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List of stars in Leo
List of stars in Leo
List of stars in Leo
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This is the list of notable stars in the constellation Leo, sorted by decreasing brightness.

Name B F G. Var HD HIP RA Dec vis.
mag. 		abs.
mag. 		Dist. (ly) Sp. class Notes
Regulus α 32 87901 49669 10h 08m 22.46s +11° 58′ 01.9″ 1.36 −0.52 77 B7V Cor Leonis, Qalb, Kabelaced, Qalb al-Asad, Rex
Denebola β 94 102647 57632 11h 49m 03.88s +14° 34′ 20.4″ 2.14 1.92 36 A3Vvar Deneb Alased, Deneb Aleet; δ Sct variable
γ1 Leo γ1 41 89484 50583 10h 19m 58.16s +19° 50′ 30.7″ 2.37 −0.92 126 K0III Algieba, Al Gieba, Algeiba; has a confirmed planet (b) and an unconfirmed planet (c)
δ Leo δ 68 97603 54872 11h 14m 06.41s +20° 31′ 26.5″ 2.56 1.32 58 A4V Zosma, Zozma, Zozca, Zosca, Zubra, Duhr, Dhur
ε Leo ε 17 84441 47908 09h 45m 51.10s +23° 46′ 27.4″ 2.97 −1.46 251 G0II Ras Elased, Ras Elased Australis, Algenubi
θ Leo θ 70 97633 54879 11h 14m 14.44s +15° 25′ 47.1″ 3.33 −0.35 178 A2V Chertan, Chort, Coxa
ζ Leo ζ 36 89025 50335 10h 16m 41.40s +23° 25′ 02.4″ 3.43 −1.08 260 F0III Adhafera, Aldhafera, Aldhafara
η Leo η 30 87737 49583 10h 07m 19.95s +16° 45′ 45.6″ 3.48 −5.60 2131 A0Ib Al Jabhah, Al Jabbah, Al'Dzhabkhakh
ο Leo Aa ο 14 83808 47508 09h 41m 09.12s +09° 53′ 32.6″ 3.52 0.43 135 A5V+... Subra; 3.52 combined brightness
ο Leo Ab ο 14 83808 47508 09h 41m 09.12s +09° 53′ 32.6″ 3.70 0.43 135 A5V+... Subra; spectroscopic binary
γ2 Leo γ2 41 89485 10h 19m 58.60s +19° 50′ 26.0″ 3.80
ρ Leo ρ 47 14 91316 51624 10h 32m 48.68s +09° 18′ 23.7″ 3.84 −7.38 5719 B1Ib SB Shaomin;[1] α Cyg variable
μ Leo μ 24 85503 48455 09h 52m 45.96s +26° 00′ 25.5″ 3.88 0.83 133 K0III Rasalas, Ras Elased Borealis, Ras al Asad al Shamaliyy, Alshemali, has a planet (b)
ι Leo ι 78 99028 55642 11h 23m 55.37s +10° 31′ 46.9″ 4.00 2.08 79 F2IV SB Tsze Tseang,[2] Xīcìjiāng (西次將)[3]
σ Leo σ 77 46 98664 55434 11h 21m 08.25s +06° 01′ 45.7″ 4.05 −0.04 214 B9.5Vs Shang Tseang,[2] Xīshǎngjiāng (西上將)[3]
54 Leo 54 94601 53417 10h 55m 36.85s +24° 44′ 59.1″ 4.30 −0.44 289 A1
υ Leo υ 91 69 100920 56647 11h 36m 56.93s −00° 49′ 25.9″ 4.30 0.61 178 G9III
λ Leo λ 4 82308 46750 09h 31m 43.24s +22° 58′ 05.0″ 4.32 −0.75 336 K5IIIvar Alterf, Al Terf
31 Leo A 31 87837 49637 10h 07m 54.32s +09° 59′ 51.6″ 4.39 −0.23 274 K4III Yunü[1]
60 Leo b 60 95608 53954 11h 02m 19.78s +20° 10′ 47.1″ 4.42 1.53 124 A1m
φ Leo φ 74 43 98058 55084 11h 16m 39.76s −03° 39′ 05.5″ 4.45 0.56 195 A7IVn
κ Leo κ 1 81146 46146 09h 24m 39.28s +26° 10′ 56.8″ 4.47 0.39 213 K2III Al Minliar al Asad
93 Leo 93 DQ 102509 57565 11h 47m 59.23s +20° 13′ 08.2″ 4.50 0.29 226 A comp SB Tàizǐ (太子);[4] DQ Leo; RS CVn variable
72 Leo 72 FN 97778 54951 11h 15m 12.24s +23° 05′ 43.9″ 4.56 −6.99 6653 M3III Hǔbēn (虎賁);[4] FN Leo
χ Leo χ 63 33 96097 54182 11h 05m 01.23s +07° 20′ 10.0″ 4.62 2.31 94 F2III-IVvar
π Leo π 29 10 86663 49029 10h 00m 12.82s +08° 02′ 39.4″ 4.68 −1.35 525 M2III
61 Leo p2 61 28 95578 53907 11h 01m 49.67s −02° 29′ 04.2″ 4.73 −1.26 514 K5III
87 Leo e 87 62 99998 56127 11h 30m 18.88s −03° 00′ 12.5″ 4.77 −1.57 604 K4III
40 Leo 40 89449 50564 10h 19m 44.31s +19° 28′ 17.2″ 4.78 3.15 69 F6IV
58 Leo d 58 26 95345 53807 11h 00m 33.64s +03° 37′ 03.1″ 4.84 −0.26 342 K1III
τ Leo τ 84 58 99648 55945 11h 27m 56.23s +02° 51′ 22.6″ 4.95 −1.45 621 G8II-III
