (884.83 ± 0.62 mi/s)[1]
Distance| 75.25 ± 2.72 Mly (23.072 ± 0.835 Mpc)[1]
Apparent magnitude (V)| 11.0[2]
Characteristics
Type| SAB(rs)bc [1]
Size| ~114,300 ly (35.03 kpc) (estimated)[1]
Apparent size (V)| 3.9′ × 3.2′[1]
Notable features| Seyfert galaxy
Other designations
IRAS 20366+6555, 2MASS J20371406+6606201, NGC 6952, UGC 11604, MCG+11-25-002, PGC 65086[1]

NGC 6951 (also catalogued as NGC 6952) is a barred spiral galaxy located in the constellation Cepheus. It is located at a distance of about 75 million light-years from Earth, which, given its apparent dimensions, means that NGC 6951 is about 100,000 light-years across. It was discovered by Jérôme Eugène Coggia in 1877 and independently by Lewis Swift in 1878.[3]

## Contents

* 1 Characteristics
* 1.1 Active nucleus
* 1.2 Circumnuclear ring
* 2 Supernovae
* 3 See also
* 4 References
* 5 External links

## Characteristics

Image of NGC 6951 taken by the GALEX ultraviolet telescope.

NGC 6951 has a large stellar bar with dust lanes running across it. These lanes come in contact with the circumnuclear ring at its north and south points.[4] Gas is channeled inwards, towards the ring, through the bar. Observations in CO revealed also the presence of molecular gas with inflow motion towards the galactic nucleus. Since there are no signs of interaction with another galaxy in the isolated NGC 6951 for the last one billion years, it is believed that the origin of the gas is internal.[5] Gas kinematics have also been observed for the rest of the galaxy, where the gravitational torques caused by the bar have a dominant role.[6]

### Active nucleus

The nucleus of NGC 6951 is active. It has been classified both as a type 2 Seyfert galaxy and a LINER and it has been suggested that it is in transition form, between a Seyfert galaxy and a very-high-excitation LINER, with very strong [N II] and [S II] lines.[7] A supermassive black hole which accretes material in the centre of the galaxy is believed to be the cause of the nuclear activity. The upper mass limit of the supermassive black hole at the centre of NGC 6951 is estimated to be between 6 and 14 million M☉ based on velocity dispersion.[8] Molecular gas, most probably a circumnuclear dust disk or torus less than 50 parsec in radius, has been detected around the nucleus.[9]

### Circumnuclear ring

Around the nucleus of NGC 6951 has been observed a star formation ring with a radius of 5 arcseconds.[7] It also emits radio waves.[10] The total gas mass at and inside the ring is estimated to be 3×108 M☉.[11] Inside the ring is detected a spiral-like structure, with two spiral arms, that extends up to 0.5 arcseconds from the nucleus, while no inner bar was detected in the images obtained by Hubble Space Telescope. The central part of the nuclear area contains red supergiant stars.[7] The ring is complete and features H II regions. It is characterised by a gradient in stellar population ages, with the younger stars being a few million years old while the older are more than a hundred million years old.[12]

The stars in the ring form star clusters with masses between 104 and 106.8 M☉. Although there have been observed clusters with ages as little as 4 million years or over one billion years, the star clusters predominantly have intermediate ages, with average ages of 200–300 million years, and are massive. Based on the ages of the clusters it is suggested that the most intense star formation in the ring took place 800 million years ago, then lowered, only to increase again 400 million years ago.[4]

## Supernovae

Five supernovae have been observed in NGC 6951:

* SN 1999el (Type IIn, mag 15.4) was discovered by the Beijing Astronomical Observatory on 20 October 1999.[13][14]
* SN 2000E (Type Ia, mag 14.3) was discovered by the Collurania-Teramo Observatory on 26 January 2000.[15][16] This supernova was visible at the same time as SN 1999el.
* SN 2015G (Type Ibn, mag 15.5) was discovered by Kunihiro Shima on 23 March 2015.[17][18]
* SN 2020dpw (Type IIP, mag. 17) was discovered by Patrick Wiggins on 26 February 2020.[19]
* SN 2021sjt (Type IIb, mag. 18.58) was discovered by the Zwicky Transient Facility on 7 July 2021.[20]

