Short description: M-type star in the constellation Leo

Coordinates:  10h 19m 36.277s, +19° 52′ 12.06″

AD Leonis

U, B, V and R light curves for a flare on AD Leonis, adapted from Hawley and Pettersen (1991)[1]

Observation data
Equinox J2000.0]] (ICRS)
Constellation | Leo
Right ascension |  10h 19m 36.277s[2]
Declination | +19° 52′ 12.06″[2]
Apparent magnitude (V) | 9.32[3]
Characteristics
Spectral type | M3.5eV[4]
U−B color index | +1.06[3]
B−V color index | +1.54[3]
Variable type | Flare star[5]
Astrometry
Radial velocity (Rv)| +10.8[6] km/s
Proper motion (μ)|  RA: –501.8[2] mas/yr
Dec.: –42.8[2] mas/yr
Parallax (π)| 201.4064 ± 0.0296[7] mas
Distance| 16.194 ± 0.002 ly
(4.9651 ± 0.0007 pc)
Absolute magnitude (MV)| 10.87[8]
Details
Mass| 0.39–0.42[8][9] M☉
Radius| 0.39[9] R☉
Luminosity| 0.024[10] L☉
Surface gravity (log g)| 4.79[10] cgs
Temperature| 3,390 ± 19[11] K
Metallicity [Fe/H]| +0.28 ± 0.17[11] dex
Rotational velocity (v sin i)| 3[9][12] km/s
Age| 25-300[13] Myr
Other designations

Gliese 388, BD+20 2465, G 54-23, LHS 5167, LTT 12761, NLTT 24015, SAO 81292, PLX 2420, TYC 1423-174-1[14]

Database references
SIMBAD| data

AD Leonis

Location of AD Leonis in the constellation Leo

AD Leonis (Gliese 388) is a red dwarf star. It is located relatively near the Sun, at a distance of about 16 light years, in the constellation Leo. AD Leonis is a main sequence star with a spectral classification of M3.5V.[4] It is a flare star that undergoes random increases in luminosity.[5][14]

## Contents

* 1 Properties
* 2 Planetary system
* 3 See also
* 4 References
* 5 External links

## Properties

AD Leonis is an M-type star with a spectral type M3.5eV, indicating it is a main sequence star that displays emission lines in its spectrum. At a trigonometric distance of 15.9 ly (4.9 pc), it has an apparent visual magnitude of 9.43.[8][10] It has about 39–42% of the Sun's mass — above the mass at which a star is fully convective[15] — and 39% of the Sun's radius.[8][9] The projected rotation of this star is only 3 km/s,[12] but it completes a rotation once every 2.24 days.[15] It is a relatively young star with an estimated age of 25–300 million years,[13] and is considered a member of the young disk population.[16]

The variable nature of this star was first observed in 1949 by Katherine C. Gordon and Gerald E. Kron at Lick Observatory.[17] AD Leonis is one of the most active flare stars known, and the emissions from the flares have been detected across the electromagnetic spectrum as high as the X-ray band.[18][19] The net magnetic flux at the surface is about 3 kG.[12] Besides star spots, about 73% of the surface is covered by magnetically active regions.[20] Examination of the corona in X-ray shows compact loop structures that span up to 30% of the size of the star.[21] The average temperature of the corona is around 6.39 MK.[22]

During a 1943 proper motion study by Dirk Reuyl at McCormick Observatory, it was suspected of having a companion. However, a 1968 study by Sarah L. Lippincott at Sproul Observatory was unable to confirm this result.[23] A 1997 search with a near-infrared speckle interferometer failed to detect a companion orbiting 1–10 AU from the star.[24] In 2001, an optical coronagraph was used to example the star, but no companion was found.[25] There is no sign of variability in its radial velocity, which would otherwise indicate the presence of an unseen companion.[10]

This star is orbiting through the Milky Way galaxy with an eccentricity of 0.028 . This carries the star as close as 8.442 kpc from the galactic core, and as far as 8.926 kpc. The orbital inclination carries it as far as 0.121 kpc from the plane of the galaxy.[26]

In 2021, a superflare on AD Leo was observed simultaneously in X-ray by XMM-Newton and in optical by TESS.[27]

## Planetary system

In 2019 one candidate planet signal was detected by the radial velocity method[28] but was refuted in 2020.[29]