59 Leo c 59 27 95382 53824 11h 00m 44.83s +06° 06′ 05.4″ 4.98 1.65 151 A5III
ξ Leo ξ 5 82395 46771 09h 31m 56.79s +11° 18′ 00.1″ 4.99 0.67 238 K0IIIvar
10 Leo 10 4 83240 47205 09h 37m 12.71s +06° 50′ 08.8″ 5.00 0.80 226 K1IIIvar
6 Leo h 6 82381 46774 09h 31m 57.58s +09° 42′ 56.9″ 5.07 −0.78 482 K3III
48 Leo 48 15 91612 51775 10h 34m 48.07s +06° 57′ 13.0″ 5.07 0.12 319 G8II-III
75 Leo 75 44 98118 55137 11h 17m 17.37s +02° 00′ 39.3″ 5.18 −0.31 408 M0III comp
ν Leo ν 27 86360 48883 09h 58m 13.39s +12° 26′ 41.4″ 5.26 −0.79 529 B9IV
92 Leo 92 101484 56975 11h 40m 47.11s +21° 21′ 10.2″ 5.26 1.00 232 K1III Cóngguān (從官);[4]
22 Leo g 22 85376 48390 09h 51m 53.02s +24° 23′ 44.9″ 5.29 2.27 131 A5IV
73 Leo n 73 97907 55016 11h 15m 51.90s +13° 18′ 27.3″ 5.31 −0.52 478 K3III
53 Leo l 53 93702 52911 10h 49m 15.43s +10° 32′ 42.9″ 5.32 0.27 334 A2V
ψ Leo ψ 16 84194 47723 09h 43m 43.90s +14° 01′ 18.1″ 5.36 −1.34 713 M2III
79 Leo 79 51 99055 55650 11h 24m 02.34s +01° 24′ 27.9″ 5.39 0.14 365 G8IIICN...
ω Leo ω 2 2 81858 46454 09h 28m 27.38s +09° 03′ 24.4″ 5.40 2.72 112 F9V
69 Leo p5 69 37 97585 54849 11h 13m 45.58s −00° 04′ 10.2″ 5.40 −0.42 477 A0V
37 Leo 37 89056 50333 10h 16m 40.75s +13° 43′ 42.1″ 5.42 −0.51 499 M1III
46 Leo 46 ES 91232 51585 10h 32m 11.80s +14° 08′ 14.0″ 5.43 −2.18 1083 M2III ES Leo
HD 94402 p1 21 94402 53273 10h 53m 43.76s −02° 07′ 45.3″ 5.45 0.55 312 G8III double star
52 Leo k 52 93291 52689 10h 46m 25.35s +14° 11′ 41.3″ 5.49 0.76 287 G4III:
51 Leo m 51 93257 52686 10h 46m 24.49s +18° 53′ 29.8″ 5.50 1.81 178 K3III
65 Leo p4 65 34 96436 54336 11h 06m 54.43s +01° 57′ 20.6″ 5.52 1.55 203 G9IIICN...
95 Leo o 95 103578 58159 11h 55m 40.53s +15° 38′ 48.5″ 5.53 −0.65 560 A3V
86 Leo 86 100006 56146 11h 30m 29.08s +18° 24′ 35.1″ 5.54 0.55 325 K0III
83069 47168 09h 36m 42.85s +31° 09′ 42.6″ 5.57 −0.25 475 M2III
81 Leo 81 99285 55765 11h 25m 36.46s +16° 27′ 23.6″ 5.58 2.21 154 F2V
44 Leo 44 13 DE 90254 51008 10h 25m 15.19s +08° 47′ 05.8″ 5.61 −1.06 704 M2IIIs DE Leo
15 Leo f 15 84107 47701 09h 43m 33.27s +29° 58′ 29.0″ 5.64 2.20 159 A2IV
18 Leo 18 84561 47959 09h 46m 23.34s +11° 48′ 36.0″ 5.67 −0.99 701 K4III
TX Leonis 49 16 TX 91636 51802 10h 35m 02.19s +08° 39′ 01.6″ 5.67 −0.09 462 A2V TX Leo; Algol variable
EO Leo 87015 49220 10h 02m 48.96s +21° 56′ 57.4″ 5.68 −2.75 1583 B2.5IV
67 Leo 67 96738 54487 11h 08m 49.08s +24° 39′ 30.4″ 5.70 0.21 408 A3IV 53 Leonis Minoris
3 Leo 3 3 81873 46457 09h 28m 29.19s +08° 11′ 18.1″ 5.72 −0.29 518 K0III
8 Leo 8 83189 47189 09h 37m 02.59s +16° 26′ 16.7″ 5.73 −1.60 953 K1III
85 Leo 85 99902 56080 11h 29m 41.86s +15° 24′ 48.2″ 5.74 0.11 435 K4III
86513 48982 09h 59m 36.28s +29° 38′ 43.2″ 5.75 0.76 324 G9III:
89 Leo 89 65 100563 56445 11h 34m 22.06s +03° 03′ 37.5″ 5.76 3.64 87 F5V
36 G. Leo 39 97605 54863 11h 14m 01.81s +08° 03′ 39.4″ 5.79 1.61 223 K3III
5 G. Leo 5 84542 47943 09h 46m 10.04s +06° 42′ 31.0″ 5.80 −1.72 1042 M1III
99196 55716 11h 24m 58.99s +11° 25′ 49.1″ 5.80 0.02 468 K4III
100808 56601 11h 36m 17.94s +27° 46′ 52.7″ 5.80 1.52 234 F0V
39 Leo 39 89125 50384 10h 17m 14.80s +23° 06′ 23.2″ 5.81 4.03 74 F8Vw
89024 50336 10h 16m 41.84s +25° 22′ 14.5″ 5.84 0.91 315 K2III:
10 Sex (10) 8 86080 48734 09h 56m 26.03s +08° 55′ 59.2″ 5.85 −0.73 674 K2III:
DR Leo DR 83787 47544 09h 41m 35.11s +31° 16′ 40.2″ 5.90 −1.40 942 K6III
