Search Publications
Li abundances for solar twins in the open cluster M67
Carlos, Marília; Meléndez, Jorge; do Nascimento, José-Dias +1 more
We determine lithium (Li) abundances for solar twins in the M67 open cluster to add valuable information about the correlation between Li depletion and stellar age and, then, better understand stellar structure and evolution. We use high resolution and good signal-to-noise ratio spectra to characterize Li depletion in three solar twins from M67, u…
Neon Abundances of B Stars in the Solar Neighborhood
Zhao, Gang; Alexeeva, Sofya; Sadakane, Kozo +4 more
We constructed a comprehensive model atom for Ne I-Ne II using the most-up-to-date atomic data available and evaluated the nonlocal thermodynamic equilibrium (NLTE) line formation for Ne I and Ne II in classical 1D models representing the atmospheres of B-type stars. We find that the large NLTE strengthening of the Ne I lines corresponding to the …
Hi-C 2.1 Observations of Small-scale Miniature-filament-eruption-like Cool Ejections in an Active Region Plage
Winebarger, Amy R.; Panesar, Navdeep K.; Moore, Ronald L. +5 more
We examine 172 Å ultra-high-resolution images of a solar plage region from the High-Resolution Coronal Imager, version 2.1 (Hi-C 2.1, or Hi-C) rocket flight of 2018 May 29. Over its five minute flight, Hi-C resolved a plethora of small-scale dynamic features that appear near noise level in concurrent Solar Dynamics Observatory (SDO) Atmospheric Im…
New luminous blue variable candidates in the NGC 247 galaxy
Vinokurov, A.; Solovyeva, Y.; Atapin, K. +6 more
We search for luminous blue variable (LBV) stars in galaxies outside the Local Group. Here we present a study of two bright Hα sources in the NGC 247 galaxy. Object j004703.27-204708.4 (MV = -9.08 ± 0.15 mag) shows the spectral lines typical for well-studied LBV stars: broad and bright emission lines of hydrogen and helium He I with P C…
A Study of the Observational Properties of Coronal Mass Ejection Flux Ropes near the Sun
Gopalswamy, N.; Sindhuja, G.
We present the observational properties of coronal mass ejection (CME) flux ropes (FRs) near the Sun based on a set of 35 events from solar cycle 24 (2010-2017). We derived the CME FR properties using the Flux Rope from Eruption Data technique. According to this technique, the geometrical properties are obtained from a flux-rope fit to CMEs and th…
Photometric flaring fraction of M dwarf stars from the SkyMapper Southern Survey
Wolf, Christian; Onken, Christopher A.; Chang, Seo-Won
We present our search for flares from M dwarf stars in the SkyMapper Southern Survey DR1, which covers nearly the full Southern hemisphere with six-filter sequences that are repeatedly observed in the passbands uvgriz. This allows us to identify bona fide flares in single-epoch observations on time-scales of less than four minutes. Using a correla…
Search for Alignment of Disk Orientations in Nearby Star-forming Regions: Lupus, Taurus, Upper Scorpius, ρ Ophiuchi, and Orion
Suto, Yasushi; Aizawa, Masataka; Nakazato, Takeshi +2 more
Spatial correlations among protoplanetary disk orientations carry unique information on physics of multiple-star formation processes. We select five nearby star-forming regions that comprise a number of protoplanetary disks with spatially resolved images with ALMA and Hubble Space Telescope, and we search for the mutual alignment of the disk axes.…
Oversized Gas Clumps in an Extremely Metal-poor Molecular Cloud Revealed by ALMA's Parsec-scale Maps
Qiu, Keping; Chen, Yanmei; Zhang, Qizhou +8 more
Metals are thought to have profound effects on the internal structures of the molecular clouds in which stars are born. The absence of metals is expected to prevent gas from efficient cooling and fragmentation in theory. However, this effect has not yet been observed in low-metallicity environments, such as in the early universe and local dwarf ga…
Sudden and steady orbital period changes across the classical nova eruptions of DQ Her and BT Mon
Schaefer, Bradley E.
I report two new measures of the sudden change in the orbital period (P) across the nova eruption (ΔP) and the steady period change in quiescence (\dot{P}) for classical novae (CNe) DQ Her and BT Mon. The fractional changes (ΔP/P) in parts per million (ppm) are -4.46 ± 0.03 for DQ Her and +39.6 ± 0.5 for BT Mon. For BT Mon, the ΔP/P value is not l…
Deep XMM-Newton observations of the most distant SPT-SZ galaxy cluster
Allen, Steven W.; Bayliss, Matthew; Canning, Rebecca E. A. +5 more
We present results from a 577 ks XMM-Newton observation of SPT-CL J0459-4947, the most distant cluster detected in the South Pole Telescope 2500 square degree (SPT-SZ) survey, and currently the most distant cluster discovered through its Sunyaev-Zel'dovich effect. The data confirm the cluster's high redshift, z = 1.71 ± 0.02, in agreement with ear…