scholarly journals Shape model and spin-state analysis of PHA contact binary (85990) 1999 JV6 from combined radar and optical observations

2019 ◽  
Vol 631 ◽  
pp. A149
Author(s):  
A. Rożek ◽  
S. C. Lowry ◽  
M. C. Nolan ◽  
P. A. Taylor ◽  
L. A. M. Benner ◽  
...  
Keyword(s):  
Physical Model ◽  
Spin State ◽  
Rotation Period ◽  
Optical Observations ◽  
Shape Model ◽  
Optical Photometry ◽  
Binary Asteroid ◽  
Radar Images ◽  
Yorp Effect ◽  
Contact Binary

Context. The potentially hazardous asteroid (85990) 1999 JV6 has been a target of previously published thermal-infrared observations and optical photometry. It has been identified as a promising candidate for possible Yarkovsky-O’Keefe-Radzievskii-Paddack (YORP) effect detection. Aims. The YORP effect is a small thermal-radiation torque considered to be a key factor in spin-state evolution of small Solar System bodies. In order to detect YORP on 1999 JV6 we developed a detailed shape model and analysed the spin-state using both optical and radar observations. Methods. For 1999 JV6, we collected optical photometry between 2007 and 2016. Additionally, we obtained radar echo-power spectra and imaging observations with Arecibo and Goldstone planetary radar facilities in 2015, 2016, and 2017. We combined our data with published optical photometry to develop a robust physical model. Results. We determine that the rotation pole resides at negative latitudes in an area with a 5° radius close to the south ecliptic pole. The refined sidereal rotation period is 6.536787 ± 0.000007 h. The radar images are best reproduced with a bilobed shape model. Both lobes of 1999 JV6 can be represented as oblate ellipsoids with a smaller, more spherical component resting at the end of a larger, more elongated component. While contact binaries appear to be abundant in the near-Earth population, there are only a few published shape models for asteroids in this particular configuration. By combining the radar-derived shape model with optical light curves we determine a constant-period solution that fits all available data well. Using light-curve data alone we determine an upper limit for YORP of 8.5 × 10−8 rad day−2. Conclusions. The bifurcated shape of 1999 JV6 might be a result of two ellipsoidal components gently merging with each other, or a deformation of a rubble pile with a weak-tensile-strength core due to spin-up. The physical model of 1999 JV6 presented here will enable future studies of contact binary asteroid formation and evolution.

scholarly journals Detection of the YORP Effect on the contact-binary (68346) 2001 KZ66 from combined radar and optical observations

2021 ◽  
Author(s):  
Tarik J Zegmott ◽  
S C Lowry ◽  
A Rożek ◽  
B Rozitis ◽  
M C Nolan ◽  
...  
Keyword(s):  
Dynamical Evolution ◽  
Optical Observations ◽  
Stable Configuration ◽  
Shape Model ◽  
Radar Observations ◽  
Rotational Evolution ◽  
Yorp Effect ◽  
Contact Binary ◽  
Arecibo Observatory ◽  
Near Earth Asteroids

Abstract The YORP effect is a small thermal-radiation torque experienced by small asteroids, and is considered to be crucial in their physical and dynamical evolution. It is important to understand this effect by providing measurements of YORP for a range of asteroid types to facilitate the development of a theoretical framework. We are conducting a long-term observational study on a selection of near-Earth asteroids to support this. We focus here on (68346) 2001 KZ66, for which we obtained both optical and radar observations spanning a decade. This allowed us to perform a comprehensive analysis of the asteroid’s rotational evolution. Furthermore, radar observations from the Arecibo Observatory enabled us to generate a detailed shape model. We determined that (68346) is a retrograde rotator with its pole near the southern ecliptic pole, within a 15○ radius of longitude 170○ and latitude −85○. By combining our radar-derived shape model with the optical light curves we developed a refined solution to fit all available data, which required a YORP strength of $(8.43\pm 0.69)\times 10^{-8} \rm ~rad ~day^{-2}$. (68346) has a distinct bifurcated shape comprising a large ellipsoidal component joined by a sharp neckline to a smaller non-ellipsoidal component. This object likely formed from either the gentle merging of a binary system, or from the deformation of a rubble pile due to YORP spin-up. The shape exists in a stable configuration close to its minimum in topographic variation, where regolith is unlikely to migrate from areas of higher potential.

