95 research outputs found
Analysis of the possible satellite contamination in LAMOST-MRS spectra
We present the detection of false positive double-lined spectroscopic
binaries candidates (SB2) using medium-resolution survey (MRS) spectra from the
one time-domain field of LAMOST data release 10 (DR10). The secondary component
in all these binaries has near zero radial velocity and solar-like spectral
lines. Highly likely this is light from the semi-transparent clouds illuminated
by the full Moon. However we also suspect that partially this contamination can
be caused by a solar light reflected from the surface of low-orbital artificial
satellites launched in the beginning of 2022. We found several possible
contaminant candidates using archival orbital data. We propose measures to
reduce risk of such contamination for the future observations and methods to
find it in archived ones.Comment: accepted in MNRAS letters 2023 July 0
Fitting the Light Curve of 1I/`Oumuamua with a Nonprincipal Axis Rotational Model and Outgassing Torques
In this paper, we investigate the nonprincipal axis (NPA) rotational state of
1I/`Oumuamua -- the first interstellar object discovered traversing the inner
Solar System -- from its photometric light curve. Building upon Mashchenko
(2019), we develop a model which incorporates NPA rotation and {Sun-induced,
time-varying} outgassing torques to generate synthetic light curves of the
object. The model neglects tidal forces, which are negligible compared to
outgassing torques over the distances that `Oumuamua was observed. We implement
an optimization scheme that incorporates the NPA rotation model to calculate
the initial rotation state of the object. We find that an NPA rotation state
with an average period of hr best reproduces the
photometric data. The discrepancy between this period and previous estimates is
due to continuous period modulation induced by outgassing torques in the
rotational model, {as well as different periods being used}. The best fit to
the October 2017 data does not reproduce the November 2017 data (although the
later measurements are too sparse to fit). The light curve is consistent with
no secular evolution of the angular momentum, somewhat in tension with the
empirical correlations between nuclear spin-up and cometary outgassing. The
complex rotation of `Oumuamua may be {the result of primordial rotation about
the smallest principal axis} if (i) the object experienced hypervolatile
outgassing and (ii) our idealized outgassing model is accurate.Comment: 22 pages, 8 figures, 1 animation. Accepted to the Planetary Science
Journal. The animation can be found on YouTube (https://youtu.be/f5YEAMTvIeo)
and in the online publication by PSJ (when available
Assessing Potential Contributions from Outgassing and Tidal Effects on the Evolving Rotational State of 1I/'Oumuamua
In this paper, we attempt to interpret the photometric light curve of
1I/`Oumuamua, the first interstellar object discovered traversing the inner
Solar System. We compare photometric data with synthetic light curves of
ellipsoidal bodies for a range of rotational states and observing geometries.
While previous work reported an increase in the periodicity of the object
during October, we find a hour decrease in the spin period
between October and November. We investigate potential contributions to the
evolving spin period from both outgassing and tidal effects using a general
formalism which may be applied to any elongated object. While sublimation is a
stronger effect, tidal deformation could change the moment of inertia and
subsequent spin period based on the bulk material properties. We present an
open source software which simulates constant-density, constant-viscosity
liquid bodies subject to tidal forces for a range of assumed viscosites and
sizes (). These numerical simulations, when applied to
`Oumuamua, demonstrate that it may have experienced significant tidal
deformation in the presence of sublimation. However, synthetic observations
which incorporate tidal effects demonstrate that little deformation is
necessary to match the composite light curve. We find that a dynamic viscosity
of g cm s, corresponding to a 0.1\% change in
moment of inertia, best reproduces the photometric data. It is feasible that
tidal deformation contributed to the shorter timescale spin-down in October,
while outgassing induced the secular spin-up.Comment: 30 pages, 24 figures, 5 tables. Submitted to AAS Planetary Science
Journal. Comments very welcome. Publicly available software at
https://github.com/astertaylor/Oumuamu
Isotopic ratios in outbursting comet C/2015 ER61
Isotopic ratios in comets are critical to understanding the origin of
cometary material and the physical and chemical conditions in the early solar
nebula. Comet C/2015 ER61 (PANSTARRS) underwent an outburst with a total
