Search Publications
Compact Galactic Planetary Nebulae: An HST/WFC3 Morphological Catalog, and a Study of Their Role in the Galaxy
Villaver, Eva; Shaw, Richard A.; Stanghellini, Letizia
We present the images of a Hubble Space Telescope (HST/WFC3) snapshot program of angularly compact Galactic planetary nebulae (PNe), acquired with the aim of studying their size, evolutionary status, and morphology. PNe that are smaller than ∼4″ are underrepresented in most morphological studies, and today they are less well studied than their imm…
The Star Formation Rate Efficiency of Neutral Atomic-dominated Hydrogen Gas in the Outskirts of Star-forming Galaxies from z ~ 1 to z ~3
Koekemoer, Anton M.; Gardner, Jonathan P.; Teplitz, Harry I. +5 more
Current observational evidence suggests that the star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in damped Lyα systems (DLAs) at z∼ 3 is more than 10 times lower than predicted by the Kennicutt-Schmidt (KS) relation. To understand the origin of this deficit, and to investigate possible evolution with redshift and galax…
Enhancement of a Sunspot Light Wall with External Disturbances
Yang, Shuhong; Zhang, Jun; Erdélyi, Robert
Based on the Interface Region Imaging Spectrograph observations, we study the response of a solar sunspot light wall to external disturbances. A flare occurrence near the light wall caused material to erupt from the lower solar atmosphere into the corona. Some material falls back to the solar surface and hits the light bridge (I.e., the base of th…
First Detection of a Pulsar Bow Shock Nebula in Far-UV: PSR J0437-4715
Pavlov, George G.; Kargaltsev, Oleg; Rangelov, Blagoy +3 more
Pulsars traveling at supersonic speeds are often accompanied by cometary bow shocks seen in Hα. We report on the first detection of a pulsar bow shock in the far-ultraviolet (FUV). We detected it in FUV images of the nearest millisecond pulsar J0437-4715 obtained with the Hubble Space Telescope. The images reveal a bow-like structure positionally …
H II Region Ionization of the Interstellar Medium: A Case Study of NGC 7538
Anderson, L. D.; Bania, T. M.; Balser, Dana S. +2 more
Using data from the Green Bank Telescope, we analyze the radio continuum (free-free) and radio recombination line (RRL) emission of the compact H II region NGC 7538 (Sharpless 158). We detect extended radio continuum and hydrogen RRL emission beyond the photodissociation region (PDR) toward the north and east, but a sharp decrease in emission towa…
Cross-correlation between X-Ray and Optical/Near-infrared Background Intensity Fluctuations
Luo, Bin; Xue, Yongquan; Koekemoer, Anton +3 more
Angular power spectra of optical and infrared background anisotropies at wavelengths between 0.5 and 5 µm are a useful probe of faint sources present during reionization, in addition to faint galaxies and diffuse signals at low redshift. The cross-correlation of these fluctuations with backgrounds at other wavelengths can be used to separate…
Discovery of Molecular Hydrogen in SN 1987A
Fransson, Claes; Leibundgut, Bruno; Spyromilio, Jason +3 more
Both CO and SiO have been observed at early and late phases in SN 1987A. H2 was predicted to form at roughly the same time as these molecules, but was not detected at early epochs. Here, we report the detection of NIR lines from H2 at 2.12 and 2.40 µ {{m}} in VLT/SINFONI spectra obtained between days 6489 and 10,120. Th…
Measurement of the Integrated Sachs-Wolfe Effect Using the AllWISE Data Release
Wright, Edward L.; Shajib, Anowar J.
One of the physical features of a dark-energy-dominated universe is the integrated Sachs-Wolfe (ISW) effect on the cosmic microwave background (CMB) radiation, which gives us a direct observational window to detect and study dark energy. The AllWISE data release of the Wide-field Infrared Survey Explorer (WISE) has a large number of point sources …
Properties and Modeling of Unresolved Fine Structure Loops Observed in the Solar Transition Region by IRIS
Warren, Harry P.; Brooks, David H.; Reep, Jeffrey W.
Recent observations from the Interface Region Imaging Spectrograph (IRIS) have discovered a new class of numerous low-lying dynamic loop structures, and it has been argued that they are the long-postulated unresolved fine structures (UFSs) that dominate the emission of the solar transition region. In this letter, we combine IRIS measurements of th…
Concurrent Formation of Carbon and Silicate Dust in Nova V1280 Sco
Onaka, Takashi; Usui, Fumihiko; Koo, Bon-Chul +12 more
We present infrared multi-epoch observations of the dust-forming nova V1280 Sco over ∼2000 days from the outburst. The temporal evolution of the infrared spectral energy distributions at 1272, 1616, and 1947 days can be explained by the emissions produced by amorphous carbon dust of mass (6.6-8.7) × 10-8 M⊙ with a representat…