Search Publications
Constraining the Optical Emission from the Double Pulsar System J0737-3039
Dalessandro, E.; Camilo, F.; Pellizzoni, A. +10 more
We present the first optical observations of the unique system J0737-3039 (composed of two pulsars, hereafter PSR-A and PSR-B). Ultra-deep optical observations, performed with the High Resolution Camera of the Advanced Camera for Surveys on board the Hubble Space Telescope, could not detect any optical emission from the system down to m F435W…
Frequency of Maunder Minimum Events in Solar-type Stars Inferred from Activity and Metallicity Observations
Tytler, David; Lubin, Dan; Kirkman, David
We consider the common proposition that the fraction of chromospherically very inactive stars in a solar-type sample is analogous to the fraction of the Sun's main-sequence lifetime spent in a grand minimum state. In a new approach to this proposition, we examine chromospheric activity log R'HK in a stellar sample having Hipparcos paral…
Solar Cycle Variation of Sound Speed inside the Sun
Mullan, D. J.; Rabello-Soares, M. C.; MacDonald, J.
Empirical radial profiles of the changes in sound speed inside the Sun between solar minimum and solar maximum have been extracted from Michelson Doppler Imager data by Baldner & Basu and Rabello-Soares. Here, we compare these results with the theoretical radial profiles predicted by a model of magnetic inhibition of convective onset: In the m…
Cosmic Origins Spectrograph Observations of NGC 2024: An Indirect View into the Heart of the Flame
France, Kevin; Snow, Theodore P.; Burgh, Eric B.
As part of a program to study translucent interstellar clouds, NGC 2024 IRS 1 was observed by the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope. IRS 1 is a heavily reddened B0.5 V star (E(B - V) = 1.69, RV = 4.5, and AV = 7.61) lying outside the core of the NGC 2024 cluster and not considered to be the…
Probable Identification of the On-disk Counterpart of Spicules in Hinode Ca II H Observations
de Wijn, A. G.
I present a study of high-resolution time series of Ca II H images and Fe I 630.15 nm spectra taken with the Solar Optical Telescope on the Hinode spacecraft. There is excellent correspondence between the Ca II H and the Fe I line core intensity, except tenuous emission around the network field concentrations in the former that is absent in the la…
Ortho-to-para Ratio Studies of Shocked H2 Gas in the Two Supernova Remnants IC 443 and HB 21
Lee, Ho-Gyu; Moon, Dae-Sik; Shinn, Jong-Ho
We present near-infrared (2.5-5.0 µm) spectral studies of shocked H2 gas in two supernova remnants, IC 443 and HB 21, which are well known for their interactions with nearby molecular clouds. The observations were performed with the Infrared Camera aboard the AKARI satellite. At the energy range 7000 K lsim E(\upsilon,J) lsim 20,0…
A Weak-lensing and Near-infrared Study of A3192: Disassembling a Richness Class 3 Abell Cluster
Smith, Graham P.; Egami, E.; Marshall, P. J. +5 more
We present a joint gravitational lensing and near-infrared study of the galaxy cluster Abell 3192 (A3192) that has been associated both with galaxies at z = 0.168 and with the X-ray luminous cluster RXC J0358.8-2955 (RXC J0358) at z = 0.425. Weak-lensing analysis of our Hubble Space Telescope snapshot observation with the Advanced Camera for Surve…
Dramatic Infrared Variability of WISE J1810-3305: Catching Early-time Dust Ejection During the Thermal Pulse of an Asymptotic Giant Branch Star?
Gandhi, Poshak; Yamamura, Issei; Takita, Satoshi
We present the discovery of a source with broadband infrared photometric characteristics similar to Sakurai's object. WISE J180956.27-330500.2 (hereafter J1810-3305) shows very red WISE colors, but a very blue 2MASS [K] versus WISE [W1 (3.4 µm)] color. It was not visible during the IRAS era, but now has a 12 µm flux well above the IRAS…
Non-thermal Response of the Corona to the Magnetic Flux Dispersal in the Photosphere of a Decaying Active Region
Abramenko, V. I.; Harra, L. K.
We analyzed Solar Dynamics Observatory line-of-sight magnetograms for a decaying NOAA active region (AR) 11451 along with co-temporal Extreme-Ultraviolet Imaging Spectrometer (EIS) data from the Hinode spacecraft. The photosphere was studied via time variations of the turbulent magnetic diffusivity coefficient, η(t), and the magnetic power spectru…
Remnant Gas in Evolved Circumstellar Disks: Herschel PACS Observations of 10-100 Myr Old Disk Systems
Gorti, Uma; Mamajek, Eric; Meyer, Michael R. +3 more
We present Herschel PACS spectroscopy of the [O I] 63 µm gas line for three circumstellar disk systems showing signs of significant disk evolution and/or planet formation: HR 8799, HD 377, and RX J1852.3-3700. [O I] is undetected toward HR 8799 and HD 377 with 3σ upper limits of 6.8 × 10-18 W m-2 and 9.9 × 10-18