Thermal rotational lightcurve of dwarf-planet (1) Ceres at 235 GHz with the Submillimeter Array

Moullet, Arielle; Gurwell, M. A.; Carry, B.

doi:10.1051/0004-6361/201014792

Cited by 7 publications

(7 citation statements)

References 14 publications

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“…Our data reveal a double-peaked 1 https://almascience.nrao.edu/proposing/sensitivity-calculator, accessed on March 16, 2020. lightcurve of Ceres at a wavelength of 1-mm, with the two minima near longitudes of 30º and 190º and two maxima near longitudes of 120º and 330º. Both the lightcurve amplitude and the overall shape and phasing are consistent with previous observations at similar frequencies (Altenhoff et al 1996, Moullet et al 2010, although the detailed shape of those previously measured lightcurves was obscured by noise.…”

Section: Rotational Lightcurvesupporting

confidence: 89%

“…In addition, two other measurements from previous observations at similar true anomalies (Ulich et al 1984, Webster et al 1988, both based on single-dish data as well, show a similar range of brightness temperatures as the values we derive from archival ALMA data. At three other true anomalies (0º, 220º, and 310º), repeated measurements resulted in similar brightness temperatures from both interferometer data (Moullet et al 2010) and single-dish data (all other historical data). Therefore, the possibility of temporal variations in Ceres's brightness temperature at a wavelength of 1 mm near the true anomalies of 150º -180º still cannot be fully rejected.…”

Section: Brightness Temperature Variationsmentioning

confidence: 72%

“…On the other hand, inconsistent results have been reported for the rotational lightcurve of Ceres at mm wavelengths. Altenhoff et al (1996) and Moullet et al (2010) both reported a lightcurve amplitude of ~3% at 250 GHz and 235 GHz, respectively, while Chamberlain et al (2009) reported a 50% peak-to-peak amplitude at 345 GHz.…”

Section: Introductionmentioning

confidence: 98%

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Disk-integrated Thermal Properties of Ceres Measured at Millimeter Wavelengths

Moullet²,

Titus

et al. 2020

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We observed Ceres at three epochs in 2015 November and 2017 September and October with ALMA 12-meter array and in 2017 October with the ALMA Compact Array (ACA), all at ~265 GHz continuum (wavelengths of ~1.1 mm) to map the temperatures of Ceres over a full rotation at each epoch. We also used 2017 October ACA observations to search for HCN. The disk-averaged brightness temperature of Ceres is measured to be between 170 K and 180 K during our 2017 observations. The rotational lightcurve of Ceres shows a double peaked shape with an amplitude of about 4%. Our HCN search returns a negative result with an upper limit production rate of ~2´10 24 molecules s -1 , assuming globally uniform production and a Haser model. A thermophysical model suggests that Ceres's top layer has higher dielectric absorption than lunarlike materials at a wavelength of 1 mm. However, previous observations showed that the dielectric absorption of Ceres decreases towards longer wavelengths. Such distinct dielectric properties might be related to the hydrated phyllosilicate composition of Ceres and possibly abundant µm-sized grains on its surface. The thermal inertia of Ceres is constrained by our modeling as likely being between 40 and 160 tiu, much higher than previous measurements at infrared wavelengths. Modeling also suggests that Ceres's lightcurve is likely dominated by spatial variations in its physical or compositional properties that cause changes in Ceres's observed thermal properties and dielectric absorption as it rotates. Accepted by Astronomical Journal

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Section: Rotational Lightcurvesupporting

confidence: 89%

Section: Brightness Temperature Variationsmentioning

confidence: 72%

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Disk-integrated Thermal Properties of Ceres Measured at Millimeter Wavelengths

Moullet²,

Titus

et al. 2020

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“…They provide an independent set of size and shape measurements that confirm our current knowledge expressed by the DAMIT and triaxial ellipsoid models. Future ALMA observations of main belt asteroids, including both spatially unresolved photometric light curves (e.g., Moullet et al 2010) and resolved images, can be used to test and refine the existing three-dimensional models. We note that ALMA can potentially achieve significantly higher physical resolution on Juno than these initial observations offer.…”

