Search Publications
The Star Formation History of the Milky Way's Nuclear Star Cluster
Lu, Jessica R.; Morris, Mark R.; Ghez, Andrea M. +6 more
We report the first star formation history study of the Milky Ways nuclear star cluster (NSC), which includes observational constraints from a large sample of stellar metallicity measurements. These metallicity measurements were obtained from recent surveys from Gemini and the Very Large Telescope of 770 late-type stars within the central 1.5 pc. …
A Statistical Study of Short-period Decayless Oscillations of Coronal Loops in an Active Region
Long, David M.; Li, Dong
Coronal loop oscillations are common phenomena in the solar corona, which are often classified as decaying and decayless oscillations. Using the high-resolution observation measured by the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter, we statistically investigate small-scale transverse oscillations with short periods (<200 s) of …
Limit on Supernova Emission in the Brightest Gamma-Ray Burst, GRB 221009A
Carballo-Bello, Julio A.; Smith, Nathan; Wheeler, J. Craig +30 more
We present photometric and spectroscopic observations of the extraordinary gamma-ray burst (GRB) 221009A in search of an associated supernova. Some past GRBs have shown bumps in the optical light curve that coincide with the emergence of supernova spectral features, but we do not detect any significant light-curve features in GRB 221009A, nor do w…
X-Ray Polarization of BL Lacertae in Outburst
Kaaret, Philip; Wu, Kinwah; Enoto, Teruaki +128 more
We report the first >99% confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/γ-ray outburst, a 287 ks observation (2022 November 27-30) was taken using the Imaging X-ray Polarimetry Explorer (IXPE), together with contemporaneous multiwavelength observations from the Neil Gehrels Swift observatory and XMM-Newton in s…
X-Ray Polarization Observations of BL Lacertae
Wu, Kinwah; Masiero, Joseph R.; Tinyanont, Samaporn +144 more
Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus that the synchrotron emission is responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable …
Mass Models of the Milky Way and Estimation of Its Mass from the Gaia DR3 Data Set
Capuzzo-Dolcetta, Roberto; Sylos Labini, Francesco; Chrobáková, Žofia +1 more
We use data from the Gaia DR3 data set to estimate the mass of the Milky Way (MW) by analyzing the rotation curve in the range of distances 5 to 28 kpc. We consider three mass models: The first model adds a spherical dark matter (DM) halo, following the Navarro-Frenk-White (NFW) profile, to the known stellar components. The second model assumes th…
Early Insights for Atmospheric Retrievals of Exoplanets Using JWST Transit Spectroscopy
Madhusudhan, Nikku; Constantinou, Savvas; Gandhi, Siddharth
We have entered the era of the James Webb Space Telescope (JWST). We use the first JWST transmission spectrum of the hot Saturn-mass exoplanet, WASP-39 b, obtained with the NIRSpec instrument in the 3-5 µm range to investigate (a) what atmospheric constraints are possible with JWST-quality data in this spectral range, (b) requirements for at…
A JWST Near- and Mid-infrared Nebular Spectrum of the Type Ia Supernova 2021aefx
Temim, Tea; Foley, Ryan J.; Rest, Armin +55 more
We present JWST near-infrared (NIR) and mid-infrared (MIR) spectroscopic observations of the nearby normal Type Ia supernova (SN) SN 2021aefx in the nebular phase at +255 days past maximum light. Our Near Infrared Spectrograph (NIRSpec) and Mid Infrared Instrument observations, combined with ground-based optical data from the South African Large T…
CLASSY VII Lyα Profiles: The Structure and Kinematics of Neutral Gas and Implications for LyC Escape in Reionization-era Analogs
Martin, Crystal L.; Brinchmann, Jarle; Kumari, Nimisha +23 more
Lyα line profiles are a powerful probe of interstellar medium (ISM) structure, outflow speed, and Lyman-continuum escape fraction. In this paper, we present the Lyα line profiles of the Cosmic Origins Spectrograph (COS) Legacy Archive Spectroscopic SurveY, a sample rich in spectroscopic analogs of reionization-era galaxies. A large fraction of the…
Characterizing the Near-infrared Spectra of Flares from TRAPPIST-1 during JWST Transit Spectroscopy Observations
Kowalski, Adam F.; Espinoza, Néstor; MacGregor, Meredith A. +16 more
We present the first analysis of JWST near-infrared spectroscopy of stellar flares from TRAPPIST-1 during transits of rocky exoplanets. Four flares were observed from 0.6-2.8 µm with the Near Infrared Imager and Slitless Spectrograph and 0.6-3.5 µm with the Near Infrared Spectrograph during transits of TRAPPIST-1b, f, and g. We discove…