Sidus Ludoviciana

Sidus Ludoviciana
Location of Sidus Ludoviciana (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 13h 24m 51.8521s[1]
Declination +54° 53′ 50.841″[1]
Apparent magnitude (V) +7.58[2]
Characteristics
Spectral type A5-F0[3][4]
Astrometry
Radial velocity (Rv)−4.9[4] km/s
Proper motion (μ) RA: −20.171[1] mas/yr
Dec.: −5.330[1] mas/yr
Parallax (π)10.9650 ± 0.0281 mas[1]
Distance297.5 ± 0.8 ly
(91.2 ± 0.2 pc)
Details
Mass1.5[1] M☉
Radius1.6[1] R☉
Luminosity6.2[1] L☉
Surface gravity (log g)4.13[1] cgs
Temperature7,223[1] K
Age961[1] Myr
Other designations
Sidus Ludoviciana, HD 116798, SAO 28748, BD+55°1602, GC 18150, TYC 3850-257-1, 2MASS J13245185+5453509
Database references
SIMBADdata
Sidus Ludoviciana between the brighter Mizar and Alcor (north is towards the right)

Sidus Ludoviciana /ˈsaɪdəs ˌljuːdoʊˌvɪsiˈeɪnə/[citation needed], also known as HD 116798[5] is an 8th-magnitude giant star in the asterism of the Big Dipper in the constellation Ursa Major, halfway between Mizar and Alcor. It was discovered on 2 December 1722 by Johann Georg Liebknecht, who mistook it for a planet and named it after Louis V, Landgrave of Hesse-Darmstadt. A line-of-sight companion with Mizar and Alcor (with a spectral type similar to the latter), it is roughly four times more distant. It has the spectral type A8/F0 III.[4] That spectral class suggests it is a giant star, but evolutionary models place it on the main sequence.[1]

The star is six times more luminous than the Sun, 1.6 times its radius, and has a surface temperature of 7,200 K. Spectral classification based on a spectrum taken for radial velocity measurement tentatively determined a spectral and luminosity class of A8/F0III,[4] which would indicate that it has exhausted its core hydrogen and started to evolve away from the main sequence, however giant stars of this type should be at least ten times more luminous than measured for Sidus Ludoviciana.

  1. ^ a b c d e f g h i j k l Cite error: The named reference dr3 was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference tycho2 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference hr-cds was invoked but never defined (see the help page).
  4. ^ a b c d Cite error: The named reference grenier was invoked but never defined (see the help page).
  5. ^ "The Big Dipper Adds a Star". Sky & Telescope. 2009-12-11. Retrieved 2021-07-28.