Search Publications
Stellar Metallicities from DECam u-band Photometry: A Study of Milky Way Ultra-faint Dwarf Galaxies
Li, Ting S.; Chiti, Anirudh; Limberg, Guilherme +5 more
We conducted an in-depth analysis of candidate member stars located in the peripheries of three ultra-faint dwarf (UFD) galaxy satellites of the Milky Way (MW): Boötes I (Boo1), Boötes II (Boo2), and Segue I (Seg1). Studying these peripheral stars has previously been difficult due to contamination from the MW foreground. We used u-band photometry …
Probing 3D Magnetic Fields Using Starlight Polarization and Grain Alignment Theory
Hoang, Thiem; Truong, Bao
Polarization of starlight induced by dust grains aligned with the magnetic field (hereafter B-field) is widely used to measure the 2D B-fields projected onto the plane-of-sky. Here, we introduce a new method to infer 3D B-fields using starlight polarization. We show that the inclination angle or line-of-sight component of B-fields can be constrain…
The Mega-MUSCLES Treasury Survey: X-Ray to Infrared Spectral Energy Distributions of a Representative Sample of M Dwarfs
Loyd, R. O. Parke; Redfield, Seth; Roberge, Aki +15 more
We present 5–1 × 107 Å spectral energy distributions (SEDs) for 12 M dwarf stars covering spectral types M0–M8. Our SEDs are provided for community use as a sequel to the Measurements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetary Systems (MUSCLES) survey. The 12 stars include eight known exoplanet hosts and four s…
Observations of Microlensed Images with Dual-field Interferometry: On-sky Demonstration and Prospects
Mérand, Antoine; Kreidberg, Laura; Han, Cheongho +61 more
Interferometric observations of gravitational microlensing events offer an opportunity for precise, efficient, and direct mass and distance measurements of lensing objects, especially those of isolated neutron stars and black holes. However, such observations have previously been possible for only a handful of extremely bright events. The recent d…
On the Abiotic Origin of Dimethyl Sulfide: Discovery of Dimethyl Sulfide in the Interstellar Medium
Caselli, Paola; Martín, Sergio; Jiménez-Serra, Izaskun +14 more
Following the discovery of dimethyl sulfide (DMS; CH3SCH3) signatures in comet 67P/Churyumov–Gerasimenko, we report the first detection of this organosulfur species in the interstellar medium during the exploration of an ultradeep molecular line survey performed toward the Galactic center molecular cloud G+0.693-0.027 with th…
Probing X-Ray Timing and Spectral Variability in the Blazar PKS 2155–304 over a Decade of XMM-Newton Observations
Mohorian, Maksym; Bhatta, Gopal; Adhikari, Tek P. +6 more
Blazars, a class of active galactic nuclei (AGN) powered by supermassive black holes, are known for their remarkable variability across multiple timescales and wavelengths. Despite significant advancements in our understanding of AGN central engines, thanks to both ground- and space-based telescopes, the details of the mechanisms driving this vari…
A New Approach to Identifying Red Supergiant Stars in Metal-poor Galaxies: A Case Study of NGC 6822
Yang, Ming; Ren, Yi; Jiang, Biwei +1 more
A complete sample of red supergiant (RSG) stars is important for studying their properties. Identifying RSGs in extragalactic fields first requires removing the Galactic foreground dwarfs. The color–color diagram (CCD) method, specifically using r ‑ z/z ‑ H and J ‑ H/H ‑ K, has proven successful in several studies. However, in metal-poor galaxies,…
Deconstructing the Properties of Solar Super Active Region 13664 in the Context of the Historic Geomagnetic Storm of 2024 May 10–11
Nandy, Dibyendu; Jaswal, Priyansh; Sinha, Suvadip
Active regions (ARs) are sites of strong magnetic fields on the solar surface whose size can be several times that of Earth. They spawn dynamic activity, sometimes resulting in severe space weather. Some ARs characterized by extraordinary magnetic properties and exhibiting extreme activity are termed as super active regions (SARs). Recently, solar…
Rising Near-ultraviolet Spectra in Stellar Megaflares
Notsu, Yuta; Kowalski, Adam F.; Maehara, Hiroyuki +5 more
Flares from M dwarf stars can attain energies up to 104 times larger than solar flares but are generally thought to result from similar processes of magnetic energy release and particle acceleration. Larger heating rates in the low atmosphere are needed to reproduce the shape and strength of the observed continua in stellar flares, whic…
Dynamic Imprints of Colliding-wind Dust Formation from WR 140
Hamaguchi, Kenji; Corcoran, Michael F.; Morris, Mark R. +24 more
Carbon-rich Wolf–Rayet (WR) binaries are a prominent source of carbonaceous dust that contribute to the dust budget of galaxies. The "textbook" example of an episodic dust-producing WR binary, WR 140 (HD 193793), provides us with an ideal laboratory for investigating the dust physics and kinematics in an extreme environment. This study is among th…