China's Tianwen-2 spacecraft was launched on 2025 May 29 and will arrive at the Earth quasi-satellite (469219) Kamo'oalewa in 2026 July. We previously reported that Kamo'oalewa develops an LL-chondrite-compositional, highly space-weathered surface. Here, using the light-curve data and the Cellinoid model, we modeled Kamo'oalewa's shape, rotation period, and pole orientation. We then estimated the global distribution of regolith critical size using the balance method of gravity, cohesive force, and centrifugal force. Furthermore, in the temperature range of 253.15-473.15 K, we measured the thermal parameters of laser-irradiated LL chondrite powder that best matches Kamo'oalewa's spectrum, estimating Kamo'oalewa's thermal inertia and skin depth (lower limit of regolith thickness). Using the radiative transfer mixing model, we also estimated the sub-micrometer-sized iron (SMFe0) content in Kamo'oalewa's regolith. Finally, using the MIT online spectral classification tool for the laser-irradiated LL chondrite powder, we obtained a virtual spectral type of Kamo'oalewa. Our model gives a size of 68 & times; 46 & times; 39 m, a rotation period of 27.66 minutes, and a pole orientation of 134 . degrees 7 longitude and -11 . degrees 4 latitude for Kamo'oalewa. Regolith grains with a size <2 cm can remain stable over 93.8% of the global surface area of Kamo'oalewa. Laser-irradiated LL chondrite powder shows a low thermal inertia (163.14-232.31 J m(-2) K-1 s(-1/2)), corresponding to a thermal skin depth of 3.1-3.5 mm on Kamo'oalewa. An SMFe0 content of 0.29 +/- 0.05 wt.% is required to match Kamo'oalewa's spectrum. The virtual spectral type of Kamo'oalewa is given as "Sqw."

China's Tianwen-2 spacecraft will return samples from the near-Earth asteroid (469219) Kamo'oalewa. We previously reported that Kamo'oalewa develops an LL-chondrite-compositional, highly space-weathered surface. This study aims to estimate Kamo'oalewa's shape, regolith grain size and thickness, sub-micrometer iron (SMFe0) content, and spectral type. Using the lightcurve data and the Cellinoid model, we modeled Kamo'oalewa's shape, rotation period, and pole orientation. We then estimated its global distribution of regolith critical size using the balance method of gravity, cohesive force, and centrifugal force. Furthermore, in the temperature range of 253.15 to 473.15 K, we measured the thermal parameters of laser-irradiated LL chondrite powder that best matches Kamo'oalewa's spectrum, estimating Kamo'oalewa's thermal inertia and skin depth (lower limit of regolith thickness). Using the radiative transfer mixing model, we also estimated the content of SMFe0 in Kamo'oalewa's regolith. Finally, using the MIT online spectral classification tool for the laser-irradiated LL chondrite powder, we obtained a virtual spectral type of Kamo'oalewa. Our model gives a size of 68 m x 46 m x 39 m, a rotation period of 27.66 minutes, and a pole orientation of 134.7 degrees longitude and -11.4 degrees latitude for Kamo'oalewa. Regolith grains with a size <2 cm can remain stable over 93.8

By using the 1 m telescope of Yunnan Observatories and the 0.5 m telescope of Ho Koon Nature Education cum Astronomical Centre, China, we had obtained eight transit light curves for the exoplanetary system WASP-36 and three for the exoplanetary system XO-3 between 2010 and 2021. By means of the Markov Chain Monte Carlo technique, we have jointly analyzed these light curves and the relative Transiting Exoplanet Survey Satellite light curves to refine the physical parameters of both systems. Through combining the new mid-transit times with the published ones and the ones from the Exoplanet Transit Database website, we have derived transit timing variation (TTV) patterns of the two systems. By analyzing the TTV signals, we find that WASP-36's TTV favors the apsidal precession model while XO-3's TTV agrees to the orbital decay model. However, detailed physical analyses demonstrate that the two mechanisms are not the origin of the observed TTVs. Considering that the observed TTVs are induced by perturbers in the systems, based on dynamic simulations, we have constrained the mass of hypothetical perturbers by combining the rms values of both TTVs and radial velocity curve residuals. When the hypothetical perturbing planets are near mean-motion resonance with the transiting planets, the systems could potentially harbor Earth-mass perturbing planets capable of reproducing the observed TTV signals.

