List of O-type stars

An O-type star is a hot, blue star of spectral type O in the Yerkes classification system employed by astronomers. They have surface temperatures in excess of 30,000 kelvins (K). Stars of this type have strong absorption lines of ionised helium, strong lines of other ionised elements, and hydrogen and neutral helium lines weaker than spectral type B.

This is a list of O-type stars by their distance from Earth.

List Milky Way galaxy Star system←← Star Image Median distance (ly) Stars in system Spectral type Apparent magnitude (V) Comments and references Zeta Ophiuchi 440 ± 40 1 O9.5 V 2.56 – 2.58 The closest O-type star to Earth. Phi Persei B 720 ± 30 1 sdO 4.06 Has a B-type companion star. 28 Cygni B 840 ± 20 2 sdO 4.93 Has a B-type companion star. Iota Arae B 920 ± 20 2 sdO 5.18–5.26 Has a B-type companion star. Rho¹ Arae B 990 ± 10 2 sdO 6.275 Has a B-type companion star. Kappa¹ Apodis B 1,060 ± 20 1 sdO 5.52 Has a B-type companion star. Zeta Puppis (Naos) 1,080 ± 40 1 O4If(n)p 2.24 - 2.26 Gamma² Velorum B (Regor) 2 O7.5III 1.83 Has a Wolf-Rayet companion star. Theta² Orionis A 1,100 ± 80 3 O9.5IVp 5.02 Mintaka Aa1 (Delta Orionis) 1,200 3 O9.5II 2.5 V2119 Cygni 1203±22.3 1 sdO 60 Cygni 1225±57 1 sdO Upsilon Orionis 1,260±75 1 B0V or O9.7V +4.618±0.013 Alnitak Aa (Zeta Orionis) 1,260 ± 180 3 O9.5Iab 1.77 Sigma Orionis Aa 1263±4.3 2 O9.5V 4.07 Meissa A (Lambda Orionis) 1260±200 1 O8 III((f)) 3.7 AE Aurigae 1,320 ± 40 1 O9.5V 5.96 Xi Persei (Menkib) 1,340±65 1 O7.5III(n)((f)) 4.04 Theta¹ Orionis C1 1340±65 1 O6Vp 5.13 Iota Orionis Aa1 (Haytsa) 3 O9 III 2.77 LS Muscae 1383±43 1 sdO W40 IRS 1A South 1,420 1 O9.5 15 Member of Westerhout 40. IN Comae Berenices B (HD 112313) 1,650 ± 40 2 sdO 8.69 Central star of LoTr 5 Planetary Nebula. Has a G-type companion star. HD 49798 1,700 ± 46 1 sdO6p 10 Lacertae 1,800±103 1 O9V 4.880 FY Canis Majoris B 1,820 ± 70 2 sdO 4.8 - 6.25 Has a B-type companion star. Mu Columbae 1,894±111 1 O9.5 V 5.18 HD 186924 2000 1 O6fp It is the central star of NGC 6826 Planetary Nebula. HD 206267 2,000 2 O6V((f)) + O9V 5.70 UY Sextantis 2,200 ± 100 1 sdO9VII:He6 13.49 68 Cygni 2,200 ± 200 1 O7.5IIIn((f)) 5.00 Delta Circini 2,300 ± 200 1 O8IV + O9.5V 5.09 S Monocerotis (15 Monocerotis) 2,300 ± 200 3 O7V((f))zvar + O9.5Vn HD 73882 2,400 ± 100 1 O8.5IV 7.19 - 7.29 1 Camelopardalis A 2,580 ± 100 1 O9.7IIn 5.77 X Persei 2,600 ± 100 1 O9.5IIIe-B0Ve 6.778 NSVS 14256825 A 2,700 ± 100 2 sdOB 13.2 Has a M-type companion star. Lambda Cephei 3,098.5 1 O6.5If(n)p +5.050 HD 193322 3,100 2 O9Vnn + O8.5 III +5.958 Mu Normae 3,260 1 O9.7Iab 4.91 HD 35914 3,600 ± 1.0 1 O7fp It is the central star of IC 418 Planetary Nebula. 