Search Publications
Mass Transport around Comets and its Impact on the Seasonal Differences in Water Production Rates
Altwegg, K.; Thomas, N.; Combi, M. R. +4 more
Comets are surrounded by a thin expanding atmosphere, and although the nucleus' gravity is small, some molecules and grains, possibly with the inclusion of ices, can get transported around the nucleus through scattering (atoms/molecules) and gravitational pull (grains). Based on the obliquity of the comet, it is also possible that volatile materia…
Structure and Dynamics of the Accretion Process and Wind in TW Hya
Strader, Jay; Cranmer, S. R.; Smith, Graeme H. +3 more
Time-domain spectroscopy of the classical accreting T Tauri star, TW Hya, covering a decade and spanning the far UV to the near-infrared spectral regions can identify the radiation sources, the atmospheric structure produced by accretion, and properties of the stellar wind. On timescales from days to years, substantial changes occur in emission li…
The Heating of Mid-infrared Dust in the Nearby Galaxy M33: A Testbed for Tracing Galaxy Evolution
Calzetti, Daniela; Boquien, Médéric; van der Werf, Paul +10 more
Infrared emission is an invaluable tool for quantifying star formation in galaxies. Because the 8 µm polycyclic aromatic hydrocarbon (PAH) emission has been found to correlate with other well-known star formation tracers, it has widely been used as a star formation rate (SFR) tracer. There are, however, studies that challenge the accuracy an…
Metal Distributions out to 0.5 r 180 in the Intracluster Medium of Four Galaxy Groups Observed with Suzaku
Sato, Kosuke; Matsushita, Kyoko; Sasaki, Toru
We studied the distributions of metal abundances and metal-mass-to-light ratios in the intracluster medium (ICM) of four galaxy groups, MKW 4, HCG 62, the NGC 1550 group, and the NGC 5044 group, out to ~0.5 r 180 observed with Suzaku. The iron abundance decreases with radius and is about 0.2-0.4 solar beyond 0.1 r 180. At a g…
Early-type Galaxies in the Chandra COSMOS Survey
Civano, F.; Elvis, M.; Pellegrini, S. +4 more
We study a sample of 69 X-ray detected early-type galaxies (ETGs), selected from the Chandra COSMOS survey, to explore the relation between the X-ray luminosity of hot gaseous halos (L X, gas) and the integrated stellar luminosity (LK ) of the galaxies, in a range of redshift extending out to z = 1.5. In the local universe, …
A Multi-instrument Analysis of Sunspot Umbrae
Watson, F. T.; Livingston, W.; Penn, M. J.
The recent solar minimum and rise phase of solar cycle 24 have been unlike any period since the early 1900s. This article examines some of the properties of sunspot umbrae over the last 17 yr with three different instruments on the ground and in space: MDI, HMI and BABO. The distribution of magnetic fields and their evolution over time is shown an…
Understanding the Unique Assembly History of Central Group Galaxies
Treu, Tommaso; Coccato, Lodovico; Leauthaud, Alexie +7 more
Central galaxies (CGs) in massive halos live in unique environments with formation histories closely linked to that of the host halo. In local clusters, they have larger sizes (Re ) and lower velocity dispersions (σ) at fixed stellar mass M *, and much larger Re at a fixed σ than field and satellite galaxies (non-C…
3D-HST Emission Line Galaxies at z ~ 2: Discrepancies in the Optical/UV Star Formation Rates
Trump, Jonathan R.; Schneider, Donald P.; Gronwall, Caryl +6 more
We use Hubble Space Telescope near-IR grism spectroscopy to examine the Hβ line strengths of 260 star-forming galaxies in the redshift range 1.90 < z < 2.35. We show that at these epochs, the Hβ star formation rate (SFR) is a factor of ~1.8 higher than what would be expected from the systems' rest-frame UV flux density, suggesting a shift in…
Patchy Accretion Disks in Ultra-luminous X-Ray Sources
Harrison, F. A.; Fabian, A. C.; Miller, J. M. +5 more
The X-ray spectra of the most extreme ultra-luminous X-ray sources—those with L >= 1040 erg s-1—remain something of a mystery. Spectral roll-over in the 5-10 keV band was originally detected in the deepest XMM-Newton observations of the brightest sources; this is confirmed in subsequent NuSTAR spectra. This emission can be…
Multi-wavelength High-resolution Observations of a Small-scale Emerging Magnetic Flux Event and the Chromospheric and Coronal Response
Yurchyshyn, Vasyl; Vargas Domínguez, Santiago; Kosovichev, Alexander
State-of-the-art solar instrumentation is now revealing magnetic activity of the Sun with unprecedented temporal and spatial resolutions. Observations with the 1.6 m aperture New Solar Telescope (NST) of the Big Bear Solar Observatory are making next steps in our understanding of the solar surface structure. Granular-scale magnetic flux emergence …