References of "Jehin, Emmanuel"
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See detailPROSE: a PYTHON framework for modular astronomical images processing
Garcia, Lionel ULiege; Timmermans, Mathilde ULiege; Pozuelos, Francisco J. et al

in Monthly Notices of the Royal Astronomical Society (2022), 509

To reduce and analyse astronomical images, astronomers can rely on a wide range of libraries providing low-level implementations of legacy algorithms. However, combining these routines into robust and ... [more ▼]

To reduce and analyse astronomical images, astronomers can rely on a wide range of libraries providing low-level implementations of legacy algorithms. However, combining these routines into robust and functional pipelines requires a major effort that often ends up in instrument-specific and poorly maintainable tools, yielding products that suffer from a low level of reproducibility and portability. In this context, we present PROSE, a PYTHON framework to build modular and maintainable image processing pipelines. Built for astronomy, it is instrument-agnostic and allows the construction of pipelines using a wide range of building blocks, pre-implemented or user-defined. With this architecture, our package provides basic tools to deal with common tasks, such as automatic reduction and photometric extraction. To demonstrate its potential, we use its default photometric pipeline to process 26 TESS candidates follow-up observations and compare their products to the ones obtained with ASTROIMAGEJ, the reference software for such endeavours. We show that PROSE produces light curves with lower white and red noise while requiring less user interactions and offering richer functionalities for reporting. [less ▲]

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See detailAnalytic and numerical methods for the Abel transform of exponential functions for planetary and cometary atmospheres
Hubert, Benoît ULiege; Munhoven, Guy ULiege; Moulane, Youssef ULiege et al

in Icarus (2022), 371

Line-of-sight integration of emissions from planetary and cometary atmospheres is the Abel transform of the emission rate, under the spherical symmetry assumption. Indefinite integrals constructed from ... [more ▼]

Line-of-sight integration of emissions from planetary and cometary atmospheres is the Abel transform of the emission rate, under the spherical symmetry assumption. Indefinite integrals constructed from the Abel transform integral are useful for implementing remote sensing data analysis methods, such as the numerical inverse Abel transform. We propose analytical expressions obtained by a suitable, non-alternating, series development to compute those indefinite integrals. We establish expressions allowing absolute accuracy control of the convergence of these series and illustrate how this accuracy depends on the number of terms involved in the series computation. We compare the analytical method with numerical computation techniques, which are found to be sufficiently accurate as well. Inverse Abel transform fitting is then tested in order to establish that the expected emission rate profiles can be retrieved from the observation of both planetary and cometary atmospheres. We show that the method is robust, i.e. that it can be applied even when the properties of the observed atmosphere depart from the assumed ones, especially when Tikhonov regularization is included. A first application is conducted over observation of comet 46P/Wirtanen, showing some variability, possibly attributable to an evolution of the contamination by dust and icy grains. [less ▲]

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See detailTRAPPIST comet production rates: 6P/d'Arrest, 67P/C-G, 4P/Faye, 19P/Borrelly, 57P/D-N-D
Jehin, Emmanuel ULiege; Moulane, Youssef ULiege; Manfroid, Jean ULiege et al

in The Astronomer's Telegram (2021), 15117

E. Jehin, Y. Moulane, J. Manfroid, M. Vander Donckt, S. Hmiddouch, F. Pozuelos, M. Ferrais, and D. Hutsemekers (STAR Institute, University of Liege) report that they obtained from TRAPPIST-South (code=I40 ... [more ▼]

E. Jehin, Y. Moulane, J. Manfroid, M. Vander Donckt, S. Hmiddouch, F. Pozuelos, M. Ferrais, and D. Hutsemekers (STAR Institute, University of Liege) report that they obtained from TRAPPIST-South (code=I40, Chile) robotic telescopes (Jehin el al. 2011) observations using HB narrowband filters (Farnham et al. 2000) for the following comets and computed preliminary production rates at 10.000 km using a Haser Model (Vp=Vd=1km/s) (Haser 1957). [less ▲]

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See detailTRAPPIST C/2021 A1 (Leonard) comet production rates
Jehin, Emmanuel ULiege; Moulane, Youssef ULiege; Manfroid, Jean ULiege

in The Astronomer's Telegram (2021), 15128

E. Jehin, Y. Moulane, and J. Manfroid, report that they obtained on 19 December, from 00:15 to 01:15 UT, with the TRAPPIST-South (code=I40) robotic telescope (Jehin el al. 2011) located at the ESO La ... [more ▼]