## See also

* NGC 5135 \- a similar active galaxy
* List of NGC objects (6001–7000)

## References

1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "Results for object NGC 6951". NASA and Caltech. https://ned.ipac.caltech.edu/byname?objname=NGC+6951.
2. ↑ "Revised NGC Data for NGC 6951". http://spider.seds.org/ngc/revngcic.cgi?NGC6951.
3. ↑ Seligman, Courtney. "NGC 6951 (= PGC 64650)". http://cseligman.com/text/atlas/ngc69a.htm#6951.
4. ↑ 4.0 4.1 van der Laan, T. P. R.; Schinnerer, E.; Emsellem, E.; Hunt, L. K.; McDermid, R. M.; Liu, G. (26 February 2013). "How does star formation proceed in the circumnuclear starburst ring of NGC 6951?". Astronomy & Astrophysics 551: A81. doi:10.1051/0004-6361/201220285. Bibcode: 2013A&A...551A..81V.
5. ↑ van der Laan, T. P. R.; Schinnerer, E.; Boone, F.; García-Burillo, S.; Combes, F.; Haan, S.; Leon, S.; Hunt, L. et al. (29 March 2011). "Molecular gas in NUclei of GAlaxies (NUGA)". Astronomy & Astrophysics 529: A45. doi:10.1051/0004-6361/201014488.
6. ↑ Haan, Sebastian; Schinnerer, Eva; Emsellem, Eric; García-Burillo, Santiago; Combes, Francoise; Mundell, Carole G.; Rix, Hans-Walter (20 February 2009). "Dynamical Evolution of AGN Host Galaxies - Gas In/out-Flow Rates in 7 NUGA Galaxies". The Astrophysical Journal 692 (2): 1623–1661. doi:10.1088/0004-637X/692/2/1623. https://authors.library.caltech.edu/14260/1/Haan2009p66610.10880004-637X69221623.pdf.
7. ↑ 7.0 7.1 7.2 Pérez, E.; Márquez, I.; Marrero, I.; Durret, F.; González Delgado, R. M.; Masegosa, J.; Maza, J.; Moles, M. (1 January 2000). "Circumnuclear structure and kinematics in the active galaxy NGC 6951". Astronomy and Astrophysics 353: 893–909. ISSN 0004-6361. Bibcode: 2000A&A...353..893P.
8. ↑ Beifiori, A.; Sarzi, M.; Corsini, E. M.; Bontà, E. Dalla; Pizzella, A.; Coccato, L.; Bertola, F. (10 February 2009). "Upper Limits on the Masses of 105 Supermassive Black Holes from Hubble Space Telescope/Space Telescope Imaging Spectrograph Archival Data". The Astrophysical Journal 692 (1): 856–868. doi:10.1088/0004-637X/692/1/856. Bibcode: 2009ApJ...692..856B.
9. ↑ Krips, M.; Neri, R.; García-Burillo, S.; Combes, F.; Schinnerer, E.; Baker, A. J.; Eckart, A.; Boone, F. et al. (11 January 2007). "Molecular gas in NUclei of GAlaxies (NUGA): VI. Detection of a molecular gas disk/torus via HCN in the Seyfert 2 galaxy NGC 6951?". Astronomy & Astrophysics 468 (3): L63–L66. doi:10.1051/0004-6361:20066785. Bibcode: 2007A&A...468L..63K.
10. ↑ Saikia, D. J.; Phookun, B.; Pedlar, A.; Kohno, K. (15 February 2002). "Radio observations of the circumnuclear ring in NGC 6951". Astronomy & Astrophysics 383 (1): 98–103. doi:10.1051/0004-6361:20011710. Bibcode: 2002A&A...383...98S.
11. ↑ García-Burillo, S.; Combes, F.; Schinnerer, E.; Boone, F.; Hunt, L. K. (23 September 2005). "Molecular gas in NUclei of GAlaxies (NUGA)". Astronomy & Astrophysics 441 (3): 1011–1030. doi:10.1051/0004-6361:20052900.
12. ↑ Mazzuca, Lisa M.; Knapen, Johan H.; Veilleux, Sylvain; Regan, Michael W. (February 2008). "A Connection between Star Formation in Nuclear Rings and Their Host Galaxies". The Astrophysical Journal Supplement Series 174 (2): 337–365. doi:10.1086/522338. Bibcode: 2008ApJS..174..337M.
13. ↑ Cao, L.; Qiu, Y. L.; Qiao, Q. Y.; Hu, J. Y.; Li, W.; Filippenko, A. (1999). "Supernova 1999el in NGC 6951". International Astronomical Union Circular (7288): 1. Bibcode: 1999IAUC.7288....1C. http://www.cbat.eps.harvard.edu/iauc/07200/07288.html#Item1.
14. ↑ "SN 1999el". IAU. https://www.wis-tns.org/object/1999el.
15. ↑ Valentini, G.; Di Carlo, E.; Guidubaldi, D.; Brocato, E.; Di Paola, A.; d'Alessio, F.; Speziali, R.; Li Causi, G. et al. (2000). "Supernova 2000E in NGC 6951". International Astronomical Union Circular (7351): 1. Bibcode: 2000IAUC.7351....1V. http://www.cbat.eps.harvard.edu/iauc/07300/07351.html#Item1.
16. ↑ "SN 2000E". IAU. https://www.wis-tns.org/object/2000E.
17. ↑ Yusa, T.; Buczynski, D.; Noguchi, T.; Nakano, S.; Kiyota, S.; Masi, G.; Ayani, K.; Foley, R. J. et al. (2015). "Supernova 2015G in NGC 6951 = PSN J20372558+6607115". Central Bureau Electronic Telegrams 4087: 1. Bibcode: 2015CBET.4087....1Y.
18. ↑ "SN 2015G". IAU. https://www.wis-tns.org/object/2015G.
19. ↑ "SN 2020dpw". IAU. https://www.wis-tns.org/object/2020dpw.
20. ↑ "SN 2021sjt". IAU. https://www.wis-tns.org/object/2021sjt.