The AD Leonis planetary system  Companion
(in order from star) | Mass | Semimajor axis
(AU) | Orbital period
(days) | Eccentricity | Inclination | Radius

|
|
|
|
|
|

b (unconfirmed) | 23.1+6.2−5.6 M⊕ | 0.025+0.002−0.003 | 2.22599+0.00087−0.00042 | 0.03+0.15−0.03 | —  | —

## See also

* List of nearest stars

## References

1. ↑ Hawley, Suzanne L.; Pettersen, Bjorn R. (September 1991). "The Great Flare of 1985 April 12 on AD Leonis". The Astrophysical Journal 378: 725. doi:10.1086/170474. Bibcode: 1991ApJ...378..725H. https://ui.adsabs.harvard.edu/abs/1991ApJ...378..725H. Retrieved 17 January 2022.
2. ↑ 2.0 2.1 2.2 2.3 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G. et al. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics 355: L27–L30. doi:10.1888/0333750888/2862. Bibcode: 2000A&A...355L..27H.
3. ↑ 3.0 3.1 3.2 Nicolet, B. (October 1978). "Catalogue of homogeneous data in the UBV photoelectric photometric system". Astronomy and Astrophysics Supplement Series 34: 1–49. Bibcode: 1978A&AS...34....1N.
4. ↑ 4.0 4.1 Shkolnik, Evgenya; Liu, Michael C.; Reid, I. Neill (July 2009). "Identifying the young low-mass stars within 25 pc. I. Spectroscopic observations". The Astrophysical Journal 699 (1): 649–666. doi:10.1088/0004-637X/699/1/649. Bibcode: 2009ApJ...699..649S.
5. ↑ 5.0 5.1 Kukarkin, B. V.; Kholopov, P. N.; Pskovsky, Y. P.; Efremov, Y. N.; Kukarkina, N. P.; Kurochkin, N. E.; Medvedeva, G. I. (1971). "The third edition, containing information on 20,437 variable stars discovered and designated till 1968". General Catalogue of Variable Stars (3rd ed.). Bibcode: 1971GCVS3.C......0K.
6. ↑ Evans, D. S. (20–24 June 1966). "The revision of the General Catalogue of Radial Velocities". in Batten, Alan Henry; Heard, John Frederick. University of Toronto: International Astronomical Union. Bibcode: 1967IAUS...30...57E.
7. ↑ Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
8. ↑ 8.0 8.1 8.2 8.3 "The One Hundred Nearest Star Systems". Georgia State University. 1 January 2009. http://www.astro.gsu.edu/RECONS/TOP100.posted.htm.
9. ↑ 9.0 9.1 9.2 9.3 Reiners, Ansgar; Basri, Gibor; Browning, Matthew (February 2009). "Evidence for magnetic flux saturation in rapidly rotating M stars". The Astrophysical Journal 692 (1): 538–545. doi:10.1088/0004-637X/692/1/538. Bibcode: 2009ApJ...692..538R. https://ore.exeter.ac.uk/repository/bitstream/handle/10871/10302/Evidence for Magnetic Flux Saturation in Rapidly Rotating M Stars.pdf.
10. ↑ 10.0 10.1 10.2 10.3 Pettersen, B. R.; Coleman, L. A. (December 1981). "Chromospheric lines in red dwarf flare stars, I - AD Leonis and GX Andromedae". Astrophysical Journal 251 (12): 571–82. doi:10.1086/159500. Bibcode: 1981ApJ...251..571P.
11. ↑ 11.0 11.1 Rojas-Ayala, Bárbara; Covey, Kevin R.; Muirhead, Philip S.; Lloyd, James P. (April 2012). "Metallicity and temperature indicators in M dwarf K band spectra: Testing new and updated calibrations with observations of 133 Solar neighborhood M dwarfs". The Astrophysical Journal 748 (2): 93. doi:10.1088/0004-637X/748/2/93. Bibcode: 2012ApJ...748...93R.
12. ↑ 12.0 12.1 12.2 Reiners, Ansgar (May 2007). "The narrowest M dwarf line profiles and the rotation-activity connection at very slow rotation". Astronomy and Astrophysics 467 (1): 259–268. doi:10.1051/0004-6361:20066991. Bibcode: 2007A&A...467..259R.
13. ↑ 13.0 13.1 Shkolnik, Evgenya; Liu, Michael C.; Reid, I. Neill (July 2009). "Identifying the young low-mass stars within 25 pc. I. Spectroscopic observations". The Astrophysical Journal 699 (1): 649–666. doi:10.1088/0004-637X/699/1/649. Bibcode: 2009ApJ...699..649S.
14. ↑ 14.0 14.1 "V* AD Leo – Flare Star". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GJ+388.
