Sidus Ludoviciana

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Sidus Ludoviciana
Mizar, Alcor and Sidus Ludoviciana.jpg
Red circle.svg
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
Evolutionary stage main sequence [1]
Spectral type A5-F0 [3] [4]
Astrometry
Radial velocity (Rv)−3.42±0.35 [1] km/s
Proper motion (μ)RA: −20.171 mas/yr [1]
Dec.: −5.330 mas/yr [1]
Parallax (π)10.9650±0.0281  mas [1]
Distance 297.5 ± 0.8  ly
(91.2 ± 0.2  pc)
Details
Mass 1.5 [1]   M☉
Radius 1.6 [1]   R☉
Luminosity 6.2 [1]   L☉
Surface gravity (log g)4.13 [1]   cgs
Temperature 7,223 [1]   K
Age 961 [1]   Myr
Other designations
Sidus Ludoviciana, BD+55°1602, GC 18150, HD 116798, SAO 28748, TYC 3850-257-1, 2MASS J13245185+5453509 [5] [6]
Database references
SIMBAD data
Sidus Ludoviciana between the brighter Mizar and Alcor (north is towards the right) Thomas Bresson - Mizar+alcor (by).jpg
Sidus Ludoviciana between the brighter Mizar and Alcor (north is towards the right)

Sidus Ludoviciana, also known as HD 116798, [6] is an 8th-magnitude star in the asterism of the Big Dipper in the constellation Ursa Major, halfway between Mizar and Alcor. 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 was observed on 2 December 1722 by Johann Georg Liebknecht, who mistook it for a planet and named it after Louis V, Landgrave of Hesse-Darmstadt. In different sources the name may be written as "Sidus Ludovicianum", [7] "Sidus Ludoviciana", [6] or "Stella Ludoviciana". Unknown to Liebknecht, it had been previously observed by Benedetto Castelli in 1616. [8] : 257 

The star is six times more luminous than the Sun, 1.6 times its radius, and has a surface temperature of 7,200  K . [1] 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] It shows evidence of Gamma Doradus pulsations, and is a likely member of a young stellar association known as Group-X. [9]

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  2. ↑ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H.
  3. ↑ Henry Draper Catalogue and Extension, A. J. Cannon and E. C. Pickering, CDS ID III/135A.
  4. 1 2 3 Grenier, S.; Baylac, M.-O.; Rolland, L.; Burnage, R.; Arenou, F.; Briot, D.; Delmas, F.; Duflot, M.; Genty, V.; Gómez, A. E.; Halbwachs, J.-L.; Marouard, M.; Oblak, E.; Sellier, A. (1999). "Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS" (PDF). Astronomy and Astrophysics Supplement. 137 (3): 451. Bibcode:1999A&AS..137..451G. doi: 10.1051/aas:1999489 .
  5. ↑ "HD 116798". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 23 April 2025.
  6. 1 2 3 "The Big Dipper Adds a Star". Sky & Telescope. 2009-12-11. Retrieved 2021-07-28.
  7. ↑ Allen, R. H. (1899). Star Names: Their Lore and Meaning. p. 446.
  8. ↑ Siebert, Harald (August 2005). "The early search for stellar parallax: Galileo, Castelli, and Ramponi". Journal for the History of Astronomy . 36: 251–271. Bibcode:2005JHA....36..251S. doi:10.1177/002182860503600301.
  9. ↑ Newton, Elisabeth R.; Rampalli, Rayna; et al. (September 2022). "TESS Hunt for Young and Maturing Exoplanets (THYME). VII. Membership, Rotation, and Lithium in the Young Cluster Group-X and a New Young Exoplanet". The Astronomical Journal . 164 (3): 115. arXiv: 2206.06254 . Bibcode:2022AJ....164..115N. doi: 10.3847/1538-3881/ac8154 .
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