Search Publications
A Solar-cycle Study of Coronal Rotation: Large Variations, Rapid Changes, and Implications for Solar-wind Models
Morgan, Huw; Williams, Thomas; Kuridze, David +1 more
Information on the rotation rate of the corona, and its variation over latitude and solar cycle, is valuable for making global connections between the corona and the Sun, for global estimates of reconnection rates and as a basic parameter for solar-wind modeling. Here, we use a time series of tomographical maps gained from coronagraph observations…
GJ 229B: Solving the Puzzle of the First Known T Dwarf with the APOLLO Retrieval Code
Mandell, Avi M.; McElwain, Michael W.; Howe, Alex R.
GJ 229B was the first T dwarf to be discovered in 1995, and its spectrum has been more thoroughly observed than that of most other brown dwarfs. Yet a full spectroscopic analysis of its atmosphere has not been done with modern techniques. This spectrum has several peculiar features, and recent dynamical estimates of GJ 229B's mass and orbit have d…
A Deep View into the Nucleus of the Sagittarius Dwarf Spheroidal Galaxy with MUSE. III. Discrete Multicomponent Population-dynamical Models Based on the Jeans Equations
Lützgendorf, Nora; Böker, Torsten; Kamann, Sebastian +12 more
We present comprehensive multicomponent dynamical models of M54 (NGC 6715), the nuclear star cluster of the Sagittarius (Sgr) dwarf galaxy, which is undergoing a tidal disruption in the Milky Way halo. Previous papers in this series used a large MUSE mosaic data set to identify multiple stellar populations in the system and study their kinematic d…
SPYGLASS. II. The Multigenerational and Multiorigin Star Formation History of Cepheus Far North
Murphy, Simon J.; Rizzuto, Aaron C.; Kraus, Adam L. +4 more
Young stellar populations provide a record of past star formation, and by establishing their members' dynamics and ages, it is possible to reconstruct the full history of star formation events. Gaia has greatly expanded the number of accessible stellar populations, with one of the most notable recently discovered associations being Cepheus Far Nor…
A Multiwavelength Study of GRS 1716-249 in Outburst: Constraints on Its System Parameters
Soria, Roberto; Gandhi, Poshak; Homan, Jeroen +27 more
We present a detailed study of the evolution of the Galactic black hole transient GRS 1716-249 during its 2016-2017 outburst at optical (Las Cumbres Observatory), mid-infrared (Very Large Telescope), near-infrared (Rapid Eye Mount telescope), and ultraviolet (the Neil Gehrels Swift Observatory Ultraviolet/Optical Telescope) wavelengths, along with…
10 Yr Transformation of the Obscuring Wind in NGC 5548
Gu, Liyi; Kriss, Gerard A.; Mehdipour, Missagh +4 more
A decade ago, the archetypal Seyfert-1 galaxy NGC 5548 was discovered to have undergone major spectral changes. The soft X-ray flux had dropped by a factor of 30 while new broad and blueshifted UV absorption lines appeared. This was explained by the emergence of a new obscuring wind from the accretion disk. Here we report on the striking long-term…
Prevalence of Thermal Nonequilibrium over an Active Region
Antolin, Patrick; Şahin, Seray
Recent observations have shown that besides the characteristic multimillion degree component, the corona also contains a large amount of cool material called coronal rain, whose clumps are 10-100 times cooler and denser than the surroundings and are often organized in larger events, termed showers. Thermal instability (TI) within a coronal loop in…
Warm Absorbers in the Radiation-driven Fountain Model of Low-mass Active Galactic Nuclei
Wada, Keiichi; Ueda, Yoshihiro; Mizumoto, Misaki +1 more
To investigate the origins of the warm absorbers in active galactic nuclei (AGNs), we study the ionization-state structure of the radiation-driven fountain model in a low-mass AGN and calculate the predicted X-ray spectra utilizing the spectral synthesis code Cloudy. The spectra show many absorption and emission line features originating in the ou…
Hubble Space Telescope Detection of the Nucleus of Comet C/2014 UN271 (Bernardinelli-Bernstein)
Jewitt, David; Mutchler, Max J.; Hui, Man-To +1 more
We present a high-resolution observation of the distant comet C/2014 UN271 (Bernardinelli-Bernstein) using the Hubble Space Telescope on 2022 January 8. The signal of the nucleus was successfully isolated by means of a nucleus extraction technique, with an apparent V-band magnitude measured to be 21.65 ± 0.11, corresponding to an absolu…
Detectability of Rotational Modulation in Kepler Sun-like Stars as a Function of Age
Masuda, Kento
We examine how the fraction f of stars for which rotational modulation has been detected in Kepler light curves depends on the stellar mass M ⋆ and age t ⋆. Our sample consists of ≈850 FGK stars hosting transiting planet candidates detected from the prime Kepler mission. For these stars, atmospheric parameters have been deriv…