E. Jehin, Y. Moulane, and J. Manfroid, report that they obtained on 19 December, from 00:15 to 01:15 UT, with the TRAPPIST-South (code=I40) robotic telescope (Jehin el al. 2011) located at the ESO La Silla Observatory (Chile), three sets of cometary HB narrowband filters (Farnham et al. 2000) and broad band filters (B,V,Rc,Ic) on comet C/2021 A1 (Leonard) at high airmass under photometric conditions. [less ▲]

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See detailTransit Timings Variations in the three-planet system: TOI-270
Kaye, Laurel; Vissapragada, Shreyas; Günther, Maximilian N. et al

in Monthly Notices of the Royal Astronomical Society (2021)

We present ground and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright ... [more ▼]

We present ground and space-based photometric observations of TOI-270 (L231-32), a system of three transiting planets consisting of one super-Earth and two sub-Neptunes discovered by TESS around a bright (K-mag=8.25) M3V dwarf. The planets orbit near low-order mean-motion resonances (5:3 and 2:1), and are thus expected to exhibit large transit timing variations (TTVs). Following an extensive observing campaign using 8 different observatories between 2018 and 2020, we now report a clear detection of TTVs for planets c and d, with amplitudes of ~10 minutes and a super-period of ~3 years, as well as significantly refined estimates of the radii and mean orbital periods of all three planets. Dynamical modeling of the TTVs alone puts strong constraints on the mass ratio of planets c and d and on their eccentricities. When incorporating recently published constraints from radial velocity observations, we obtain masses of $M_{\mathrm{b}}=1.48\pm 0.18\, M_{\oplus}$, $M_{\mathrm{c}}=6.20\pm 0.31\, M_{\oplus}$ and $M_{\mathrm{d}}=4.20\pm 0.16\, M_{\oplus}$ for planets b, c and d, respectively. We also detect small, but significant eccentricities for all three planets : e[SUB]b[/SUB] = 0.0167 ± 0.0084, e[SUB]c[/SUB] = 0.0044 ± 0.0006 and e[SUB]d[/SUB] = 0.0066 ± 0.0020. Our findings imply an Earth-like rocky composition for the inner planet, and Earth-like cores with an additional He/H[SUB]2[/SUB]O atmosphere for the outer two. TOI-270 is now one of the best-constrained systems of small transiting planets, and it remains an excellent target for atmospheric characterization. [less ▲]

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See detailTOI-2257 b: A highly eccentric long-period sub-Neptune transiting a nearby M dwarf
Schanche, N.; Pozuelos, F. J.; Günther, M. N. et al

E-print/Working paper (2021)

Thanks to the relative ease of finding and characterizing small planets around M dwarf stars, these objects have become cornerstones in the field of exoplanet studies. The current paucity of planets in ... [more ▼]

Thanks to the relative ease of finding and characterizing small planets around M dwarf stars, these objects have become cornerstones in the field of exoplanet studies. The current paucity of planets in long-period orbits around M dwarfs make such objects particularly compelling as they provide clues about the formation and evolution of these systems. In this study, we present the discovery of TOI-2257 b (TIC 198485881), a long-period (35 d) sub-Neptune orbiting an M3 star at 57.8pc. Its transit depth is about 0.4%, large enough to be detected with medium-size, ground-based telescopes. The long transit duration suggests the planet is in a highly eccentric orbit ($e \sim 0.5$), which would make it the most eccentric planet that is known to be transiting an M-dwarf star. We combined TESS and ground-based data obtained with the 1.0-m SAINT-EX, 0.60-m TRAPPIST-North and 1.2-m FLWO telescopes to find a planetary size of 2.2 $R_{\oplus}$ and an orbital period of 35.19 days. In addition, we make use of archival data, high-resolution imaging, and vetting packages to support our planetary interpretation. With its long period and high eccentricity, TOI-2257 b falls in a novel slice of parameter space. Despite the planet's low equilibrium temperature ($\sim$ 256 K), its host star's small size ($R_* = 0.311 \pm{0.015}$) and relative infrared brightness (K$_{mag}$ = 10.7) make it a suitable candidate for atmospheric exploration via transmission spectroscopy. [less ▲]

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See detailA second Arid shower outburst in 2021
Jenniskens, P.; Heathcote, S.; Jehin, Emmanuel ULiege et al

in eMeteorNews (2021), 6(7), 534

The predicted Arid meteor shower outburst on October 6-7, 2021, caused by Earth encountering the debris ejected by comet 15P/Finlay during its activity outbursts in 2014 and 2015, did materialize. The ... [more ▼]

