Photographic measures of double stars

Stearns, Carl L.

doi:10.1086/105531

Cited by 2 publications

(2 citation statements)

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“…They were obtained mostly with visual micrometers or photographically. We have supplemented these observations with additional photographic measurements reported by Stearns (1939) and Heintz (1975), as well as more recent and accurate adaptive optics measurements by He lminiak et al (2009). A tentative 388-yr orbit by Heintz (1975) based on his photographic data and earlier observations is also shown, but does not seem to represent the bulk of the observations very well.…”

Section: Capella As a Member Of A Multiple Systemmentioning

confidence: 96%

“…The 11 velocities show no Heintz (1975) (dashed), and our revised orbit (solid). Filled symbols represent measures from the Washington Double Star Catalog, Stearns (1939), andHe lminiak et al (2009), and open symbols are for the photographic measurements by Heintz. The line of nodes in the revised orbit is indicated with a dotted line, and the motion on the plane of the sky is direct (arrow).…”

Section: Capella As a Member Of A Multiple Systemmentioning

confidence: 99%

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Capella (alpha Aurigae) revisited: New binary orbit, physical properties, and evolutionary state

Torres,

Claret,

Pavlovski

et al. 2015

Preprint

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Knowledge of the chemical composition and absolute masses of Capella are key to understanding the evolutionary state of this benchmark binary system comprising two giant stars. Previous efforts, including our own 2009 study, have largely failed to reach an acceptable agreement between the observations and current stellar evolution models, preventing us from assessing the status of the primary. Here we report a revision of the physical properties of the components incorporating recently published high-precision radial velocity measurements, and a new detailed chemical analysis providing abundances for more than 20 elements in both stars. We obtain highly precise (∼0.3%) masses of 2.5687 ± 0.0074 M ⊙ and 2.4828 ± 0.0067 M ⊙ , radii of 11.98 ± 0.57 R ⊙ and 8.83 ± 0.33 R ⊙ , effective temperatures of 4970 ± 50 K and 5730 ± 60 K, and independently measured luminosities based on the orbital parallax (78.7 ± 4.2 L ⊙ and 72.7 ± 3.6 L ⊙ ). We find an excellent match to stellar evolution models at the measured composition of [Fe/H] = −0.04 ± 0.06. Three different sets of models place the primary star firmly at the end of the core helium-burning phase (clump), while the secondary is known to be evolving rapidly across the Hertzprung gap. The measured lithium abundance, the C/N ratio, and the 12 C/ 13 C isotopic carbon abundance ratio, which change rapidly in the giant phase, are broadly in agreement with expectations from models. Predictions from tidal theory for the spin rates, spin-orbit alignment, and other properties do not fare as well, requiring a 40-fold increase in the efficiency of the dissipation mechanisms in order to match the observations.

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