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  • TESS Investigation—Demographics of Young Exoplanets (TI-DYE). III. An Inner Super-Earth in TOI 2076
    Young (<500 Myr) multiplanet transiting systems are valuable environments for understanding planet evolution by offering an opportunity to make direct comparisons between planets from the same formation conditions. TOI 2076 is known to harbor three 2.5–4 R⊕ planets on 10–35 days orbits. All three are JWST cycle 3 targets (for transmission spectroscopy). Here, we present the detection of TOI 2076 e; a smaller (1.35 R⊕) inner (3.02 days) planet in the system. We update the age of the system by analyzing the rotation periods, lithium equivalent widths, color–magnitude diagram, and variability of likely comoving stars, finding that TOI 2076 and comoving planetary system TOI 1807 are 210 ± 20 Myr. The discovery of TOI 2076 e is motivation to revisit known transiting systems in search of additional planets that are now detectable with new TESS data and updated search methods.

  • The True Stellar Obliquity of a Sub-Saturn Planet from the Tierras Observatory and the Keck Planet Finder
    We measure the true obliquity of TOI-2364, a K dwarf with a sub-Saturn-mass (Mp = 0.18 MJ) transiting planet on the upper edge of the hot-Neptune desert. We used new Rossiter–McLaughlin observations gathered with the Keck Planet Finder to measure the sky-projected obliquity λ = 7° + 10°–11°. Combined with a stellar rotation period of 23.47 ± 0.29 days measured with photometry from the Tierras Observatory, this yields a stellar inclination of 90° ± 13° and a true obliquity ψ = 15 6 + 7 7–7 3, indicating that the planet’s orbit is well aligned with the rotation axis of its host star. The determination of ψ is important for investigating a potential bimodality in the orbits of short-period sub-Saturns around cool stars, which tend to be either aligned with or perpendicular to their host stars’ spin axes.

  • Observation and Simulation of Mutual Approximations between Five Main Uranian Satellites
    Mutual approximation is an emerging method for obtaining high-precision astrometric measurements of natural satellites and asteroids. We used the 80 cm YaoAn High Precision Telescope to observe mutual approximation events of the main Uranian satellites during the period from 2021 to 2023. The average of internal errors along the directions of apparent relative motion and position are 20.0 and 5.1 mas, respectively. On the other hand, the rms of differences between observational results and the Jet Propulsion Laboratory ephemeris along the direction of apparent relative motion and position are 42.5 and 20.6 mas, respectively. We also investigated the factors affecting astrometric precision and found two simple indicators to exclude the invalid mutual approximation events, i.e., the events that do not contribute to precision enhancement. One indicator is the impact parameters divided by the difference of two satellites’ apparent semimajor axes; the other is the apparent relative velocity divided by the difference of their apparent orbital velocities. The resulting quotients of all invalid events are significantly larger than 1.1. Simulations confirm that the indicators are suitable for all the main Uranian satellites' mutual approximation events in recent years and the near future. Consequently, it is recommended to exclude invalid events from future observation campaigns by using the two indicators.

  • Determining the Methanol Deuteration in the Disk Around V883 Orionis with Laboratory Measured Spectroscopy
    Deuterium fractionation, as studied through mono-deuterated methanol, is frequently used as a diagnostic tool to trace the physical conditions and chemical evolution of interstellar sources. This study investigates methanol deuteration in the disk around V883 Ori, utilising recent laboratory spectroscopic data for CH2DOH and CH3OD along with Atacama Large Millimeter/submillimeter Array observations. The derived column densities for CH2DOH and CH3OD are (5.14 ± 0.08) × 1016 cm−2 and (4.22 ± 0.06) × 1016 cm−2, respectively. The analysis demonstrates the influence of spectroscopic data on determining molecular column density, excitation temperature, and, most importantly, the inferred D/H ratio. The D/H ratio for CH2DOH is calculated to be (7.3 ± 1.5) × 10−3 after applying a statistical correction, while the D/H ratio for CH3OD is (1.79 ± 0.36) × 10−2. The discovery of an unexpectedly low CH2DOH/CH3OD ratio (1.22 ± 0.02) in V883 Ori, however, raises further questions about the synthesis and chemical processes involved in CH3OD formation. Overall, this study underscores the importance of accurate spectroscopic data for studies of isotopic fractionation and provides new insights into methanol deuteration chemistry in star-forming regions. Future research, combining updated spectroscopy and chemical modeling, will help further constrain these processes across different masses and evolutionary stages.

  • Photometric Analysis of Asteroids in the Phocaea Region
    The Phocaea asteroid family, one of the large ancient families located in the inner main belt, may be the sources of near-Earth asteroids (NEAs) due to the nearby 3:1 mean motion resonance with Jupiter, the ν6 secular resonance, and the Yarkovsky and Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effects. Thus, understanding the influence of the Yarkovsky and YORP effects on the Phocaea family is one of the keys to figuring out the source of NEAs. However, the physical properties of most of the Phocaea family members are unknown at present. We perform a photometric analysis for 44 asteroids in the Phocaea region using photometric data obtained by ground-based and space-based telescopes (i.e., the Transiting Exoplanet Survey Satellite and Gaia). Based on the derived physical properties, we find significant footprints of the Yarkovsky and YORP effects on the Phocaea family members. Selecting five asteroids nearby the inside boundary of the V shape in the absolute-magnitude semimajor-axis (H, a) space, we estimate their densities considering their migration in semimajor-axis arises from the Yarkovsky effect. The bulk density of (852) Wladilena (3.54 g cm−3) suggests a link to the H chondrite meteorites. Incorporating the grain density of the H chondrites, we estimate the macroporosities of the asteroids (290) Bruna, (1164) Kobolda, and (587) Hypsipyle, respectively, as 41%, 47%, and 65%, implying rubble pile structures. Considering the H chondrites link to asteroid (25) Phocaea, we suggest the parent body of the Phocaea family has been composed of H chondrite like material and the Phocaea family may be one of the sources of H chondrite meteorites.