The predicted Arid meteor shower outburst on October 6-7, 2021, caused by Earth encountering the debris ejected by comet 15P/Finlay during its activity outbursts in 2014 and 2015, did materialize. The 2014 outburst dust was documented by CAMS low-light video networks in Chile. The observed activity was higher than that during the 1995-dust trail crossing, especially at small particle sizes, suggesting that the cometary activity had an influence on the density of the 2014 dust trail. [less ▲]

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See detailNGTS clusters survey - III. A low-mass eclipsing binary in the Blanco 1 open cluster spanning the fully convective boundary
Smith, Gareth D.; Gillen, Edward; Queloz, Didier et al

in Monthly Notices of the Royal Astronomical Society (2021), 507

We present the discovery and characterization of an eclipsing binary identified by the Next Generation Transit Survey in the ~115-Myr-old Blanco 1 open cluster. NGTS J0002-29 comprises three M dwarfs: a ... [more ▼]

We present the discovery and characterization of an eclipsing binary identified by the Next Generation Transit Survey in the ~115-Myr-old Blanco 1 open cluster. NGTS J0002-29 comprises three M dwarfs: a short-period binary and a companion in a wider orbit. This system is the first well-characterized, low-mass eclipsing binary in Blanco 1. With a low mass ratio, a tertiary companion, and binary components that straddle the fully convective boundary, it is an important benchmark system, and one of only two well-characterized, low-mass eclipsing binaries at this age. We simultaneously model light curves from NGTS, TESS, SPECULOOS, and SAAO, radial velocities from VLT/UVES and Keck/HIRES, and the system's spectral energy distribution. We find that the binary components travel on circular orbits around their common centre of mass in Porb = 1.098 005 24 ± 0.000 000 38 d, and have masses Mpri = 0.3978 ± 0.0033 M⊙ and Msec = 0.2245 ± 0.0018 M⊙, radii Rpri = 0.4037 ± 0.0048 R⊙ and Rsec = 0.2759 ± 0.0055 R⊙, and effective temperatures $T_{\rm pri}=\mbox{$3372\, ^{+44}_{-37}$}$ K and $T_{\rm sec}=\mbox{$3231\, ^{+38}_{-31}$}$ K. We compare these properties to the predictions of seven stellar evolution models, which typically imply an inflated primary. The system joins a list of 19 well-characterized, low-mass, sub-Gyr, stellar-mass eclipsing binaries, which constitute some of the strongest observational tests of stellar evolution theory at low masses and young ages. [less ▲]

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See detailChlorine-bearing species and the 37Cl/35Cl isotope ratio in the coma of comet 67P/Churyumov-Gerasimenko
Dhooghe, Frederik; De Keyser, Johan; Hänni, Nora et al

in Monthly Notices of the Royal Astronomical Society (2021), 508

A full-mission analysis has been conducted of Cl-bearing species in the coma of comet 67P/Churyumov-Gerasimenko as detected by the Double Focusing Mass Spectrometer (DFMS) of Rosetta's ROSINA instrument ... [more ▼]

A full-mission analysis has been conducted of Cl-bearing species in the coma of comet 67P/Churyumov-Gerasimenko as detected by the Double Focusing Mass Spectrometer (DFMS) of Rosetta's ROSINA instrument. The isotope ratio of the two stable chlorine isotopes 37Cl/35Cl is found to be 0.336 ± 0.017, to be compared with the standard mean ocean chloride value of 0.320. The isotope ratio does not change appreciably throughout the mission. The Cl-bearing species fingerprint in DFMS indicates that there is at least one additional chlorine-bearing species in the coma next to HCl, CH3Cl, and NH4Cl. The identity of this volatile or semivolatile species is unknown at this time. [less ▲]

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See detailprose: A Python framework for modular astronomical images processing
Garcia, Lionel ULiege; Timmermans, Mathilde ULiege; Pozuelos, Francisco J. et al

in Monthly Notices of the Royal Astronomical Society (2021)

To reduce and analyse astronomical images, astronomers can rely on a wide range of libraries providing low-level implementations of legacy algorithms. However, combining these routines into robust and ... [more ▼]