brightness increase of 2 magnitudes on the night of 2017 April 4. The sharp
increase in brightness offered a rare opportunity to measure the isotopic
ratios of the light elements in the coma of this comet. We obtained two
high-resolution spectra of C/2015 ER61 with UVES/VLT on the nights of 2017
April 13 and 17. At the time of our observations, the comet was fading
gradually following the outburst. We measured the nitrogen and carbon isotopic
ratios from the CN violet (0,0) band and found that C/C=100
15, N/N=130 15. In addition, we determined the
N/N ratio from four pairs of NH isotopolog lines and measured
N/N=140 28. The measured isotopic ratios of C/2015 ER61 do
not deviate significantly from those of other comets.Comment: 4 pages, 4 figures, accepted to be published by A&
Activity of comet 103P/Hartley 2 at the time of the EPOXI mission fly-by
Comet 103P/Hartley~2 was observed on Nov. 1-6, 2010, coinciding with the
fly-by of the space probe EPOXI. The goal was to connect the large scale
phenomena observed from the ground, with those at small scale observed from the
spacecraft. The comet showed strong activity correlated with the rotation of
its nucleus, also observed by the spacecraft. We report here the
characterization of the solid component produced by this activity, via
observations of the emission in two spectral regions where only grain
scattering of the solar radiation is present. We show that the grains produced
by this activity had a lifetime of the order of 5 hours, compatible with the
spacecraft observations of the large icy chunks. Moreover, the grains produced
by one of the active regions have a very red color. This suggests an organic
component mixed with the ice in the grains.Comment: 11 pages, 7 figures, Icarus in pres
Inner solar system material discovered in the Oort cloud
We have observed C/2014 S3 (PANSTARRS), a recently discovered object on a cometary orbit coming from the Oort cloud that is physically similar to an inner main belt rocky S-type asteroid. Recent dynamical models successfully reproduce the key characteristics of our current solar system; some of these models require significant migration of the giant planets, whereas others do not. These models provide different predictions on the presence of rocky material expelled from the inner solar system in the Oort cloud. C/2014 S3 could be the key to verifying these predictions of the migration-based dynamical models. Furthermore, this object displays a very faint, weak level of comet-like activity, five to six orders of magnitude less than that of typical ice-rich comets on similar Orbits coming from the Oort cloud. For the nearly tailless appearance, we are calling C/2014 S3 a Manx object. Various arguments convince us that this activity is produced by sublimation of volatile ice, that is, normal cometary activity. The activity implies that C/2014 S3 has retained a tiny fraction of the water that is expected to be present at its formation distance in the inner solar system. We may be looking at fresh inner solar system Earth-forming material that was ejected from the inner solar system and preserved for billions of years in the Oort cloud
TNO or Comet? The Search for Activity and Characterization of Distant Object 418993 (2009 MS9)
2009 MS9 is a trans-Neptunian object (TNO) whose perihelion brings it close
to the distance where some long period comets are seen to become active.
Knowing this, and the fact that this object appears to brighten in excess of
it's predicted nucleus brightness suggests that 2009 MS9 has a delayed onset of
activity brought on by the sublimation of a species more volatile than water.
In this paper we characterize 2009 MS9's physical properties and investigate
potential outgassing through composite images, sublimation models, and
measurements of spectral reflectivity. We find that deep composite images of
the object at various epochs along its orbit show no evidence of dust yet place
sensitive limits to the dust production. We estimate the nucleus radius to be
11.5 km km using thermal IR modeling from NEOWISE data and use this
and data pre-perihelion to estimate a geometric albedo of 0.25. We compare a
CO-sublimation activity model to its post perihelion heliocentric light curve
and find this data supports an active fractional area of
assuming 2 m sized grains and other typical comet parameters. The spectral
reflectivity of the surface materials obtained with the Gemini Observatory and
CFHT at different epochs shows a reddening spectral slope. We compare the
physical properties of 2009 MS9 to both TNO and comet populations, and
speculate that 2009 MS9's reddening may be due to the buildup of a dust mantle
on the surface and could be an explanation of why TNOs exhibit a color
bimodality.Comment: 25 pages, 8 figures, Accepted to PS
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