Search Publications
NGC 1365: A Low Column Density State Unveiling a Low Ionization Disk Wind
Porquet, D.; Reeves, J. N.; Braito, V. +3 more
We present the time-resolved spectral analysis of the XMM-Newton data of NGC 1365 collected during one XMM-Newton observation, which caught this "changing-look" active galactic nucleus in a high flux state characterized also by a low column density (N H ~ 1022 cm-2) of the X-ray absorber. During this observation, t…
Kiloparsec-scale Properties of Emission-line Galaxies
Papovich, Casey; Ferguson, Henry C.; Koekemoer, Anton M. +6 more
We perform a detailed study of the resolved properties of emission-line galaxies at kiloparsec scales to investigate how small-scale and global properties of galaxies are related. We use a sample of 119 galaxies in the GOODS fields. The galaxies are selected to cover a wide range in morphologies over the redshift range 0.2 < z < 1.3. High re…
Expansion of Hydrogen-poor Knots in the Born-again Planetary Nebulae A30 and A78
Gruendl, R. A.; Hamann, W. -R.; Chu, Y. -H. +8 more
We analyze the expansion of hydrogen-poor knots and filaments in the born-again planetary nebulae A30 and A78 based on Hubble Space Telescope (HST) images obtained almost 20 yr apart. The proper motion of these features generally increases with distance to the central star, but the fractional expansion decreases, i.e., the expansion is not homolog…
A Rare Encounter with Very Massive Stars in NGC 3125-A1
Leitherer, Claus; Chandar, Rupali; Wofford, Aida +1 more
Super star cluster A1 in the nearby starburst galaxy NGC 3125 is characterized by broad He II λ1640 emission (FWHM ~ 1200 km s-1) of unprecedented strength (equivalent width, EW = 7.1 ± 0.4 Å). Previous attempts to characterize the massive star content in NGC 3125-A1 were hampered by the low resolution of the UV spectrum and the lack of…
Big Fish in Small Ponds: Massive Stars in the Low-mass Clusters of M83
O'Connell, R. W.; Calzetti, D.; Kennicutt, R. C. +8 more
We have used multi-wavelength Hubble Space Telescope WFC3 data of the starbursting spiral galaxy M83 in order to measure variations in the upper end of the stellar initial mass function (uIMF) using the production rate of ionizing photons in unresolved clusters with ages <= 8 Myr. As in earlier papers on M51 and NGC 4214, the uIMF in M83 is con…
Extreme Conditions in a Close Analog to the Young Solar System: Herschel Observations of epsilon Eridani
Walker, H. J.; Ivison, R. J.; Fridlund, M. +22 more
Far-infrared Herschel images of the epsilon Eridani system, seen at a fifth of the Sun's present age, resolve two belts of debris emission. Fits to the 160 µm PACS image yield radial spans for these belts of 12-16 and 54-68 AU. The south end of the outer belt is ≈10% brighter than the north end in the PACS+SPIRE images at 160, 250, and 350 &…
Multifrequency Studies of the Peculiar Quasar 4C +21.35 during the 2010 Flaring Activity
Maraschi, L.; Troja, E.; Covino, S. +289 more
The discovery of rapidly variable Very High Energy (VHE; E > 100 GeV) γ-ray emission from 4C +21.35 (PKS 1222+216) by MAGIC on 2010 June 17, triggered by the high activity detected by the Fermi Large Area Telescope (LAT) in high energy (HE; E > 100 MeV) γ-rays, poses intriguing questions on the location of the γ-ray emitting region in this f…
C60 in Photodissociation Regions
Wolfire, Mark G.; Sheffer, Yaron; Berné, Olivier +2 more
Recent studies have confirmed the presence of buckminsterfullerene (C60) in different interstellar and circumstellar environments. However, several aspects regarding C60 in space are not yet well understood, such as the formation and excitation processes, and the connection between C60 and other carbonaceous compou…
Determining Heating Timescales in Solar Active Region Cores from AIA/SDO Fe XVIII Images
Warren, Harry P.; Ugarte-Urra, Ignacio
We present a study of the frequency of transient brightenings in the core of solar active regions as observed in the Fe XVIII line component of AIA/SDO 94 Å filter images. The Fe XVIII emission is isolated using an empirical correction to remove the contribution of "warm" emission to this channel. Comparing with simultaneous observations from EIS/…
Simulated Galaxy Interactions as Probes of Merger Spectral Energy Distributions
Smith, Howard A.; Hernquist, Lars; Zezas, Andreas +5 more
We present the first systematic comparison of ultraviolet-millimeter spectral energy distributions (SEDs) of observed and simulated interacting galaxies. Our sample is drawn from the Spitzer Interacting Galaxy Survey and probes a range of galaxy interaction parameters. We use 31 galaxies in 14 systems which have been observed with Herschel, Spitze…