99 Herculis

Last updated
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]
Astrometry
Radial velocity (Rv)+1.7 [6]  km/s
Proper motion (μ)RA: –100.32 [1]   mas/yr
Dec.: +110.08 [1]   mas/yr
Parallax (π)63.93 ± 0.34  mas [1]
Distance 51.0 ± 0.3  ly
(15.64 ± 0.08  pc)
Absolute magnitude  (MV)4.08 [7]
Orbit [5]
Period (P)56.3 ± 0.1 yr
Semi-major axis (a)1.06 ± 0.02″
Eccentricity (e)0.766 ± 0.004
Inclination (i)39° ± 2°
Longitude of the node (Ω)41° ± 2°
Periastron epoch (T)1997.62 ± 0.05
Argument of periastron (ω)
(secondary)
116° ± 2°
Details
99 Her A
Mass 0.94 [5]   M
Radius 1.1 [8]   R
Luminosity 1.96 [5]   L
Surface gravity (log g)4.17 [4]   cgs
Temperature 5,938 [4]   K
Metallicity [Fe/H]–0.60 [4]   dex
Rotational velocity (v sin i)5 [7]  km/s
Age 9.37 [4]   Gyr
99 Her B
Mass 0.46 [5]   M
Radius 0.74 [8]   R
Luminosity0.14 [5]   L
Other designations
b Her, 99 Her, BD+30°3128, GJ  704, HD  165908, HIP  88745, HR  6775, SAO  66648 [9]
Database references
SIMBAD 99 Her AB
99 Her A
99 Her B

99 Herculis is the Flamsteed designation for a binary star system in the northern constellation of Hercules. It has the Bayer designation b Herculis, while 99 Herculis is the Flamsteed designation. This system has an 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 W. R. Dawes. [10] The two stellar components orbit around their common center of mass, or barycenter, with a period of 56.3 years and an eccentricity of 0.766. The semi-major axis of their orbit spans an angle of 1.06 arcseconds, which corresponds to a physical dimension of 16.5  AU. The 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]

Related Research Articles

<span class="mw-page-title-main">Alpha Herculis</span> Multiple star system in the constellation Hercules

Alpha Herculis, also designated Rasalgethi and 64 Herculis, is a multiple star system in the constellation of Hercules. Appearing as a single point of light to the naked eye, it is resolvable into a number of components through a telescope. It has a combined apparent magnitude of 3.08, although the brightest component is variable in brightness. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 360 light-years (110 parsecs) distant from the Sun. It is also close to another bright star Rasalhague in the vicinity.

<span class="mw-page-title-main">Zeta Reticuli</span> Binary star system in the constellation Reticulum

Zeta Reticuli, Latinized from ζ Reticuli, is a wide binary star system in the southern constellation of Reticulum. From the southern hemisphere the pair can be seen with the naked eye as a double star in very dark skies. Based upon parallax measurements, this system is located at a distance of about 39.3 light-years from Earth. Both stars are solar analogs that have characteristics similar to those of the Sun. They belong to the Zeta Herculis Moving Group of co-moving stars that share a common origin.

Xi Boötis, Latinised from ξ Boötis, is a binary star system located at a distance of 22 light-years away from Earth. It is the nearest visible star in the constellation Boötes. The brighter, primary component of the pair has a visual magnitude of 4.70, making it visible to the naked eye.

Pi<sup>4</sup> Orionis Binary star system in the constellation Orion

Pi4 Orionis4 Ori, π4 Orionis) is a binary star system in the western part of the Orion constellation. It is visible to the naked eye with an apparent visual magnitude of 3.7. Based upon an annual parallax shift of 3.1 mass, it is located roughly 1,050 light-years from the Sun.

<span class="mw-page-title-main">Groombridge 34</span> Binary star system in the constellation of Andromeda

Groombridge 34 is a binary star system in the northern constellation of Andromeda. It was listed as entry number 34 in A Catalogue of Circumpolar Stars, published posthumously in 1838 by British astronomer Stephen Groombridge. Based upon parallax measurements taken by the Gaia spacecraft, the system is located about 11.6 light-years from the Sun. This positions the pair among the nearest stars to the Solar System.

Xi Serpentis, Latinized from ξ Serpentis, is a triple star system in the Serpens Cauda (tail) section of the equatorial constellation Serpens. Based upon an annual parallax shift of 30.98 mas as seen from Earth, it is located 105.3 light years from the Sun. The star system is visible to the naked eye with a base apparent visual magnitude of +3.54. It is moving closer to the Sun and will make perihelion passage at a distance of 27 ly (8.2 pc) in around 690,000 years.