Radar observations and a physical model of contact binary Asteroid 4486 Mithra

Icarus ◽  
2010 ◽  
Vol 208 (1) ◽  
pp. 207-220 ◽  
Author(s):  
Marina Brozovic ◽  
Lance A.M. Benner ◽  
Christopher Magri ◽  
Steven J. Ostro ◽  
Daniel J. Scheeres ◽  
...  
Keyword(s):  
Physical Model ◽  
Radar Observations ◽  
Binary Asteroid ◽  
Contact Binary

scholarly journals Optical observations of NEA 3200 Phaethon (1983 TB) during the 2017 apparition

2018 ◽  
Vol 619 ◽  
pp. A123 ◽  
Author(s):  
M.-J. Kim ◽  
H.-J. Lee ◽  
S.-M. Lee ◽  
D.-H. Kim ◽  
F. Yoshida ◽  
...  
Keyword(s):  
Optical Observations ◽  
Inversion Method ◽  
Observation Data ◽  
Convex Model ◽  
Convex Shape ◽  
Axis Ratio ◽  
Shape Model ◽  
Spin Properties ◽  
Pole Orientation ◽  
Ecliptic Longitude

Context. The near-Earth asteroid 3200 Phaethon (1983 TB) is an attractive object not only from a scientific viewpoint but also because of JAXA’s DESTINY+ target. The rotational lightcurve and spin properties were investigated based on the data obtained in the ground-based observation campaign of Phaethon. Aims. We aim to refine the lightcurves and shape model of Phaethon using all available lightcurve datasets obtained via optical observation, as well as our time-series observation data from the 2017 apparition. Methods. Using eight 12-m telescopes and an optical imager, we acquired the optical lightcurves and derived the spin parameters of Phaethon. We applied the lightcurve inversion method and SAGE algorithm to deduce the convex and non-convex shape model and pole orientations. Results. We analysed the optical lightcurve of Phaethon and derived a synodic and a sidereal rotational periods of 3.6039 h, with an axis ratio of a∕b = 1.07. The ecliptic longitude (λp) and latitude (βp) of the pole orientation were determined as (308°, −52°) and (322°, −40°) via two independent methods. A non-convex model from the SAGE method, which exhibits a concavity feature, is also presented.

Ultraviolet and Optical Observations of the Mass-Losing Contact Binary SV Centauri

1981 ◽  
pp. 487-489
Author(s):  
H. Drechsel ◽  
H. D. Radecke ◽  
J. Rahe ◽  
G. Rupprecht ◽  
W. Wargau ◽  
...  
Keyword(s):  
Optical Observations ◽  
Contact Binary

scholarly journals Multiperiodicity in light variations of 53 Persei: results from optical photometry in 1990 October–1991 January

1994 ◽  
Vol 162 ◽  
pp. 33-36
Author(s):  
L. Huang ◽  
Z. Guo ◽  
J. Hao ◽  
J.R. Percy ◽  
M.S. Fieldus ◽  
...  
Keyword(s):  
Line Profile ◽  
Separate Group ◽  
Single Site ◽  
Optical Observations ◽  
Optical Photometry ◽  
Period Analysis ◽  
Preliminary Results ◽  
Rotational Modulation ◽  
Uv Photometry ◽  
Nonradial Pulsation

The B type star 53 Persei was discovered in 1977 by Smith (1977) as the prototype of a separate group of B-type variables showing light and line profile variability. The physical cause of the variability was thought to be nonradial pulsation (NRP) (see, e.g. Smith et al. 1984). However, the NRP model for this star has been questioned by Balona (1986) who suggested the rotational modulation (RM) model to explain the variability. In order to resolve the long lasting debate about 53 Persei, a campaign was initiated to organize coordinated optical photometry and spectroscopy from the ground, and Far-UV photometry from Voyager in 1991 January. This paper presents the results of period analysis on the groundbased UBV data. In another paper, Smith & Huang (1994) report the new identification of pulsation modes using Voyager Far-UV photometry combined with the results from optical observations. Some preliminary results from APT uvby observations taken at a single site are also cited for comparison.

