HR 8799

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Star
HR 8799 / V342 Pegasi
HR 8799 (center, behind circular cover) with HR 8799b (top left), HR 8799c (top right), HR 8799d (bottom right), HR 8799e (center right) taken from the Keck observatory
HR 8799 (center, behind circular cover) with HR 8799b (top left), HR 8799c (top right), HR 8799d (bottom right), HR 8799e (center right) taken from the Keck observatory
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Pegasus
Right ascension 23 h 07 m 28.72 s
declination + 21 ° 08 ′ 3.3 ″
Apparent brightness 5.95 likes
Typing
B − V color index +0.26 
U − B color index −0.04 
Spectral class F0 + VkA5mA5
Variable star type γ-Doradus star 
Astrometry
Radial velocity −12.6 km / s
parallax 24.2175  mas
distance 134.678  Lj
41.29  pc  
Visual absolute brightness M vis +3.0 mag
Proper movement 
Rec. Share: +108,301  mas / a
Dec. portion: -49,480  mas / a
Physical Properties
Dimensions 1.5  M ☉
radius 1.3  R ☉
Luminosity

4.9  L ☉

Effective temperature 7430  K
Metallicity [Fe / H] −0.47
Age 60 +100
−30Million  a
Other names
and catalog entries
Bonn survey BD + 20 ° 5278
Bright Star Catalog HR 8799 [1]
Henry Draper Catalog HD 218396 [2]
Hipparcos catalog HIP 114189 [3]
SAO catalog SAO 91022 [4]
Tycho catalog TYC 1718-2350-1 [5]Template: Infobox star / maintenance / specification of the TYC catalog
Other names V342 Pegasi • FK5  3850
annotation
  1. ↑ Estimated from apparent brightness and distance.
  2. ↑ The age of HR 8799 is a hotly debated topic in the literature and values ​​from around 30 million years to 1 billion years are given there (Geiler et al., The scattered disc of HR 8799, MNRAS 2019).

HR 8799 , also known under the variable name V342 Pegasi , is a 60 million year old main sequence star about 130  light years away . It is a γ-Doradus variable and a λ-Bootis star . It has an apparent magnitude of 5.96 mag. HR 8799 is part of a system in which there are both a debris disk and at least four massive planets.

Planets

In 2008, Christian Marois from the National Research Council of Canada's Herzberg Institute of Astrophysics and his team discovered three planets orbiting this star with the help of the Keck and Gemini telescopes . These are named HR 8799 b , c and d . With the help of adaptive optics - as the first candidates in a multiplanet system - they could be photographed in infrared light.

A fourth, further inward orbiting planet (HR 8799  e ) with an orbital period of around 45 years could be directly mapped by the same research team in 2009. The four planets have about 5 to 8 times the mass of Jupiter and a 20 to 30 percent larger diameter. The oldest image on which the three planets could subsequently be directly detected comes from the Hubble space telescope in 1998 . Since 2016, based on observations made by the ALMA Upper Vatorium in Chile, it has been assumed that HR 8799 has a fifth planet, but it has not yet been verified.

In November 2018, the existence of water in the atmosphere of HR 8799 c was confirmed. This was achieved through spectroscopic measurements supported by adaptive optics at the Keck Observatory.

Surname Large semi-axis in AE
for stable, co-planar orbits		 Mass
in M Jup 		Radius
in R Jup 		Orbital period in years
HR 8799 b 70.8+0.19
-0.18		 5.8 ± 0.5 1.2 ≈ 456
HR 8799 c 43.1+1.3
-1.4		 7.2+0.6
- 0.7		 1.3 ≈ 228
HR 8799 d 26.2+0.9
--0.7		 7.2+0.6
- 0.7		 1.3 ≈ 114
HR 8799 e 16.2 ± 0.5 7.2+0.6
- 0.7		 - ≈ 46-57

Web links

Individual evidence

  1. ↑ a b c d e f g SIMBAD Astronomical Database provided by CDS
  2. ↑ a b Bright Star Catalog provided by VizieR
  3. ↑ Christian Marois, et al .: Direct Imaging of Multiple Planets Orbiting the Star HR 8799 . In: Science . 322, No. 5906, November 2008, pp. 1348-1352. arxiv : 0811.2606 . bibcode : 2008Sci ... 322.1348M . doi : 10.1126 / science.1166585 . PMID 19008415 .
  4. ↑ Astronomers Capture First Images Of Newly-Discovered Planetary System . Press release from the Keck Observatory, November 13, 2008; accessed on December 21, 2018
  5. ^ Gemini Releases Historic Discovery Image Of Planetary "First Family". Press release from the GEMINI observatory, November 13, 2008; accessed on December 21, 2018
  6. ^ Keck Observatory Pictures show Fourth Planet in Giant Solar System . Press release from the Keck Observatory, December 8, 2010; accessed on December 21, 2018
  7. ↑ Fourth exoplanet discovered in the HR 8799 system . In: News from Spektrum.de, December 9, 2010; accessed on December 21, 2018
  8. ↑ Spectrum of Science January 2009, p. 11, extrasolar planets photographed
  9. ↑ Exoplanets in old Hubble images . In: News from Spektrum.de, October 11, 2011; accessed on December 21, 2018
  10. ↑ Mark Booth, Andrés Jordán, Simon Casassus, Antonio S. Hales, William RF Dent, Virginie Faramaz, Luca Matrà, Denis Barkats, Rafael Brahm, Jorge Cuadra: Resolving the planetesimal belt of HR 8799 with ALMA. In: Monthly Notices of the Royal Astronomical Society: Letters. 460, 2016, S. L10, doi: 10.1093 / mnrasl / slw040 , bibcode : 2016MNRAS.460L..10B
  11. ↑ Disk Around HR 8799 Hints at Hidden Fifth Planet . In: Sky & Telescope News , May 25, 2016; accessed on December 21, 2018
  12. ↑ Astronomers Confirm Water on Young Gas Giant HR 8799c . In: Science News , November 23, 2018; accessed on December 21, 2018
  13. ^ J. Wang et al .: Detecting Water in the Atmosphere of HR 8799 c with L-band High-dispersion Spectroscopy Aided by Adaptive Optics . In: Astronomical Journal , 156, 2018, p. 272
  14. ↑ a b J. Wang et al .: Dynamical Constraints on the HR 8799 Planets with GPI . In: Astronomical Journal , 156, 2018, p. 192
  15. ↑ A.-L. Maire et al .: The LEECH Exoplanet Imaging Survey. Further constraints on the HR 8799 planet architecture . In: Astronomical & Astrophysics , 576, 2015, A133