The Near-earth asteroid (469219) Kamo'oalewa, a quasi-satellite of the Earth, is going to be observed in site and sampled by the Chinese space mission Tianwen-2 in near future. Here. we analyze its photometric and spectroscopic data to figure out its basic physical properties, which are very important for the sample return task of the Tianwen-2 mission. With photometry inversion methods, we derived a pole (276^o.79, -21^o.43) with a spin period of 28.4517 minutes and a slightly flat convex shape. The estimated photometry slope of 0.998 mag/rad implies a large albedo of the Kamo'oalewa, i.e. S-type. Using the estimated absolute magnitude of 24.98 mag, its size could be 27.4m assuming a typical albedo of S-type asteroids. The taxonomy analysis with a constructed ANN tool also supports that the Kamo'oalewa should belong to S-type asreroids, it may be a strong weathering fragment of an A-type or Q-type asteroid. Using derived pole, size and shape information of the target, we estimated its thermal inertia as 163.0 Jm^-2K^-1s^-1/2 based on the new derived Yarkovski draft A_2=-13.29349563×10^-14au/day^2, which means the target has a surface of mixture of grains and small bounds, like the surface of asteroid Bennu.

Context. The third Gaia data release (DR3) contains high-precision, sparse-in-time brightness measurements of over 150000 asteroids. Aims. We employed a light-scattering inversion technique to estimate the rotation periods, spin pole orientations, shapes, and photometric phase function parameters (slope and absolute magnitude) of over 8000 asteroids based solely on DR3 photometry. Methods. Using triaxial ellipsoid and convex shapes, we sought the best-fit shape, spin, and linear slope, along with their uncertainties, via a Markov chain Monte Carlo sampling technique. We also fit H,G12 and H,G1,G2 phase functions from predicted brightnesses derived from the fit shapes. Using previously reported diameters, the Gaia G-band geometric albedos were calculated. Variations in the spin and shape properties were assessed among various families and background populations of the Main Belt. Results. We found that for the vast majority of our objects the best-fit ellipsoid spin poles are comparable to that of a convex shape. We rejected 15% of convex shapes and used the acceptable solutions to investigate differences in the shape distribution of families in the Main Belt. Revisiting the amplitude phase relationship, we found a strong dependence on the shape b/a elongation. The Bond albedo was calculated from the phase integral and shown to correlate well with the G12 slope parameter and known taxonomic classifications. The G-band absolute magnitudes and geometric albedos are systematically fainter than V-band values. Conclusions. The assumption of ellipsoid shape for sparse datasets is sufficient for estimating the spin pole longitude and latitude. We find no correlation between the shapes and spins of main-belt asteroid families and their ages. Absolute magnitudes and phase functions derived from Gaia photometry should be favored over the V band when estimating the solar energy budget, such as in thermal modeling applications. Asteroid taxonomies can be assessed to some degree from the photometric slopes and albedos.

China's Tianwen-2 mission plans to return samples from a small, rapidly spinning Earth quasi-satellite (469219) Kamo'oalewa. Previous studies linked Kamo'oalewa to lunar composition and origin. Here, we propose another scenario. We reanalyzed the reflectance spectrum of Kamo'oalewa and obtained an absorption band center at 1.001+-0.028 um (error is 1sigma), consistent with LL chondrites. We then conducted space weathering (SW) experiments on meteorites and found that highly space-weathered LL chondrite powder (but not slab) successfully reproduced the reflectance spectrum of Kamo'oalewa. We further traced the dynamical origin of Kamo'oalewa and found that it probably originated from the v6 secular resonance, and more specifically, the Flora family. Kamo'oalewa exhibits a similar composition to Itokawa and 7 objects in the Flora family, but with a higher degree of space weathering. We, therefore, proposed that Kamo'oalewa probably originated from the Flora family and developed an Itokawa-compositional, highly space-weathered, fine-regolith-dominated surface.

