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

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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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(455432) 2003 RP8

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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).

(74144) 1998 QV77

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Number: 74144
Designation: 1998 QV77
Name:
First Date: 2018/02/22
Points: 101
P1: 2.48
P1 error: 0.07
Max. Ampl.: 0.61

 

Lightcurve obtained from SARA South Observatory , Chile. Under EURONEAR project.

Amadeo Aznar Macías and Ovidiu Vaduvescu.

Binary asteroid discovery IAU announcement

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IAU CBET nº4321

(27675) 1981 CH
D. Pray, Sugarloaf Mountain Observatory, South Deerfield, MA, U.S.A.;
P. Pravec, H. Kucakova, K. Hornoch, P. Kusnirak and J. Vrastil, Ondrejov
Observatory; A. Carbognani, Astronomical Observatory of the Aosta Valley
Autonomous Region, Italy; A. Aznar, Isaac Aznar Observatory, Centro
Astronomico del Alto Turia, Aras de los Olmos, Spain; V. Benishek, Belgrade
Astronomical Observatory; W. Cooney and J. Gross, Sonoita Research
Observatory, Sonoita, AZ, U.S.A.; D. Terrell, Southwest Research Institute;
and R. Montaigut and A. Leroy, OPERA Observatory, France, report that
photometric observations taken with a 0.50-m telescope at the Sugarloaf
Mountain Observatory, a 0.65-m telescope at the Ondrejov Observatory, a
0.81-m telescope at the Observatory of the Aosta Valley Autonomous Region,
a 0.35-m telescope at the Isaac Aznar Observatory, a 0.35-m telescope at the
Sopot Observatory in Serbia, a 0.50-m telescope at the Sonoita Research
Observatory, and a 0.20-m telescope at the OPERA Observatory during 2016 Dec.
21-2017 Feb. 1 reveal that minor planet (27675) is a binary system with an
orbital period of 120.1 ± 0.4 hr. The primary shows a period of 2.9661 ±
0.0004 hr and has a lightcurve amplitude of 0.11 mag at solar phases 9-13
degrees, suggesting a nearly spheroidal shape. Mutual eclipse/occultation
events that are 0.04- to 0.06-magnitude deep indicate a lower limit on the
secondary-to-primary mean-diameter ratio of 0.20.

Curiosidades sobre la superluna.

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¿Qué hay detrás de la próxima superluna? Este mes de noviembre podremos contemplar la luna llena más grande desde hace décadas pero, ¿a qué se debe este aumento de tamaño? ¿Qué implicaciones tiene?

El próximo día 14 de noviembrela luna saldrá por el horizonte mostrando un tamaño ligeramente más grande de lo habitual: será una superluna.. Si de por sí, la salida de la Luna es un fenómeno que llama la atención por su belleza, en esta ocasión con más motivo.

El cambio de tamaño aparente del Sol y la Luna es un fenómeno que se da cuando salen y se ponen por el horizonte; se debe a un efecto óptico que se produce al comparar estos astros con objetos terrestres (árboles, casas….), así que no es más que una ilusión óptica.

Medio: Muy interesante (ver artículo completo en medio)