76 Leo 76 45 98366 55249 11h 18m 54.98s +01° 39′ 01.9″ 5.90 1.00 311 K0III:
102590 57606 11h 48m 38.77s +14° 17′ 03.1″ 5.90 1.55 242 F0V
55 Leo 55 22 94672 53423 10h 55m 42.34s +00° 44′ 13.0″ 5.91 2.70 143 F2III
56 Leo 56 23 VY 94705 53449 10h 56m 01.48s +06° 11′ 07.4″ 5.91 0.92 325 M5IIIvar VY Leo
35 Leo 35 89010 50319 10h 16m 32.42s +23° 30′ 10.8″ 5.95 3.54 99 G2IV
62 Leo p3 62 31 95849 54049 11h 03m 36.63s −00° 00′ 03.0″ 5.95 −0.21 557 K3III
90 Leo 90 100600 56473 11h 34m 42.50s +16° 47′ 48.9″ 5.95 −2.98 1988 B4V
45 Leo 45 CX 90569 51213 10h 27m 38.99s +09° 45′ 44.7″ 6.01 0.65 385 A0sp... CX Leo; α² CVn variable
R Leo R 84748 09h 47m 33.50s +11° 25′ 44.0″ 6.02 Mira variable
88737 50174 10h 14m 29.84s +21° 10′ 05.6″ 6.02 2.44 169 F9V
101980 57240 11h 44m 13.17s +25° 13′ 05.9″ 6.02 −1.25 929 K5III
11 Sex (11) 9 86369 48876 09h 58m 07.62s +08° 18′ 50.6″ 6.05 −0.04 539 K3III
88639 50109 10h 13m 49.72s +27° 08′ 09.0″ 6.05 0.67 389 G5III-IV
50 G. Leo 50 98960 55595 11h 23m 17.97s +00° 07′ 55.4″ 6.05 −0.53 675 K3
102660 57646 11h 49m 14.77s +16° 14′ 34.8″ 6.05 2.07 204 A3m
43 Leo 43 12 89962 50851 10h 23m 00.46s +06° 32′ 34.4″ 6.06 1.82 229 K3III
20 Leo 20 DG 85040 48218 09h 49m 50.12s +21° 10′ 46.0″ 6.10 0.11 514 A8IV DG Leo; α² CVn variable
20 G. Leo 20 94363 53240 10h 53m 25.04s −02° 15′ 18.0″ 6.12 1.61 261 K0III+...
30 G. Leo 30 95771 54027 11h 03m 14.55s −00° 45′ 07.4″ 6.12 2.43 178 F0V
90472 51161 10h 27m 00.52s +19° 21′ 52.4″ 6.15 1.13 329 K0
42 Leo 42 89774 50755 10h 21m 50.32s +14° 58′ 32.9″ 6.16 0.34 476 A1V
94720 53472 10h 56m 16.88s +22° 21′ 06.0″ 6.17 −0.28 637 K2
59 G. Leo 59 99651 55941 11h 27m 53.73s −01° 41′ 59.8″ 6.23 0.21 522 K2III:
82670 46938 09h 33m 59.17s +23° 27′ 14.8″ 6.26 0.29 509 K7III
13 Leo 13 83821 47550 09h 41m 38.50s +25° 54′ 46.6″ 6.26 0.16 541 K2III:
92941 52513 10h 44m 14.62s +19° 45′ 32.0″ 6.27 2.20 212 A5V
HD 97658 97658 54906 11h 14m 33s +25° 42′ 37″ 6.27 69 K1V has a planet (b)
88 Leo 88 100180 56242 11h 31m 45.14s +14° 21′ 53.9″ 6.27 4.46 75 G0V
54 Leo 54 94602 10h 55m 37.30s +24° 44′ 56.0″ 6.30
97244 54688 11h 11m 43.79s +14° 24′ 00.7″ 6.30 2.38 198 A5V
81361 46232 09h 25m 32.55s +16° 35′ 08.3″ 6.31 1.70 272 G9III:
19 G. Leo 19 94237 53167 10h 52m 36.10s −00° 12′ 05.7″ 6.31 −0.72 830 K5III
7 Leo 7 83023 47096 09h 35m 52.91s +14° 22′ 46.5″ 6.32 0.35 510 A1V
80 Leo 80 55 KV 99329 55791 11h 25m 50.10s +03° 51′ 36.7″ 6.35 2.41 200 F3IV KV Leo, γ Dor variable
87500 49445 10h 05m 40.96s +15° 45′ 27.1″ 6.36 1.07 372 F2Vn
18 G. Leo 18 94180 53141 10h 52m 13.69s +01° 01′ 29.9″ 6.37 −1.16 1045 A3V
102910 57779 11h 50m 55.42s +12° 16′ 44.3″ 6.37 2.66 180 A5m
37 Sex (37) 17 93244 52660 10h 46m 05.68s +06° 22′ 23.8″ 6.38 1.22 351 K1III:
96372 54319 11h 06m 44.01s +17° 44′ 14.7″ 6.40 −0.46 769 K5
6 LMi (6) 80956 46058 09h 23m 31.85s +25° 10′ 58.2″ 6.41 −0.18 679 G5III-IV
89344 50516 10h 19m 00.74s +24° 42′ 43.6″ 6.42 −1.36 1173 K0
34 Leo 34 88355 49929 10h 11m 38.19s +13° 21′ 18.7″ 6.43 2.24 225 F7V
67 G. Leo 67 100659 56500 11h 34m 58.93s −04° 21′ 40.2″ 6.43 0.05 616 K0
19 Leo 19 84722 48029 09h 47m 25.99s +11° 34′ 05.4″ 6.44 1.67 293 A7Vn
23 Leo 23 85268 48324 09h 51m 01.97s +13° 03′ 58.5″ 6.45 −2.32 1852 M0III
HD 100655 100655 56508 11h 35m 03.79s +20° 26′ 29.6″ 6.45 0.71 459 G9III Formosa,[5] has a planet (b)
HN Leo HN 86358 48895 09h 58m 26.12s +27° 45′ 32.6″ 6.48 2.36 218 F3V γ Dor variable
