Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material. (arXiv:2003.13711v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Rogers_L/0/1/0/all/0/1">Laura K. Rogers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Xu_S/0/1/0/all/0/1">Siyi Xu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bonsor_A/0/1/0/all/0/1">Amy Bonsor</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hodgkin_S/0/1/0/all/0/1">Simon Hodgkin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Su_K/0/1/0/all/0/1">Kate Y. L. Su</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hippel_T/0/1/0/all/0/1">Ted von Hippel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jura_M/0/1/0/all/0/1">Michael Jura</a>
The inwards scattering of planetesimals towards white dwarfs is expected to
be a stochastic process with variability on human time-scales. The
planetesimals tidally disrupt at the Roche radius, producing dusty debris
detectable as excess infrared emission. When sufficiently close to the white
dwarf, this debris sublimates and accretes on to the white dwarf and pollutes
its atmosphere. Studying this infrared emission around polluted white dwarfs
can reveal how this planetary material arrives in their atmospheres. We report
a near-infrared monitoring campaign of 34 white dwarfs with infrared excesses
with the aim to search for variability in the dust emission. Time series
photometry of these white dwarfs from the United Kingdom Infrared Telescope
(Wide Field Camera) in the J, H and K bands were obtained over baselines of up
to three years. We find no statistically significant variation in the dust
emission in all three near-infrared bands. Specifically, we can rule out
variability at ~1.3% for the 13 white dwarfs brighter than 16th mag in K band,
and at ~10% for the 32 white dwarfs brighter than 18th mag over time-scales of
three years. Although to date two white dwarfs, SDSS J095904.69-020047.6 and WD
1226+110, have shown K band variability, in our sample we see no evidence of
new K band variability at these levels. One interpretation is that the tidal
disruption events which lead to large variabilities are rare, occur on short
time-scales, and after a few years the white dwarfs return to being stable in
the near-infrared.
The inwards scattering of planetesimals towards white dwarfs is expected to
be a stochastic process with variability on human time-scales. The
planetesimals tidally disrupt at the Roche radius, producing dusty debris
detectable as excess infrared emission. When sufficiently close to the white
dwarf, this debris sublimates and accretes on to the white dwarf and pollutes
its atmosphere. Studying this infrared emission around polluted white dwarfs
can reveal how this planetary material arrives in their atmospheres. We report
a near-infrared monitoring campaign of 34 white dwarfs with infrared excesses
with the aim to search for variability in the dust emission. Time series
photometry of these white dwarfs from the United Kingdom Infrared Telescope
(Wide Field Camera) in the J, H and K bands were obtained over baselines of up
to three years. We find no statistically significant variation in the dust
emission in all three near-infrared bands. Specifically, we can rule out
variability at ~1.3% for the 13 white dwarfs brighter than 16th mag in K band,
and at ~10% for the 32 white dwarfs brighter than 18th mag over time-scales of
three years. Although to date two white dwarfs, SDSS J095904.69-020047.6 and WD
1226+110, have shown K band variability, in our sample we see no evidence of
new K band variability at these levels. One interpretation is that the tidal
disruption events which lead to large variabilities are rare, occur on short
time-scales, and after a few years the white dwarfs return to being stable in
the near-infrared.
http://arxiv.org/icons/sfx.gif
