17:15 〜 18:45
[PPS03-P08] ALMA Observations of 1 Ceres in 2017
キーワード：アルマ、ケレス、小惑星
Millimeter and submillimeter-wave observations are known to be a powerful tool to investigate the surface and atmospheric properties of solar system bodies. In particular, the high spatial resolution capability of the Atacama Large Millimeter/submillimeter Array (ALMA) has enabled us to study disk resolved surface properties of asteroids. To date, several asteroid observations have been performed with the ALMA, e.g. 1 Ceres: Li et al. (2020), 3 Juno: ALMA Partnership et al. 2015), 16 Psyche: Shepard et al. (2021) and de Kleer et al. (2021), and TNOs: Lellouch et al. (2017).
For the previous study of dwarf planet 1 Ceres, Li et al. (2020) has deduced the disk-averaged brightness temperature and a rotational light curve at ∼265 GHz continuum with 2015 and 2017 data. The results are that a disk-averaged brightness temperature was 170-180 K in 2017 and the thermal inertia range were constrained to be between 40 and 160 thermal inertia units (tiu).
We have re-processed the 2015 and 2017 data from the common archival science data model (ASDM) and succeeded to calibrate and image 9 asdm files with high spatial resolutions, much finer than the apparent diameter of Ceres, 0.45 to 0.50 arcseconds in the observed period.
In this meeting, we will show the analysis results of these disk-resolved ALMA data of 1 Ceres in 2017. We revealed the position of maximum temperate on the surface was located not under the direct sub-solar point but moved into the afternoon side, around 12.5h-14h solar time.
From the deviation of the maximum temperature point, we estimated the range of the thermal inertia was around 50-150 tiu by using the thermophysical model. Rognini et al. (2020) showed that, using Dawn spacecraft data there were two possibilities of the thermal inertia ranges; i) between about 1 and 15 tiu, and ii) up to ∼60 tiu, however our results seem that the value range may be higher than their study and be consistent with the results by Li et al. (2020).
For millimeter wavelengths, subsurface emission is important to understand the observed thermal flux. One of the key parameters is the dielectric constant of the surface and subsurface materials. We will present the possible dielectric constant and other parameters used in the thermophysical model. The deduced parameters will be discussed by comparing with the past radiometric and Dawn spacecraft data. The new results would be of interest in studying 1 Ceres in the post Dawn period.
References:
ALMA Partnership et al. ApJL 808, L2 (2015)
de Kleer et al. PSJ 2, 149 (2021)
Lellouch et al. A&A 608, 21 (2017)
Li et al. AJ 159, 215 (2020)
Rognini et al. JGR 125(3) (2020)
Shepard et al. PSJ 2, 125 (2021)
For the previous study of dwarf planet 1 Ceres, Li et al. (2020) has deduced the disk-averaged brightness temperature and a rotational light curve at ∼265 GHz continuum with 2015 and 2017 data. The results are that a disk-averaged brightness temperature was 170-180 K in 2017 and the thermal inertia range were constrained to be between 40 and 160 thermal inertia units (tiu).
We have re-processed the 2015 and 2017 data from the common archival science data model (ASDM) and succeeded to calibrate and image 9 asdm files with high spatial resolutions, much finer than the apparent diameter of Ceres, 0.45 to 0.50 arcseconds in the observed period.
In this meeting, we will show the analysis results of these disk-resolved ALMA data of 1 Ceres in 2017. We revealed the position of maximum temperate on the surface was located not under the direct sub-solar point but moved into the afternoon side, around 12.5h-14h solar time.
From the deviation of the maximum temperature point, we estimated the range of the thermal inertia was around 50-150 tiu by using the thermophysical model. Rognini et al. (2020) showed that, using Dawn spacecraft data there were two possibilities of the thermal inertia ranges; i) between about 1 and 15 tiu, and ii) up to ∼60 tiu, however our results seem that the value range may be higher than their study and be consistent with the results by Li et al. (2020).
For millimeter wavelengths, subsurface emission is important to understand the observed thermal flux. One of the key parameters is the dielectric constant of the surface and subsurface materials. We will present the possible dielectric constant and other parameters used in the thermophysical model. The deduced parameters will be discussed by comparing with the past radiometric and Dawn spacecraft data. The new results would be of interest in studying 1 Ceres in the post Dawn period.
References:
ALMA Partnership et al. ApJL 808, L2 (2015)
de Kleer et al. PSJ 2, 149 (2021)
Lellouch et al. A&A 608, 21 (2017)
Li et al. AJ 159, 215 (2020)
Rognini et al. JGR 125(3) (2020)
Shepard et al. PSJ 2, 125 (2021)