Beta Delphini

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Double star
β Delphini
Observation
dates equinox :  J2000.0 , epoch : J2000.0
AladinLite
Constellation dolphin
Right ascension 20 h 37 m 32.94 s
declination + 14 ° 35 ′ 42.3 ″
Apparent brightness  3.63 likes
Known exoplanets

1 (?)

Astrometry
Radial velocity −24.10 km / s
parallax 32.33 ± 0.47 mas
distance  101 ± 2 ly
(30.9 ± 0.5 pc )
Absolute visual brightness M vis 1.2 mag
Proper movement :
Rec. Share: 118.09 ± 0.47 mas / a
Dec. portion: −48.06 ± 0.43 mas / a
orbit 
period 9 745.6 ± 1.4 d
Major semi-axis 0.436 76 ± 0.000 16 ″
(≙ 13.5 AU )
eccentricity 0.356 32 ± 0.000 70
Orbit inclination 61.289 ± 0.035 °
Argument of the node 357.206 ± 0.033 °
Epoch of the periastron modif. heliocentr. JD
37 960.0 ± 4.1
(≙ 1962.8)
Argument of the periapsis 168.81 ± 0.14 °
Individual data
Names A; B.
Observation data:
Apparent brightness A. 4.0 likes
B. 4.9 likes
Typing:
Spectral class A. F5 (± 1) III
B. F2 (± 2) IV
B − V color index A. ≈ 0.4
B. ≈ 0.5
Physical Properties:
Absolute vis.
Brightness M vis 		A. 1.6 mag
B. 2.6 likes
Dimensions A. 1.75 M ☉
B. 1.5 M ☉
radius A. ≈ 3.9 R ☉
B.
Effective temperature A. 6 440 ± 60 K
B. 6,890 ± 370 K
Age ≈ 1.8 billion a
Other names
and catalog entries
Bayer name β Delphini
Flamsteed name 6 Delphini
Bonn survey BD + 14 ° 4369
Bright Star Catalog HR 7882 [1]
Henry Draper Catalog HD 196524 [2]
SAO catalog SAO 106316 [3]
Tycho catalog TYC 1100-1720-1 [4]
Hipparcos catalog HIP 101769 [5]
WDS catalog WDS 20375 + 1436
Further designations: BU 151; Σ2704; CCDM 20375 + 1436; GSC 01100-01720

β Delphini ( Beta Delphini , β Del for short ) is a double star in the constellation Dolphin . With an apparent magnitude of 3.63 mag, β Delphini is brighter than α Delphini (Alpha Delphini, V  = 3.77 mag) and thus the brightest star in the dolphin. The Italian astronomer Niccolò Cacciatore brought the proper name Rotanev into circulation with his Palermo Star Catalog (1814). His surname was Latinized "Venator" (Eng. "Jäger"), which read backwards means "Rotanev" ( analogous to this see also: Sualocin ).

The binary star system has an orbital period of 26.7 years. The single stars β Del A ( V  = 4.0 mag, spectral type F5) and β Del B ( V  = 4.9 mag, spectral type F2) have an apparent distance of 0.3 "( epoch 2016). There are two subgiants with masses of 1.75  M ⊙ (β Del A) and 1.5 M ⊙ (β Del B). Highly precise astrometric measurements on the Palomar Testbed Interferometer indicate another celestial body in orbit around one of the two components, which is either an exoplanet with ≈ 9  M Jupiter ( U  ≈ 202 days) or a brown dwarf with ≈ 15 M Jupiter ( U  ≈ 435 days ) should be. The star system is 101 ± 2  light years away from us (according to the trigonometric parallax of 32.33 ± 0.47  mas ). At this distance, the estimated star disk diameter for β Del A (1.188 mas) corresponds to a true radius of ≈ 3.9  R ⊙ . The system has a metallicity of [Fe / H]  = −0.05 and an age of approx. 1.8 billion years.

The star's binary nature was discovered in 1873 by SW Burnham . The double star shows the next apparent maximum distance at the beginning of the 2030s with 0.6 ″. Even amateur astronomers with large instruments (mirror diameter> 30 cm) can then resolve it - provided that there is good seeing and high magnification. The following ephemeris can be calculated from the orbit elements in the info box on the right (distance ρ and position angle θ from β Del B to A for the middle of the year):

  • Epoch 2016.5: ρ = 0.28 ″, θ = 177 °
  • Epoch 2019.5: ρ = 0.20 ″, θ = 233 °
  • Epoch 2022.5: ρ = 0.28 ″, θ = 309 °
  • Epoch 2025.5: ρ = 0.46 ″, θ = 335 °
  • Epoch 2028.5: ρ = 0.57 ″, θ = 348 °
  • Epoch 2031.5: ρ = 0.58 ″, θ = 358 °

