Search Publications
Calibrating the Cepheid Period-Wesenheit Relation in the Gaia Bands Using Galactic Open-cluster Cepheids
Xu, Ye; Liu, Dejian; Hao, Chaojie +3 more
Establishing the period-Wesenheit relation requires independent and accurate distance measurements of classical Cepheids (DCEPs). The precise distances provided by associated open clusters independently calibrate the period-Wesenheit relations of DCEPs. 51 DCEPs associated with open clusters are compiled using the constraints of five-dimensional a…
A Hydro-based MCMC Analysis of SNR 0509-67.5: Revealing the Explosion Properties from Fluid Discontinuities Alone
Hughes, John P.; Arunachalam, Prasiddha; Hovey, Luke +1 more
Using Hubble Space Telescope/ACS Hα images of SNR 0509-67.5 taken ~10 yr apart, we measure the forward shock (FS) proper motions (PMs) at 231 rim locations. The average shock radius and velocity are 3.66 ± 0.036 pc and 6315 ± 310 km s-1. Hydrodynamic simulations, recast as similarity solutions, provide models for the supernova remnant's…
The Dynamic Coupling of Streamers and Pseudostreamers to the Heliosphere
Antiochos, S. K.; Higginson, A. K.; Wyper, P. F. +3 more
The slow solar wind is generally believed to result from the interaction of open and closed coronal magnetic flux at streamers and pseudostreamers. We use three-dimensional magnetohydrodynamic simulations to determine the detailed structure and dynamics of open-closed interactions that are driven by photospheric convective flows. The photospheric …
Observed Rate Variations in Superflaring G-type Stars
Yang, Kai; Crowley, James; Wheatland, Michael S.
Flare occurrence on the Sun is highly variable, exhibiting both short-term variation due to the emergence and evolution of active regions, and long-term variation from the solar cycle. On solar-like stars, more energetic stellar flares (superflares) have been observed, and it is of interest to determine whether the observed rates of superflare occ…
A Ghost in Boötes: The Least-Luminous Disrupted Dwarf Galaxy
Conroy, Charlie; Ting, Yuan-Sen; Cargile, Phillip A. +9 more
We report the discovery of Specter, a disrupted ultrafaint dwarf galaxy revealed by the H3 Spectroscopic Survey. We detected this structure via a pair of comoving metal-poor stars at a distance of 12.5 kpc, and further characterized it with Gaia astrometry and follow-up spectroscopy. Specter is a 25° × 1° stream of stars that is entirely invisible…
He II Lyα Transmission Spikes and Absorption Troughs in Eight High-resolution Spectra Probing the End of He II Reionization
Richter, Philipp; Hennawi, Joseph F.; Worseck, Gábor +3 more
We present statistics of He II Lyα transmission spikes and large-scale absorption troughs using archival high-resolution (R = λ/Δλ ≃ 12,500-18,000) far-UV spectra of eight He II-transparent quasars obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. The sample covers the redshift range 2.5 ≲ z ≲ 3.8, thereby probing the ra…
The ALPINE-ALMA [C II] Survey: The Infrared-Radio Correlation and Active Galactic Nucleus Fraction of Star-forming Galaxies at z 4.4-5.9
Shen, Lu; Koekemoer, Anton M.; Jones, Gareth C. +26 more
We present the radio properties of 66 spectroscopically confirmed normal star-forming galaxies (SFGs) at 4.4 < z < 5.9 in the COSMOS field that were [C II]-detected in the Atacama Large Millimeter/submillimeter Array Large Program to INvestigate [C II] at Early times (ALPINE). We separate these galaxies ("C II-detected-all") into lower-redsh…
Spectroscopic Study of Four Metal-poor Carbon Stars from the Hamburg/ESO Survey: On Confirming the Low-mass Nature of Their Companions
Shejeelammal, J.; Goswami, Aruna
Elemental abundances of extrinsic carbon stars provide insight into the poorly understood origin and evolution of elements in the early Galaxy. In this work, we present the results of a detailed spectroscopic analysis of four potential carbon star candidates from the Hamburg/ESO Survey (HES): HE 0457-1805, HE 0920-0506, HE 1241-0337, and HE 1327-2…
Asteroseismology of the DAV Star L19-2
Chen, Yanhui
L19-2 is a DAV star, which was intermittently observed from 1976 to 2013. Five independent pulsation modes of 350, 192, 143, 118, and 113 s are identified. The five modes can be used to constrain the fitting models. The rates of period change can be obtained through the O-C method for the modes of 192 and 113 s, which can be used to study the evol…
A Very Metal-poor RR Lyrae Star with a Disk Orbit Found in the Solar Neighborhood
Kobayashi, Naoto; Maehara, Hiroyuki; Hattori, Kohei +28 more
Metal-deficient stars are important tracers for understanding the early formation of the Galaxy. Recent large-scale surveys with both photometric and spectroscopic data have reported an increasing number of metal-deficient stars whose kinematic features are consistent with those of the disk stellar populations. We report the discovery of an RR Lyr…