63 Ophiuchi 3,600 ± 300 1 O8II((f)) 6.20 UW Canis Majoris 3,800 2 O7.5-8Iabf + O9.7Ib 4.95 Trumpler 27-27 3,900 1 O8III((f)) V3903 Sagittarii A (11 Sagittarii) 3,900 ± 100 1 O7V(n)z 7.00–7.45 Has a B-type companion. HD 148937 3,900 ± 100 1 O6f?p 6.73 19 Cephei 3,913.88 1 O9Ib 5.08 HD 54879 4100 ± 200 1 O9.7V 7.65 HD 164492 A 4100 ± 200 1 O7.5III Part of Trifid Nebula 9 Sagittarii 4,100 ± 400 1 O4V((f))z (O3.5V((f+)) + O5–5.5V((f))) 5.97 15 Sagittarii 4,200±650 1 O9.7 Iab or B0 Iab 5.37 AO Cassiopeiae (Pearce's Star) 4,300 ± 300 2 O8V((f)) + O9.2II 6.07-6.24 HD 149404 (V918 Scorpii) 4,300 ± 400 2 O7.5I(f) + ON9.7I 5.42 - 5.50 HD 150136 4,310 ± 390 3 O3 V((f*)) - O3.5 V((f+)) + O5.5-6 V((f)) + O6.5-7 V((f)) 5.54 16 Sagittarii 4,600 1 O9.5 III 6.02 BE Ursae Majoris A 4,600 ± 200 2 DO 14.8 to 17.8 Has a M-type companion star. Y Cygni 4,900 2 O9.5V + O9.5V 7.3 - 7.9 WR 140 B (SBC9 1232) 4950 ± 21 2 O5.5fc 6.85 Has a Wolf-Rayet Companion. HD 92206 5,000 3 O8V + O9.7V 8.966 Has a B-type companion. HD 229196 5,000 1 O5 HD 93521 B 5,000 ± 300 1 O9.5IIInn or O9.5Vp 7.03 Tau Canis Majoris Aa 5,120.66 3 O9II 4.40 HD 46223 5,200 1 O4V HD 46150 5,200 1 O5V 4U 1700-37 (V884 Scorpii) 5,200 ± 200 1 O6Iafcp 6.51 Plaskett's Star (V640 Monocerotis) 5,245 2 O8I + O7.5III 6.06 Cygnus OB2-8A 5,400 ± 200 1 O6If + O5.5III(f) 9.06 BD+43 3654 5,400 ± 300 1 O4If 10.06 HD 15558 (HIP 11832) 5,700 1 O4.5III(f) (O5.5III(f) + O7V) 7.87 HD 168076 5,700±400 2 O3.5V + O7.5V +8.24 NGC 7662 Central star 5,730 ± 340 1 sdO Central star of NGC 7662 Planetary Nebula. RY Scuti 5,870 2 O7 + O9.7 Ibpe 9.12 – 9.72 Prisms 24-17 5,900 1 O3.5III HD 48099 5,965 2 O5.5V((f)) + O9V 6.37 HD 165319 6,000 1 O9.7Ib Central star of Sh2-46 Nebula. Alpha Camelopardalis 6,000 1 O9Ia 4.29 WR 133 B (V1676 Cyg) 6,100 ± 300 2 O9I 6.75 - 6.84 Has a Wolf-Rayet Companion. HD 191612 A 6,100 ± 300 1 O8fp 7.84 – 7.91 HD 108 6,230 ± 360 1 O4–8f?p 7.40 HD 59088 6,500 1 O(H)6f It is the central star of NGC 2392 Planetary Nebula. WR 25 (HD 93162) 6,500 2 O2.5If*/WN6 + OB 8.80 Pismis 24-1 (HD 319718) 6,500 2 O3.5If*+O4III(f+) WR 137 B 6,700 ± 200 1 O9V 7.91 Has a Wolf-Rayet Companion. CV Serpentis B 6,700 ± 200 2 O8-9IV 9.08 Has a Wolf-Rayet Companion. LY Aurigae 6,800 3 O9II + O9III 6.85 (6.66 - 7.35) Has B-type companion. HD 151804 (V973 Scorpii) 7,000 1 O8 Iaf 5.22 - 5.28 HD 138403 7175.44 1 O8(f)ep It is the central star of Hen 2-131 Planetary Nebula. Cygnus X-1 (HDE 226868) 7,300 ± 200 2 O9.7Iab 8.95 Has a Black Hole Companion. Theta Muscae 7,400 4 O6/7V + O9.5/B0Iab+O9III 5.53 Has a Wolf-Rayet Companion. HD 92206 