64 Leo 64 96528 54388 11h 07m 39.72s +23° 19′ 25.5″ 6.48 2.09 246 A5m
84252 47779 09h 44m 30.00s +18° 51′ 49.1″ 6.49 0.72 464 K0
84680 48023 09h 47m 22.20s +23° 38′ 51.7″ 6.49 0.02 643 K0
83 Leo A 83 57 99491 55846 11h 26m 45.75s +03° 00′ 45.6″ 6.49 5.25 58 K0IV binary star
64 100456 56388 11h 33m 36.33s +02° 29′ 56.7″ 6.49 −1.44 1254 K5
82523 46891 09h 33m 18.32s +28° 22′ 04.9″ 6.50 1.68 300 A3Vnn
18 LMi (18) 86012 48742 09h 56m 31.36s +32° 23′ 04.6″ 6.55 3.02 165 F2
9 Leo 9 83273 47247 09h 37m 49.96s +24° 40′ 13.1″ 6.61 2.41 225 G0III
11 Leo 11 83343 47266 09h 38m 01.31s +14° 20′ 50.8″ 6.63 2.58 210 F2
57 Leo 57 94738 53460 10h 56m 10.53s +00° 25′ 58.6″ 6.65 −0.15 746 K0
52 LMi (52) 96418 54347 11h 07m 04.91s +25° 32′ 13.8″ 6.86 3.14 181 F8IV
71 Leo 71 98824 55533 11h 22m 29.02s +17° 26′ 13.4″ 7.03 0.16 773 K1III
HD 89307 89307 50473 10h 18m 21.28s +12° 37′ 16.0″ 7.06 4.61 101 G0V has a planet (b)
38 Sex (38) 93431 53460 10h 47m 19.16s +06° 20′ 46.4″ 7.13 2.23 311 A2
49 LMi (49) 94671 53439 10h 55m 56.09s +18° 09′ 10.8″ 7.25 0.82 631 G5
83 Leo B 83 99492 55848 11h 26m 46.28s +03° 00′ 22.8″ 7.57 6.29 59 K2V component of the 83 Leo system; has two planets (b and c)
HD 94834 94834 53545 10h 57m 15.1s +24° 08′ 34″ 7.6 264 K1 has a planet (b)
HD 81040 81040 46076 09h 23m 47.09s +20° 21′ 52.0″ 7.74 5.18 106 G2/G3 has a planet (b)
HD 87646 87646 53666 10h 58m 47.74s +01° 43′ 45.2″ 7.95 2.08 486 K0D has a planet (b)
HD 95089 95089 49522 10h 06m 40.8s +17° 53′ 42″ 8.0 G1IV has a planet (b & c)
HD 83225 83225 47211 09h 37m 17.3s +15° 15′ 09.2″ 8.04 2.92 345 F2 Scheiner's Star
HD 88133 88133 49813 10h 10m 07.68s +18° 11′ 12.7″ 8.06 3.70 243 G5IV has a planet (b)
HD 96063 96063 54158 11h 04m 44 s −02° 30′ 48″ 8.37 515 K0 Dingolay,[6] has a planet (b)
HD 100777 100777 56572 11h 35m 51.53s −04° 45′ 20.5″ 8.42 4.81 172 K0V Sagarmatha,[7] has a planet (b)
HD 98736 98736 55486 11h 21m 49.0s +18° 11′ 24″ 8.52 101 G5 has a planet (b)
HD 102272 102272 57428 11h 46m 23.54s +14° 07′ 26.3″ 8.71 0.93 1200 K0III has two planets (b & c)
HD 99109 99109 55664 11h 24m 17.0s −01° 31′ 44″ 9.1 197 K4V Shama,[8] has a planet (b)
AD Leo AD 10h 19m 36.277s +19° 52′ 12.06″ 9.32 16.1 M3.5Ve Flare star
HD 89345 89345 50496 10h 18m 41.0s +10° 07′ 45″ 9.4 413 G5V has two planets (b)
BD+20°2457 10h 16m 44.86s +19° 53′ 29.0″ 9.73 650 K2II has a planet (c) and a brown dwarf (b)
Gl 436 57087 11h 42m 11.09s +26° 42′ 23.7″ 10.68 10.63 33 M2.5 nearby, has a transiting planet (b)
ο Leo B ο 14 83809 09h 41m 13.40s +09° 54′ 35.0″ 11.0 optical component of the ο Leo system
WASP-104 10h 42m 24.6s +07° 26′ 06″ 11.12 466 G8 has a transiting planet (b)
WASP-106 11h 05m 43.1s −05° 04′ 46″ 11.21 923 F9 has a transiting planet (b)
WASP-183 10h 55m 09.0s −00° 44′ 14″ 12.76 1070 G9/K0 has a transiting planet (b)
Wolf 359 CN 10h 56m 28.99s +07° 00′ 52.0″ 13.45 16.64 7.78 M6 V CN Leo; 3rd nearest star system; Proxima Leonis; flare star
CW Leo CW 09h 47m 57.38s +13° 16′ 43.6″ 14.5 200 C9,5e AGB star, carbon star, variable; brightest star at N-band (10 μm wavelength)
Caffau's Star 10h 29m 15.15s +17° 29′ 28″ 16.92 4469 Caffau's Star
DP Leonis DP 11h 17m 16.00s +17° 57′ 41.1″ 17.5 9.49 1304 DA/M5V? has a planet (b)
2MASS 0937+2931 09h 37m 34.9s +29° 31′ 41″ 20.0 T6
2MASS J1047+21 10h 47m 53.85s +21° 24′ 23.47″ 34 T6.5
Table legend:

