Search Publications
Halfway to the Peak: The JWST MIRI 5.6 µm Number Counts and Source Population
Veilleux, Sylvain; Marchesini, Danilo; Alberts, Stacey +9 more
We present an analysis of eight JWST Mid-Infrared Instrument (MIRI) 5.6 µm images with 5σ depths of ≈0.1 µJy. We detect 2854 sources within our combined area of 18.4 arcmin2. We compute the MIRI 5.6 µm number counts, including an analysis of the field-to-field variation. Compared to earlier published MIRI 5.6 µm …
How Small-scale Jetlike Solar Events from Miniature Flux Rope Eruptions Might Produce the Solar Wind
Panesar, Navdeep K.; Moore, Ronald L.; Sterling, Alphonse C.
We consider small-scale jetlike events that might make the solar wind, as has been suggested in recent studies. We show that the events referred to as "coronal jets" and as "jetlets" both fall on a power-law distribution that also includes large-scale eruptions and spicule-sized features; all of the jetlike events could contribute to the solar win…
The Remarkable X-Ray Spectra and Variability of the Ultraluminous Weak-line Quasar SDSS J1521+5202
Brandt, W. N.; Yu, Zhibo; Zou, Fan +5 more
We present a focused X-ray and multiwavelength study of the ultraluminous weak-line quasar (WLQ) SDSS J1521+5202, one of the few X-ray weak WLQs that is amenable to basic X-ray spectral and variability investigations. J1521+5202 shows striking X-ray variability during 2006–2023, by up to a factor of ≈32 in 0.5–2 keV flux, and our new 2023 Chandra …
Linking High-z and Low-z: Are We Observing the Progenitors of the Milky Way with JWST?
Marconi, Alessandro; Salvadori, Stefania; Rusta, Elka +2 more
The recent JWST observation of the Firefly Sparkle at z = 8.3 offers a unique opportunity to link the high- and the low-z Universe. Indeed, the claim of it being a Milky Way (MW) type of assembly at the cosmic dawn opens the possibility of interpreting the observation with locally calibrated galaxy-formation models. Here, we use the a state-of-the…
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…