Section: Discussionmentioning

confidence: 99%

The 2014 Alma Long Baseline Campaign: Observations of Asteroid 3 Juno at 60 Kilometer Resolution

Partnership¹,

Hunter

Kneißl

et al. 2015

ApJ

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We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum images of the asteroid 3 Juno obtained with an angular resolution of 0. 042 ″ (60 km at 1.97 AU). The data were obtained over a single 4.4 hr interval, which covers 60% of the 7.2 hr rotation period, approximately centered on local transit. A sequence of 10 consecutive images reveals continuous changes in the asteroidʼs profile and apparent shape, in good agreement with the sky projection of the three-dimensional model of the Database of Asteroid Models from Inversion Techniques. We measure a geometric mean diameter of 259 ± 4 km, in good agreement with past estimates from a variety of techniques and wavelengths. Due to the viewing angle and inclination of the rotational pole, the southern hemisphere dominates all of the images. The median peak brightness temperature is 215 ± 13 K, while the median over the whole surface is 197 ± 15 K. With the unprecedented resolution of ALMA, we find that the brightness temperature varies across the surface with higher values correlated to the subsolar point and afternoon areas and lower values beyond the evening terminator. The dominance of the subsolar point is accentuated in the final four images, suggesting a reduction in the thermal inertia of the regolith at the corresponding longitudes, which are possibly correlated to the location of the putative large impact crater. These results demonstrate ALMAʼs potential to resolve thermal emission from the surface of main belt asteroids and to measure accurately their position, geometric shape, rotational period, and soil characteristics.

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“…They provide an independent set of size and shape measurements which confirm our current knowledge expressed by the DAMIT and triaxial ellipsoid models. Future ALMA observations of main belt asteroids, including both spatially-unresolved photometric lightcurves (e.g., Moullet et al 2010) and resolved images, can be used to test and refine the existing three-dimensional models. We note that ALMA can potentially achieve significantly higher physical resolution on Juno that these initial observations offer.…”

Section: Discussionmentioning

confidence: 99%

ALMA Observations of Asteroid 3 Juno at 60 Kilometer Resolution

Partnership,

Hunter,

Kneissl

et al. 2015

Preprint

Self Cite

View full text Add to dashboard Cite

We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum images of the asteroid 3 Juno obtained with an angular resolution of 0.042 ′′ (60 km at 1.97 AU). The data were obtained over a single 4.4 hr interval, which covers 60% of the 7.2 hr rotation period, approximately centered on local transit. A sequence of ten consecutive images reveals continuous changes in the asteroid's profile and apparent shape, in good agreement with the sky projection of the three-dimensional model of the Database of Asteroid Models from Inversion Techniques. We measure a geometric mean diameter of 259±4 km, in good agreement with past estimates from a variety of techniques and wavelengths. Due to the viewing angle and inclination of the rotational pole, the southern hemisphere dominates all of the images. The median peak brightness temperature is 215±13 K, while the median over the whole surface is 197 ± 15 K. With the unprecedented resolution of ALMA, we find that the brightness temperature varies across the surface with higher values correlated to the subsolar point and afternoon areas, and lower values beyond the evening terminator. The dominance of the subsolar point is accentuated in the final four images, suggesting a reduction in the thermal inertia of the regolith at the corresponding longitudes, which are possibly correlated to the location of the putative large impact crater. These results demonstrate ALMA's potential to resolve thermal emission from the surface of main belt asteroids, and to measure accurately their position, geometric shape, rotational period, and soil characteristics.

show abstract

Thermal rotational lightcurve of dwarf-planet (1) Ceres at 235 GHz with the Submillimeter Array

Cited by 7 publications

References 14 publications

Disk-integrated Thermal Properties of Ceres Measured at Millimeter Wavelengths

Disk-integrated Thermal Properties of Ceres Measured at Millimeter Wavelengths

The 2014 Alma Long Baseline Campaign: Observations of Asteroid 3 Juno at 60 Kilometer Resolution

ALMA Observations of Asteroid 3 Juno at 60 Kilometer Resolution

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