To reduce and analyse astronomical images, astronomers can rely on a wide range of libraries providing low-level implementations of legacy algorithms. However, combining these routines into robust and functional pipelines requires a major effort which often ends up in instrument-specific and poorly maintainable tools, yielding products that suffer from a low-level of reproducibility and portability. In this context, we present prose, a Python framework to build modular and maintainable image processing pipelines. Built for astronomy, it is instrument-agnostic and allows the construction of pipelines using a wide range of building blocks, pre-implemented or user-defined. With this architecture, our package provides basic tools to deal with common tasks such as automatic reduction and photometric extraction. To demonstrate its potential, we use its default photometric pipeline to process 26 TESS candidates follow-up observations and compare their products to the ones obtained with AstroImageJ, the reference software for such endeavors. We show that prose produces light curves with lower white and red noise while requiring less user interactions and offering richer functionalities for reporting. [less ▲]

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See detailSample return of primitive matter from the outer Solar System
Vernazza, P.; Beck, P.; Ruesch, O. et al

in Experimental Astronomy (2021)

The last thirty years of cosmochemistry and planetary science have shown that one major Solar System reservoir is vastly undersampled in the available suite of extra-terrestrial materials, namely small ... [more ▼]

The last thirty years of cosmochemistry and planetary science have shown that one major Solar System reservoir is vastly undersampled in the available suite of extra-terrestrial materials, namely small bodies that formed in the outer Solar System (>10 AU). Because various dynamical evolutionary processes have modified their initial orbits (e.g., giant planet migration, resonances), these objects can be found today across the entire Solar System as P/D near-Earth and main-belt asteroids, Jupiter and Neptune Trojans, comets, Centaurs, and small (diameter < 200 km) trans-Neptunian objects. This reservoir is of tremendous interest, as it is recognized as the least processed since the dawn of the Solar System and thus the closest to the starting materials from which the Solar System formed. Some of the next major breakthroughs in planetary science will come from studying outer Solar System samples (volatiles and refractory constituents) in the laboratory. Yet, this can only be achieved by an L-class mission that directly collects and returns to Earth materials from this reservoir. It is thus not surprising that two White Papers advocating a sample return mission of a primitive Solar System small body (ideally a comet) were submitted to ESA in response to its Voyage 2050 call for ideas for future L-class missions in the 2035-2050 time frame. One of these two White Papers is presented in this article. [less ▲]

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See detailA surprising similarity to solar system comets from high resolution optical spectroscopy of 2I/Borisov
Opitom, Cyrielle; Jehin, Emmanuel ULiege; Hutsemekers, Damien ULiege et al

in Bulletin of the American Astronomical Society (2021, October 01), 53(7), 50502

2I/Borisov, discovered on August 20, 2019, is the first visibly active interstellar comet observed in the solar system. We observed 2I with UVES, the high-resolution optical spectrograph mounted on the ... [more ▼]

2I/Borisov, discovered on August 20, 2019, is the first visibly active interstellar comet observed in the solar system. We observed 2I with UVES, the high-resolution optical spectrograph mounted on the UT2 telescope at Paranal observatory in Chile, between November 15, 2019, and March 16, 2020. Our 12 epochs covered a heliocentric distance range from 2.1 au pre-perihelion to 2.6 au post-perihelion. We will present the results of this observing campaign. We performed several key measurements, some being made for the first time in the coma of an interstellar comet. We detected emissions from the radicals OH, NH, CN, CH, C[SUB]2[/SUB], and NH[SUB]2[/SUB], the [OI] forbidden oxygen lines at 557.73, 630.03, and 636.37 nm, and more surprisingly several FeI and NiI lines. We derived the abundance of iron and nickel, log[Q(NiI)]=21.88±0.07 molecules/s and log[Q(FeI)]=21.67±0.16. This corresponds to a ratio of log(NiI/FeI)=0.21±0.18, in agreement with the value measured for solar system comets. We used the (0,8,0) and (0,9,0) ro-vibronic bands to derive an NH[SUB]2[/SUB] ortho-to-para ratio of 3.21±0.15, also consistent with measurements in solar system comets. We measured the ratio between the green [OI] line and the red doublet and find a value of G/R=0.31±0.05 close to perihelion, with a tentative increasing trend with the heliocentric distance. This high value of the G/R is consistent with the high CO abundance already reported in the coma of 2I and the increase of the CO/H[SUB]2[/SUB]O ratio as the comet moved away from the Sun. Finally, we used the OH (0-0) band around 309 nm to derive a water production rate of (2.2±0.2)x10[SUP]26[/SUP] molecules/s on December 24 and 26, 2019. In conclusion, high spectral resolution observations of the interstellar comet 2I/Borisov at the VLT, and the NH[SUB]2[/SUB] ortho-to-para ratio and Ni/Fe ratios we measured reveal a remarkable similarity to solar system comets. The G/R ratio is unusually high but this is consistent with a high CO abundance, and potentially suggests a formation in a colder environment. [less ▲]