See also

[edit]

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

List of stars in Leo

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from Grokipedia
The list of stars in Leo encompasses the astronomical catalog of all stars positioned within the boundaries of the constellation Leo, as officially defined by the (IAU) to cover the entire without overlap. Leo, representing the mythical and one of the twelve zodiac constellations, is the twelfth-largest constellation, occupying an area of 947 square degrees in the northern celestial hemisphere. This list includes hundreds of stars cataloged by various systems, such as designations (Greek letters prefixed to "Leonis"), Flamsteed numbers, and modern surveys like the or catalogs, with a focus on those visible to the or notable for scientific interest. The constellation contains 16 stars bearing IAU-approved proper names and at least 54 stars known to host confirmed exoplanets (as of 2025). Among the most prominent are (α Leonis), the brightest star in Leo at apparent visual magnitude 1.35 and the 21st-brightest in the , a rapidly rotating blue-white located 79 light-years away (as measured by DR3) as part of a quadruple system; and (β Leonis), a white main-sequence star of magnitude 2.14 situated 35.9 light-years from . Further notable entries include Algieba (γ Leonis), a of orange giants with a combined magnitude of 2.23 and an of about 500 years, at 130 light-years distant; Zosma (δ Leonis), a white main-sequence of magnitude 2.56 and 58 light-years away; Chertan (θ Leonis), a white main-sequence of magnitude 3.33 featuring a circumstellar disk, 165 light-years from the Sun; Ras Elased Australis (ε Leonis), a yellow giant of magnitude 2.98 at 247 light-years; and Adhafera (ζ Leonis), a white giant of magnitude 3.33 located 274 light-years away. The list also highlights the faint red dwarf Wolf 359 (magnitude 13.5), one of the closest s to at just 7.8 light-years, a of spectral type M6.5. These s form the asterism of the Sickle of Leo, a backward shape that outlines the lion's head, with Regulus marking its base as the "heart of the lion."

Constellation Context

Boundaries and Position

The boundaries of the constellation Leo were formally defined by the (IAU) in 1930, based on delineations proposed by Belgian astronomer Eugène Delporte and approved at the IAU General Assembly in 1928. These boundaries encompass an area of 947 square degrees on the , making Leo the 12th largest of modern constellations. Delporte's method established precise borders along lines of constant and , calibrated to the epoch B1875.0, ensuring that every point in the sky is unambiguously assigned to one constellation. In the , Leo spans a range from approximately 9h 22m to 11h 58m and a range from +33° to −7°. This positioning places Leo primarily in the , though it extends slightly across the , allowing visibility from a wide range of latitudes. The constellation's irregular shape reflects the historical outline of the figure, with its boundaries adjusted to fit the grid of celestial coordinates without overlapping adjacent regions. Leo borders several neighboring constellations: Cancer to the west, to the north, to the northeast, Virgo to the east, and Hydra and to the south. Additional adjacent areas touch , , and , but the primary directional neighbors define its spatial context within the zodiac and northern sky. These borders facilitate systematic cataloging of stars and deep-sky objects within Leo. Historically, the boundaries of Leo evolved from the imprecise, pattern-based definitions in ancient astronomy to the rigorous modern system. In Ptolemy's 2nd-century catalog, Leo was one of 48 constellations described without fixed limits, often incorporating nearby stars like those in as part of the lion's tail tuft. Over centuries, as astronomy advanced, the need for standardized divisions grew, culminating in Delporte's IAU-approved framework that resolved ambiguities from pre-telescopic eras. This transition ensured consistency for global observations and stellar nomenclature.