Context. We study the taxonomic classification of asteroids observed by Gaia as a continuation of the lightcurve inversion work presented in Paper I. Aims. We examine the taxonomic classification of asteroids by using both Gaia Data Release 3 (DR3) photometric and spectroscopic data. Particular focus is placed on Ch-class asteroids, as their potentially hydrated nature makes them promising candidates for sample-return missions and the asteroid mining industry. Methods. We utilized the photometric slopes and geometric albedos (via absolute magnitudes) derived from lightcurve inversion, and the Gaia DR3 spectra (from 418 nm to 770 nm) as classification parameters. We also considered how different parameter sets affect classification accuracies for separate asteroid classes. We classified the asteroids with a combination of linear discriminant analysis and a nearest neighbor classifier. Results. We achieve a classification accuracy of 92% for known S-class asteroids and an accuracy of 85% for Ch-class asteroids with a known set of 328 asteroids. Given the three classification parameters, tentative class designations for 1668 previously unclassified asteroids are provided in the Mahlke taxonomy. We also show that the photometric slope values vary significantly within asteroid classes, with a standard deviation three to four times the mean slope uncertainties. Conclusions. We show that the combination of photometry and spectroscopy can be useful in the taxonomic classification of asteroids observed by Gaia. Further studies of the surface roughness at different scales could help clarify the potential of the photometric slope in classification efforts.

Context. We study the taxonomic classification of asteroids observed by Gaia as a continuation of the lightcurve inversion work presented in Paper I. Aims. We examine the taxonomic classification of asteroids by using both Gaia Data Release 3 (DR3) photometric and spectroscopic data. Particular focus is placed on Ch-class asteroids, as their potentially hydrated nature makes them promising candidates for sample-return missions and the asteroid mining industry. Methods. We utilized the photometric slopes and geometric albedos (via absolute magnitudes) derived from lightcurve inversion, and the Gaia DR3 spectra (from 418 nm to 770 nm) as classification parameters. We also considered how different parameter sets affect classification accuracies for separate asteroid classes. We classified the asteroids with a combination of linear discriminant analysis and a nearest neighbor classifier. Results. We achieve a classification accuracy of 92% for known S-class asteroids and an accuracy of 85% for Ch-class asteroids with a known set of 328 asteroids. Given the three classification parameters, tentative class designations for 1668 previously unclassified asteroids are provided in the Mahlke taxonomy. We also show that the photometric slope values vary significantly within asteroid classes, with a standard deviation three to four times the mean slope uncertainties. Conclusions. We show that the combination of photometry and spectroscopy can be useful in the taxonomic classification of asteroids observed by Gaia. Further studies of the surface roughness at different scales could help clarify the potential of the photometric slope in classification efforts.

The third Gaia data release (DR3) contains high-precision, sparse-in-time brightness measurements of over 150,000 asteroids. We employed a light-scattering inversion technique to estimate the rotation periods, spin pole orientations, shapes, and photometric phase function parameters (slope and absolute magnitude) of over 8000 asteroids based solely on DR3 photometry. Using triaxial ellipsoid and convex shapes, we sought the best-fit shape, spin, and linear slope, along with their uncertainties, via a Markov chain Monte Carlo sampling technique. We also fit H,!G_12 and H,!G_1,!G_2 phase functions from predicted brightnesses derived from the fit shapes. Using previously reported diameters, the Gaia G-band geometric albedos were calculated. Variations in the spin and shape properties were assessed among various families and background populations of the . We found that for the vast majority of our objects the best-fit ellipsoid spin poles are comparable to that of a convex shape. We rejected 15% of convex shapes and used the acceptable solutions to investigate differences in the shape distribution of families in the Main Belt. Revisiting the amplitude phase relationship, we found a strong dependence on the shape b/a elongation. The Bond albedo was calculated from the phase integral and shown to correlate well with the G_12 slope parameter and known taxonomic classifications. The G-band absolute magnitudes and geometric albedos are systematically fainter than V-band values. The assumption of ellipsoid shape for sparse datasets is sufficient for estimating the spin pole longitude and latitude. We find no correlation between the shapes and spins of main-belt asteroid families and their ages. Absolute magnitudes and phase functions derived from photometry should be favored over the V band when estimating the solar energy budget, such as in thermal modeling applications. Asteroid taxonomies can be assessed to some degree from the photometric slopes and albedos.