<span class="mw-page-title-main">Sigma Tauri</span> Star in the constellation Taurus

Sigma Tauri is the Bayer designation for a pair of white-hued stars in the zodiac constellation of Taurus. The system is a visual double star, whose components are designated σ1 Tauri and σ2 Tauri, with the latter being the more northerly star. The two are separated by 7.2 arcminutes on the sky and can be readily split with a pair of binoculars. They have apparent visual magnitudes of +5.07 and +4.70, respectively, which indicates they are both visible to the naked eye. Based upon parallax measurements, σ1 Tauri is about 147 light years from the Sun, while σ2 Tauri is 156 light years distant.

<span class="mw-page-title-main">Nu Cancri</span> Binary star system in the constellation Cancer

Nu Cancri, Latinised from ν Cancri, is a binary star in the zodiac constellation of Cancer. It is faintly visible to the naked eye with an apparent visual magnitude of +5.46. Based upon an annual parallax shift of 8.31 mas as seen from the Earth, the star is located roughly 390 light-years from the Sun.

<span class="mw-page-title-main">Zeta Herculis</span> Multiple star system in the constellation Hercules

Zeta Herculis, Latinized from ζ Herculis, is a multiple star system in the constellation Hercules. It has a combined apparent visual magnitude of 2.81, which is readily visible to the naked eye. Parallax measurements put it at a distance of about 35.0 light-years from Earth.

HD 6114 is a visual binary star system in the northern constellation of Andromeda. With a combined apparent magnitude of 6.46, the star can only be seen with the naked eye by keen-eyed observers even on the best of nights. Based upon an annual parallax shift of 10.4 mas as seen from Earth's orbit, the system is located approximately 108 parsecs (350 ly) distant.

HD 158614 is a visual binary star system in the equatorial constellation of Ophiuchus. The system is visible to the naked eye with a combined apparent visual magnitude of +5.31. It is located at a distance of 53.3 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −77 km/s and is predicted to come to within 11.0 light-years in around 196,000 years. The system has been included as a candidate member of the Zeta Herculis moving group. However, chemical abundances appear to rule that out.

<span class="mw-page-title-main">Epsilon Herculis</span> Multiple star systen in the constellation Hercules

Epsilon Herculis, Latinized from ε Herculis, is a fourth-magnitude multiple star system in the northern constellation of Hercules. The combined apparent visual magnitude of 3.9111 is bright enough to make this system visible to the naked eye. Based upon an annual parallax shift of 21.04 mas as seen from Earth, it is located 155 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −25 km/s.

<span class="mw-page-title-main">89 Herculis</span> Star in the constellation Hercules

89 Herculis is a binary star system located about 4,700 light years away from the Sun in the northern constellation of Hercules. It is visible to the naked eye as a faint, fifth magnitude star. The system is moving closer to the Earth with a heliocentric radial velocity of −28.5 km/s.

<span class="mw-page-title-main">Sigma Herculis</span> Binary star in the constellation Hercules

Sigma Herculis, Latinized from σ Her, is a binary star system in the northern constellation of Hercules. It has a combined apparent visual magnitude of 4.18, making it bright enough to be visible to the naked eye. Based upon an annual parallax shift of 10.36 mas as seen from Earth, Sigma Herculis is located about 310 light years away from the Sun.

Chi Herculis, Latinized from χ Herculis, is a Sun-like star in the northern constellation of Hercules. Based upon an annual parallax shift of 63.16 mas as seen from Earth, it is located 51.6 light years from the Sun. The star is faintly visible to the naked eye with an apparent visual magnitude of 4.59. It has a relatively high proper motion, showing a transverse movement of 0.769 arc seconds per year and is drifting closer to the Sun with a radial velocity of −56 km/s.

<span class="mw-page-title-main">68 Herculis</span> Triple star system in the constellation Hercules

68 Herculis is a triple star system located around 950 light-years away from the Sun in the northern constellation of Hercules. In the astronomical community it is often referred to by its Bayer designation of u Herculis, while 68 Herculis is the Flamsteed designation. The system is visible to the naked eye as a faint, blue-white-hued point of light with a peak apparent visual magnitude of 4.80. It is approaching the Earth with a heliocentric radial velocity of −17 km/s.

