Search Publications
A Crossed Molecular Beams Study on the Formation of the Exotic Cyanoethynyl Radical in Titan's Atmosphere
Yung, Y. L.; Gu, X.; Kaiser, R. I. +5 more
The reaction of the dicarbon molecule (C2) in its 1Σg + electronic ground state with hydrogen cyanide HCN(X1Σ+) is investigated in a crossed molecular beam setup to untangle the formation of the cyanoethynyl radical CCCN(X2Σ+) in hydrocarbon-rich atmospheres of…
The Spectral Types of White Dwarfs in Messier 4
Rich, R. Michael; Richer, Harvey B.; Kalirai, Jason S. +2 more
We present the spectra of 24 white dwarfs in the direction of the globular cluster Messier 4 obtained with the Keck/LRIS and Gemini/GMOS spectrographs. Determining the spectral types of the stars in this sample, we find 24 type DA and 0 type DB (i.e., atmospheres dominated by hydrogen and helium, respectively). Assuming the ratio of DA/DB observed…
A New Diagnostic Method for Assessment of Stellar Stratification in Star Clusters
Gouliermis, Dimitrios A.; de Grijs, Richard; Xin, Yu
We propose a new method for the characterization of stellar stratification in stellar systems. The method uses the mean-square radius (also called the Spitzer radius) of the system as a diagnostic tool. An estimate of the observable counterpart of this radius for stars of different magnitude ranges is used as the effective radius of each stellar s…
Driving Currents for Flux Rope Coronal Mass Ejections
Vourlidas, Angelos; Subramanian, Prasad
We present a method for measuring electrical currents enclosed by flux rope structures that are ejected within solar coronal mass ejections (CMEs). Such currents are responsible for providing the Lorentz self-force that propels CMEs. Our estimates for the driving current are based on measurements of the propelling force obtained using data from th…
Parameter Constraints for High-Energy Models of Colliding Winds of Massive Stars: The Case WR 147
Reimer, A.; Reimer, O.
We explore the ability of high-energy observations to constrain orbital parameters of long-period massive binary systems by means of an inverse Compton (IC) model acting in colliding wind environments. This is particularly relevant for (very) long-period binaries where orbital parameters are often poorly known from conventional methods, as is the …
Young Brown Dwarfs in the Core of the W3 Main Star-Forming Region
Tamura, M.; Ojha, D. K.; Ghosh, S. K. +4 more
We present the results of deep and high-resolution (FWHM ~ 0farcs35) JHK near-infrared (NIR) observations with the Subaru telescope, to search for very low mass young stellar objects in the W3 Main star-forming region. The NIR survey covers an area of ~ 2.6 arcmin2 with 10σ limiting magnitude exceeding 20 mag in the JHK bands. The surve…
The Optical Spectra of Spitzer 24 µm Galaxies in the Cosmic Evolution Survey Field. II. Faint Infrared Sources in the zCOSMOS-Bright 10k Catalog
Kneib, J. -P.; Maccagni, D.; Aussel, H. +67 more
We have used the zCOSMOS-bright 10k sample to identify 3244 Spitzer/MIPS 24 µm-selected galaxies with 0.06 mJy < S 24 µm lsim 0.50 mJy and I AB < 22.5, over 1.5 deg2 of the COSMOS field, and studied different spectral properties, depending on redshift. At 0.2 < z < 0.3, we found that differe…
Helioseismic Signature of Chromospheric Downflows in Acoustic Travel-Time Measurements From Hinode
Zhao, Junwei; Kosovichev, Alexander G.; Tarbell, Theodore D. +2 more
We report on a signature of chromospheric downflows in two emerging flux regions detected by time-distance helioseismology analysis. We use both chromospheric intensity oscillation data in the Ca II H line and photospheric Dopplergrams in the Fe I 557.6 nm line obtained by Hinode/SOT for our analyses. By cross-correlating the Ca II oscillation sig…
Serendipitous XMM-Newton Detection of X-Ray Emission from the Bipolar Planetary Nebula Hb 5
Frank, Adam; Balick, Bruce; Kastner, Joel H. +1 more
We report the serendipitous detection by the XMM-Newton X-ray Observatory of an X-ray source at the position of the Type I (He- and N-rich) bipolar planetary nebula (PN) Hb 5. The Hb 5 X-ray source appears marginally resolved. While the small number of total counts (~170) and significant off-axis angle of the X-ray source (~7farcm8) precludes a de…
Is the 3.5 µm Infrared Feature on Enceladus Due to Hydrogen Peroxide?
Loeffler, M. J.; Baragiola, R. A.
We use new and previously published measurements from our laboratory to examine the assignment of a 3.5 µm feature in the infrared spectrum of Enceladus. The spectral feature, taken with Cassini's VIMS Spectrometer, has recently been interpreted as an absorption band from hydrogen peroxide on the surface. Such identification is important bec…