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See detailThe discovery of Fe and Ni free atoms in comets atmospheres even far from the Sun
Jehin, Emmanuel ULiege; Manfroid, Jean ULiege; Hutsemekers, Damien ULiege

in Bulletin of the American Astronomical Society (2021, October 01), 53(7), 10506

In this talk I will present the unexpected discovery of iron and nickel free atoms in the coma of comets, even far from the Sun. We have identified dozens of FeI and NiI lines in the high resolution ... [more ▼]

In this talk I will present the unexpected discovery of iron and nickel free atoms in the coma of comets, even far from the Sun. We have identified dozens of FeI and NiI lines in the high resolution optical spectra of most of the comets observed by our team in the last 20 years using UVES at the VLT [1]. These lines are ubiquitous in cometary comae, we found them also in the interstellar comet 2I/Borisov [2,3] and they were recently identified in archival spectra of the Great comet Hyakutake [3,4]. If various metallic lines were already detected in the sungrazer comet C/1965 Ikeya-Seki [5], that approached the Sun so close that dust grains vaporized, it was a surprise to find them in comets as far as 3.25 au, where the equilibrium temperature is far too low to allow sublimation of silicates (Tsub ≥ 1200K) and sulfides (Tsub ≥ 600K). The spatial extension of the lines is very short indicating that the FeI and NiI atoms originate from the inner coma, close to the nucleus. We developed a fluorescence model that allowed to compute their production rates. The NiI/FeI abundance ratios cluster around NiI/FeI~1 and does not depend on the heliocentric distance or the comet dynamical type [1], but there is a correlation with the level of carbon-chain depletion (C[SUB]2[/SUB]/CN) [3]. This Ni/Fe ratio is about 10x higher than what is measured in the Sun and the meteorites, as well as in the coma of Ikeya-Seki and the dust of 1P/Halley [6] indicating an other orgins. We made the hypothesis that these atoms could be released from organometallic complexes, yet undetected in the cometary material, such as carbonyls that have much lower sublimation temperatures. In particular Fe(CO)[SUB]5[/SUB] and Ni(CO)[SUB]4[/SUB] are expected to sublimate at Tsub~ 100K, intermediate between the sublimation temperature of H[SUB]2[/SUB]O and CO[SUB]2[/SUB]. The higher sublimation rate of Ni(CO)[SUB]4[/SUB] with respect to Fe(CO)[SUB]5[/SUB] would naturally explain the overabundance of nickel. In the present contribution, we summarize this discovery and the challenges it raises. References: [1] Manfroid, J., Hutsemékers, D., Jehin, E.: Nature 593, 372 (2021) [2] Opitom, C., Jehin, E., Hutsemékers, D., et al.: A&A, accepted (2021) [3] Hutsemékers, D., Manfroid, J., Jehin, E. et al.: A&A, accepted (2021) [4] Bromley, S., Ne, B., Loch, S., et al. 2021, arXiv e-prints, arXiv:2106.04701 [5] Preston, G.W.: ApJ 147, 718 (1967). Illustration: Detection of heavy metals in the atmosphere of comet C/2016 R2. Credit: ESO/L. Calçada, SPECULOOS Team/E. Jehin, Manfroid et al. [less ▲]

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See detailRotation period determination of NASA Lucy mission target (52246) Donaldjohanson
Ferrais, Marin ULiege; Jehin, Emmanuel ULiege; Manfroid, Jean ULiege et al

in Bulletin of the American Astronomical Society (2021, October 01), 53(7), 30619

(52246) Donaldjohanson is a small 4 km in diameter main-belt asteroid, and a C-type belonging to the Erigone collisional family [1]. The Lucy Mission is a NASA Discovery class mission that will launch a ... [more ▼]

(52246) Donaldjohanson is a small 4 km in diameter main-belt asteroid, and a C-type belonging to the Erigone collisional family [1]. The Lucy Mission is a NASA Discovery class mission that will launch a spacecraft in October 2021 to explore several Jupiter Trojan asteroids. On its way to Jupiter's orbit, Lucy will first encounter Donaldjohanson in 2025. However, few physical characteristics are known about this body at present time. <P />Here, we present new photometric observations of Donaldjohanson acquired from November 2020 to February 2021 with the two 60-cm TRAPPIST telescopes [3]. During this apparition, we obtained 91 individual series that revealed a very slow rotator featuring a large amplitude of the rotational lightcurve. We determined a rotation period of ~252 h and an amplitude of ~1 magnitude. <P />References: <P />[1] Nesvorný, D., Broz, M., Carruba, V., et al., 2015, In: Asteroids IV, pp. 297-321 <P />[2] Marchi, S., Levison, H., Olkin, C., et al., 2020, EPSC, 163 <P />[3] Jehin, E., Gillon, M., Queloz, D., et al., 2011, The Messenger, 145, 2 [less ▲]