Zeta<sup>1</sup> Lyrae Star in the constellation Lyra

Zeta1 Lyrae, Latinized from ζ1 Lyrae, is a binary star in the northern constellation of Lyra. Based upon an annual parallax shift of 20.89 mas as seen from Earth, the pair are located about 156 light years from the Sun. It is visible to the naked eye with an apparent visual magnitude of 4.37.

<span class="mw-page-title-main">AC Herculis</span> Spectroscopic binary star in the constellation Hercules

AC Herculis, is an RV Tauri variable and spectroscopic binary star in the constellation of Hercules. It varies in brightness between apparent magnitudes 6.85 and 9.0.

9 Puppis is a binary star system in the southern constellation of Puppis. It was originally designated 9 Argus, being part of the now defunct Argo Navis constellation. The system is faintly visible to the naked eye as a point of light with a combined apparent visual magnitude of 5.16. The magnitude difference between the two stars is 0.65. Parallax measurements yield a distance estimate to 9 Puppis of approximately 54 light years from the Sun, with the dynamic and trigonometric parallaxes for the system being in close agreement. It is drifting closer with a systemic radial velocity of –21 km/s. The motion of the system through space is predicted to bring it as close as 42.2 light-years in about 292,000 years.

HD 72945 and HD 72946 form a co-moving star system in the northern constellation of Cancer. HD 72945 is a binary star that is dimly visible to the naked eye as a point of light with an apparent visual magnitude of 5.91. At an angular separation of 10.10″ is the fainter companion star HD 72946 at magnitude 7.25. It is being orbited by a brown dwarf. The system as a whole is located at a distance of approximately 84 light years from the Sun based on parallax measurements.

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752 , Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID   18759600.
  2. 1 2 3 4 Rakos, K. D.; et al. (February 1982), "Photometric and astrometric observations of close visual binaries", Astronomy and Astrophysics Supplement Series, 47: 221–235, Bibcode:1982A&AS...47..221R.
  3. Eggen, O. J. (February 1965), "Masses, luminosities, colors, and space motions of 228 visual binaries", Astronomical Journal, 70: 90, Bibcode:1965AJ.....70...19E, doi:10.1086/109676.
  4. 1 2 3 4 5 6 7 Maldonado, J.; et al. (May 2012). "Metallicity of solar-type stars with debris discs and planets". Astronomy & Astrophysics. 541: A40. arXiv: 1202.5884 . Bibcode:2012A&A...541A..40M. doi:10.1051/0004-6361/201218800. S2CID   46328823.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 Kennedy, G. M.; et al. (April 2012), "99 Herculis: host to a circumbinary polar-ring debris disc", Monthly Notices of the Royal Astronomical Society , 421 (3): 2264–2276, arXiv: 1201.1911 , Bibcode:2012MNRAS.421.2264K, doi: 10.1111/j.1365-2966.2012.20448.x , S2CID   53710762.
  6. 1 2 Nordström, B.; et al. (May 2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ˜14,000 F and G dwarfs", Astronomy and Astrophysics, 418 (3): 989–1019, arXiv: astro-ph/0405198 , Bibcode:2004A&A...418..989N, doi:10.1051/0004-6361:20035959, S2CID   11027621.
  7. 1 2 Takeda, Yoichi; et al. (February 2005), "High-Dispersion Spectra Collection of Nearby F--K Stars at Okayama Astrophysical Observatory: A Basis for Spectroscopic Abundance Standards", Publications of the Astronomical Society of Japan, 57 (1): 13–25, Bibcode:2005PASJ...57...13T, doi: 10.1093/pasj/57.1.13 .
  8. 1 2 3 4 Pasinetti Fracassini, L. E.; et al. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics. 367 (2): 521–524. arXiv: astro-ph/0012289 . Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. 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.
  10. van Biesbroeck, G. (1947), "The orbit of 99 Herculis = Alvan Clark 15", Astronomical Journal, 53: 23–24, Bibcode:1947AJ.....53...23V, doi: 10.1086/106040 .
  11. "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on March 18, 2012, retrieved 2012-01-16.
  12. Adelman, Saul J.; et al. (August 2000), "Elemental abundance analyses with DAO spectrograms - XXIII. The superficially normal stars 28 And (A7III) and 99 Her (F7V)", Monthly Notices of the Royal Astronomical Society, 316 (3): 514–518, Bibcode:2000MNRAS.316..514A, doi: 10.1046/j.1365-8711.2000.03577.x .