B 7,400 ± 300 1 O6.5V or O6V((f))z PSR B1259−63/LS 2883 A 7,500 2 O9.5Ve 10.34 Has a Pulsar Companion. Eta Carinae A (Eta Argus) 7,500 2 O −1.0 to ~7.6 part of Trumpler 16 in the Carina Nebula. HD 93129 7,500 2 O2If* (O2If+O3.5V) + O3.5 V((f))z 6.90 Part of Trumpler 14. QZ Carinae (HD 93206) 7,501.6 4 O9.7I+O8III+O9V 6.24 HD 93205 (V560 Carinae) 7,600 ± 400 2 O3.5Vf + O8V 7.75 HD 97319 7,800-9,800 1 O Part of NGC 3576. HD 93250 7,900 ± 400 1 O4 IV(fc) 7.41 6 Cassiopeiae B 8,000 2 O9.75 5.34 - 5.45 Has a A-type Hypergiant Companion. HD 93160 8,000 1 O6III LS 5039 A 8200±300 1 O(f)N6.5V 11.27 Has a Black Hole Companion. WR 22 B 8,300 ± 700 2 O9III-V 6.42 Has a Wolf-Rayet Companion. HD 92206 8,400 ± 500 2 O6.5V + O6.5V, O6V((f))z (combined) +8.219 Abell 63 Central star 8,810 1 sdO Center Star of Abell 63 Planetary Nebula. HD 303308 9,200 1 O3V LSS 4067 (CD−38°11748) 9,500–12,700 1 O4.5Ifpe 11.44 DH Cephei 9,600 ± 400 2 O5.5 V + O6 V 8.61 BD+60°2522 9,800 ± 400 1 O6.5(f)(n)p 8.67 HD 93130 10,000 1 O7II(f) HD 93403 10,000 1 O5.5III(fc)var 7.272 HD 93632 10,000 1 O5III(f) LSS 4067 11,000 1 O4.5Ifpe Part of HM 1. HM 1-6 11,000 1 O5If Part of HM 1. HM 1-8 11,000 2 O4.5IV(f) + O9.7V Part of HM 1. HD 35619 12,000 1 O7.5V((f))z 8.572 WR 9 B 12,000 ± 600 2 O7 10.50 Has a Wolf-Rayet Companion star. MY Camelopardalis 13,050 1 O6nn (O6V((f)) + O6V((f))) 9.80 - 10.15 WR 21a 13,100 ± 700 1 O3/WN5ha + O3Vz((f*)) 12.661 Has a Wolf-Rayet Companion. CD Crucis B (WR 47) 14,000 2 O5V 10.81 Has a Wolf-Rayet Companion. WR 20a 14,000 ± 1,000 2 O3If*/WN6 + O3If*/WN6 13.28 HD 64568 15,000 ± 1,000 1 O3V((f*))z 9.39 TU Muscae 15500 2 O7V + O8V 8.307 NGC 1624-2 16,800 1 O7f?cp 11.57 GCIRS 16SW 20,000 1 Ofpe/WN9 GCIRS 8* 20,000 1 O5 V1936 Aquilae 20,000 1 O4I 15.1 Westerhout 51d 20,000 1 O Member of Westerhout 51. Westerhout 51-3 20,000 1 O3-8V Member of Westerhout 51. Westerhout 51-57 20,000 1 O4V Member of Westerhout 51. MSP 183 20,000 1 O3V(f) Part of Westerlund 2. HD 116852 (HIP 65890) 20,580 1 O8.5 II-III ((f)) 8.47 WR 30a B 2 O5((f)) 12.73 Has a Wolf-Rayet Companion. Centaurus X-3 (Krzemiński's star) 24,000 ± 2,000 2 O6-7 II-III + ? 13.25 (- 13.39) - 13.46 HD 15558 A 24,400 1 O5.5III(f) Part of IC 1805. MTT 68 24,787.88 1 O2If* 14.72 HD 97950 A3 24,800 1 O3III WR 42e (2MASS J11144550-115001) 25,000 1 O3If*/WN6 14.53 HD 97950 25,000 1 O Arches-F15 25,000 1 O6-7 Ia+ Arches-F18 25,000 1 O4-5 Ia+ WR 102ka (Peony star) 26,000 2 Ofpe/WN9 WR 148 B 27,000 2 O5V? 10.3 Has a Wolf-Rayet Companion. Westerhout 49-2 36,200 1 O2-3.5If* Westerhout 49-3 36,200 1 O3-O7V Mercer 30-1 A 40,000 1 O6-7.5lf+ US 708 60,300 ± 8,500 1 sdOHe 18.8