15. ↑ 15.0 15.1 Reiners, Ansgar; Basri, Gibor (March 2009). "On the magnetic topology of partially and fully convective stars". Astronomy and Astrophysics 496 (3): 787–790. doi:10.1051/0004-6361:200811450. Bibcode: 2009A&A...496..787R.
16. ↑ Sciortino, S.; Maggio, A.; Favata, F.; Orlando, S. (February 1999). "X-ray spectroscopy of the active dM stars: AD Leo and EV Lac". Astronomy & Astrophysics 342 (2): 502–14. Bibcode: 1999A&A...342..502S.
17. ↑ Gordon, Katherine C.; Kron, Gerald E. (October 1949). "Flare of a dMe star, BD+20°2465, observed photoelectrically". Publications of the Astronomical Society of the Pacific 61 (362): 210–214. doi:10.1086/126179. Bibcode: 1949PASP...61..210G.
18. ↑ Osten, Rachel A.; Bastian, T. S. (February 2008). "Ultra-high time resolution observations of radio bursts on AD Leonis". The Astrophysical Journal 674 (2): 1078–1085. doi:10.1086/525013. Bibcode: 2008ApJ...674.1078O.
19. ↑ Schmitt, Jürgen H. M. M.; Fleming, T. A.; Giampapa, M. S. (September 1995). "The X-ray view of the low-mass stars in the solar neighborhood". Astrophysical Journal 450 (9): 392–400. doi:10.1086/176149. Bibcode: 1995ApJ...450..392S.
20. ↑ Crespo-Chacón, I.; Montes, D.; García-Alvarez, D.; Fernández-Figueroa, M. J.; López-Santiago, J.; Foing, B. H. (June 2006). "Analysis and modeling of high temporal resolution spectroscopic observations of flares on AD Leonis". Astronomy and Astrophysics 452 (3): 987–1000. doi:10.1051/0004-6361:20053615. Bibcode: 2006A&A...452..987C.
21. ↑ Christian, D. J.; Mathioudakis, M.; Bloomfield, D. S.; Dupuis, J.; Keenan, F. P.; Pollacco, D. L.; Malina, R. F. (August 2006). "Opacity in the upper atmospheres of active stars. II. AD Leonis". Astronomy and Astrophysics 454 (3): 889–894. doi:10.1051/0004-6361:20054404. Bibcode: 2006A&A...454..889C. http://scholarworks.csun.edu/bitstream/10211.3/172062/1/christian-etal-opacity-2006.pdf.
22. ↑ Johnstone, C. P.; Güdel, M. (June 2015). "The coronal temperatures of low-mass main-sequence stars". Astronomy & Astrophysics 578: 4. doi:10.1051/0004-6361/201425283. A129. Bibcode: 2015A&A...578A.129J.
23. ↑ Lippincott, S. L. (March 1969). "Astrometric study of BD+20 2465 from photographs taken with the Sproul 24 inch refractor". Astronomical Journal 74: 224–228. doi:10.1086/110795. Bibcode: 1969AJ.....74..224L.
24. ↑ Leinert, C.; Henry, T.; Glindemann, A.; McCarthy, D. W., Jr. (September 1997). "A search for companions to nearby southern M dwarfs with near-infrared speckle interferometry". Astronomy and Astrophysics 325: 159–166. Bibcode: 1997A&A...325..159L.
25. ↑ Oppenheimer, B. R.; Golimowski, D. A.; Kulkarni, S. R.; Matthews, K.; Nakajima, T.; Creech-Eakman, M.; Durrance, S.T. (April 2001). "A coronagraphic survey for companions of stars within 8 parsecs". The Astronomical Journal 121 (4): 2189–2211. doi:10.1086/319941. Bibcode: 2001AJ....121.2189O.
26. ↑ Allen, C.; Herrera, M. A. (April 1998). "The galactic orbits of nearby UV Ceti stars". Revista Mexicana de Astronomía y Astrofísica 34: 37–46. Bibcode: 1998RMxAA..34...37A.
27. ↑ Stelzer, B.; Caramazza, M.; Raetz, St.; Argiroffi, C.; Coffaro, M. (2022). "The Great Flare of 2021 November 19 on AD Leo. Simultaneous XMM-Newton and TESS observations". Solar and Stellar Astrophysics. doi:10.48550/ARXIV.2209.05068.
28. ↑ Tuomi, M.; Jones, H. R. A.; Butler, R. P.; Arriagada, P.; Vogt, S. S.; Burt, J.; et al. (2019-06-11). "Frequency of planets orbiting M dwarfs in the Solar neighbourhood". arXiv:1906.04644 [astro-ph.EP].
29. ↑ Carleo, I.; Malavolta, L.; Lanza, A. F.; Damasso, M.; Desidera, S.; Borsa, F. et al. (2020). "The GAPS Programme at TNG XXI – A GIARPS case-study of known young planetary candidates: Confirmation of HD 285507 b and refutation of AD Leo b". Astronomy & Astrophysics A5: 638. doi:10.1051/0004-6361/201937369. Bibcode: 2020A&A...638A...5C.