China's ongoing Tianwen-2 mission will return samples from a small, rapidly spinning Earth quasi-satellite (469219) Kamo'oalewa. Previous studies linked Kamo'oalewa to lunar composition and origin. Here, we propose another scenario. We reanalyze the reflectance spectrum of Kamo'oalewa and obtain an absorption band center at 1.001 ± 0.028 μm (error is 1σ), consistent with LL chondrites. We then conduct space weathering experiments on meteorites and find that highly space-weathered LL chondrite powder (but not slab) successfully reproduces the reflectance spectrum of Kamo'oalewa. We further trace the dynamical origin of Kamo'oalewa and find that it probably originated from the ν6 secular resonance, and more specifically, the Flora family. Kamo'oalewa exhibits a similar composition to Itokawa and 7 objects in the Flora family, but with a higher degree of space weathering. We, therefore, propose that Kamo'oalewa probably originated from the Flora family and developed an Itokawa-compositional, more space-weathered, fine-regolith-dominated surface.

Context. The third Gaia data release (DR3) contains high-precision, sparse-in-time brightness measurements of over 150000 asteroids. Aims. We employed a light-scattering inversion technique to estimate the rotation periods, spin pole orientations, shapes, and photometric phase function parameters (slope and absolute magnitude) of over 8000 asteroids based solely on DR3 photometry. Methods. Using triaxial ellipsoid and convex shapes, we sought the best-fit shape, spin, and linear slope, along with their uncertainties, via a Markov chain Monte Carlo sampling technique. We also fit H,G12 and H,G1,G2 phase functions from predicted brightnesses derived from the fit shapes. Using previously reported diameters, the Gaia G-band geometric albedos were calculated. Variations in the spin and shape properties were assessed among various families and background populations of the Main Belt. Results. We found that for the vast majority of our objects the best-fit ellipsoid spin poles are comparable to that of a convex shape. We rejected 15% of convex shapes and used the acceptable solutions to investigate differences in the shape distribution of families in the Main Belt. Revisiting the amplitude phase relationship, we found a strong dependence on the shape b/a elongation. The Bond albedo was calculated from the phase integral and shown to correlate well with the G12 slope parameter and known taxonomic classifications. The G-band absolute magnitudes and geometric albedos are systematically fainter than V-band values. Conclusions. The assumption of ellipsoid shape for sparse datasets is sufficient for estimating the spin pole longitude and latitude. We find no correlation between the shapes and spins of main-belt asteroid families and their ages. Absolute magnitudes and phase functions derived from Gaia photometry should be favored over the V band when estimating the solar energy budget, such as in thermal modeling applications. Asteroid taxonomies can be assessed to some degree from the photometric slopes and albedos.

The study on active binaries can provide detailed insights to understand how binarity affects dynamo actions inside stellar interiors. Here we report two active eclipsing binaries, USNO-B1.0 0743-0306638 and 0763-0282368, discovered in the Yunnan–Hong Kong wide-field photometric (YNHK) survey. Both of the two systems are detached binaries and show spot activities, while USNO-B1.0 0763-0282368 is more close to its Roche lobe. By means of the Wilson–Devinney (WD) code, their photometric solutions are determined based on parts of the YNHK photometric light curves. Furthermore, the spot distribution and evolution are investigated using time series of the YNHK light curves from 2016 to 2023. The results show that the spot activities appeared on the primary components for the two binary systems. There exist two kinds of spots: one is polar spots that lead to the variation of overall luminosity of the binaries, while the other is low-latitude spots that cause the rotational modulation. The polar spots behave more long-lived than the low-latitude spots on both binaries. For the low-latitude spot, its longitudinal distribution becomes more stable and closer to the substellar point as the binary system is close to the Roche lobe.

