Search Publications
X-Ray Emission from the Nuclear Region of Arp 220
Elvis, Martin; Risaliti, Guido; Karovska, Margarita +6 more
We present an imaging and spectral analysis of the nuclear region of the ultraluminous infrared galaxy merger of Arp 220, using deep Chandra-ACIS observations summing up to ∼ 300 {{ks}}. Narrowband imaging with subpixel resolution of the innermost nuclear region reveals two distinct Fe-K emitting sources, coincident with the infrared and radio nuc…
Sunspots, Starspots, and Elemental Abundances
Doschek, G. A.; Warren, H. P.
Element abundances in the solar photosphere, chromosphere, transition region, and corona are key parameters for investigating sources of the solar wind and for estimating radiative losses in the quiet corona and in dynamical events such as solar flares. Abundances in the solar corona and photosphere differ from each other depending on the first io…
Far-infrared Properties of Infrared-bright Dust-obscured Galaxies Selected with IRAS and AKARI Far-infrared All-sky Survey
Goto, Tomotsugu; Yamamura, Issei; Koyama, Yusei +6 more
We investigate the star-forming activity of a sample of infrared (IR)-bright dust-obscured galaxies (DOGs) that show an extreme red color in the optical and IR regime, {(I-[22])}{AB}> 7.0. Combining an IR-bright DOG sample with the flux at 22 µm > 3.8 mJy discovered by Toba & Nagao with the IRAS faint source catalog vers…
Hot Gas in the Wolf-Rayet Nebula NGC 3199
Gruendl, R. A.; Marston, A. P.; Chu, Y. -H. +2 more
The Wolf-Rayet (WR) nebula NGC 3199 has been suggested to be a bow shock around its central star, WR 18, which is presumably a runaway star, because optical images of the nebula show a dominating arc of emission southwest of the star. We present the XMM-Newton detection of extended X-ray emission from NGC 3199, unveiling the powerful effect of the…
Modeling Type II-P/II-L Supernovae Interacting with Recent Episodic Mass Ejections from Their Presupernova Stars with MESA and SNEC
Das, Sanskriti; Ray, Alak
We show how dense, compact, discrete shells of circumstellar gas immediately outside of red supergiants affect the optical light curves of Type II-P/II-L supernovae (SNe), using the example of SN 2013ej. Earlier efforts in the literature had used an artificial circumstellar medium (CSM) stitched to the surface of an evolved star that had not gone …
The Evolution of Star formation Activity in Cluster Galaxies over 0.15 < z < 1.5
Stanford, S. A.; Stern, Daniel; Snyder, Gregory F. +3 more
We explore 7.5 billion years of evolution in the star formation activity of massive ({M}\star > {10}10.1 {M}⊙ ) cluster galaxies using a sample of 25 clusters over 0.15< z< 1 from the Cluster Lensing And Supernova survey with Hubble and 11 clusters over 1< z< 1.5 from the IRAC Shallow Cluster Survey.…
PTF11kx: A Type Ia Supernova with Hydrogen Emission Persisting after 3.5 Years
Fox, O. D.; Filippenko, A. V.; Nugent, P. E. +4 more
The optical transient PTF11kx exhibited both the characteristic spectral features of Type Ia supernovae (SNe Ia) and the signature of ejecta interacting with circumstellar material (CSM) containing hydrogen, indicating the presence of a nondegenerate companion. We present an optical spectrum at 1342 days after peak from Keck Observatory, in which …
Active Longitude and Coronal Mass Ejection Occurrences
Srivastava, A. K.; Erdélyi, R.; Singh, T. +2 more
The spatial inhomogeneity of the distribution of coronal mass ejection (CME) occurrences in the solar atmosphere could provide a tool to estimate the longitudinal position of the most probable CME-capable active regions in the Sun. The anomaly in the longitudinal distribution of active regions themselves is often referred to as active longitude (A…
Near-Infrared Knots and Dense Fe Ejecta in the Cassiopeia A Supernova Remnant
Koo, Bon-Chul; Lee, Jae-Joon; Moon, Dae-Sik +2 more
We report the results of broadband (0.95-2.46 µm) near-infrared spectroscopic observations of the Cassiopeia A supernova remnant. Using a clump-finding algorithm in two-dimensional dispersed images, we identify 63 “knots” from eight slit positions and derive their spectroscopic properties. All of the knots emit [Fe II] lines together with ot…
Absolute Magnitudes of Seismic Red Clumps in the Kepler Field and SAGA: The Age Dependency of the Distance Scale
Zhao, G.; Casagrande, L.; Bovy, J. +4 more
Red clump stars are fundamental distance indicators in astrophysics, although theoretical stellar models predict a dependence of absolute magnitudes with age. This effect is particularly strong below ∼2 Gyr, but even above this limit a mild age dependence is still expected. We use seismically identified red clump stars in the Kepler field for whic…