## External links

* NGC 6951 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
* NGC 6951 on SIMBAD

* v
* t
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Astronomical catalogs

NGC|

* Astronomy:NGC 6946
* Astronomy:NGC 6947
* Astronomy:NGC 6948
* Astronomy:NGC 6949
* Astronomy:NGC 6950
* NGC 6951
* Astronomy:NGC 6952
* Astronomy:NGC 6953
* Astronomy:NGC 6954
* Astronomy:NGC 6955
* Astronomy:NGC 6956

PGC|

* Astronomy:PGC 65082
* Astronomy:PGC 65083
* Astronomy:PGC 65084
* Astronomy:PGC 65085
* PGC 65086
* Astronomy:PGC 65087
* Astronomy:PGC 65088
* Astronomy:PGC 65089
* Astronomy:PGC 65090

UGC|

* Astronomy:UGC 11600
* Astronomy:UGC 11601
* Astronomy:UGC 11602
* Astronomy:UGC 11603
* UGC 11604
* Astronomy:UGC 11605
* Astronomy:UGC 11606
* Astronomy:UGC 11607
* Astronomy:UGC 11608

* v
* t
* e

New General Catalogue 6500 to 6999

* 6500
* 6501
* 6502
* 6503
* 6504
* 6505
* 6506
* 6507
* 6508
* 6509
* 6510
* 6511
* 6512
* 6513
* 6514
* 6515
* 6516
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* 6518
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* 6886
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* 6891
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* 6896
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* 6984
* 6985
* 6986
* 6987
* 6988
* 6989
* 6990
* 6991
* 6992
* 6993
* 6994
* 6995
* 6996
* 6997
* 6998
* 6999

* Astronomical catalog
* List of NGC objects

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Cepheus constellation

Stars (list)|

| Bayer|

* α (Alderamin)
* β (Alfirk)
* γ (Errai)
* δ
* ε
* ζ
* η
* θ
* ι
* κ
* λ
* μ (Garnet Star)
* ν
* ξ (Kurhah)
* ο
* π
* ρ1
* ρ2

|

Flamsteed|

* 4
* 6
* 7
* 9
* 11
* 12
* 13
* 14
* 15
* 16
* 18
* 19
* 20
* 24
* 25
* 26
* 30
* 31
* 77 Dra
* 78 Dra
* 79 Dra
* 80 Dra
* 2 UMi