We conducted photometric observations for transit events of three exoplanetary systems HAT-P-36, XO-2 and WASP-76 using the 1 m and 2.4 m telescopes at Yunnan Observatories and the 0.85 m telescope at National Astronomical Observatories of China. By combining the photometric data from the TESS mission, we have performed a detailed analysis for the obtained transit light curves using the Markov chain Monte Carlo technique, and obtained precise transit midtimes for the three systems. Based on our new measurements and other available transit mid-times, we have determined more accurate orbital periods for these systems. From the analysis, we find that all of these planetary systems exhibit certain transit-timing variations (TTVs). The TTV patterns are simulated by using the constant period model, orbital decay model and apsidal precession model, but we do not obtain reasonable models to account for the TTVs. Furthermore, to assess the presence of additional planets in these systems, we have constrained the masses of perturbing planets using the root mean square (rms) values of the observed TTVs and the rms values of radial velocity residuals. The results demonstrate that, under the condition of mean motion resonances, these systems may harbor perturbing planets with masses from a few tenths to more than one hundred Earth mass.

Understanding the nature and evolution of near-Earth asteroids (NEAs) are of paramount importance to planetary science1 and security2. So far, three asteroid sample-return missions, Hayabusa, Hayabusa2, and OSIRIS-REx to asteroids have greatly increased our knowledge of several-hundred-meter rubble-pile NEAs. However, limited by ground-based observation spatial resolution, little is known about smaller NEAs. Recently, the China National Space Administration has proposed a new asteroid mission, Tianwen-2, which plans to first return a sample from an Earth quasi-satellite (469219) 2016 HO3 Kamoʻoalewa, and then orbit and characterize an active main-belt asteroid: 311P/PANSTARRS. Here we report that Kamoʻoalewa is an S-type, sub-hundred-meter-sized (69.45 m × 58.49 m × 51.78 m), rapid-rotating (period is 27.37 minutes) NEA developed with grain size < 2 cm regolith. We analyzed telescopic observations of Kamoʻoalewa, whose visible to near-infrared (VIS-NIR) reflectance spectrum shows a 0.984 (+0.003,-0.004) μm absorption center, suggesting that it resembles LL ordinary chondrites in composition. Orbital dynamical calculations show that Kamoʻoalewa holds a 72 ± 5% probability of originating from the inner main belt ν6 secular resonance adjacent to the Flora family. Notably, Kamoʻoalewa exhibits an extremely red (positively steep) VIS-NIR spectral slope, making it a typical space weathering (SW)-matured object. Our spectral model calculations further suggest that the sub-microphase iron content in Kamoʻoalewa’s regolith is 0.29 ± 0.05 wt.% and the SW timescale is ~0.5–1 × 10^8 years. This means that Kamoʻoalewa is indeed a SW-matured object and the separation from its parent body likely took place in the inner main belt long before it evolved into an NEA. We ascribe Kamoʻoalewa’s extremely red spectral slope to the combined effects of SW, YORP spin-up, thermal degradation, low-frequency impacts, and non-rubble pile structure. We further predict that sub-hundred-meter, rapidly spinning silicate-rich NEAs with small perihelion may generally exhibit extremely red spectral slopes and SW-matured surfaces.

