Delta1 Tauri

For other stars with this Bayer designation, see δ Tauri.
Delta¹ Tauri
Location of δ¹ Tauri (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Taurus
Right ascension 04h 22m 56.09253s[1]
Declination +17° 32′ 33.0487″[1]
Apparent magnitude (V) +3.772[2] (3.90 + 9.50)[3]
Characteristics
Spectral type G9.5 III CN0.5[4]
U−B color index +0.801[2]
B−V color index +0.919[2]
Astrometry
Proper motion (μ) RA: +106.56[1] mas/yr
Dec.: −29.18[1] mas/yr
Parallax (π)20.96 ± 0.58 mas[1]
Distance156 ± 4 ly
(48 ± 1 pc)
Absolute magnitude (MV)+0.41[5]
Orbit[6]
Period (P)529.8 d
Eccentricity (e)0.42
Periastron epoch (T)2434356.5 JD
Argument of periastron (ω)
(secondary)		335°
Semi-amplitude (K1)
(primary)		3.0 km/s
Details[7]
δ¹ Tau Aa
Mass2.8±0.5 M☉
Radius11.4 R☉
Luminosity69 L☉
Temperature5,000 K
Metallicity [Fe/H]+0.10 dex
Rotation138.2 d
Rotational velocity (v sin i)4.2 km/s
Age620[8] Myr
δ¹ Tau Ab
Mass1.28±0.1 M☉
Other designations
Hyadum II, δ¹ Tau, 61 Tauri, BD+17°712, FK5 162, HD 27697, HIP 20455, HR 1373, SAO 93897[9]
Database references
SIMBADdata

Delta¹ Tauri (δ¹ Tauri, abbreviated Delta¹ Tau, δ¹ Tau) is a double star in the zodiac constellation of Taurus. Based upon an annual parallax shift of 20.96 mas as seen from Earth,[1] it is located roughly 156 light-years distant from the Sun. The system is faintly visible to the naked eye with a combined apparent visual magnitude of +3.772.[2] It is considered a member of the Hyades cluster.[7]

The two constituents are designated δ¹ Tauri A and B. A is itself a binary star with components designated δ¹ Tauri Aa (officially named Secunda Hyadum /sɪˈkʌndə ˈhaɪədəm/, the traditional name for the entire system)[10] and Ab.

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference Jennens1975 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference WDSC2014 was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference perkins1989 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Cardini2005 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Pourbaix2004 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Beck2015 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Jofre2015 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ "Naming Stars". IAU.org. Retrieved 16 December 2017.