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See detailPhysical characterization of the active asteroid (6478) Gault from a multi-apparition campaign (2018-2020)
Devogele, Maxime; Ferrais, Marin ULiege; Jehin, Emmanuel ULiege et al

in Bulletin of the American Astronomical Society (2021, October 01), 53(7), 30904

(6478) Gault is a main-belt asteroid that was found to display cometary activity in late 2018-early 2019 [1]. During its 2018-2019 apparition, Gault experienced several activity events leading to the ... [more ▼]

(6478) Gault is a main-belt asteroid that was found to display cometary activity in late 2018-early 2019 [1]. During its 2018-2019 apparition, Gault experienced several activity events leading to the development of up to three distinct tails [2,3,4]. Many hypotheses such as impacts with smaller objects, YORP induced spin-up [5], sublimation of volatiles [6], or even the presence of a satellite in a highly eccentric and chaotic orbit, were considered to explain these events. <P />In this talk we present new photometric and spectroscopic observations of Gault obtained during the 2018-2019 and 2020 apparitions. These observations were obtained both when Gault was active (during the 2018-2019 apparition) and when it was found to be inactive during the 2020 apparition. For the first time we determine an accurate rotation period with high confidence of P=2.4929 ± 0.0003 h with a low amplitude of only 0.06 mag. This rotation period associated with a low lightcurve amplitude is consistent with a bulk density no smaller than 1.85 g cm3 in order for its activity to be triggered by the YORP spin-up mechanism. Our spectral analysis is consistent with Gault being of ordinary chondrite-like composition. Several spectra and a large datasets of broad band spectro-photometric observations obtained over the two oppositions do not show any sign of spectral variation over time. <P />Finally, we did not find any statistically significant signal of non-gravitational accelerations due to its activity even after the addition of previously unidentified detections of Gault dating back to 1958, which increased its orbital arc by a factor of almost 2. <P />These results were published in [7]. <P />References: <P />[1]: Smith K. W., Denneau L., Vincent J. B., et al., 2019, CBET, 4594 <P />[2]: Jehin E., Ferrais M., Moulane Y., et al. 2019, CBET, 4606 <P />[3]: Ye Q., et al., 2019, The ApJ Letters, 874, L16 <P />[4]: Jewitt D., Kim Y., Luu J., et al. 2019, The ApJ Letters, 876, L19 <P />[5]: Kleyna J. T., et al., 2019, The ApJ Letters, 874, L20 <P />[6]: Ferrín I., Fornari C., Acosta A., 2019, MNRAS, 490, 219 <P />[7]: Devogèle M., Ferrais M, Jehin E, et al. 2021, MNRAS, 505, 245 [less ▲]

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See detailProperties of slowly rotating asteroids from the Convex Inversion Thermophysical Model
Marciniak, A.; Ďurech, J.; Alí-Lagoa, V. et al

in Astronomy and Astrophysics (2021), 654

Context. Recent results for asteroid rotation periods from the TESS mission showed how strongly previous studies have underestimated the number of slow rotators, revealing the importance of studying those ... [more ▼]

Context. Recent results for asteroid rotation periods from the TESS mission showed how strongly previous studies have underestimated the number of slow rotators, revealing the importance of studying those targets. For most slowly rotating asteroids (those with P > 12 h), no spin and shape model is available because of observation selection effects. This hampers determination of their thermal parameters and accurate sizes. Also, it is still unclear whether signatures of different surface material properties can be seen in thermal inertia determined from mid-infrared thermal flux fitting. Aims: We continue our campaign in minimising selection effects among main belt asteroids. Our targets are slow rotators with low light-curve amplitudes. Our goal is to provide their scaled spin and shape models together with thermal inertia, albedo, and surface roughness to complete the statistics. Methods: Rich multi-apparition datasets of dense light curves are supplemented with data from Kepler and TESS spacecrafts. In addition to data in the visible range, we also use thermal data from infrared space observatories (mainly IRAS, Akari and WISE) in a combined optimisation process using the Convex Inversion Thermophysical Model. This novel method has so far been applied to only a few targets, and therefore in this work we further validate the method itself. Results: We present the models of 16 slow rotators, including two updated models. All provide good fits to both thermal and visible data.The obtained sizes are on average accurate at the 5% precision level, with diameters found to be in the range from 25 to 145 km. The rotation periods of our targets range from 11 to 59 h, and the thermal inertia covers a wide range of values, from 2 to <400 J m^−2 s^−1∕2 K^−1, not showing any correlation with the period. Conclusions: With this work we increase the sample of slow rotators with reliable spin and shape models and known thermal inertia by 40%. The thermal inertia values of our sample do not display a previously suggested increasing trend with rotation period, which mightbe due to their small skin depth. [less ▲]

