Search Publications
SOFIA-EXES Observations of Betelgeuse during the Great Dimming of 2019/2020
Harper, Graham M.; Guinan, Edward F.; Ryde, Nils +5 more
In 2019 October Betelgeuse began a decline in V-band brightness that went beyond the minimum expected from its quasi-periodic ∼420 day cycle, becoming the faintest in recorded photometric history. Observations obtained in 2019 December with Very Large Telescope/SPHERE have shown that the southern half of the star has become markedly fainter than i…
Initial Evaluation of SNEMO2 and SNEMO7 Standardization Derived from Current Light Curves of Type Ia Supernovae
Galbany, L.; Sako, M.; Rubin, D. +7 more
To determine if the SuperNova Empirical Model (SNEMO) can improve Type Ia supernova (SN Ia) standardization of several currently available photometric data sets, we perform an initial test, comparing results with the much-used SALT2 approach. We fit the SNEMO light-curve parameters and pass them to the Bayesian hierarchical model UNITY1.2 to estim…
Insights into the Formation and Evolution History of the Galactic Disk System
Beers, Timothy C.; Lee, Young Sun; Kim, Young Kwang +1 more
We present a kinematic analysis of a sample of 23,908 G- and K-type dwarfs in the Galactic disk. Based on the α-abundance ratio, [α/Fe], we separated our sample into low-α thin-disk and high-α thick-disk stars. We find a ${V}_{\phi }$ gradient of -28.2 km s-1 dex-1 over [Fe/H] for the thin disk and an almost flat trend of the…
2016 Outburst of H 1743-322: XMM-Newton and NuSTAR View
Dewangan, G. C.; Chand, Swadesh; Tripathi, Prakash +2 more
We report the detection of a type C quasi-periodic oscillation (QPO) along with an upper harmonic in the commensurate ratio of 1:2 in two observations of the low-mass black hole transient H 1743-322 jointly observed by XMM-Newton and NuSTAR during the 2016 outburst. We find that the QPO and the upper harmonic exhibit shifts in their centroid frequ…
The Age Dependence of Mid-infrared Emission around Young Star Clusters
Calzetti, Daniela; Lin, Zesen; Kong, Xu +9 more
Using the star cluster catalogs from the Hubble Space Telescope program Legacy Extragalactic UV survey (LEGUS) and 8 µm images from the IRAC camera on the Spitzer Space Telescope for five galaxies within 5 Mpc, we investigate how the 8 µm dust luminosity correlates with the stellar age on the 30-50 pc scale of star-forming regions. We …
Relations between Coronal Mass Ejections and the Photospheric Magnetic Field in Cycles 23 and 24
Bilenko, Irina A.
The number of coronal mass ejections (CMEs) and their parameters and cycle variations were investigated and compared to the photospheric magnetic field evolution in cycles 23 and 24. The Coordinated Data Analysis Workshops (CDAW) catalog of white-light CMEs detected by the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagrap…
Characterizing X-Ray Properties of the Gamma-Ray Pulsar PSR J1418-6058 in the Rabbit Pulsar Wind Nebula
An, Hongjun; Kim, Minjun
We report on X-ray studies of the gamma-ray pulsar PSR J1418-6058 in the Rabbit pulsar wind nebula (PWN) carried out using archival Chandra and XMM-Newton observations. A refined timing analysis performed with the 120 ks XMM-Newton data finds significant (p ≈ 10-7) pulsation at P ≈ 110 ms which is consistent with that measured with the …
A Method for the Estimation of f- and p-mode Parameters and Rotational Splitting Coefficients from Un-averaged Solar Oscillation Power Spectra
Kosovichev, A. G.; Scherrer, P. H.; Larson, T. P. +3 more
We present a new methodology for the fitting of the peaks in solar oscillation power spectra that is equally well-suited for the estimation of low-, medium, and high-degree f- and p-mode parameters and frequency-splitting coefficients. The method can provide accurate input data over a wide portion of the dispersion plane for both structural and ro…
Correlation of Structure and Stellar Properties of Galaxies in Stripe 82
Ho, Luis C.; Sachdeva, Sonali; Shankar, Francesco +1 more
Establishing a correlation (or lack thereof) between the bimodal color distribution of galaxies and their structural parameters is crucial to understand the origin of bimodality. To achieve that, we have performed a 2D mass-based structural decomposition (bulge+disk) of all disk galaxies (total = 1263) in the Herschel imaging area of the Stripe 82…
Optical Counterpart to the Ultraluminous X-Ray Source in the UGC 6456 Galaxy
Vinokurov, A.; Solovyeva, Y.; Atapin, K.
We report the identification of the optical counterpart to the transient ultraluminous X-ray source in the blue dwarf galaxy UGC 6456 (VII Zw 403). The source is highly variable in both the X-ray (by a factor of at least 100, 0.3-10 keV) and optical (by a factor of three, V-band) ranges. The peak X-ray luminosity of UGC 6456 ultraluminous X-ray so…