  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Leo |
| Pronunciation | /dəˈnɛbələ/,[1] |
| Right ascension | 11h 49m 03.57834s[2] |
| Declination | +14° 34′ 19.4090″[2] |
| Apparent magnitude (V) | 2.14[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | A3Va[5] |
| U−Bcolor index | +0.07[6] |
| B−Vcolor index | +0.09[6] |
| Variable type | δ Sct[3] |
| Astrometry | |
| Radial velocity (Rv) | −0.2[7] km/s |
| Proper motion (μ) | RA: −497.68[2]mas/yr Dec.: −114.67[2]mas/yr |
| Parallax (π) | 90.91±0.52 mas[2] |
| Distance | 35.9 ± 0.2 ly (11.00 ± 0.06 pc) |
| Absolute magnitude (MV) | +1.93[8] |
| Details | |
| Mass | 1.78±0.46[4] M☉ |
| Radius | 1.75±0.02[9] R☉ |
| Luminosity | 12.9±0.1[9] L☉ |
| Surface gravity (log g) | 4.0[10] cgs |
| Temperature | 8,262±36[9] K |
| Metallicity[Fe/H] | +0.00[4] dex |
| Rotational velocity (v sin i) | 128[11] km/s |
| Age | 100–380[4] Myr |
| Other designations | |
| Deneb Aleet,β Leonis,94 Leo,BD+15°2383,FK5 444,GJ 448,HD 102647,HIP 57632,HR 4534,SAO 99809,LHS 2462,LTT 13249[12][13] | |
| Database references | |
| SIMBAD | data |
Denebola is thesecond-brightest star in thezodiacconstellation ofLeo. It is the easternmost of the bright stars of Leo. It has theBayer designationBeta Leonis orβ Leonis, which are abbreviatedBeta Leo orβ Leo. Denebola is anA-type main sequence star with 75% more mass than theSun and 15 times the Sun's luminosity. Based onparallax measurements from theHipparcos astrometry satellite, the star is at a distance of 36light-years (11parsecs) from the Sun. Itsapparent visual magnitude is 2.14, making it readily visible to the naked eye. Denebola is aDelta Scuti typevariable star, meaning its luminosity varies very slightly over a period of a few hours.
β Leonis (Latinised toBeta Leonis) is the star'sBayer designation. InJohann Bayer'sUranometria (1603), it was designated β (Beta) as the second-brightest star in the constellation. It also bears theFlamsteed designation of94 Leonis (assigned on the basis of increasingright ascension rather than luminosity) and additional designations followed as the star was recorded in subsequentstar catalogues.
The traditional nameDenebola is shortened fromDeneb Alased, from theArabic phraseذنب الاسدðanab al-asad 'tail of the lion', as it represents the lion's tail, the star's position in the Leo constellation.[14] (Deneb inCygnus has a similar name origin.) In theAlphonsine Tables it was recorded as Denebalezeth.[15] OnR. A. Proctor's 1871 star chart of theNorthern Hemisphere it was designatedDeneb Aleet. In 2016, theInternational Astronomical Union organized aWorking Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[17] included a table of the first two batches of names approved by the WGSN, which includedDenebola for this star. It is now so entered in the IAU Catalog of Star Names.[18]
15th century astronomerUlugh Beg, gives the nameAl Ṣarfah, the Changer (i.e. of the weather), as the star's individual title.[19]Al-Biruni, a Muslim scholar and polymath of the 11th century, wrote of it: "The heat turns away when it rises, and the cold turns away when it disappears."[19]
Ancient Chinese astronomers designated it the first star of the five-star asterism "Seat of the Five Emperors", hence itsChinese name 五帝座一 (Wǔdìzuò-yī).
InHindu astronomy, Denebola corresponds to theNakshatra (a sector along theecliptic) namedUttara Phalgunī (second reddish one).[20]
Denebola, along withSpica andArcturus, is part of theSpring Triangle asterism, and by extension, also of theGreat Diamond together with the starCor Caroli.[21]
Denebola is a relatively young star with an age estimated at less than 400 million years. Interferometric observations give a radius that is about 173% that of the Sun. Its high rate of rotation results in an oblate shape with anequatorial bulge. It has 75% more mass than the Sun, which results in a much higher overall luminosity and a shorter life span on themain sequence.[4]
Based upon the star'sspectrum, it has astellar classification of A3 Va,[5] with theluminosity class 'Va' indicating this is a particularly luminous dwarf, amain sequence star that is generating energy through thenuclear fusion of hydrogen at its core. Theeffective temperature of Denebola's outer envelope is about8,500 K, which results in the white hue typical ofA-type stars. Denebola has a highprojected rotational velocity of 128 km/s, which is of the sameorder of magnitude as for the very rapidly rotating starAchernar. The Sun, in comparison, has an equatorial rotation velocity of 2 km/s.[10] This star is believed to be aDelta Scuti variable star that exhibits fluctuations in luminosity of 0.025 magnitudes roughly ten times per day.[22]
Denebola shows a stronginfrared excess, indicating there is a circumstellardebris disk of cool dust in orbit around it.[23] This dust has a temperature of about 120 K (−153 °C). Observations with theHerschel Space Observatory have provided resolved images, which show the disk to be located at a mean radius of 39 astronomical units from the star.[24] As theSolar System is believed to have formed out of such a disk, Denebola and similar stars such asVega andBeta Pictoris may be candidate locations forextrasolar planets.
Kinematic studies have shown that Denebola is part of astellar association dubbed theIC 2391 supercluster. All the stars of this group share a roughly common motion through space, although they are not gravitationally bound. This suggests that they were born in the same location, and perhaps initially formed anopen cluster. Other stars in this association includeAlpha Pictoris,Beta Canis Minoris and theopen cluster IC 2391. In total more than sixty probable members of the group have been identified.[25]
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