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See detailCharacterizing the aftermath of a medium-sized outburst of Centaur 29P/Schwassmann-Wachmann 1 using HST/WFC3
Allen, Johannes; Venkataramani, Kumar; Yang Li, Jian et al

in Bulletin of the American Astronomical Society (2021, October 01), 53(7), 30704

Comet 29P/Schwassmann-Wachmann 1 (hereafter, 29P) is a highly active andprominent member of the Centaur population. Centaurs are icy bodies with orbits between Jupiter and Neptune, which dynamically link ... [more ▼]

Comet 29P/Schwassmann-Wachmann 1 (hereafter, 29P) is a highly active andprominent member of the Centaur population. Centaurs are icy bodies with orbits between Jupiter and Neptune, which dynamically link the Jupiter-family comets to the trans-Neptunian objects of the outer solar system. Hovering at large heliocentricdistances, where the sublimation of water ice is negligible, the mechanism driving the outbursts of comet 29P remains undetermined. We present target of opportunity observations collected with the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3), acquired following reports of a possible fragmentation event of 29P before Oct. 1.3, 2019 (M.S.P. Kelley, et al., ATEL 13164, 2019). Our observing cadence captured 29P within two days of a 0.9 mag, thus medium-sized outburst, and provided observations before and after the event for context and to probe the development of the ejecta. Between the purported fragmentation event and the HST observations, 29P underwent two small outbursts on Oct. 7 and Oct. 16, 2019 (both of amplitude 0.4-0.5 mag; Q. Z. Ye et al., ATEL 13179, 2019; M. S. P. Kelley, UMD, priv. comm.), followed by a medium-sized outburst with an amplitude of 0.9 mag around Oct. 19.5, 2019 (D. Bodewits, AU; R. Miles, BAA comet section, priv. comm). HST observed 29P three times, on Oct. 14.75, Oct. 20, and Oct. 28.5, 2019. A detailed characterization of the coma morphology, dynamics, and the results of deep, sub-km search for fragments will be provided in our presentation. <P />Cross-listed as presentation #503.02. [less ▲]

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See detailPhysical properties of the cubewano 19521 Chaos from a multi-chord stellar occultation
Vara-Lubiano, Mónica; Morales, Nicolás; Rommel, Flavia et al

in Bulletin of the American Astronomical Society (2021, October 01), 53(7), 30711

Trans-Neptunian Objects (TNOs) have had an increasing interest since the discovery of (15760) Albion in 1992. These objects are considered remnants of the Solar System formation, and can thus provide ... [more ▼]

Trans-Neptunian Objects (TNOs) have had an increasing interest since the discovery of (15760) Albion in 1992. These objects are considered remnants of the Solar System formation, and can thus provide clues about its origin and evolution. One of the best techniques to study TNOs from ground-based telescopes are stellar occultations which, if combined with photometric data, permit to obtain physical properties of the TNO such as its size, shape, and albedo. With this in mind, we predicted, observed, and analyzed the stellar occultation of the Gaia source 3444789965847631104 caused by the cubewano (19521) Chaos on the 20th of November 2020. The prediction was part of the searching program carried out by the Lucky Star project collaboration. We observed the object with the 1.23-m telescope at Calar Alto Observatory (Almería, Spain) two days before the event to update the prediction. The occultation observing campaign involved 19 observing stations, both professional and amateur, and resulted in three positive detections and 11 negative detections. Five teams could not observe due to bad weather. We fitted the positive chords' extremities to an ellipse to derive Chaos' projected size and shape and determine its geometric albedo. The preliminary area-equivalent diameter obtained is slightly smaller than the one derived with Herschel thermal data. However, we are still analyzing photometric data to complement and improve these results. [less ▲]

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See detailPhysical properties of Hi'iaka from stellar occultation data
Fernández-Valenzuela, Estela; Ortiz Moreno, Jose Luis; Holler, Bryan et al

in Bulletin of the American Astronomical Society (2021, October 01), 53(7), 50305