The Gaia Data Release 3 (DR3) contains high-precision sparse-in-time photometric data of more than 150 000 asteroids and spectroscopy of more than 60 000 asteroids (Tanga et al., A&A, 674, A12, 2023). We have fitted simple triaxial and general convex shapes to estimate the rotational periods, spin axes, and linear photometric slopes of the asteroids with the lightcurve inversion algorithm developed by Muinonen et al. (A&A, 642, A138, 2020). Sample selection of the asteroids follows Cellino et al. (A&A, in press, 2024), and we use the ellipsoid results from their genetic evolution algorithm to initiate our ellipsoid and convex shape inversion solutions. In total, we have modelled linear photometric slopes for 8660 asteroids, which have at least 25 Gaia observations (MacLennan et al., in preparation). The slopes are used to compute H,G1,G2 phase functions (Muinonen et al., Icarus, 209, 542, 2010) to derive absolute magnitudes for the asteroids. As the absolute magnitudes have been calculated using Gaia’s G-band, they account for a larger portion of the incident solar spectrum compared to e.g. V-band. This is particularly useful for estimating the amount of absorbed sunlight for thermal infrared studies of asteroids via calculation of the Bond albedo. Selecting the asteroids for which there are spectroscopic data as well, gives us 2381 asteroids to analyse further. We have kept the data from the Gaia red and blue photometers (RP and BP) separate due to problems merging them. The wavelength range of both ends have also been cut to eliminate unreliable behaviour in the spectra. We are left with the following wavelengths: 418, 462, 506, 550, 594 nm (in the BP), and 638, 682, 726, 770 nm (in the RP). We have taken asteroid diameters from NASA’s NEOWISE survey (Mainzer et al., NEOWISE Diameters and Albedos V2.0, 2019) and the absolute magnitudes derived from the lightcurve inversion to calculate geometric albedos for the asteroids. Bond albedos are calculated from the geometric albedo and using the phase integral, q(G1,G2), from Muinonen et al. (Icarus, 209, 542, 2010). Traditionally, geometric albedos have been used to examine the inclusion of asteroids in asteroid families (Masiero et al., ApJ, 770, 7, 2013). Yet, taken together with the mean photometric slope of the families there seems to be a steep inverse linear trend with slopes smaller than 2 mag/rad at α = 20◦. We now investigate the parameters further by creating bins of the photometric slope and geometric albedo pair using Principal Component Analysis (PCA) on the data of individual asteroids. The asteroid spectra within the bins are examined in order to evaluate how well the parameter pair aids in the classification of asteroids.

The shapes and rotation states (periods and pole orientations) of main-belt asteroids are important for understanding their formation and evolution. In order to obtain sufficient photometric data covering different apparitions for asteroid (81) Terpsichore, ground-based photometric observations in 2020 and 2021 were carried out. By combining published and newly obtained photometric data, we calculated the shape and spin parameters for (81) Terpsichore using the convex inversion method. With this method, we have derived a best fitted pole orientation- ( 22.2 +/-(3.3 degrees)( 3.1) , 17.5 +/-( 5.5) (10.8 degrees) ) with a spin period of 10.94 +/- (0.01) (0.01 )h. Based on the derived convex shape of (81) Terpsichore, we have fitted the H, G 1, G 2 phase function using the calibrated TESS data and Gaia data after accounting for the lightcurve amplitude correction. As a result, we have derived its absolute magnitude H = 8.68 +/- (0.19) (0.22) mag with corresponding phase function parameters G 1 = 0.82 +/- (0.10) (0.09) and G 2 = 0.02 +/- (0.02) (0.03) .

