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Title: FINDING ROCKY ASTEROIDS AROUND WHITE DWARFS BY THEIR PERIODIC THERMAL EMISSION

Since white dwarfs (WDs) are small, the contrast between the thermal emission of an orbiting object and a WD is dramatically enhanced compared to a main-sequence host. Furthermore, rocky objects much smaller than the moon have no atmospheres and are tidally locked to the WD. We show that this leads to temperature contrasts between their day and night side of the order of unity that should lead to temporal variations in infrared flux over an orbital period of ∼0.2 to ∼2 days. Ground-based telescopes could detect objects with a mass as small as 1% of the lunar mass M{sub L} around Sirius B with a few hours of exposure. The James Webb Space Telescope may be able to detect objects as small as 10{sup –3} M{sub L} around most nearby WDs. The tightest constraints will typically be placed on 12,000 K WDs, whose Roche zone coincides with the dust sublimation zone. Constraining the abundance of minor planets around WDs as a function of their surface temperatures (and therefore age) provides a novel probe for the physics of planetary formation.
Authors:
 [1] ;  [2]
  1. Harvard College, Cambridge, MA 02138 (United States)
  2. Harvard Astronomy Department, Harvard University, Cambridge, MA 02138 (United States)
Publication Date:
OSTI Identifier:
22364952
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 793; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTEROIDS; COMPARATIVE EVALUATIONS; COSMIC DUST; MAIN SEQUENCE STARS; MASS; MOON; PERIODICITY; PHOTON EMISSION; PLANETS; PROBES; SPACE; SUBLIMATION; TELESCOPES; WHITE DWARF STARS