Search Publications
The SLUGGS survey: combining stellar and globular cluster metallicities in the outer regions of early-type galaxies
Spitler, Lee R.; Forbes, Duncan A.; Romanowsky, Aaron J. +9 more
The outer halo regions of early-type galaxies carry key information about their past accretion history. However, spectroscopically probing the stellar component at such galactocentric radii is still challenging. Using the DEep Imaging Multi-Object Spectrograph on the Keck, we have been able to measure the metallicities of the stellar and globular …
No evidence for the blue-tilted power spectrum of relic gravitational waves
Huang, Qing-Guo; Wang, Sai
In this paper, we constrain the tilt of the power spectrum of relic gravitational waves by combining the data from BICEP2/Keck Array and Planck (BKP) and the Laser Interferometer Gravitational-Waves Observatory (LIGO). Supposing the linearly uniform priors for both the tensor-to-scalar ratio r and the tensor tilt nt, we find nt
Limb Event Brightenings and Fast Ejection Using IRIS Mission Observations
Koutchmy, S.; Golub, L.; Tavabi, E.
The Interface Region Imaging Spectrograph (IRIS) of the recently commissioned NASA small explorer mission provides significantly more complete and higher resolution spectral coverage of the dynamical conditions inside the chromosphere and transition region (TR) than has been available ever before. High temporal, spatial (0.3″) and spect…
SHAPEMOL: a 3D code for calculating CO line emission in planetary and protoplanetary nebulae. Detailed model-fitting of the complex nebula NGC 6302
Santander-García, M.; Bujarrabal, V.; Steffen, W. +1 more
Context. Modern instrumentation in radioastronomy constitutes a valuable tool for studying the Universe: ALMA has reached unprecedented sensitivities and spatial resolution, while Herschel/HIFI has opened a new window (most of the sub-mm and far-infrared ranges are only accessible from space) for probing molecular warm gas (~50-1000 K). On the oth…
Phenomenological approaches of inflation and their equivalence
Mena, Olga; Boubekeur, Lotfi; Ramírez, Héctor +1 more
In this work, we analyze two possible alternative and model-independent approaches to describe the inflationary period. The first one assumes a general equation of state during inflation due to Mukhanov, while the second one is based on the slow-roll hierarchy suggested by Hoffman and Turner. We find that, remarkably, the two approaches are equiva…
On the distances of planetary nebulae
Smith, Haywood
Past calibrations of statistical distance scales for planetary nebulae have been problematic, especially with regard to `short' versus `long' scales. Reconsidering the calibration process naturally involves examining the precision and especially the systematic errors of various distance methods. Here, we present a different calibration strategy, n…
Strong Erosion-Driven Nongravitational Effects in Orbital Motions of the Kreutz Sungrazing System’s Dwarf Comets
Sekanina, Zdenek; Kracht, Rainer
We investigate the relationships among the angular orbital elements—the longitude of the ascending node Ω, the inclination i, and the argument of perihelion ω—of the Kreutz system’s faint, dwarf sungrazers observed only with the Solar and Heliospheric Observatory/STEREO coronagraphs; their published orbits were derived using a parabolic, purely gr…
The magnetic field and spectral variability of the He-weak star HR 2949
Stahl, O.; Rivinius, Th.; Wade, G. A. +6 more
We analyse a high-resolution spectropolarimetric data set collected for the He-weak B3p IV star HR 2949. The Zeeman effect is visible in the circularly polarized component of numerous spectral lines. The longitudinal magnetic field varies between approximately -650 and +150 G. The polar strength of the surface magnetic dipole is calculated to be 2…
The geological history of Nili Patera, Mars
Fawdon, P.; Skok, J. R.; Balme, M. R. +3 more
Nili Patera is a 50 km diameter caldera at the center of the Syrtis Major Planum volcanic province. The caldera is unique among Martian volcanic terrains in hosting: (i) evidence of both effusive and explosive volcanism, (ii) hydrothermal silica, and (iii) compositional diversity from olivine-rich basalts to silica-enriched units. We have produced…
Null Point Distribution in Global Coronal Potential Field Extrapolations
Parnell, C. E.; Edwards, S. J.
Magnetic null points are points in space where the magnetic field is zero. Thus, they can be important sites for magnetic reconnection by virtue of the fact that they are weak points in the magnetic field and also because they are associated with topological structures, such as separators, which lie on the boundary between four topologically disti…