The changing rotational lightcurve of Varuna and evidence for a close-in satelite

From CCD observations carried out with different telescopes, we present short-term photometric measurements of the large trans-Neptunian object Varuna in 10 epochs, spanning around 19 years.

We observe that the amplitude of the rotational light curve has changed considerably during this period of time from 0.41 to 0.55 mag… We propose that these changes in the rotational light-curve shape are due to a large and close-in satellite whose rotation induces the additional periodicity. The peak-to-valley amplitude of this oscillation is in the order of 0.04 mag. We estimate that the satellite orbits Varuna with a period of 11.9819 hr (or 23.9638 hr).

The Astrophysical Journal Letters, 883:L21 (7pp), 2019 September 20 © 2019. The American Astronomical Society.

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(416032) 2002 EX11

Number: 416032
Designation: 2002 EX11
Name:  –
First Date: 2015/03/14
Points: 115
P1: 5.36
P1 error: 0.01
Max. Ampl.: 0.66

 

Optical Ground Station Telescope

Observatorio del Teide

EURONEAR

(285331) 1999 FN53

Number: 285331
Designation: 1999 FN53
Name:  –
First Date: 2015/04/21
Points: 393
P1: 4.42
P1 error: 0.01
Max. Ampl.: 1.07

 

IAC80 telescope

Observatorio del Teide, IAC

EURONEAR

(624) Hektor

Number: 624
Designation:-
Name:  Hektor
First Date: 2019/08/28
Points: 224
P1: 6.924
P1 error: 0.001
Max. Ampl.: 0.16

 

 

First Date: 2019/09/05
Points: 80
P1: 6.92
P1 error: 0.01
Max. Ampl.: 0.14

 

 

 

Hektor star occultation: 2019/08/28

Troyan asteroid

(293054) 2006 WO127

Number: 293054
Designation: 2006 WP127
Name:  –
First Date: 2019/07/19
Points: 398
P1: 5.9659
P1 error: 0.0001
Max. Ampl.: 0.25

 

Lightcurve from Isaac Aznar Observatory  and TAR2 telescope (IAC-Solar System Group).

(455432) 2003 RP8

Number: 455432
Designation: 2003 RP8
Name:  –
First Date: 2019/07/27
Points: 228
P1: 2.289
P1 error: 0.004
Max. Ampl.: 0.42

 

Lightcurve from POP Observatory and TAR2 telescope (IAC-Solar System Group).

(453778) 2011 JK

Number: 453778
Designation: 2011 JK
Name:  –
First Date: 2019/06/07
Points: 158
P1: 2.578
P1 error: 0.003
Max. Ampl.: 0.14

 

Lightcurve from Isaac Aznar Observatory and TAR2 telescope (IAC, Solar System Group).

(355256) 2007 KN4

Number: 355256
Designation: 2007 KN4
Name:  –
First Date: 2019/04/27
Points: 516
P1: 7.142
P1 error: 0.001
Max. Ampl.: 0.35

 

Lightcurve from Isaac Aznar Observatory and TAR2 telescope (IAC, Solar System Group).