Two very bright stellar occultations by Hi'iaka, the largest satellite of the dwarf planet Haumea, were predicted to take place during in April 2021. Since the uncertainty on Hi'iaka's shadow path was ... [more ▼]

Two very bright stellar occultations by Hi'iaka, the largest satellite of the dwarf planet Haumea, were predicted to take place during in April 2021. Since the uncertainty on Hi'iaka's shadow path was large due to uncertainty on Hi'iaka's position with respect to Haumea, we performed an observational campaign using medium-sized telescopes to obtain high accuracy astrometric data of Hi'iaka's orbit around Haumea. The astrometric data allowed us to successfully observe the first stellar occultation on April 6[SUP]th[/SUP], with final path crossing North Africa. We only obtained one positive chord in this event from the TRAPPIST-North telescope at Oukaïmeden Observatory (Morocco), but thanks to this detection, we were able to obtain a more accurate path for the second event on April 16[SUP]th[/SUP]. The second shadow path was predicted to cross the continental US from East to West. We carried out a huge observational campaign involving more than 50 professional and amateur observatories across the US and southern Canada. The final path of this second stellar occultation moved slightly to the North of the predicted path and, as a result, we were able to obtain 5 positive chords and negative chords only from the south of the shadow. We also collected photometric data in order to obtain Hi'iaka's rotational light-curve and calculate its three-dimensional shape. The rotational light-curve was obtained by observing the unresolved system of Haumea-Hi'iaka and removing Haumea's rotational light-curve from the data. Using Hi'iaka's rotational light-curve we obtained the rotational phase at which each stellar occultation took place, which allowed us to obtain a three-dimensional model of the satellite. Preliminary results from the stellar occultation show that Hi'iaka, with a triaxial shape as suggested in previous publications, is larger than what has been thought before and with a similar albedo to that of Haumea. In this talk we will present our analysis and preliminary results of some of Hi'iaka's physical properties. [less ▲]

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See detailVLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis
Vernazza, P.; Ferrais, Marin ULiege; Jorda, L. et al

in Astronomy and Astrophysics (2021), 654

Context. Until recently, the 3D shape, and therefore density (when combining the volume estimate with available mass estimates), and surface topography of the vast majority of the largest (D ≥ 100 km ... [more ▼]

Context. Until recently, the 3D shape, and therefore density (when combining the volume estimate with available mass estimates), and surface topography of the vast majority of the largest (D ≥ 100 km) main-belt asteroids have remained poorly constrained. The improved capabilities of the SPHERE/ZIMPOL instrument have opened new doors into ground-based asteroid exploration. Aims: To constrain the formation and evolution of a representative sample of large asteroids, we conducted a high-angular-resolution imaging survey of 42 large main-belt asteroids with VLT/SPHERE/ZIMPOL. Our asteroid sample comprises 39 bodies with D ≥ 100 km and in particular most D ≥ 200 km main-belt asteroids (20/23). Furthermore, it nicely reflects the compositional diversity present in the main belt as the sampled bodies belong to the following taxonomic classes: A, B, C, Ch/Cgh, E/M/X, K, P/T, S, and V. Methods: The SPHERE/ZIMPOL images were first used to reconstruct the 3D shape of all targets with both the ADAM and MPCD reconstruction methods. We subsequently performed a detailed shape analysis and constrained the density of each target using available mass estimates including our own mass estimates in the case of multiple systems. Results: The analysis of the reconstructed shapes allowed us to identify two families of objects as a function of their diameters, namely "spherical" and "elongated" bodies. A difference in rotation period appears to be the main origin of this bimodality. In addition, all but one object (216 Kleopatra) are located along the Maclaurin sequence with large volatile-rich bodies being the closest to the latter. Our results further reveal that the primaries of most multiple systems possess a rotation period of shorter than 6 h and an elongated shape (c∕a ≤ 0.65). Densities in our sample range from ~1.3 g cm^−3 (87 Sylvia) to ~4.3 g cm^−3 (22 Kalliope). Furthermore, the density distribution appears to be strongly bimodal with volatile-poor (ρ ≥ 2.7 g cm^−3) and volatile-rich (ρ ≤ 2.2 g cm^−3) bodies. Finally, our survey along with previous observations provides evidence in support of the possibility that some C-complex bodies could be intrinsically related to IDP-like P- and D-type asteroids, representing different layers of a same body (C: core; P/D: outer shell). We therefore propose that P/ D-types and some C-types may have the same origin in the primordial trans-Neptunian disk. [less ▲]

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