Abstract We apply the statistical lightcurve inversion method developed by Muinonen et al. (2020, convex inversion in magnitude space CIM) to re-analyze the photometric data of (346) Hermentaria. As a main goal, we compare the results derived by the CIM and original convex inversion method in flux space (CIF) provided by Kaasalainen & Torppa (2001) and Kaasalainen et al. (2001). The comparison concerns the solutions of spin and shape parameters.1. Introduction The idea to invert 3-D shapes of asteroids from their brightness variations can be traced to 1906 (Russell 1906). Now, several methods have been established to invert the shape of asteroids, the shape models range from triaxial ellipsoids to convex, and even non-convex shapes. Kaasalainen et al. (1992a,b) and Lamberg (1993) suggested a way to invert the convex shape of an asteroid by using the Gaussian surface density. Kaasalainen & Torppa (2001) and Kaasalainen et al. (2001) implemented the idea by the Levenberg-Marquardt algorithm. Now, statistical techniques have been introduced into the photometry inversions of asteroids, e. g., a genetic algorithm (Cellino et al. 2015) and a Markov-chain Monte Carlo approach (MCMC, Muinonen et al. 2015). Wang et al. (2015b,a) presented a virtual observation method to figure out the uncertainties of parameters due to the observational uncertainties. Muinonen et al. (2020) developed a full statistical MCMC algorithm in the convex inversion of asteroids in the magnitude space (CIM), and gives a way to assess the uncertainties of spin parameters and convex shape parameters. We re-analyse the photometric data of (346) Hermentaria with CIM and CIF algorithms, and show the main differences of the results in the derivation of the convex shapes.2. Convex inversion with Bayesian inference The brightness model used in the CIM (Muninonen et a l. 2020)) involves a convex shape represented with the Gaussian surface density and the Lommel-Seeliger scattering law. In the CIM, the free parameters are the spin parameters, shape parameters, geometric albedo, and two parameters of the H,G1,G2 phase function. As for constructing the convex shape from its Gaussian surface density, Muinonen et al. (2020) developed a computationally easier, stochastic optimization metod.3. Results and discussion In total, 23 lightcurves of (346) Hermentaria on 4 apparitions are involved. 10 light curves are from the APC database (Lagerkvist et al. 1993) and rest of the lightcurves are ours observations. Based on these data, we performed the shape inversion with the CIM and CIF methods. As only relative intensities are involved, the parameters of the H G1 G2 phase function in the CIM and the scattering parameters a, k,d and c in the CIF are not fitted. Table 1 list the derived spin parameters. Figure 1 shows the lightcurves fits for the case of the pole 2 solution.Table 1. Spin parameters of HermentariaMethod Pole 1 (Ecliptic frame of J2000.0 ) Pole 2 (Ecliptic frame of J2000.0 ) Peroid (h) Pole 1, Pole 2 CIF (133o.0,+17o.2) (319o.5,+16o.8) 17.790043, 17.790039 CIM (133o.8,+09o.6) (321o.9,+17o.2) 17.790016, 17.790097 Figure 1. Lightcurves of Hermentaria (black circles) with the CIM and CIF model intensities ( red crosses and blue pluses respectively). The CIM gives a consistent result on spin parameters. From Figure 1, the modeled lightcurves with the CIF fit well to the features. We think this is partly due to the fact that we use a lower degree of spherical harmonics in the CIM and partly due to the differing model for the observational uncertainties. The theory by Minkowski (1903) provides a way to construct the three-dimensional shape of an object from its Gaussian surface density G. According to Minkowski, Muinonen et al.(2020) developed a stochastic optimization method to construct convex shape. Figure 2 shows the convex shapes of Hermentaria derived by the two methods.Figure 2. Convex shapes of Hermentaria corresponding to Pole 2 solution: the CIM (left) and CIF solutions (right) We have also compared the 3-D shapes constructed by the CIM and the CIF using the same Gaussian surface density originally derived by the CIM. Figure 3 shows the CIM and CIF results and by visual inspection, the results are very close to one another.Figure 3 Convex shapes of Hermentaria corresponding to the same Gaussian surface density:the CIF (left) and CIM reconstructions (right).4. Summary We applied the statistical convex inversion method (Muninonen et al. 2020) to analyze the photometric data of Hermentaria. The best-fit solution of the spin parameters and shape as well as the uncertainties of the estimated parameters can be derived. We compared the results to that of the CIF and found that the spin parameters are consistent with one another. The Gaussian surface density derived by the two methods is slightly different which leads to slightly different convex shapes. For validating the new shape reconstruction method in Muinonen et al. (2020), we compared the shape derived by the methods of Kaasalainen tel al.(2001) and Muinonen et al. (2020) from the same Gaussian surface density, and found them to be similar.ReferencesCellino, A., Hestroffer, D., Tanga, P., Mottola, S., & Dell’Oro, A. 2009, A&A, 506, 935Cellino, A., Muinonen, K., Hestroffer, D., & Carbognani, A. 2015, PSS, 118, 221Kaasalainen, M., Lamberg, L., & Lumme, K. 1992a, A&A, 259, 333Kaasalainen, M., Lamberg, L., Lumme, K., & Bowell, E. 1992b, A&A, 259, 318Kaasalainen, M. & Torppa, J. 2001a, Icarus, 153, 24Kaasalainen, M., Torppa, J., & Muinonen, K. 2001b, Icarus, 153, 37Lagerkvist, C.-I., Erikson, A., Debehogne, H., et al. 1995, A&A Supplement Series, 113, 115Lamberg, L. 1993, Ph.D. thesis, University of Helsinki, Finland, vol. 315LLumme, K. & Bowell, E. 1981, Astron J, 86, 1694 Minkowski, H. 1903, Mathematische Annalen, 57, 447Muinonen, K. & Lumme, K. 2015a, A&A, 584, A23Muinonen, K., Wilkman, O., Cellino, A., Wang, X., & Wang, Y. 2015b, PSS, 118, 227Muinonen ,K., Torppa, J., Wang, X.-B., Cellino,A., Penttilä , A., 2020, submited to A&A, in revisedRussell, H. N. 1906, Astrophys J, 24, 1Wang, X., Muinonen, K., & Wang, Y. 2015a, PSS, 118, 242Wang, X., Muinonen, K., Wang, Y., et al. 2015b, A&A, 581, A55