Visibility and Seasonal Appearance

The constellation Leo is best observed from the during spring evenings, particularly in when it transits the meridian around , reaching its highest point in the sky for optimal visibility. During this period, the constellation culminates prominently after sunset, allowing clear views as it arches across the evening sky before gradually shifting to earlier evening appearances through May. In the , Leo appears in the autumn sky, though it remains lower on the horizon and is less favorably positioned for extended observation. Leo's apparent orientation in the sky is distinctive, spanning about 947 square degrees and ranking as the 12th largest constellation, with its key stars forming the prominent asterism that resembles a backward or curved blade. This asterism outlines the lion's head and forequarters, with the bright positioned at its base, serving as a primary identifier for locating the constellation against the starry backdrop. Leo is visible across a wide range of latitudes, from 90°N to 65°S, but viewing conditions are optimal between 0° and 40° latitude where the constellation rises high overhead, minimizing atmospheric distortion. South of 60°N, it remains accessible year-round with seasonal variations, though northern observers beyond 50°N may find it lower and shorter in visibility duration. significantly impacts fainter stars within Leo, but the brighter components, such as the , remain discernible even in moderately urban environments; darker rural skies enhance the full pattern and reveal subtler details. As a zodiacal constellation positioned between Cancer and Virgo along the , Leo follows a predictable seasonal path: it rises in the east during late winter evenings ( to ), dominates the spring sky, and sets in the west by late summer and autumn, becoming invisible near the Sun in late . This trajectory aligns with , making Leo a reliable marker for springtime stargazing in the .

Stellar Catalog

Brightest Stars

The brightest stars in the constellation Leo dominate its naked-eye appearance, forming key parts of the asterism and the lion's outline, making the constellation easily recognizable in spring skies for observers. These stars, all brighter than 3.5, range from hot blue-white main-sequence types to cooler giants, showcasing a variety of evolutionary stages and physical properties. Their prominence stems not only from intrinsic luminosities but also from relatively modest distances, allowing them to outshine fainter neighbors despite Leo's vast span across 947 square degrees. The following table summarizes the primary stars brighter than magnitude 3.5, based on their visual magnitudes, spectral classifications, distances, and notable features:
Common NameDesignationApparent MagnitudeSpectral TypeDistance (ly)Notable Features
Regulusα Leo1.4B8IVn78Quadruple system; primary ~288 L⊙
Denebolaβ Leo2.14A3Va36; ~12 L⊙
Algiebaγ¹ Leo2.2 (system)K1III130 with ~510-year orbit; primary ~60 L⊙
Zosmaδ Leo2.56A5IV58 ~20 L⊙
Algenubiε Leo3.0G1III227 ~140 L⊙
Chertanθ Leo3.33A2IV161; ~58 L⊙
Adhaferaζ Leo3.4F0III232 ~85 L⊙
Regulus, the constellation's alpha star, marks the lion's heart and anchors the base of the , a backward question-mark shape symbolizing the lion's head and mane; its B8IVn classification indicates a hot, rapidly rotating with a surface temperature around 12,500 K, contributing to its bluish-white hue and high luminosity of approximately 288 times that of the Sun. This heads a quadruple system, where the primary orbits a close companion every 40 days, while wider companions—a K2V orange dwarf and an —form a distant pair separated by over 4,000 AU. Denebola, at the tail's tip, completes the lion's body outline and serves as a navigational marker; as an A3Va main-sequence , it exhibits subtle Delta Scuti pulsations with brightness variations of about 0.2 magnitude over hours, and its luminosity is about 12 times solar, powered by a surface temperature of roughly 8,500 K. Further along the Sickle, Algieba (γ¹ Leo) represents the lion's mane, appearing as a golden-yellow giant (K1III) in a binary system with a G7III companion, separated by about 4 arcseconds; the pair orbits with a period of roughly 510 years at an average distance of 170 AU, and the primary's evolved state yields a luminosity of 60 solar units from a cool 4,500 K surface. Zosma (δ Leo), on the lion's haunch, is an A5IV star with a luminosity 20 times solar, highlighting the progression from hot, compact main-sequence stars like Regulus to more luminous giants like Algenubi (ε Leo), a G1III bright giant 227 light years away that shines at 140 solar luminosities despite its greater distance, forming part of the lion's underbelly. These stars' diverse spectral types—from B to G—illustrate Leo's mix of young, massive objects and older, expanded ones, enhancing the constellation's astronomical interest.

