Journal: The Astronomical Journal

Abbreviation

Astron. j.

Publisher

IOP Publishing

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ISSN

0004-6256
1538-3881

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Publications 1 - 10 of 79
  • Spiral Structure and Differential Dust Size Distribution in the LkH alpha 330 Disk
    Item type: Journal Article
    Akiyama, Eiji; Hashimoto, Jun; Liu, Hauyu B.; et al. (2016)
    The Astronomical Journal
  • TOI-5205b: A Short-period Jovian Planet Transiting a Mid-M Dwarf
    Item type: Journal Article
    Kanodia, Shubham; Mahadevan, Suvrath; Libby-Roberts, Jessica; et al. (2023)
    The Astronomical Journal
    We present the discovery of TOI-5205b, a transiting Jovian planet orbiting a solar metallicity M4V star, which was discovered using Transiting Exoplanet Survey Satellite photometry and then confirmed using a combination of precise radial velocities, ground-based photometry, spectra, and speckle imaging. TOI-5205b has one of the highest mass ratios for M-dwarf planets, with a mass ratio of almost 0.3%, as it orbits a host star that is just 0.392 ± 0.015 M ⊙. Its planetary radius is 1.03 ± 0.03 R J, while the mass is 1.08 ± 0.06 M J. Additionally, the large size of the planet orbiting a small star results in a transit depth of ∼7%, making it one of the deepest transits of a confirmed exoplanet orbiting a main-sequence star. The large transit depth makes TOI-5205b a compelling target to probe its atmospheric properties, as a means of tracing the potential formation pathways. While there have been radial-velocity-only discoveries of giant planets around mid-M dwarfs, this is the first transiting Jupiter with a mass measurement discovered around such a low-mass host star. The high mass of TOI-5205b stretches conventional theories of planet formation and disk scaling relations that cannot easily recreate the conditions required to form such planets.
  • TOI-5375 B: A Very Low Mass Star at the Hydrogen-burning Limit Orbiting an Early M-type Star
    Item type: Journal Article
    Lambert, Mika; Bender, Chad F.; Kanodia, Shubham; et al. (2023)
    The Astronomical Journal
    The Transiting Exoplanet Survey Satellite (TESS) mission detected a companion orbiting TIC 71268730, categorized it as a planet candidate, and designated the system TOI-5375. Our follow-up analysis using radial-velocity data from the Habitable-zone Planet Finder, photometric data from Red Buttes Observatory, and speckle imaging with NN-EXPLORE Exoplanet Stellar Speckle Imager determined that the companion is a very low mass star near the hydrogen-burning mass limit with a mass of 0.080 +/- 0.002M(circle dot) (83.81 +/- 2.10M(J)), a radius of 0.1114(-0.0050)(+0.0048)R(circle dot) (1.0841(0.0487)(0.0467)R(J)), and brightness temperature of 2600 +/- 70 K. This object orbits with a period of 1.721553 +/- 0.000001 days around an early M dwarf star (0.62 +/- 0.016M(circle dot)). TESS photometry shows regular variations in the host star's TESS light curve, which we interpreted as an activity-induced variation of similar to 2%, and used this variability to measure the host star's stellar rotation period of 1.9716(-0.0083)(+0.0080) days. The TOI-5375 system provides tight constraints on stellar models of low-mass stars at the hydrogen-burning limit and adds to the population in this important region.
  • Spatially Resolving the Star Formation Histories of Three Nearby Nuclear Star Clusters
    Item type: Journal Article
    Hannah, Christian H.; Seth, Anil C.; Nguyen, Dieu D.; et al. (2021)
    The Astronomical Journal
    The formation of nuclear star clusters (NSCs) remains an open question. In this work, we use spatially-resolved HST/STIS spectroscopic observations of three nearby NSCs (hosted by NGC 5102, NGC 5206, and NGC 205) to constrain their formation histories by exploring radial variations of the stellar populations within each cluster. Utilizing full-spectrum fitting, we find substantial age and metallicity gradients within the central 0.'' 9 (16 pc) of the NSC in NGC 5102 where populations near the center are young/metal-rich (age similar to 400 Myr and [M/H] similar to -0.4) and become older/metal-poor at larger radii (mean age similar to 1 Gyr and mean [M/H] similar to -1.6 in the radial range [0.'' 3, 0.'' 9]). This behavior suggests that the young/metal-rich population at the center was formed from a period of in situ formation, while the older/metal-poor populations were likely formed by inspiraled globular clusters. The two broad populations observed in the NGC 5102 NSC (young/metal-rich and old/metal-poor) appear to be linked to the transition between the two morphological components of the NSC derived from the surface-brightness profile in Nguyen et al. (2018). The radial ranges explored in NGC 5206 and NGC 205 were much smaller due to poor data quality; in NGC 5206 we find a similar metallicity gradient to NGC 5102 (but with much lower significance), while the data for NGC 205 is too poor to reach any conclusions. Overall, this data highlights the links between the morphological and stellar population complexity of NSCs and their formation mechanisms. © 2021. The American Astronomical Society. All rights reserved.
  • Searching for GEMS: TOI-6383Ab, a Giant Planet Transiting an M3-dwarf Star in a Binary System
    Item type: Journal Article
    Bernabò, Lia Marta; Kanodia, Shubham; Cañas, Caleb I.; et al. (2024)
