Browsing by Author "Calvet, Nuria"

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    Gemini-LIGHTS: Herbig Ae/Be and Massive T Tauri Protoplanetary Disks Imaged with Gemini Planet Imager
    (IOP Publishing, 2022) Rich, Evan A.; Monnier, John D.; Aarnio, Alicia; Laws, Anna S. E.; Setterholm, Benjamin R.; Wilner, David J.; Calvet, Nuria; Harries, Tim; Miller, Chris; Davies, Claire L.; Adams, Fred C.; Andrews, Sean M.; Bae, Jaehan; Espaillat, Catherine; Greenbaum, Alexandra Z.; Hinkley, Sasha; Kraus, Stefan; Hartmann, Lee; Isella, Andrea; McClure, Melissa; Oppenheimer, Rebecca; Pérez, Laura M.; Zhu, Zhaohuan
    We present the complete sample of protoplanetary disks from the Gemini- Large Imaging with the Gemini Planet Imager Herbig/T Tauri Survey, which observed bright Herbig Ae/Be stars and T Tauri stars in near-infrared polarized light to search for signatures of disk evolution and ongoing planet formation. The 44 targets were chosen based on their near- and mid-infrared colors, with roughly equal numbers of transitional, pre-transitional, and full disks. Our approach explicitly did not favor well-known, “famous” disks or those observed by the Atacama Large Millimeter/submillimeter Array, resulting in a less-biased sample suitable to probe the major stages of disk evolution during planet formation. Our optimized data reduction allowed polarized flux as low as 0.002% of the stellar light to be detected, and we report polarized scattered light around 80% of our targets. We detected point-like companions for 47% of the targets, including three brown dwarfs (two confirmed, one new), and a new super-Jupiter-mass candidate around V1295 Aql. We searched for correlations between the polarized flux and system parameters, finding a few clear trends: the presence of a companion drastically reduces the polarized flux levels, far-IR excess correlates with polarized flux for nonbinary systems, and systems hosting disks with ring structures have stellar masses <3 M⊙. Our sample also included four hot, dusty “FS CMa” systems, and we detected large-scale ( >100 au) scattered light around each, signs of extreme youth for these enigmatic systems. Science-ready images are publicly available through multiple distribution channels using a new FITS file standard that has been jointly developed with members of the Very Large Telescope Spectro-polarimetric High-contrast Exoplanet Research team.
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    Twenty-five Years of Accretion onto the Classical T Tauri Star TW Hya
    (IOP Publishing Ltd, 2023) Herczeg, Gregory J.; Chen, Yuguang; Donati, Jean-Francois; Dupree, Andrea K.; Walter, Frederick M.; Hillenbrand, Lynne A.; Johns-Krull, Christopher M.; Manara, Carlo F.; Günther, Hans Moritz; Fang, Min; Schneider, P. Christian; Valenti, Jeff A.; Alencar, Silvia H. P.; Venuti, Laura; Alcalá, Juan Manuel; Frasca, Antonio; Arulanantham, Nicole; Linsky, Jeffrey L.; Bouvier, Jerome; Brickhouse, Nancy S.; Calvet, Nuria; Espaillat, Catherine C.; Campbell-White, Justyn; Carpenter, John M.; Chang, Seok-Jun; Cruz, Kelle L.; Dahm, S. E.; Eislöffel, Jochen; Edwards, Suzan; Fischer, William J.; Guo, Zhen; Henning, Thomas; Ji, Tao; Jose, Jessy; Kastner, Joel H.; Launhardt, Ralf; Principe, David A.; Robinson, Connor E.; Serna, Javier; Siwak, Michal; Sterzik, Michael F.; Takasao, Shinsuke
    Accretion plays a central role in the physics that governs the evolution and dispersal of protoplanetary disks. The primary goal of this paper is to analyze the stability over time of the mass accretion rate onto TW Hya, the nearest accreting solar-mass young star. We measure veiling across the optical spectrum in 1169 archival high-resolution spectra of TW Hya, obtained from 1998–2022. The veiling is then converted to accretion rate using 26 flux-calibrated spectra that cover the Balmer jump. The accretion rate measured from the excess continuum has an average of 2.51 × 10−9 M ⊙ yr−1 and a Gaussian distribution with an FWHM of 0.22 dex. This accretion rate may be underestimated by a factor of up to 1.5 because of uncertainty in the bolometric correction and another factor of 1.7 because of excluding the fraction of accretion energy that escapes in lines, especially Lyα. The accretion luminosities are well correlated with He line luminosities but poorly correlated with Hα and Hβ luminosity. The accretion rate is always flickering over hours but on longer timescales has been stable over 25 years. This level of variability is consistent with previous measurements for most, but not all, accreting young stars.