Variable Stars

Variable stars in the constellation Leo exhibit brightness fluctuations due to intrinsic physical processes within the or extrinsic geometric effects such as eclipses in binary systems. Intrinsic variability often arises from pulsations caused by thermal instabilities in stellar envelopes, where opacity changes during compression and expansion phases lead to periodic energy buildup and release, particularly in evolved giants and supergiants. Extrinsic causes include rotational modulation from starspots or obscuration by companions, though Leo's prominent variables are predominantly intrinsic pulsators. These stars provide insights into late-stage and are monitored by organizations like the American Association of Variable Star Observers (AAVSO). R Leonis is a classic Mira-type long-period variable, a pulsating with spectral classification M8e, undergoing dramatic brightness changes from visual magnitude 5.0 at maximum to 10.5 at minimum over a period of 312 days. Located approximately 240 light-years away, its variability stems from radial pulsations driven by thermal instability in the outer layers, where helium ionization zones cause cyclic expansion and contraction. This star, one of the brightest and most accessible Miras for amateur observation, highlights the envelope dynamics of stars. Rho Leonis, a of spectral type G5 Ib situated about 535 light-years distant, displays semi-regular pulsations characteristic of an Alpha Cygni-type variable, with brightness varying between magnitudes 3.9 and 4.7 over an approximate 45-day period. These non-radial pulsations arise from turbulent in its extended atmosphere, leading to irregular but recurring amplitude changes of around 0.2 magnitudes. As a massive evolved star, Rho Leonis exemplifies how supergiants maintain variability through atmospheric instabilities without strict periodicity. Beta Leonis, commonly known as , is a with subtle brightness fluctuations of about 0.2 magnitudes occurring over short periods of hours, attributed to both radial and non-radial pulsations in its A3 V main-sequence atmosphere. These high-frequency oscillations, driven by the kappa mechanism in the partial ionization zone, make it a low-amplitude example of post-main-sequence precursors. Denebola's variability, though small, underscores the role of young, intermediate-mass stars in probing internal structure via asteroseismology. Among other notable variables, S Leonis is a semi-regular giant with magnitude swings from 5.5 to 6.9, reflecting irregular pulsations in its late evolutionary phase. Similarly, W Leonis behaves as a Mira-like variable with a period of around 179 days, exhibiting long-term brightness cycles typical of red giants undergoing thermal pulsing. These fainter members contribute to Leo's diverse variability profile, emphasizing pulsation as a dominant mechanism across stellar types in the constellation.

Multiple and Binary Systems

The constellation Leo hosts several notable multiple and systems, where gravitational binding leads to complex orbital interactions observable through visual separation or variations. These systems provide insights into , , and dynamical stability, with Leo's bright stars allowing detailed study via both direct imaging and . Hierarchical configurations, common in such multiples, help maintain long-term stability by minimizing close encounters that could disrupt inner orbits. Alpha Leonis, commonly known as , forms a quadruple system dominated by a primary star of spectral type B8IVn, accompanied by a close companion in a 40-day at a separation of approximately 0.35 AU. This inner binary is orbited by a wider pair of companions separated by about 177 arcseconds (roughly 4,200 AU), contributing to a total system mass of around 5.5 solar masses. The hierarchical structure ensures stability, with the outer components completing their over an estimated 130,000 years. Gamma¹ Leonis, or Algieba, is a prominent consisting of two giant stars classified as K0III and G7III, each with radii approximately 25 solar radii. The components are visually resolvable at a separation of 4.6 arcseconds (about 170 AU at the system's distance), with an of roughly 930 years that renders the pair accessible to small telescopes. Their combined brightness highlights the system's evolutionary stage as post-main-sequence giants, though the wide orbit precludes significant tidal interactions. 54 Leonis exemplifies a triple system, featuring a visual binary with components of magnitudes 4.8 and 5.9 separated by 740 arcseconds, augmented by a spectroscopic companion to the primary. This configuration combines direct resolvability of the outer pair with detections for the inner spectroscopic element, illustrating hierarchical multiplicity where the close companion orbits undetected visually but influences the system's dynamics. Iota Leonis represents a Beta Lyrae-type eclipsing binary, characterized by giant components that produce brightness variations from magnitude 3.9 to 4.1 over a 29-hour period. The eclipses arise from the partial overlap of the stars' lobes, enabling and photometric monitoring that reveals the system's nature without requiring high-resolution imaging. In Leo's binaries, visual systems like Algieba allow measurement of angular separation and to infer orbits, while spectroscopic binaries such as the inner component of 54 Leonis rely on Doppler shifts for period and velocity amplitudes. Hierarchical arrangements predominate for stability, as inner close pairs (e.g., Regulus's 40-day binary) are shielded from outer perturbations, reducing chaotic ejections or collisions over gigayear timescales. These dynamics underscore Leo's role in testing models of multiple-star formation and longevity.

Stars with Exoplanets

As of November 2025, at least 19 stars within the boundaries of the constellation Leo are confirmed to host exoplanets, detected mainly through transit photometry and measurements. These systems feature a range of planet types, from compact super-Earths to massive gas giants, with some planets positioned in the habitable zones of their host stars, prompting studies of atmospheric compositions for signs of or . Representative examples highlight the diversity of these planetary systems and their scientific interest. K2-18 is an M2.5V situated 124 light-years from , hosting the K2-18b with a mass of 8.6 masses, a radius of 2.6 radii, and an orbital period of 33 days. This planet resides in the star's and is classified as a hycean , where observations in 2023 detected potential biosignatures such as in its hydrogen-rich atmosphere. HIP 67522, an F7V star 410 light-years away, harbors three gas giant identified via monitoring in 2020: HIP 67522 b (7.5 Jupiter masses, 289-day period), HIP 67522 c (7 Jupiter masses, 583-day period), and HIP 67522 d (3.5 Jupiter masses, 1280-day period). The K0V star 94 Leonis, located 49 light-years from Earth, hosts two detected by in 2007: 94 Leonis b (14.3 Earth masses, 4.1-day period) and a candidate designated 94 Leonis c. These systems underscore Leo's role in advancing research, with transit and methods enabling detailed characterizations that inform models of planetary formation and .

