Extreme Asteroids in the Pan-STARRS 1 Survey

Using the first 18 months of the Pan-STARRS 1 survey, we have identified 33 candidate high-amplitude objects for follow-up observations and carried out observations of 22 asteroids. Four of the observed objects were found to have observed amplitude Aobs ≥ 1.0 mag. We find that these high-amplitude objects are most simply explained by single rubble-pile objects with some density-dependent internal strength, allowing them to resist mass shedding even at their highly elongated shapes. Three further objects, although below the cutoff for “high amplitude,” had a combination of elongation and rotation period which also may require internal cohesive strength, depending on the density of the body. We find that none of the “high-amplitude asteroids” identified here require any unusual cohesive strengths to resist rotational fission. Three asteroids were sufficiently observed to allow for shape and spin-pole models to be determined through light curve inversion. Asteroid 45864 was determined to have retrograde rotation with spin-pole axes λ = 218° ± 10°, β = −82° ± 5° and asteroid 206167 was found to have best-fit spin-pole axes λ = 57° ± 5°, β = −67° ± 5°. An additional object not initially measured with Aobs > 1.0 mag, 49257, was determined to have a shape model that does suggest a high-amplitude object. Its spin-pole axes were best fit for values λ = 112°± 6°, β = 6° ± 5°. In the course of this project, to date no large superfast rotators (Prot < 2.2 hr) have been identified.

[1]  Nicholas Moskovitz,et al.  The fast spin of near-Earth asteroid (455213) 2001 OE84, revisited after 14 years: Constraints on internal structure , 2017, 1707.01367.

[2]  Thomas A. Prince,et al.  LARGE SUPER-FAST ROTATOR HUNTING USING THE INTERMEDIATE PALOMAR TRANSIENT FACTORY , 2016, 1608.07910.

[3]  D. Scheeres,et al.  Disruption patterns of rotating self-gravitating aggregates: A survey on angle of friction and tensile strength , 2016 .

[4]  K. Chambers,et al.  Brightness variation distributions among main belt asteroids from sparse light curve sampling with Pan-STARRS 1 , 2016, 1604.04444.

[5]  D. Oszkiewicz,et al.  Asteroid models from the Lowell photometric database , 2016, 1601.02909.

[6]  C. A. Thomas,et al.  A 2 km-size asteroid challenging the rubble-pile spin barrier – A case for cohesion , 2015, Icarus.

[7]  S. Kulkarni,et al.  ASTEROID SPIN-RATE STUDY USING THE INTERMEDIATE PALOMAR TRANSIENT FACTORY , 2015, 1506.08493.

[8]  E. Ofek,et al.  ASTEROID LIGHT CURVES FROM THE PALOMAR TRANSIENT FACTORY SURVEY: ROTATION PERIODS AND PHASE FUNCTIONS FROM SPARSE PHOTOMETRY , 2015, 1504.04041.

[9]  J. Masiero,et al.  BINARY CANDIDATES IN THE JOVIAN TROJAN AND HILDA POPULATIONS FROM NEOWISE LIGHT CURVES , 2014, 1412.1853.

[10]  P. Descamps.  Dumb-bell-shaped equilibrium figures for fiducial contact-binary asteroids and EKBOs , 2014, 1410.7962.

[11]  S. Green,et al.  Physical characterisation of near-Earth asteroid (1620) Geographos. Reconciling radar and thermal-infrared observations , 2014, 1407.2127.

[12]  N. Peixinho,et al.  The unusual Kuiper belt object 2003 SQ317 , 2013, 1309.1671.

[13]  T. Owen,et al.  Constraints on the Composition of Trojan Asteroid 624 Hektor , 2013 .

[14]  Prasanth H. Nair,et al.  Astropy: A community Python package for astronomy , 2013, 1307.6212.

[15]  P. A. Price,et al.  THE PAN-STARRS 1 PHOTOMETRIC REFERENCE LADDER, RELEASE 12.01 , 2013, 1303.3634.

[16]  A. Bobet,et al.  Drucker–Prager Criterion , 2012, Rock Mechanics and Rock Engineering.

[17]  R. J. Wainscoat,et al.  THE Pan-STARRS1 PHOTOMETRIC SYSTEM , 2012, 1203.0297.

[18]  Munetaka Ueno,et al.  Asteroid Catalog Using AKARI: AKARI/IRC Mid-Infrared Asteroid Survey , 2011 .

[19]  E. L. Wright,et al.  NEOWISE STUDIES OF SPECTROPHOTOMETRICALLY CLASSIFIED ASTEROIDS: PRELIMINARY RESULTS , 2011, 1109.6407.

[20]  T. B. Spahr,et al.  MAIN BELT ASTEROIDS WITH WISE/NEOWISE. I. PRELIMINARY ALBEDOS AND DIAMETERS , 2011, 1109.4096.