Variable|

* S
* T
* U
* V
* W
* RW
* RZ
* SV
* VV
* VW
* WX
* WZ
* XX
* XZ
* ZZ
* AH
* AK
* BH
* BO
* CP
* CQ
* CR
* CW
* CX
* DH
* DI
* DO
* DQ
* EE
* EG
* EI
* EK
* EM
* GP
* GW
* IL
* IR
* IV
* NY
* OV
* PQ
* PV
* V350
* V354
* V368
* V374
* V379
* V380
* V381
* V388
* V398
* V408
* V414
* V419
* V421
* V422
* V426
* V431
* V438
* V444
* V458

HR|

* 20
* 55
* 158
* 240
* 306
* 312
* 333
* 357
* 386
* 572
* 597
* 774
* 881
* 906
* 961
* 965
* 1107
* 1304
* 1317
* 1523
* 1616
* 1885
* 7742
* 7925
* 7938
* 7955
* 7967
* 7993
* 8029
* 8043
* 8049
* 8065
* 8099
* 8119
* 8133
* 8150
* 8168
* 8174
* 8179
* 8226
* 8239
* 8243
* 8281
* 8312
* 8327
* 8342
* 8347
* 8357
* 8374
* 8375
* 8384
* 8388
* 8395
* 8442
* 8472
* 8474
* 8476
* 8479
* 8483
* 8490
* 8493
* 8506
* 8535
* 8537
* 8546
* 8557
* 8568
* 8595
* 8598
* 8599
* 8625
* 8677
* 8683
* 8687
* 8696
* 8702
* 8707
* 8736
* 8745
* 8748
* 8779
* 8808
* 8811
* 8844
* 8867
* 8918
* 8938
* 8952
* 8971
* 8972
* 9005
* 9013
* 9038
* 9104

HD|

* 12918
* 12927
* 25904
* 200775
* 204521
* 204827
* 207538
* 207826
* 208132
* 208392
* 212136
* 215588
* 217903
* 224890

Gliese|

* Gliese 48
* Gliese 809
* GJ 1277

Other|

* Cepheus A HW 2
* Cepheus X-4
* IRAS 21391+5802
* Kruger 60
* NGC 7538 IRS 1
* NGC 7538 IRS 9
* OH 104.9+2.4
* PSR B2224+65
* PSR J2229+6114
* S140 IRS 1
* TYC 3980-1081-1
* 4U 2206+54
* WISE 0313+7807
* WR 152
* WR 156

Star clusters|

| Association|

* Cepheus OB2
* Cepheus OB3
* Cepheus OB4

|

Open|

* NGC 188
* NGC 6939
* NGC 7023
* NGC 7129
* NGC 7142
* NGC 7160
* NGC 7226
* NGC 7234
* NGC 7261
* NGC 7281
* NGC 7380
* NGC 7419
* NGC 7423
* NGC 7429
* NGC 7510
* NGC 7762
* S 140
* Trumpler 37

Globular|

* Palomar 1

Molecular clouds|

* Cepheus A
* Cepheus B
* Cepheus C

Nebulae|

| Dark|

* Barnard 150
* CB 244
* Elephant's Trunk Nebula
* IC 1396N
* L1157
* L1228

|

H II|

* IC 1396
* NGC 7538
* NGC 7822
* S 128
* S 140
* S 155
* S 156

Reflection|

* Ghost Nebula
* Iris Nebula
* NGC 7129
* VdB 157

Planetary|

* NGC 40
* NGC 7076
* NGC 7139
* NGC 7354

SNR|

* CTA 1
* SSTGFLS J222557+601148

Galaxies|

| NGC|

* 1184
* 1544
* 2276
* 2300
* 6949
* 6952

|

Other|

* 3C 61.1
* 3C 427.1
* 4C +74.26
* QSO B2021+614
* S5 0014+81

Other|

* GRB 980519
* SN 2008S

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