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  NGTS-31b and NGTS-32b: two inflated hot Jupiters orbiting subgiant stars

  Instituto de Astronomía, Universidad Católica del Norte, Angamos 0610, 1270709 Antofagasta, Chile;; Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército 441, 8370191 Santiago, Chile; Centro de Astrofísica y Tecnologías Afines (CATA), Casilla 36-D, 7591245 Santiago, Chile; Instituto de Astronomía, Universidad Católica del Norte, Angamos 0610, 1270709 Antofagasta, Chile; Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Casilla 36-D, 7591245 Santiago, Chile;; Centre for Exoplanet Research, School of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK; Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, CH-1290 Versoix, Switzerland; Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA;; Perth Exoplanet Survey Telescope, Perth, Australia; Royal Astronomical Society, Burlington House, Piccadilly, London W1J 0BQ, UK; Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA;; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK;; Observatoire Astronomique de l'Université de Genève, Chemin Pegasi 51, CH-1290 Versoix, Switzerland; Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking RH5 6NT, UK;; et al. (Monthly Notices of the Royal Astronomical Society, 2025-01-01)

  We present the discoveries of NGTS-31b(= TOI-2721), and NGTS-32b, two hot Jupiters from the Next Generation Transit Survey (NGTS) transiting slightly evolved stars. The orbital periods, radii, and masses are 4.16 and 3.31 d, 1.61 and 1.42 <inline-formula><tex-math id=TM0001 notation=LaTeX>$R_{J}$</tex-math></inline-formula>, and 1.12 and 0.57 <inline-formula><tex-math id=TM0002 notation=LaTeX>$M_{J}$</tex-math></inline-formula>, respectively. Both planets have an incident stellar flux significantly above the threshold where inflation occurs, with both planets showing signs of inflation. These planets have widely different equilibrium temperatures than other hot Jupiters of similar mass and radius, with NGTS-31b having a significantly lower temperature, and NGTS-32b being hotter. This dichotomy raises the question of how prevalent the roles of other inflation mechanisms are in the radius anomaly phenomena and will help further constrain different inflationary models.
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  Leveraging Movement Representation from Contrastive Learning for Asteroid Detection

  Faculty of ICT, Mahidol University 999 Phutthamonthon Sai 4 Rd, Tambon Salaya, Phutthamonthon, Nakhon Pathom, 73170, Thailand; National Astronomical Research Institute of Thailand, 260 Moo 4, T. Donkaew, A. Maerim, Chiangmai, 50180, Thailand; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; School of Physics &amp; Astronomy, Monash University, Clayton VIC 3800, Australia; Astrophysics Research Cluster, School of Mathematical and Physical Sciences, University of Sheffield, Sheffield S3 7RH, UK; Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain; Astrophysics Research Cluster, School of Mathematical and Physical Sciences, University of Sheffield, Sheffield S3 7RH, UK; School of Physics Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK; Armagh Observatory Planetarium, College Hill, Armagh, BT61 9DG, UK; Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife, Spain; Department of Physics Astronomy, University of Turku, Vesilinnantie 10, Turku, FI-20014, Finland; et al. (Publications of the Astronomical Society of the Pacific, 2024-12-01)

  To support asteroid-related studies, current motion detectors are utilized to select moving object candidates based on their visualizations and movements in sequences of sky exposures. However, the existing detectors encounter the manual parameter settings which require experts to assign proper parameters. Moreover, although the deep learning approach could automate the detection process, these approaches still require synthetic images and hand-engineered features to improve their performance. In this work, we propose an end-to-end deep learning model consisting of two branches. The first branch is trained with contrastive learning to extract a contrastive feature from sequences of sky exposures. This learning method encourages the model to capture a lower-dimensional representation, ensuring that sequences with moving sources (i.e., potential asteroids) are distinct from those without moving sources. The second branch is designed to learn additional features from the sky exposure sequences, which are then concatenated into the movement features before being processed by subsequent layers for the detection of asteroid candidates. We evaluate our model on sufficiently long-duration sequences and perform a comparative study with detection software. Additionally, we demonstrate the use of our model to suggest potential asteroids using photometry filtering. The proposed model outperforms the baseline model for asteroid streak detection by +7.70% of f1-score. Moreover, our study shows promising performance for long-duration sequences and improvement after adding the contrastive feature. Additionally, we demonstrate the uses of our model with the filtering to detect potential asteroids in wide-field detection using the long-duration sequences. Our model could complement the software as it suggests additional asteroids to its detection result.
• Stellar X-Ray Variability and Planetary Evolution in the DS Tucanae System

  Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Department of Astronomy, University of Michigan, Ann Arbor, MI 48109, USA; Geneva Observatory, University of Geneva, Chemin Pegasi 51b, CH-1290 Versoix, Switzerland; Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA; Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK; Armagh Observatory and Planetarium, College Hill, Armagh, NIR BT61 9DG, UK; King, George W.; Corrales, Lía R.; Bourrier, Vincent; Dos Santos, Leonardo A.; et al. (The Astrophysical Journal, 2025-02-01)

  We present an analysis of four Chandra observations of the 45 Myr old DS Tuc binary system. We observed X-ray variability of both stars on timescales from hours to months, including two strong X-ray flares from star A. The implied flaring rates are in agreement with past observations made with XMM-Newton, though these rates remain imprecise due to the relatively short total observation time. We find a clear, monotonic decline in the quiescent level of the star by a factor of 1.8 across 8 months, suggesting stellar variability that might be due to an activity cycle. If proven through future observations, DS Tuc A would be the youngest star for which a coronal activity cycle has been confirmed. The variation in our flux measurements across the four visits is also consistent with the scatter in empirical stellar X-ray relationships with Rossby number. In simulations of the possible evolution of the currently super-Neptune-sized planet DS Tuc A b, we find a range of scenarios for the planet once it reaches a typical field age of 5 Gyr, from Neptune size down to a completely stripped super-Earth. Improved constraints on the planet's mass in the future would significantly narrow these possibilities. We advocate for further Chandra observations to better constrain the variability of this important system.
• A search for close binary systems in the SALT survey of hydrogen-deficient stars using TESS

  Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DB, UK;; Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DB, UK; School of Mathematics and Physics, The Queen's University of Belfast, University Road, Belfast BT7 1NN, UK;; Institut für Physik und Astronomie, Universität Potsdam, Haus 28, Karl-Liebknecht-Str 24/25, D-14476 Potsdam-Golm, Germany; Dr Karl Remeis-Observatory &amp; ECAP, Friedrich-Alexander University Erlangen-Nürnberg, Sternwartstr 7, D-96049 Bamberg, Germany;; Snowdon, E. J.; Jeffery, C. S.; Schlagenhauf, S.; Dorsch, M. (Monthly Notices of the Royal Astronomical Society, 2025-02-01)

  The TESS periodograms of the SALT survey catalogue of hydrogen-deficient stars were searched for evidence of short-period variability. Periodic light-curve variations were identified in 16 stars out of 153 catalogue objects, of which 10 were false positives. From the remaining 6 identified variables, Ton S 415 is a known close binary system and the sixth close binary containing a hydrogen-deficient hot subdwarf. Radial velocity and SED analyses ruled out the remaining 5 as close binary systems; the causes of their variability remain uncertain. With one or more K-type companions, BPS CS 22956-0094 may be a wide binary or triple. From this SALT + TESS sample, the fraction of close binaries stands at <inline-formula><tex-math id=TM0001 notation=LaTeX>$1/29 \approx 3.5~{{\ \rm per\ cent}}$</tex-math></inline-formula> for intermediate helium hot subdwarfs and <inline-formula><tex-math id=TM0002 notation=LaTeX>$0/124 = 0~{{\ \rm per\ cent}}$</tex-math></inline-formula> for extreme helium subdwarfs.
• Polarimetry of Solar System minor bodies and planets: Polarimetry of Solar System minor bodies and planets

  Armagh Observatory &amp; Planetarium, College Hill, BT61 9DG, Armagh, Northern Ireland, UK ;; Institute of Astronomy, V. N. Karazin Kharkiv National University, 35 Sumska str., 61022, Kharkiv, Ukraine ;; INAF, Osservatorio Astrofisico di Torino, 10025, Torino, Italy ;; Infrared Processing and Analysis Center (IPAC), California Institute of Technology, 1200 E California Blvd, MC 100-22, 91125, Pasadena, CA, USA ;; Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008, Granada, Spain ;; Leiden Observatory, Einsteinweg 55, 2333 CC, Leiden, The Netherlands ;; Bagnulo, Stefano; Belskaya, Irina; Cellino, Alberto; Kwon, Yuna G.; et al. (Astronomy and Astrophysics Review, 2024-12-01)

  The study of the polarisation of light is a powerful tool for probing the physical and compositional properties of astrophysical sources, including Solar System objects. In this article, we provide a comprehensive overview of the state-of-the-art in polarimetric studies of various celestial bodies within our Solar System: planets, moons, asteroids, and comets. Additionally, we review relevant laboratory measurements and summarise the fundamental principles of polarimetric observational techniques.

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