Alpha Delphini

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Double star
α Delphini
Observation
dates equinox :  J2000.0 , epoch : J2000.0
AladinLite
Constellation dolphin
Right ascension 20 h 39 m 38.29 s
declination + 15 ° 54 ′ 43.5 ″
Apparent brightness  3.77 likes
Astrometry
Radial velocity −2.9 ± 1.6 km / s
parallax 12.85 ± 0.44 mas
distance  254 ± 9 ly
(78 ± 3 pc )
Absolute visual brightness M vis −0.7 mag
Proper movement :
Rec. Share: 53.82 ± 0.43 mas / a
Dec. portion: 8.47 ± 0.31 mas / a
orbit 
period 17 a
Major semi-axis 0.158 ″ (≙ 12 AU )
eccentricity 0.47
Orbit inclination 160 °
Argument of the node 129 °
Epoch of the periastron 1983.8
Argument of the periapsis 99 °
Individual data
Names Aa; From
Observation data:
Apparent brightness Aa 3.86 likes
From 6.43 mag
Typing:
Spectral class Aa B9 IV;
alternatively:
A0 (± 3) V
From ≈ G9 V
Physical Properties:
Absolute vis.
Brightness M vis 		Aa −0.6 mag
From 2.0 mag
Dimensions Aa 3.5 M ☉
From
radius Aa 3.9 ± 0.2 R ☉
From
Luminosity Aa ≈ 250 L ☉
From
Effective temperature Aa 10 700 K
From 5 360 ± 285 K
Other names
and catalog entries
Bayer name α Delphini
Flamsteed name 9 Delphini
Bonn survey BD + 15 ° 4222
Bright Star Catalog HR 7906 [1]
Henry Draper Catalog HD 196867 [2]
SAO catalog SAO 106357 [3]
Tycho catalog TYC 1633-2442-1 [4]
Hipparcos catalog HIP 101958 [5]
WDS catalog WDS 20396 + 1555
Further designations: WCK 2; BU 298; FK5 774; CCDM 20396 + 1555; GSC 01633-02442

α Delphini ( Alpha Delphini , α Del for short ) is a double star in the dolphin constellation . α Delphini has an apparent magnitude of 3.77 mag and is therefore (contrary to the name "Alpha") only the second brightest star in the dolphin (behind β Delphini with 3.63 mag). The Italian astronomer Niccolò Cacciatore brought the proper name Sualocin into circulation with his Palermo Star Catalog (1814). His first name was Latinized "Nicolaus", which read backwards means "Sualocin" ( analogous to this see also: Rotanev ).

The single stars of the double star are called α Del Aa ( V  = 3.9 mag) and α Del Ab ( V  = 6.4 mag). The companion α Del Ab was discovered in 1974 and orbits the main star with an orbital period of 17 years. The apparent distance varies between 0.1 "and 0.2" during one revolution. The trigonometric parallax of 12.85 ± 0.44 mas (revised Hipparcos catalog , van Leeuwen 2007) corresponds to a distance of the star system of approx. 250 light years . According to new Gaia measurements ( Gaia DR2 ) the distance is shorter ( d  ≈ 220 ly).

The standard spectral class for α Del is B9 IV. An investigation of the individual stars carried out at the Starfire Optical Range using adaptive optics revealed the spectral type A0 (± 3 subclasses) for α Del Aa, while α Del Ab appears to be a late G star. For the main star, the effective temperature , mass and luminosity estimated using star evolutionary models are 10 700 K , 3.5  M ⊙ and ≈ 250  L ⊙ . The projected equatorial rotation speed ( v  ∙ sin i ) is 138 km / s. Using the Hipparcos parallax, the star system mass is calculated from the orbit of the double star as 6.4 ± 3.6 M ⊙ .

The Washington Double Star Catalog lists five optical companions 11th - 13th size class (α Del B, C, D, E and F) within a radius of 1.3 ′ around α Del .

Web links

Remarks

  1. ↑ The fact that the components are called Aa / Ab instead of the usual A / B is related to several background stars that were previously assigned to the system.

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. ↑ Juliette C. Becker et al. : Extracting radial velocities of A- and B-type stars from echelle spectrograph calibration spectra . In: The Astrophysical Journal Supplement Series . Vol. 217, Issue 2, 2015, Art.-ID 29, p. 11. bibcode : 2015ApJS..217 ... 29B , doi: 10.1088 / 0067-0049 / 217/2/29 , arxiv : 1503.03874 .
  4. ↑ Derived from parallax ( π = 12.85 ± 0.44 mas, van Leeuwen 2007).
  5. ↑ a b Staffan Söderhjelm: Visual binary orbits and masses POST HIPPARCOS . In: Astronomy and Astrophysics . Vol. 341, 1999, p. 139. bibcode : 1999A & A ... 341..121S . VizieR catalog entry .
  6. ↑ a b c d 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 .
  7. ^ A b William Wilson Morgan , Philip C. Keenan : Spectral classification . In: Annual Review of Astronomy and Astrophysics . Vol. 11, 1973, p. 33. bibcode : 1973ARA & A..11 ... 29M , doi: 10.1146 / annurev.aa.11.090173.000333 .
  8. ↑ a b c d Theo A. ten Brummelaar et al. : Differential Binary Star Photometry Using the Adaptive Optics System at Starfire Optical Range . In: Astronomical Journal . Vol. 112, Ed. 3, 1996, pp. 1184-1185. bibcode : 1996AJ .... 112.1180T . doi: 10.1086 / 118088 .
  9. ^ A b c d e Juan Zorec, Frederic Royer: VizieR Online Data Catalog: Rotational velocities of A-type stars. IV. (Zorec +, 2012) . In: VizieR On-line Data Catalog: J / A + A / 537 / A120. Originally published in: 2012A & A ... 537A.120Z . 2011. bibcode : 2011yCat..35370120Z . VizieR catalog entry .
  10. ↑ Calculated from the apparent brightness m V and parallax π (in arc seconds) according to m V  −5 ∙ lg (1 / π) + 5 .
  11. ↑ Edward L. Fitzpatrick, Derck Massa: Determining the Physical Properties of the B stars. II. Calibration of Synthetic Photometry . In: The Astronomical Journal . Vol. 129, Ausg. 3, 2005, p. 1650. bibcode : 2005AJ .... 129.1642F , doi: 10.1086 / 427855 , arxiv : astro-ph / 0412542 .
  12. ^ Richard Hinckley Allen, Star-Names and their Meanings . GE Stechert, New York / London / Leipzig / Paris 1899, pp. 200–201.
  13. ^ William C. Wickes: Interferometric measurements of binary stars . In: Astronomical Journal . Vol. 80, 1975, pp. 655-656. bibcode : 1975AJ ..... 80..655W , doi: 10.1086 / 111790 .
  14. ↑ Calculated with the Binary Star Calculator (Vers. 3) by Brian Workman based on the orbital elements of Söderhjelm 1999.
  15. ↑ Gaia Collaboration : VizieR Online Data Catalog: Gaia DR2 (Gaia Collaboration, 2018) . In: VizieR On-line Data Catalog: I / 345. Originally published in: 2018A & A ... 616A ... 1G . 2018. bibcode : 2018yCat.1345 .... 0G . VizieR catalog entry .
  16. ↑ Oleg Yu. Malkov et al. : VizieR Online Data Catalog: Orbits of visual binaries and dynamical masses (Malkov +, 2012) . In: VizieR On-line Data Catalog: J / A + A / 546 / A69. Originally published in: 2012A & A ... 546A..69M . 2012. bibcode : 2012yCat..35460069M . VizieR catalog entry .