Search Publications
The Long-term Spectral Changes of Eta Carinae: Are they Caused by a Dissipating Occulter as Indicated by CMFGEN Models?
Hamaguchi, Kenji; Corcoran, Michael F.; Russell, Christopher M. P. +23 more
Eta Carinae (η Car) exhibits a unique set of P Cygni profiles with both broad and narrow components. Over many decades, the spectrum has changed-there has been an increase in observed continuum fluxes and a decrease in Fe II and H I emission-line equivalent widths. The spectrum is evolving toward that of a P Cygni star such as P Cygni itself and H…
A Nearby Isolated Dwarf: Star Formation and Structure of ESO 006-001
Koribalski, Bärbel S.; Anand, Gagandeep S.; Tully, R. Brent +4 more
Observations with the Hubble Space Telescope unexpectedly revealed that the dwarf galaxy ESO 006-001 is a near neighbor to the Local Group at a distance of 2.70 ± 0.11 Mpc. The stellar population in the galaxy is well resolved into individual stars to a limit of M I ~ - 0.5 mag. The dominant population is older than 12 Gyr yet display…
Sustained Heating of the Chromosphere and Transition Region Over a Sunspot Light Bridge
Mathew, Shibu K.; Louis, Rohan E.; Beck, Christian +2 more
Sunspot light bridges (LBs) exhibit a wide range of short-lived phenomena in the chromosphere and transition region. In contrast, we use here data from the Multi-Application Solar Telescope (MAST), the Interface Region Imaging Spectrograph (IRIS), Hinode, the Atmospheric Imaging Assembly (AIA), and the Helioseismic and Magnetic Imager (HMI) to ana…
Lateral Confinement and the Remarkably Self-similar Nature of Coronal Pseudostreamer Mass Ejections
Hess, P.; Wang, Y. -M.
Coronal mass ejections (CMEs) that originate from pseudostreamers, which separate coronal holes of the same magnetic polarity, are characterized by a narrow (~5°-30°), fan-shaped appearance in white-light coronagraph images. Despite this striking morphological similarity, a wide variety of underlying eruptions are observed, including not only coro…
Comparison of the Composition of ICMEs from Active Regions and Quiet-Sun Regions
Chen, Yao; Fu, Hui; Li, Leping +4 more
The composition of interplanetary coronal mass ejections (ICMEs), including the ionic charge states and elemental abundances of heavy elements, is tightly correlated with their source regions and eruption processes. This can help in analyzing the eruption mechanisms and plasma origins of CMEs, and deepen our understanding of energetic solar activi…
Globular Clusters in NGC 4839 Falling into Coma: Evidence for the Second Infall?
Lee, Myung Gyoon; Jang, In Sung; Oh, Seong-A.
NGC 4839 is the brightest galaxy (cD) of the NGC 4839 group at R ≈ 1 Mpc in the southwest of the Coma cluster, which is known to be falling into Coma. However, it has been controversial whether it is in the first phase of infall or in the second phase of infall after passing the Coma center. We present a wide field study of globular clusters (GCs)…
A Statistical Relation between Mass, Age, and Velocity Dispersion in the Solar Neighborhood
Sajadian, Sedighe; Fatheddin, Hossein
The stellar kinematics of the Galactic disk are the main factors constraining disk formation and evolution processes in the Milky Way. In this paper, we investigate a statistical relation between stellar mass, age, and velocity dispersion for stars in the solar neighborhood. Age-velocity dispersion relations, with their applications, have been stu…
Multiple Stellar Populations at Less Evolved Stages. III. A Possible Helium Spread in NGC 2210
Milone, Antonino P.; Wang, Long; Li, Chengyuan +6 more
Helium variations are common features of globular clusters (GCs) with multiple stellar populations. All the formation scenarios predict that secondary population stars are enhanced in helium, but the exact helium content depends on the polluters. Therefore, searching for helium variations in a star cluster is a straightforward method to understand…
Evidence for AGN-regulated Cooling in Clusters at z 1.4: A Multiwavelength View of SPT-CL J0607-4448
Bayliss, Matthew; Kim, Keunho J.; Khullar, Gourav +9 more
We present a multiwavelength analysis of the galaxy cluster SPT-CL J0607-4448 (SPT0607), which is one of the most distant clusters discovered by the South Pole Telescope at z = 1.4010 ± 0.0028. The high-redshift cluster shows clear signs of being relaxed with well-regulated feedback from the active galactic nucleus (AGN) in the brightest cluster g…
Eta Carinae: The Dissipating Occulter Is an Extended Structure
Hamaguchi, Kenji; Corcoran, Michael F.; Moffat, Anthony F. J. +11 more
Previous Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS) longslit observations of Eta Carinae (η Car) identified numerous absorption features in both the stellar spectrum, and in the adjacent nebular spectra, along our line of sight (LOS). The absorption features became temporarily stronger when the ionizing far-ultraviole…