CDS

2020A&A...643A.125S

Query : 2020A&A...643A.125S

2020A&A...643A.125S - Astronomy and Astrophysics, volume 643A, 125-125 (2020/11-1)

A multi-chord stellar occultation by the large trans-Neptunian object (174567) Varda.

SOUAMI D., BRAGA-RIBAS F., SICARDY B., MORGADO B., ORTIZ J.L., DESMARS J., CAMARGO J.I.B., VACHIER F., BERTHIER J., CARRY B., ANDERSON C.J., SHOWERS R., THOMASON K., MALEY P.D., THOMAS W., BUIE M.W., LEIVA R., KELLER J.M., VIEIRA-MARTINS R., ASSAFIN M., SANTOS-SANZ P., MORALES N., DUFFARD R., BENEDETTI-ROSSI G., GOMES-JUNIOR A.R., BOUFLEUR R., PEREIRA C.L., MARGOTI G., PAVLOV H., GEORGE T., OESPER D., BARDECKER J., DUNFORD R., KEHRLI M., SPENCER C., COTA J.M., GARCIA M., LARA C., McCANDLESS K.A., SELF E., LECACHEUX J., FRAPPA E., DUNHAM D. and EMILIO M.

Abstract (from CDS):


Context. We present results from the first recorded stellar occultation by the large trans-Neptunian object (174567) Varda that was observed on September 10, 2018. Varda belongs to the high-inclination dynamically excited population, and has a satellite, Ilmare, which is half the size of Varda.
Aims. We determine the size and albedo of Varda and constrain its 3D shape and density.
Methods. Thirteen different sites in the USA monitored the event, five of which detected an occultation by the main body. A best-fitting ellipse to the occultation chords provides the instantaneous limb of the body, from which the geometric albedo is computed. The size and shape of Varda are evaluated, and its bulk density is constrained using Varda's mass as is known from previous works.
Results. The best-fitting elliptical limb has semi-major (equatorial) axis of (383±3)km and an apparent oblateness of 0.066±0.047, corresponding to an apparent area-equivalent radius R'equiv=(370±7)km and geometric albedo pv=0.099±0.002 assuming a visual absolute magnitude HV=3.81±0.01. Using three possible rotational periods for the body (4.76, 5.91, and 7.87h), we derive corresponding MacLaurin solutions. Furthermore, given the low-amplitude (0.06±0.01)mag of the single-peaked rotational light-curve for the aforementioned periods, we consider the double periods. For the 5.91 h period (the most probable) and its double (11.82h), we find bulk densities and true oblateness of ρ=(1.78±0.06)g/cm3, e=0.235±0.050, and ρ=(1.23±0.04)g/cm3, e=0.080±0.049. However, it must be noted that the other solutions cannot be excluded just yet.

Abstract Copyright: © D. Souami et al. 2020

Journal keyword(s): methods: observational - occultations - Kuiper belt objects: individual : Varda

VizieR on-line data: <Available at CDS (J/A+A/643/A125): astrom.dat fig3b.dat>

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023 		#notes
1 Gaia DR3 4367203805493754752 * 17 18 25.1238628104 -02 05 14.178964776           ~ 1 0

Query : 2020A&A...643A.125S

Basic data :
Gaia DR3 4367203805493754752 -- Star
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types: 		* (Gaia)
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) : 		17 18 25.1238628104 -02 05 14.178964776 (Optical) [ 0.0203 0.0168 90 ] A 2020yCat.1350....0G
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) : 		17 15 48.9783667435 -02 02 07.078636549 [ 0.0203 0.0168 90 ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) : 		019.9108351502936 +19.5448662094354 [ 0.0203 0.0168 90 ]
Syntax of proper motions is : "pm-ra pm-dec [error ellipse] quality bibcode"
  • pm-ra : mu-ra*cos(dec) (expressed in the ICRS system in mas/yr)
  • pm-dec : mu-dec (expressed in the ICRS system in mas/yr)
  • [error ellipse] : error major axis and minor axis (in mas), orientation angle (in deg)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the proper motion reference
Proper motions mas/yr : 		0.781 -13.333 [0.023 0.018 90] A 2020yCat.1350....0G
Syntax of parallax is : 'value quality [error] bibcode'
  • value : parallax value
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • [error] : mean error
  • bibcode : bibcode of the parallax reference
Parallaxes (mas): 		0.6213 [0.0254] A 2020yCat.1350....0G
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (1) :
G 14.701274 [0.002769] C 2020yCat.1350....0G
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Gaia DR2 4367203805493754752 Gaia DR3 4367203805493754752

References (1 between 1850 and 2023) (Total 1)
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2023.06.02-23:37:17

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