Search Publications
Investigating the reflection contribution to the X-ray emission of Ton S180
Fabian, A. C.; Nardini, E.; Walton, D. J.
There is now growing evidence that the soft X-ray excess is almost ubiquitous among unobscured active galaxies. In spite of the various interpretations that have been considered in the past few years, the nature of this foremost spectral feature is not firmly established yet. In this context, we review from a reflection perspective the three highe…
A Search for Pulsations in Helium White Dwarfs
Howell, Steve B.; Fulton, Benjamin J.; Marsh, T. R. +5 more
The recent plethora of sky surveys, especially the Sloan Digital Sky Survey, have discovered many low-mass (M < 0.45 M⊙) white dwarfs that should have cores made of nearly pure helium. These WDs come in two varieties: those with masses 0.2 < M < 0.45 M⊙ and H envelopes so thin that they rapidly cool and those with M …
Accurate localization and identification of six hard X-ray sources from Chandra and XMM-Newton data
Lutovinov, A. A.; Revnivtsev, M. G.; Karasev, D. I. +1 more
We present the results of Chandra and XMM-Newton observations for six hard X-ray sources (IGR J12134-6015, IGR J18293-1213, IGR J18219-1347, IGR J17350-2045, IGR J18048-1455, XTE J1901+014) from the INTEGRAL all-sky survey. Based on these observations, we have improved significantly the localization accuracy of the objects and, therefore, have man…
The S4G Perspective on Circumstellar Dust Extinction of Asymptotic Giant Branch Stars in M100
Holwerda, Benne; Ho, Luis C.; Meidt, Sharon E. +19 more
We examine the effect of circumstellar dust extinction on the near-IR (NIR) contribution of asymptotic giant branch (AGB) stars in intermediate-age clusters throughout the disk of M100. For our sample of 17 AGB-dominated clusters we extract optical-to-mid-IR spectral energy distributions (SEDs) and find that NIR brightness is coupled to the mid-IR…
Adhesion and collisional release of particles in dense planetary rings
Schmidt, Jürgen; Spahn, Frank; Bodrova, Anna +1 more
We propose a simple theoretical model for aggregative and fragmentative collisions in Saturn’s dense rings. In this model the ring matter consists of a bimodal size distribution: large (meter sized) boulders and a population of smaller particles (tens of centimeters down to dust). The small particles can adhesively stick to the boulders and can be…
Dynamical Mass Constraints on the Ultraluminous X-Ray Source NGC 1313 X-2
Orosz, Jerome; Bregman, Joel N.; Liu, Jifeng
Dynamical mass measurements hold the key to answering whether ultraluminous X-ray sources (ULXs) are intermediate-mass black holes (IMBHs) or stellar-mass black holes with special radiation mechanisms. NGC 1313 X-2 is so far the only ULX with Hubble Space Telescope light curves, the orbital period, and the black hole's radial velocity amplitude ba…
Co-registration of Chang'E-1 stereo images and laser altimeter data with crossover adjustment and image sensor model refinement
Di, Kaichang; Hu, Wenmin; Liu, Yiliang +1 more
Topographic information is of fundamental importance for various scientific investigations in lunar and planetary exploration. To provide high-precision, seamless mapping capability, it is critical to co-register image and altimetry data, the two major data sources for topographic modeling. This paper presents a method for co-registration of Chang…
On Magnetic Fields of Active Regions at Coronal Heights
Bogod, V. M.; Stupishin, A. G.; Yasnov, L. V.
This paper analyzes the magnetic field structure of active regions at coronal heights determined by means of multi-wavelength observations of polarized radio emission in the microwave range, and compares it with the force-free magnetic field extrapolation into the corona from the photospheric magnetograms. Our method of one-dimensional radio stere…
Physical Structure and Nature of Supernova Remnants in M101
Chu, You-Hua; Gruendl, Robert A.; Chen, C. -H. Rosie +6 more
Supernova remnant (SNR) candidates in the giant spiral galaxy M101 have been previously identified from ground-based Hα and [S II] images. We have used archival Hubble Space Telescope (HST) Hα and broadband images as well as stellar photometry of 55 SNR candidates to examine their physical structure, interstellar environment, and underlying stella…
Retrieval of ionospheric profiles from the Mars Express MARSIS experiment data and comparison with radio occultation data
Sánchez-Cano, B.; Witasse, O.; Blelly, P. -L. +4 more
Since 2005 the Mars Advanced Radar and Ionospheric Sounding experiment (MARSIS) aboard Mars Express has acquired a unique dataset on the ionosphere of Mars made up of ionospheric soundings taken by the instrument working in its active ionospheric sounding (AIS) mode. These soundings play a role similar to those of modern Terrestrial digisondes in …