[21]  P. Lacerda.  A CHANGE IN THE LIGHT CURVE OF KUIPER BELT CONTACT BINARY (139775) 2001 QG298 , 2011, 1107.3507.

[22]  Harold F. Levison,et al.  OBSERVED BINARY FRACTION SETS LIMITS ON THE EXTENT OF COLLISIONAL GRINDING IN THE KUIPER BELT , 2011, 1102.5706.

[23]  J. Margot,et al.  Binary Asteroid Systems: Tidal End States and Estimates of Material Properties , 2011, 1101.4639.

[24]  A. V. Sergeev,et al.  Formation of asteroid pairs by rotational fission , 2010, Nature.

[25]  Mikko Kaasalainen,et al.  DAMIT: a database of asteroid models , 2010 .

[26]  Petr Pravec,et al.  The asteroid lightcurve database , 2009 .

[27]  M. Zechmeister,et al.  The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms , 2009, 0901.2573.

[28]  Joseph A. Burns,et al.  Approximate Equilibrium Shapes for Spinning, Gravitating Rubble Asteroids , 2007 .

[29]  Franck Marchis,et al.  Nature of the small main belt Asteroid 3169 Ostro , 2007 .

[30]  K. Holsapple.  Spin limits of Solar System bodies: From the small fast-rotators to 2003 EL61 , 2007 .

[31]  D. Jewitt,et al.  Densities of Solar System Objects from Their Rotational Light Curves , 2006, astro-ph/0612237.

[32]  D. Jewitt,et al.  Fraction of Contact Binary Trojan Asteroids , 2006, 0706.0233.

[33]  S. Ostro,et al.  Near-Earth Asteroid 2005 CR37: Radar Images and Photometry of a Candidate Contact Binary , 2006 .

[34]  R. Roy,et al.  Photometric Survey of Binary Near-Earth Asteroids , 2006 .

[35]  Larry Denneau,et al.  The Pan-STARRS Moving Object Processing System , 2005, 1302.7281.

[36]  Daniel Hestroffer,et al.  Mass and density of Asteroid 121 Hermione from an analysis of its companion orbit , 2005 .

[37]  K. Holsapple.  Equilibrium figures of spinning bodies with self-gravity , 2004 .

[38]  D. Jewitt,et al.  Extreme Kuiper Belt Object 2001 QG298 and the Fraction of Contact Binaries , 2004, astro-ph/0402277.

[39]  Derek C. Richardson,et al.  The formation of asteroid satellites in large impacts: Results from numerical simulations , 2004 .

[40]  Keith A. Holsapple,et al.  Equilibrium Configurations of Solid Cohesionless Bodies , 2001 .

[41]  M. Kaasalainen,et al.  Optimization Methods for Asteroid Lightcurve Inversion: I. Shape Determination , 2001 .

[42]  M. N. Meshkov,et al.  Radar observations and physical model of asteroid 6489 Golevka , 2000 .

[43]  S. Ostro,et al.  Radar observations of asteroid 216 kleopatra , 2000, Science.

[44]  Steven J. Ostro,et al.  Physical Model of Asteroid 1620 Geographos from Radar and Optical Data , 1999 .

[45]  Steve B. Howell,et al.  TWO-DIMENSIONAL APERTURE PHOTOMETRY: SIGNAL-TO-NOISE RATIO OF POINT-SOURCE OBSERVATIONS AND OPTIMAL DATA-EXTRACTION TECHNIQUES , 1989 .

[46]  S. Baliunas,et al.  A Prescription for period analysis of unevenly sampled time series , 1986 .

[47]  S. Weidenschilling,et al.  Hektor: Nature and origin of a binary asteroid , 1980 .

[48]  W. Brouw,et al.  HIGH RESOLUTION RADIO CONTINUUM SURVEY OF M51 AND NGC 5195 AT 1415 MHz. , 1971 .

[49]  J. Dunlap,et al.  Minor planets. III - Lightcurves of a Trojan asteroid. , 1969 .

[50]  S. Chandrasekhar.  The Equilibrium and the Stability of the Roche Ellipsoids. , 1963 .

[51]  S. Chandrasekhar,et al.  The Potentials and the Superpotentials of Homogeneous Ellipsoids. , 1962 .

[52]  Tom Gaertner.  Ellipsoidal Figures Of Equilibrium , 2016 .

[53]  M. Shepard,et al.  A radar survey of M- and X-class asteroids. III. Insights into their composition, hydration state, & structure , 2015 .

[54]  D. Crawford,et al.  Precision CCD Photometry , 1999 .

[55]  H. P.,et al.  Problems of Cosmogony and Stellar Dynamics , 1920, Nature.