Observational, physical, and orbital parameters of Varda.
|Radius (km)||V14||Varda radius|
|V14||Effective radius(a) from radiometric modelling (Herschel data)|
|G15||Assuming that Varda and Ilmarë have spherical shapes and the same albedo,|
|with brightness difference of Δmag = 1.734 ± 0.042,|
|using photometric data of HST, Keck II, and Gemini North Telescopes,|
|resulting in km and km.|
|Mass (1020 kg)||2.664 ± 0.064||G15||System mass|
|Geometric albedo||0.102||V14||Radiometric modelling, Herschel data (“TNOs are Cool" programme)|
|Absolute magnitude (HV)||3.61 ± 0.05||V14|
|3.988 ± 0.048||A16||with a phase coefficient(b) β = −0.455 ± 0.071|
|Rotational period (h)||5.9/7.87||T10||Single-peaked light-curve with an amplitude of 0.06 ± 0.01 mag|
|5.91||T14||Other possible solutions (aliases) are mentioned: 4.76 h and 7.87 h|
|Spectral slope (%/100 nm)||19.2 ± 0.6||F09|
|Density ρ (g cm−3)||1.12/0.63||T10||Associated with the periods (5.9 and 7.87 h) and sizes, respectively|
|Bulk density of the system||V14||Assuming that Varda and Ilmarë have equal albedo and density values|
|Varda-Ilmarë (g cm−3)||G15||Using the mass and radius described above|
|Ecliptic orbital elements of Varda|
|a (AU)||46.046||LS||NIMA ephemeris, see text|
|Orbital elements of Ilmarë (ref:G15)|
|solution 1||solution 2|
|a (km)||4812 ± 35||4805 ± 35|
|e||0.0181 ± 0.0045||0.0247 ± 0.0048|
|Orbital pole (J2000)|
|αp (deg)||273.0 ± 1.5||229.5 ± 1.5|
|δp (deg)||− 11.0 ± 1.9||4.9 ± 1.8|
Notes. (a) Vilenius et al. (2014) defined the radiometric (area-equivalent) effective diameter of a binary system as , where D1 and D2 are the primary and secondary diameters, respectively. (b)This assumes a linear trend of the phase curves and considers a magnitude variability that is due to the rotational light-curve.
References. T10: Thirouin et al. (2010), T14: Thirouin et al. (2014), F09: Fornasier et al. (2009), V14: Vilenius et al. (2014), G15: Grundy et al. (2015), A16: Alvarez-Candal et al. (2016), LS : NIMA ephemerides (https://lesia.obspm.fr/lucky-star/obj.php?p=426).
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