Nearby Stars

The constellation Leo hosts several nearby stars within 50 light-years of the Solar System, predominantly low-mass red dwarfs that are faint and invisible to the . These stars provide valuable insights into stellar population, with their high proper motions and precise parallaxes measured by the mission (exceeding 20 mas, corresponding to distances under approximately 163 light-years) enabling detailed studies of galactic dynamics and in the solar neighborhood. Astrometric data from has refined their positions and velocities, highlighting Leo's contribution to understanding the density of M-type dwarfs in the of the . Among the closest is , a prototypical M6V located 7.86 light-years away with an of 13.5. This exhibits intense magnetic activity, producing emissions and occasional bursts that can increase its brightness by up to 100 times for several minutes, as observed in spectroscopic studies of its chromospheric activity. At a distance of 32 light-years, is an M2.5V with an of 10.7. It is noteworthy for hosting the Gliese 436b, whose hydrogen-rich atmosphere is actively evaporating due to stellar radiation, forming a comet-like tail detectable in observations. Other notable examples include AD Leonis (16.2 light-years, M3V, magnitude 9.4), a with frequent that release energies equivalent to billions of hydrogen bombs, and Gliese 408 (22 light-years, M2.5V), a quiet useful for baseline studies of M-star magnetism. EE Leonis (Gliese 402, 23 light-years, , magnitude 11.6) also demonstrates flare activity, underscoring the prevalence of magnetically active low-mass stars in this proximity. These systems are key for probing challenges around cool stars, including radiation impacts on potential planetary atmospheres.
Star NameSpectral TypeDistance (ly)Apparent MagnitudeNotable Features
Wolf 359M6V7.8613.5Flare star with emissions; brightness flares up to 100× normal
AD LeonisM3V16.29.4Active flare star; superflares observed in multi-wavelength data
Gliese 408M2.5V22~10.9Quiet ; low magnetic activity benchmark
EE Leonis (Gliese 402)M4V2311.6Flare star; variable emissions in UV and s
Gliese 436M2.5V3210.7Hosts evaporating with comet-like tail

Special Features

Asterisms Involving Stars

The is a distinctive asterism within the constellation Leo, forming a backward question-mark shape that outlines the lion's head, mane, and shoulders. It consists of six prominent stars: η Leonis (magnitude 3.5), γ Leonis (Algieba, magnitude 2.1), ζ Leonis (Adhafera, magnitude 3.3), μ Leonis (Rasalas, magnitude 3.9), ε Leonis (Algenubi, magnitude 3.0), and α Leonis (, magnitude 1.4) marking the base or "dot" of the question mark. This pattern is one of the most recognizable features in the spring sky, aiding amateur astronomers in identifying the constellation. Extending westward from the , the lion's body and hindquarters are depicted by a triangular asterism formed by β Leonis (, magnitude 2.1), δ Leonis (Zosma, magnitude 2.6), and θ Leonis (Chertan, magnitude 3.3). This triangle represents the lion's haunches and tail base, providing a structural extension that completes the crouching posture of the celestial . Leo, including its key asterisms like the , was cataloged as one of the 48 ancient constellations by the 2nd-century astronomer in his . In modern astronomy, these patterns serve as navigational aids for stargazers, helping to locate Leo relative to nearby bright stars such as those in the (, , and ). For visual identification, observers can note key angular separations within the , such as the approximately 8° distance between and Algieba, which spans much of the asterism's curve.

Scientific Significance

The constellation Leo holds significant historical and cultural importance in astronomy, particularly through its brightest star, (Alpha Leonis), which was designated by in his 1603 star atlas Uranometria. In ancient , was revered as one of the four "," known as the Watcher of the North and associated with , symbolizing guardianship and seasonal transitions. Leo's stellar reflects deep influences from medieval astronomers, with names preserving descriptive and mythological elements. derives from the Arabic Qalb al-Asad, meaning "heart of the lion," later Latinized to denote the "little king." Similarly, (Beta Leonis) originates from Dhanab al-Asad, or "tail of the lion," highlighting the constellation's leonine form. The (IAU) formalized these and other Leo names, such as Algieba and Zosma, in through its on Star Names, drawing from historical sources to standardize global usage. Research milestones in Leo include pioneering work on binary star orbits, exemplified by Algieba (Gamma Leonis), a first identified in 1782 whose orbit has been studied since the late , contributing to early understandings of . More recently, the mission's Data Release 3 (DR3) in 2022 has refined distances to Leo's key stars using precise measurements: Regulus at approximately 79 light-years, Algieba at 130 light-years, and Denebola at 36 light-years, enabling accurate assessments of their luminosities and evolutionary stages. Leo's stars have advanced exoplanet research, with the Kepler K2 and TESS missions surveying its fields and yielding multiple discoveries by 2025, including the habitable-zone super-Earth K2-18b orbiting a red dwarf 124 light-years away. In 2025, observations with the James Webb Space Telescope revealed tentative evidence of dimethyl sulfide (DMS), a potential biosignature, in the atmosphere of K2-18b, though this finding remains controversial and requires further confirmation. These findings underscore Leo's role in probing planetary atmospheres and potential biosignatures. Additionally, the nearby red dwarf Wolf 359, at 7.8 light-years, has been intensively studied for its frequent superflares, which release energies up to several times those of the most powerful solar flares and pose challenges to habitability in its system. This star has also inspired science fiction, notably as the site of a major battle in the Star Trek universe.

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