Search Publications
A Comparative Study between M30 and M92: M92 is a Merger Remnant with a Large Helium Enhancement
Lee, Jae-Woo
We perform a comparative study of the ex situ second-parameter pair globular clusters (GCs) M30 and M92, having similar metallicities but different horizontal branch morphologies. We obtain similar mean primordial carbon abundances for both clusters. However, M92 shows a large dispersion in carbon due to a more extended C–N anticorrelation, while …
Shock and Cosmic-Ray Chemistry Associated with the Supernova Remnant W28
Safi-Harb, Samar; Zhou, Ping; Chen, Yang +2 more
Supernova remnants (SNRs) exert a strong influence on the physics and chemistry of the nearby molecular clouds through shock waves and the cosmic rays (CRs) they accelerate. To investigate the SNR–cloud interaction in the prototype interacting SNR W28 (G6.4‑0.1), we present new observations of the HCO+, $\mathrm{HCN}$ , and HNC J = 1–0 …
Eruption of a Million-Kelvin Warm Magnetic Flux Rope on the Sun
Peter, Hardi; Li, Leping; Chitta, Lakshmi Pradeep +4 more
Solar magnetic flux rope (MFR) plays a central role in the physics of coronal mass ejections (CMEs). It mainly includes a cold filament at typical chromospheric temperatures (∼10,000 K) and a hot channel at high coronal temperatures (∼10 MK). The warm MFR at quiescent coronal temperatures of a million Kelvin is, however, rarely reported. In this s…
On the Scarcity of Dense Cores (n > 105 cm‑3) in High-latitude Planck Galactic Cold Clumps
Sanhueza, Patricio; Ward-Thompson, Derek; Whitworth, Anthony +34 more
High-latitude (∣b∣ > 30°) molecular clouds have virial parameters that exceed 1, but whether these clouds can form stars has not been studied systematically. Using JCMT SCUBA-2 archival data, we surveyed 70 fields that target high-latitude Planck Galactic cold clumps (HLPCs) to find dense cores with density of 105–106 cm
The Ancient Star Formation History of the Extremely Low-mass Galaxy Leo P: An Emerging Trend of a Post-reionization Pause in Star Formation
McQuinn, Kristen B. W.; Cannon, John M.; Dolphin, Andrew E. +12 more
Isolated, low-mass galaxies provide the opportunity to assess the impact of reionization on their star formation histories (SFHs) without the ambiguity of environmental processes associated with massive host galaxies. There are very few isolated, low-mass galaxies that are close enough to determine their SFHs from resolved star photometry reaching…
The White-light Superflares from Cool Stars in GWAC Triggers
Wang, Jing; Wang, Liang; Liang, En-Wei +16 more
M-type stars are the ones that flare most frequently, but how big their maximum flare energy can reach is still unknown. We present 163 flares from 162 individual M2 through L1-type stars that triggered the GWAC, with flare energies ranging from 1032.2 to 1036.4 erg. The flare amplitudes range from △G = 0.84 to ∼10 mag. Flare…
Metis Observation of the Onset of Fully Developed Turbulence in the Solar Corona
Telloni, Daniele; Zank, Gary P.; Adhikari, Laxman +70 more
This Letter reports the first observation of the onset of fully developed turbulence in the solar corona. Long time series of white-light coronal images, acquired by Metis aboard Solar Orbiter at 2 minutes cadence and spanning about 10 hr, were studied to gain insight into the statistical properties of fluctuations in the density of the coronal pl…
Accurate, Precise, and Physically Self-consistent Ages and Metallicities for 400,000 Solar Neighborhood Subgiant Branch Stars
Reggiani, Henrique; Schlaufman, Kevin C.; Nataf, David M. +1 more
Age is the most difficult fundamental stellar parameter to infer for isolated stars. While isochrone-based ages are in general imprecise for both main-sequence dwarfs and red giants, precise isochrone-based ages can be obtained for stars on the subgiant branch transitioning from core to shell hydrogen burning. We synthesize Gaia Data Release 3–bas…
Velocity-space Signatures of Resonant Energy Transfer between Whistler Waves and Electrons in the Earth's Magnetosheath
Verscharen, Daniel; Klein, Kristopher G.; Li, Hui +4 more
Wave-particle interactions play a crucial role in transferring energy between electromagnetic fields and charged particles in space and astrophysical plasmas. Despite the prevalence of different electromagnetic waves in space, there is still a lack of understanding of fundamental aspects of wave-particle interactions, particularly in terms of ener…
High-resolution X-Ray Spectroscopy of Interstellar Iron toward Cygnus X-1 and GX 339-4
Lee, Julia C.; Paerels, Frits; Gatuzz, Efrain +7 more
We present a high-resolution spectral study of Fe L-shell extinction by the diffuse interstellar medium (ISM) in the direction of the X-ray binaries Cygnus X-1 and GX 339–4, using the XMM-Newton reflection grating spectrometer. The majority of interstellar Fe is suspected to condense into dust grains in the diffuse ISM, but the compounds formed fr…