## External links

* Segura, Antígona; Walkowicz, Lucianne M.; Meadows, Victoria; Kasting, James; Hawley, Suzanne (2010). "The effect of a strong stellar flare on the atmospheric chemistry of an Earth-like planet orbiting an M dwarf". Astrobiology 10 (7): 751–771. doi:10.1089/ast.2009.0376. PMID 20879863. Bibcode: 2010AsBio..10..751S.

* v
* t
* e

← Celestial objects within 15–20 light-years

| Primary member type|

Celestial objects by systems. Secondary members are listed in small print.

| Subgiant stars|

| G-type|

* δ Pav (19.923±0.021 ly)

|

| Main-sequence
stars|

| A-type|

* Altair (α Aql) (16.73±0.05 ly)

|

G-type|

* σ Dra (18.769±0.019 ly)
* η Cas (19.42±0.06 ly)
* K-type main-sequence star B
* e (82 G.) Eri (19.711±0.023 ly)
* 3 planets: b
* c
* d

K-type|

* Groombridge 1618 (15.89±0.04 ly)
* ο² (40) Eri (16.257±0.019 ly)
* white dwarf B
* red dwarf C
* 70 Oph (16.58±0.07 ly)
* K-type main-sequence star B
* GJ 570 (19.05+0.11−0.10 ly)
* 2 red dwarfs: B
* C
* T-type brown dwarf D
* 36 Oph (19.35±0.06 ly)
* 2 K-type main-sequence stars: B
* C
* HR 7703 (19.62±0.03 ly)
* red dwarf B

M-type
(red dwarfs)|

* GJ 876 (15.198±0.014 ly)
* 4 (6?) planets: d
* f?
* g?
* c
* b
* e
* LHS 288 (15.61+0.21−0.20 ly)
* GJ 1002 (15.74+0.24−0.23 ly)
* GJ 412 (15.81±0.08 ly)
* red dwarf B
* AD Leo (16.00±0.22 ly)
* GJ 832 (16.16±0.08 ly)
* 2 planets: c
* b
* EV Lac (16.37±0.08 ly)
* GJ 682 (16.56±0.18 ly)
* 2 planets: b
* c
* GJ 3379 (16.85±0.16 ly)
* G 9-38 (17.05+0.23−0.22 ly)
* red dwarf B
* LHS 1723 (17.29±0.07 ly)
* GJ 445 (17.58+0.14−0.13 ly)
* GJ 526 (17.73±0.10 ly)
* Stein 2051 (18.06±0.08 ly)
* white dwarf B
* GJ 251 (18.22±0.16 ly)
* GJ 205 (18.45±0.12 ly)
* LP 816-60 (18.6±0.4 ly)
* GJ 229 (18.77±0.11 ly)
* T-type brown dwarf B
* 1? planets: Ab?
* GJ 693 (18.95+0.25−0.24 ly)
* Ross 47 (18.99±0.12 ly)
* GJ 752 (19.05±0.08 ly)
* red dwarf B (vB 10)
* GJ 754 (19.30±0.18 ly)
* TYC 3980-1081-1 (19.3±4.3 ly)
* GJ 588 (19.34±0.15 ly)
* YZ CMi (19.43+0.27−0.26 ly)
* GJ 908 (19.50±0.14 ly)
* GJ 1005 (19.58±0.09 ly)
* red dwarf B
* 2MASS J05332802-4257205 (~19.6 ly)
* Scholz's Star (19.60+0.40−0.28 ly)
* T-type brown dwarf B
* GJ 268 (19.74±0.25 ly)
* red dwarf B

| Degenerate
stars|

| White dwarfs|

* LP 145-141 (15.11±0.09 ly)
* G 240-72 (19.80+0.29−0.28 ly)

|

| Brown dwarfs|

| M-type|

* 2MASS 1835+3259 (18.48±0.05 ly)

|

L-type|

* DEN 0255-4700 (16.20+0.32−0.31 ly)