The Washington Double Star Catalog lists three optical companions ( ρ and θ to β Del AB):

  • β Del C: V = 13.5 mag, ρ = 12.1 ″, θ = 139 ° (epoch 2011)
  • β Del D: V = 11.4 mag, ρ = 46.7 ″, θ = 318 ° (epoch 2011)
  • β Del E: V = 11.6 mag, ρ = 112.2 ″, θ = 271 ° (epoch 2011)

β Del C moves with a proper movement of µ α  = 50.9 ± 36 mas / year and µ δ  = −55.6 ± 36 mas / year in a similar direction as the pair AB ( µ α  = 118 mas / year, µ δ  = −48 mas / year). This common proper motion pair , however, has no physical togetherness; β Del C is a background star and the similar proper motion is purely random in nature.

Web links

Individual evidence

  1. ^ A b c Floor van Leeuwen: VizieR Online Data Catalog: Hipparcos, the New Reduction (van Leeuwen, 2007) . In: VizieR On-line Data Catalog: I / 311. Originally published in: 2007A & A ... 474..653V . 2008. bibcode : 2008yCat.1311 .... 0V . VizieR catalog entry .
  2. ^ A b Dorrit Hoffleit, Wayne H. Warren Jr .: VizieR Online Data Catalog: Bright Star Catalog, 5th Revised Ed. (Hoffleit +, 1991) . In: VizieR On-line Data Catalog: V / 50. Originally published in: 1964BS .... C ...... 0H . 1995. bibcode : 1995yCat.5050 .... 0H . VizieR catalog entry .
  3. ↑ a b c d e Matthew W. Muterspaugh et al. : The PHASES differential astrometry data archive. V. Candidate substellar companions to binary systems . In: Astronomical Journal . Vol. 140, Ed. 6, 2010, pp. 1667-1669. bibcode : 2010AJ .... 140.1657M , doi: 10.1088 / 0004-6256 / 140/6/1657 . arxiv : 1010.4048 .
  4. ↑ Nina V. Kharchenko et al. : VizieR Online Data Catalog: 2nd Cat. of Radial Velocities with Astrometric Data (Kharchenko +, 2007) . In: VizieR On-line Data Catalog: III / 254. Originally published in: 2007AN .... 328..889K . 2007. bibcode : 2007yCat.3254 .... 0K . VizieR catalog entry .
  5. ↑ Derived from parallax ( π = 32.33 ± 0.47 mas, van Leeuwen 2007).
  6. ↑ a b c d e f g h Theo A. ten Brummelaar et al. : Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory . In: Astronomical Journal . Vol. 119, Ed. 5, 2000, pp. 2408-2412. bibcode : 2000AJ .... 119.2403T , doi: 10.1086 / 301338 .
  7. ↑ a b c d e f James W. Davidson Jr. et al. : A Photometric Analysis of Seventeen Binary Stars Using Speckle Imaging . In: Astronomical Journal . Vol. 138, Ed. 5, 2009, pp. 1359-1360. bibcode : 2009AJ .... 138.1354D , doi: 10.1088 / 0004-6256 / 138/5/1354 .
  8. ^ Richard Hinckley Allen, Star-Names and their Meanings . GE Stechert, New York / London / Leipzig / Paris 1899, pp. 200–201.
  9. ↑ a b c Brian D. Mason et al. : VizieR Online Data Catalog: The Washington Visual Double Star Catalog (Mason + 2001-2014) . Version 2019-06-11. In: VizieR On-line Data Catalog: B / wds. Originally published in: 2001AJ .... 122.3466M . 2019. bibcode : 2019yCat .... 102026M . VizieR catalog entry .
  10. ↑ Donald J. Hutter et al. : Surveying the Bright Stars by Optical Interferometry. I. A Search for Multiplicity among Stars of Spectral Types FK . In: The Astrophysical Journal Supplement Series . Vol. 227, Ausg. 1, 2016, Art.-ID 4, p. 28. bibcode : 2016ApJS..227 .... 4H , doi: 10.3847 / 0067-0049 / 227/1/4 , arxiv : 1609.05254 .
  11. ↑ Calculated with the Binary Star Calculator (Vers. 3) by Brian Workman according to the orbital elements of Muterspaugh et al. 2010b.
  12. ↑ Peter R. Allen et al. : Low-mass Tertiary Companions to Spectroscopic Binaries. I. Common Proper Motion Survey for Wide Companions Using 2MASS . In: The Astronomical Journal . Vol. 144, Issue 2, 2012, Art. ID 62, pp. 6-10. bibcode : 2012AJ .... 144 ... 62A , doi: 10.1088 / 0004-6256 / 144/2/62 . VizieR catalog entry .