99 Herculis

Coordinates: Sky map 18h 07m 01.54s, +30° 33′ 43.69″
Source: Wikipedia, the free encyclopedia.
This article is about b Herculis. Not to be confused with β (Beta) Herculis.
99 Herculis
Observation data
Epoch J2000      Equinox J2000
Constellation Hercules
Right ascension 18h 07m 01.53971s[1]
Declination +30° 33′ 43.6896″[1]
Apparent magnitude (V) 5.066[2] (A: 5.10; B: 8.45)[3]
Characteristics
Spectral type F7 V[4] + K4 V[5]
U−B color index –0.056[2]
B−V color index +0.548[2]
Distance
51.0 ± 0.3 ly
(15.64 ± 0.08 pc)
Absolute magnitude (MV)4.08[7]
Argument of periastron
(ω)
(secondary)		116° ± 2°
Details
99 Her A
Gyr
99 Her B
Mass0.46[5] M☉
Radius0.74[8] R☉
Luminosity0.14[5] L☉
HR 6775, SAO 66648[9]
Database references
SIMBAD99 Her AB
99 Her A
99 Her B

99 Herculis is the

apparent visual magnitude of 5.1,[2] which, according to the Bortle scale, makes it faintly visible to the naked eye from suburban skies. Measurements made with the Hipparcos spacecraft show an annual parallax shift of 0.064″,[1] corresponding to a physical distance of about 51.0 ly (15.6 pc) from the Sun. The system is moving further from the Earth with a heliocentric radial velocity of +1.7 km/s.[6]

The binary nature of this star system was first discovered in 1859 by English astronomer

plane of their orbit is inclined by an angle of about 39° to the line-of-sight from the Earth. Reports of a third component of this system now appear doubtful.[5]

The primary component, 99 Herculis A, is an

F-type main sequence star with a stellar classification of F7 V.[4] It has 94%[5] of the Sun's mass and nearly double the luminosity, but has an estimated 10% greater radius.[8] The effective temperature of the star's outer atmosphere is 5,938 K,[4] giving it a white-hued glow.[11] This is a metal-poor star, showing overall abundances of elements—other than hydrogen or helium—equal to 60% of those in the Sun.[12]

The secondary component, 99 Herculis B, is fainter by 3.35 magnitudes compared to the primary. It is a

K-type main sequence star with a classification of K4 V.[5] With 46%[5] of the mass of the Sun, it has 74%[8] of the Sun's radius but shines with just 14%[5]
of the Sun's luminosity.

Images from the Herschel Space Observatory show that a disk of dusty debris is orbiting the barycenter at an average radius of 120 AU. Oddly, the disk appears to be misaligned with the orbital plane of the binary system. This may be the result of an interaction within another star system some time in the past. Most of the disk emission appears to be caused by icy objects having a diameter of 10 cm or less, with a net mass of about ten times the mass of the Earth.[5]

References

  1. ^
    S2CID 18759600
    .
  2. ^
    Bibcode:1982A&AS...47..221R
    .
  3. doi:10.1086/109676
    .
  4. ^
    S2CID 46328823
    .
  5. ^
    S2CID 53710762
    .
  6. ^
    S2CID 11027621
    .
  7. ^
    doi:10.1093/pasj/57.1.13
    .
  8. ^
    S2CID 425754. Note: Search the VizieR catalogue II/224
    for HD 165908.
  9. ^ "b Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2013-10-10.{{cite web}}: CS1 maint: postscript (link)
  10. doi:10.1086/106040
    .
  11. Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original
    on March 18, 2012, retrieved 2012-01-16.
  12. doi:10.1046/j.1365-8711.2000.03577.x
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=99_Herculis&oldid=1171019395"