    The Astronomical Journal
    We report on the discovery of a transiting giant planet around the 3500 K M3-dwarf star TOI-6383A located 172 pc from Earth. It was detected by the Transiting Exoplanet Survey Satellite and confirmed by a combination of ground-based follow-up photometry and precise radial velocity measurements. This planet has an orbital period of ∼1.791 days, a mass of 1.040 ± 0.094 MJ, and a radius of 1.008⁺⁰.⁰³⁶₋₀.₀₃₃, resulting in a mean bulk density of 1.26⁺⁰.¹⁸₋₀.₁₇ g cm⁻³. TOI-6383A has an M dwarf companion star, TOI-6383B, which has a stellar effective temperature of Teff ∼ 3100 K and a projected orbital separation of 3126 au. TOI-6383A is a low-mass dwarf star hosting a giant planet and is an intriguing object for planetary evolution studies due to its high planet-to-star mass ratio. This discovery is part of the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) Survey, intending to provide robust and accurate estimates of the occurrence of GEMS and the statistics on their physical and orbital parameters. This paper presents an interesting addition to the small number of confirmed GEMS, particularly notable since its formation necessitates massive, dust-rich protoplanetary discs and high accretion efficiency (>10%).
  • Iron Isotopic Compositions of Troilite (FeS) Inclusions from Iron Meteorites
    Item type: Journal Article
    Cook, David L.; Schönbächler, Maria (2017)
    The Astronomical Journal
  • The ultraviolet attenuation law in backlit spiral galaxies Based in part on observations made with the NASA Galaxy Evolution Explorer
    Item type: Journal Article
    Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; et al. (2014)
    The Astronomical Journal
  • A High-Eccentricity Warm Jupiter Orbiting TOI-4127
    Item type: Journal Article
    Gupta, Arvind F.; Jackson, Jonathan M.; Hébrard, Guillaume; et al. (2023)
    The Astronomical Journal
    We report the discovery of TOI-4127 b, which is a transiting, Jupiter-sized exoplanet on a long-period ( P = 56.39879 − 0.00010 + 0.00010 days) and a high-eccentricity orbit around a late F-type dwarf star. This warm Jupiter was first detected and identified as a promising candidate from a search for single-transit signals in TESS Sector 20 data, and was later characterized as a planet following two subsequent transits (TESS Sectors 26 and 53) and follow-up ground-based RV observations with the NEID and SOPHIE spectrographs. We jointly fit the transit and RV data to constrain the physical ( R p = 1.096 − 0.032 + 0.039 R J , M p = 2.30 − 0.11 + 0.11 M J ) and orbital parameters of the exoplanet. Given its high orbital eccentricity ( e = 0.7471 − 0.0086 + 0.0078 ), TOI-4127 b is a compelling candidate for studies of warm Jupiter populations and of hot Jupiter formation pathways. We show that the present periastron separation of TOI-4127 b is too large for high-eccentricity tidal migration to circularize its orbit, and that TOI-4127 b is unlikely to be a hot Jupiter progenitor unless it is undergoing angular momentum exchange with an undetected outer companion. Although we find no evidence for an external companion, the available observational data are insufficient to rule out the presence of a perturber that can excite eccentricity oscillations and facilitate tidal migration.
  • Identification of RR Lyrae Stars in Multiband, Sparsely Sampled Data from the Dark Energy Survey Using Template Fitting and Random Forest Classification
    Item type: Journal Article
    DES Collaboration; Stringer, Katelyn M.; Hartley, William G.; et al. (2019)
    The Astronomical Journal
  • Automated SpectroPhotometric Image REDuction (ASPIRED)
    Item type: Journal Article
    Lam, Marco C.; Smith, Robert J.; Arcavi, Iair; et al. (2023)
    The Astronomical Journal
    We provide a suite of public open-source spectral data-reduction software to rapidly obtain scientific products from all forms of long-slit-like spectroscopic observations. Automated SpectroPhotometric REDuction (ASPIRED) is a Python-based spectral data-reduction toolkit. It is designed to be a general toolkit with high flexibility for users to refine and optimize their data-reduction routines for the individual characteristics of their instruments. The default configuration is suitable for low-resolution long-slit spectrometers and provides a quick-look quality output. However, for repeatable science-ready reduced spectral data, some moderate one-time effort is necessary to modify the configuration. Fine-tuning and additional (pre)processing may be required to extend the reduction to systems with more complex setups. It is important to emphasize that although only a few parameters need updating, ensuring their correctness and suitability for generalization to the instrument can take time due to factors such as instrument stability. We compare some example spectra reduced with ASPIRED to published data processed with iraf-based and STARLINK-based pipelines, and find no loss in the quality of the final product. The Python-based, iraf-free ASPIRED can significantly ease the effort of an astronomer in constructing their own data-reduction workflow, enabling simpler solutions to data-reduction automation. This availability of near-real-time, science-ready data will allow adaptive observing strategies, particularly important in, but not limited to, time-domain astronomy.
Publications 1 - 10 of 79