Spacecraft trajectory tracking and parameter estimation around a splitting contact binary asteroid

2020 ◽  
Vol 171 ◽  
pp. 280-289
Author(s):  
Tiago M. Silva ◽  
Jean-Baptiste Bouvier ◽  
Kathleen Xu ◽  
Masatoshi Hirabayashi ◽  
Koki Ho
Keyword(s):  
Parameter Estimation ◽  
Trajectory Tracking ◽  
Binary Asteroid ◽  
Spacecraft Trajectory ◽  
Contact Binary

scholarly journals Optical observations and cyclops post-shock region modelling of the polar V348 Pav

2019 ◽  
Vol 489 (3) ◽  
pp. 4032-4042 ◽  
Author(s):  
Alexandre S Oliveira ◽  
Claudia V Rodrigues ◽  
Matheus S Palhares ◽  
Marcos P Diaz ◽  
Diogo Belloni ◽  
...  
Keyword(s):  
Circular Polarization ◽  
Orbital Period ◽  
Rotation Period ◽  
Line Emission ◽  
Radial Velocities ◽  
Optical Observations ◽  
Proper Solution ◽  
Radial Velocity Curve ◽  
Orbital Inclination ◽  
Post Shock

ABSTRACT Post-shock regions (PSR) of polar cataclysmic variables (CVs) produce most of their luminosity and give rise to high circular polarization in optical wavelengths and strong variability on the white dwarf (WD) rotation period, which are distinctive features of these systems. To investigate the polar candidate V348 Pav, we obtained a comprehensive observational set including photometric, polarimetric, and spectroscopic data, which was used to constrain the post-shock properties of the system. The object presents high circular polarization (∼30 per cent) and high He ii 4686 Å to H β line ratio, confirming it is a polar. From both radial velocities and light curves, we determined an orbital period of 79.98 min, close to the orbital period minimum of CVs. The H β radial velocity curve has a semi-amplitude of 141.4 ± 1.5 km s−1. Doppler tomography showed that most of the spectral line emission in this system is originated in the region of the companion star facing the WD, possibly irradiated by the emission related to the PSR. We modelled the PSR using the cyclops code. The PSR density and temperature profiles, obtained by a proper solution of the hydrothermodynamic equations, were used in a 3D radiative transfer solution that takes into account the system geometry. We could reproduce the V348 Pav B, V, R, and I photometric and polarimetric data using a model with a WD magnetic field of ∼28 MG, a WD mass of ∼0.85 M$\odot$, and a low (∼25°) orbital inclination. These values for the WD mass and orbital inclination are consistent with the measured radial velocities.

scholarly journals Multi-Wavelength Observations of EV Lacertae

2004 ◽  
Vol 219 ◽  
pp. 249-253
Author(s):  
Rachel A. Osten ◽  
Suzanne L. Hawley ◽  
Joel Allred ◽  
Christopher M. Johns-Krull ◽  
Christine Roark ◽  
...  
Keyword(s):  
Optical Observations ◽  
Electromagnetic Spectrum ◽  
Temperature Plasma ◽  
Optical Photometry ◽  
X Ray ◽  
Neupert Effect ◽  
Conflicting Evidence ◽  
Multi Wavelength ◽  
Flare Process ◽  
Ev Lac

We report on a large, multi-wavelength campaign to observe variability across the electromagnetic spectrum in the M dwarf flare star EV Lacertae, in 2001 September. The campaign involved X-ray (Chandra ACIS-S+HETG), UV (HST/STIS), and optical (McDonald) spectra, as well as optical photometry and multi-frequency radio (VLA) observations. EV Lac demonstrated both frequent and extreme variability during the course of the two day intensive recordings. Dispersed X-ray spectra confirm the metal underabundance seen in other active stars. The increase in continuum fluxes at short X-ray wavelengths during flare intervals compared to quiescent intervals signals the creation of high temperature plasma, a signature of the flare process. Multi-wavelength comparisons reveal interesting trends: X-ray flare frequencies are within the range predicted by optical observations, yet there is no correspondence between X-ray flares and optical flares in our data. Two UV flares occur during the rise stages of X-ray flares; a major radio flare is accompanied by a large optical flare, which has no apparent counterpart in the X-ray. The results give conflicting evidence for the applicability of the Neupert effect interpretation in stellar coronae.

Sign in / Sign up

Export Citation Format

Share Document