Magellanic Clouds The Large Magellanic Cloud (LMC) is around 163 kly distant and the Small Magellanic Cloud (SMC) is around 204 kly distant Host galaxy Star system Median distance (ly) Stars in system Spectral type Apparent magnitude (V) Comments and referencesLMC R126a4 157,000 1 O3V((f*))(n) LMC R136a5 157,000 1 O2l(n)f* LMC R136a6 157,000 1 O2I(n)f*p LMC R136a8 157,000 1 O2-3V LMC LH 10-3209 A 160,000 1 O3III(f*) Part of NGC 1763.LMC Melenick 39 A 160,000 1 O2.5If/WN6 LMC Sk -65° 47 160,000 1 O4If LMC Sk -68° 137 160,000 1 OB LMC Sk -69° 212 160,000 1 O6lf LMC Sk -69° 249 A 160,000 2 O7lf LMC ST5-31 160,000 1 O2-3(n)fp LMC TIC 276934932 160,000 2 O3If + O6V LMC R136a7 163,000 1 O3III(f*) LMC MACHO 80.7443.1718 B 163,000 2 O9.5 V 13.628 Has a B-type companion. LMC R136b 163,000 1 O4If 13.24 LMC LH 54-425 163,000 2 O3V + O5V 13.13 LMC HD 269810 163,000 1 O2III(f*) 12.22 LMC HSH95-36 163,000 1 O2lf* LMC Melnick 42 163,000 1 O2If* 12.78 Part of Tarantula Nebula.LMC LMC P3 163,000 2 O5III(f) Has a Neutron Star companion. LMC MACHO*05:34:41.3−69:31:39 163,000 2 O3If* + O6V LMC BI 253 164,000 1 O2V-III(n)((f*)) 13.76 LMC VFTS 243 (2MASS J05380840-6909190) 164,000 1 O7V(n)((f)) 15.26 Has a Known Black Hole Companion LMC VFTS 102 164,000 1 O9:Vnnne 15.806 LMC VFTS 352 164,000 2 O4.5 V(n)((fc)):z: + O5.5 V(n)((fc)):z: 14.38 LMC VFTS 506 164,000 1 ON2V((n))((f*)) LMC VFTS 621 164,000 1 O2V((f*))z LMC VFTS 1021 164,000 1 O4 lf+ LMC VFTS 16 170,000 1 O2IIIf* LMC LMC X-1 A 180,000 2 O8 IIIf or O8 f?p 14.612 ± 0.171 Has a Black hole Companion. SMC SMC AB7 197,000 2 O6I(f) 13.016 SMC SMC AB8 197,000 2 O4V 12.83 SMC HD 5980 C 200,000 3 OI 8.8 - 11.9 Has a LBV and Wolf-Rayet Companion SMC HD 346-W1 200,000 1 O5.5lf SMC HD 346-W3 200,000 1 O3V

Andromeda Galaxy and Triangulum Galaxy The Andromeda Galaxy (M31) is 2.5 Mly distant and the Triangulum Galaxy is around 3.2 Mly distant Host galaxy Star system Median distance (ly) Stars in system Spectral type Apparent magnitude (V) Comments and referencesAndromeda LGGS J004246.86+413336.4 2,500,000 1 O3-O5If Triangulum [BMS2003] 867 2,700,000 2 O4Iab+O4Ia Triangulum M33 X-7 A 2,700, 000±70000 2 O7-8III +18.70 Has a Black Hole Companion Triangulum M33-013406.63 (B416/UIT301) 3,000,000 1 O9.5Ia

Other galaxies Host galaxy Star system Median distance (ly) Stars in system Spectral type Apparent magnitude (V) Comments and references IC 3418 SDSS J1229+1122 55,000,000 1 O 22.85

See also List of Wolf–Rayet stars List of luminous blue variable stars List of nearest stars by spectral type

References