Lambda Leonis information

Lambda Leonis
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Leo
Right ascension	09h 31m 43.22754s
Declination	+22° 58′ 04.6904″
Apparent magnitude (V)	4.32
Characteristics
Spectral type	K4.5 III
U−B color index	+1.82
B−V color index	+1.54
Astrometry
Radial velocity (Rv)	24.27±0.19 km/s
Proper motion (μ)	RA: −20.17 mas/yr ; Dec.: −39.47 mas/yr
Parallax (π)	9.91 ± 0.18 mas
Distance	329 ± 6 ly ; (101 ± 2 pc)
Absolute magnitude (MV)	−0.70
Details
Radius	45 R☉
Luminosity	472 L☉
Surface gravity (log g)	1.60 cgs
Temperature	3,900 K
Metallicity [Fe/H]	−0.29 dex
Rotational velocity (v sin i)	8 km/s
Other designations
	Alterf, λ Leo, 4 Leo, BD+23°2107, HD 82308, HIP 46750, HR 3773, SAO 80885
Database references
SIMBAD	data

Lambda Leonis (λ Leonis, abbreviated Lam Leo, λ Leo), formally named Alterf /ælˈtərf/,^[11]^[12] is a star in the constellation of Leo. The star is bright enough to be seen with the naked eye, having an apparent visual magnitude of 4.32^[2] Based upon an annual parallax shift of 0.00991 arcseconds, it is located about 329 light-years from the Sun. At that distance, the visual magnitude of the star is reduced by an interstellar absorption factor of 0.06 because of extinction.^[4]

^ ^a ^b ^c ^d ^e Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).
^ Cite error: The named reference Keenan1989 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference Famaey2005 was invoked but never defined (see the help page).
^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
^ Cite error: The named reference lang2006 was invoked but never defined (see the help page).
^ Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).
^ ^a ^b ^c Cite error: The named reference McWilliam1990 was invoked but never defined (see the help page).
^ Cite error: The named reference Bernacca1970 was invoked but never defined (see the help page).
^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
^ "Naming Stars". IAU.org. Retrieved 16 December 2017.

[vanLeeuwen2007-1] Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).

[Mermilliod1986-2] Cite error: The named reference Mermilliod1986 was invoked but never defined (see the help page).

[Keenan1989-3] Cite error: The named reference Keenan1989 was invoked but never defined (see the help page).

[Famaey2005-4] Cite error: The named reference Famaey2005 was invoked but never defined (see the help page).

[Anderson2012-5] Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).

[lang2006-6] Cite error: The named reference lang2006 was invoked but never defined (see the help page).

[Mcdonald2012-7] Cite error: The named reference Mcdonald2012 was invoked but never defined (see the help page).

[McWilliam1990-8] Cite error: The named reference McWilliam1990 was invoked but never defined (see the help page).

[Bernacca1970-9] Cite error: The named reference Bernacca1970 was invoked but never defined (see the help page).

[SIMBAD-10] Cite error: The named reference SIMBAD was invoked but never defined (see the help page).

[Kunitzsch-11] Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.

[IAU-LSN-12] "Naming Stars". IAU.org. Retrieved 16 December 2017.

Observation data Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Leo
Right ascension	09^h 31^m 43.22754^s^[1]
Declination	+22° 58′ 04.6904″^[1]
Apparent magnitude (V)	4.32^[2]
Characteristics
Spectral type	K4.5 III^[3]
U−B color index	+1.82^[2]
B−V color index	+1.54^[2]
Astrometry

Radial velocity (R_v)	24.27±0.19^[4] km/s
Proper motion (μ)	RA: −20.17^[1] mas/yr Dec.: −39.47^[1] mas/yr
Parallax (π)	9.91 ± 0.18 mas^[1]
Distance	329 ± 6 ly (101 ± 2 pc)
Absolute magnitude (M_V)	−0.70^[5]

Details

Radius	45^[6] `R`_☉
Luminosity	472^[7] `L`_☉
Surface gravity (log g)	1.60^[8] cgs
Temperature	3,900^[8] K
Metallicity [Fe/H]	−0.29^[8] dex
Rotational velocity (v sin i)	8^[9] km/s

Other designations
Alterf, λ Leo, 4 Leo, BD+23°2107, HD 82308, HIP 46750, HR 3773, SAO 80885^[10]
Database references
SIMBAD	data

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