We study the surface composition of asteroids with visible and/or infrared spectroscopy. For example, asteroid taxonomy is based on the spectral features or multiple color indices in visible and near-infrared wavelengths. The composition of asteroids gives key information to understand their origin and evolution. However, we lack compositional information for faint asteroids due to the limits of ground-based observational instruments. In the near future, the Chinese Space Survey Telescope (CSST) will provide multiple colors and spectroscopic data for asteroids of apparent magnitude brighter than 25 and 23 mag, respectively. With the aim of analyzing the CSST spectroscopic data, we applied an algorithm using artificial neural networks (ANNs) to establish a preliminary classification model for asteroid taxonomy according to the design of the survey module of CSST. Using the SMASS II spectra and the Bus–Binzel taxonomic system, our ANN classification tool composed of five individual ANNs is constructed, and the accuracy of this classification system is higher than 92%. As the first application of our ANN tool, 64 spectra of 42 asteroids obtained by us in 2006 and 2007 with the 2.16 m telescope in the Xinglong station (Observatory Code 327) of National Astronomical Observatory of China are analyzed. The predicted labels of these spectra using our ANN tool are found to be reasonable when compared to their known taxonomic labels. Considering its accuracy and stability, our ANN tool can be applied to analyze CSST asteroid spectra in the future.

High-precision transit photometry supplies ideal opportunities for detecting new exoplanets and characterizing their physical properties, which usually encode valuable information for unveiling the planetary structure, atmosphere and dynamical history. We present revised properties of three transiting systems (i.e., HAT-P-13, HAT-P-16 and WASP-32) through analyzing TESS photometry and ground-based transit observations, which were obtained at the 1m and 2.4m telescopes of Yunnan Observatories, China, and the 1.2m telescope of Hamburg Observatory, Germany, as well as the data in the literature. During modelling the transit light curves, Gaussian process is employed to account for the potential systematic errors. Through comprehensive timing analysis, we find that both HAT-P-13b and HAT-P-16b show significant timing variations (TTVs) that can be explained by apsidal precession. TTVs of WASP-32b may be led by a decaying orbit due to tidal dissipation or apsidal precession. However, the current observations can not rule out the origins of three systems' TTVs from gravitational perturbations of close planetary companions conclusively.

ABSTRACT We present optimized physical parameters of the active eclipsing binary system USNO-B1.0 1387-0467554 discovered recently in Yunnan–Hong Kong wide-field photometric (YNHK) survey, based on the analysis of its two colour light curves and low resolution spectra obtained at Yunnan Observatories, China. Its spot distributions are derived by means of the Wilson–Devinney code, using photometric data of the YNHK survey from 2016 to 2021. There exist active longitude belts for the spot activities on the primary star, for which the effect of tidal force seems dominant comparing with the one of common magnetic field of the binary system. We have investigated its chromospheric activities through the indicators including Hα, Hβ, CaII H&K, and HeI D3 lines covered by the low resolution spectroscopic observations. There are obvious spatial correlations between the magnetic activities in its photosphere and chromosphere. The EHα/EHβ values suggest that both plages and prominences led to the emissions seen in the Balmer lines at most phases. A prominence structure appeared around the phase of 0.8 on 2018 October 25 and evolved in November and December, 2018. The spectra demonstrate that there were frequent flare events in the system. Moreover, the decay part of a white-light flare event was hunted by the YNHK survey on 2021 October 26.