T-type|

* DEN 0817-6155 (16.1+1.1−1.0 ly)
* WISE J0521+1025 (16.3±4.2 ly)
* 2MASS 0939-2448 (17.4±0.4 ly)
* T-type brown dwarf B
* WISE 1741+2553 (18.1+1.6−1.4 ly)
* 2MASS 1114-2618 (18.20±0.14 ly)
* 2MASS 0415-0935 (18.62±0.18 ly)
* WISE J2000+3629 (19.4±6.7 ly)
* 2MASS 0937+2931 (19.96+0.22−0.21 ly)

Y-type|

* WISE 1639-6847 (16.12+0.25−0.24 ly)
* WISE 0359−5401 (19.2+4.2−2.6 ly)

| Sub-brown dwarfs
and rogue planets|

| Y-type|

* WISE 1541−2250 (18.6±0.5 ly)

|

Italic are systems without known trigonometric parallax.

* v
* t
* e

Stars of Leo

Bayer|

* α (Regulus)
* β (Denebola)
* γ (Algieba)
* δ (Zosma)
* ε (Algenubi)
* ζ (Adhafera)
* η
* θ (Chertan)
* ι
* κ (Al Minliar al Asad)
* λ (Alterf)
* μ (Rasalas)
* ν
* ξ
* ο (Subra)
* π
* ρ
* σ
* τ
* υ
* φ
* χ
* ψ
* ω

Flamsteed|

* 3
* 6 (h)
* 7
* 8
* 9
* 10
* 11
* 12
* 13
* 15 (f)
* 18
* 19
* 20
* 21
* 22 (g)
* 23
* 26
* 31 (A)
* 33
* 34
* 35
* 37
* 39
* 40
* 42
* 43
* 44
* 45
* 46
* 48
* 49
* 50
* 51 (m)
* 52 (k)
* 53 (l)
* 54
* 55
* 56
* 57
* 58 (d)
* 59 (c)
* 60 (b)
* 61 (p2)
* 62 (p3)
* 64
* 65 (p4)
* 66
* 67
* 69 (p5)
* 71
* 72
* 73 (n)
* 75
* 76
* 79
* 80
* 81
* 82
* 83
* 85
* 86
* 87 (e)
* 88
* 89
* 90
* 92
* 93
* 95 (o)
* 6 LMi
* 18 LMi
* 49 LMi
* 52 LMi
* 10 Sex
* 11 Sex
* 37 Sex
* 38 Sex

Variable|

* R
* S
* X
* Y
* RR
* RZ
* SS
* ST
* TU
* TV
* UV
* UZ
* XY
* XZ
* AD
* AM
* AP
* AQ
* CE
* CW
* DH
* DK
* DN
* DP
* DR
* DX
* DY
* EE
* EO
* EX
* GX
* HN

HR|

* 3736
* 3792
* 3804
* 3820
* 3869
* 3876
* 3942
* 3969
* 4006
* 4012
* 4032
* 4048
* 4097
* 4197
* 4244
* 4245
* 4249
* 4253 (p1)
* 4303
* 4341
* 4358
* 4394
* 4404
* 4419
* 4459
* 4465
* 4512
* 4531
* 4535
* 4543

HD|

* 81040
* 84680
* 86986
* 88133
* 89307
* 95089
* 96063
* 96372
* 97658
* 99109
* 100456
* 100659
* 100777
* 102272

Gliese|

* Gliese 408
* Gliese 410
* Gliese 436
* GJ 3685

Other|

* BD+20 2457
* HVS 7
* K2-3
* K2-18
* 2MASSI J0937347+293142
* MACS J1149 Lensed Star 1
* PG 1031+234
* PSR B0919+06
* PSR B0943+10
* PSR B0950+08
* PSR B1133+16
* PSR J1022+1001
* SDSS J102915+172927
* WD 1105-048
* Wolf 359 (CN)

* List

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*[Primary]: Primary member of a system is the brightest one (and, in most cases, also the most massive one).