Search Publications
A moderately precise dynamical age for the Homunculus of Eta Carinae based on 13 years of HST imaging
Smith, Nathan
The Hubble Space Telescope archive contains a large collection of images of η Carinae, and this paper analyses those most suitable for measuring its expanding Homunculus Nebula. Multiple intensity tracings through the Homunculus reveal the fractional increase in the overall size of the nebula; this avoids registration uncertainty, mitigates bright…
Understanding the nature of the intriguing source X Persei: a deep look with a Suzaku observation
Maitra, Chandreyee; Paul, Biswajit; Pradhan, Pragati +1 more
We present detailed broad-band timing and spectral analysis of the persistent, low luminosity and slowly spinning pulsar X Persei using a deep Suzaku observation of the source. The spectrum is unusually hard with a cyclotron resonance scattering feature (CRSF), the presence of which has been debated. By comparing the spectral models relevant for a…
Siriusly, a newly identified intermediate-age Milky Way stellar cluster: a spectroscopic study of Gaia 1
Bernard, E. J.; Tolstoy, E.; Ferguson, A. M. N. +6 more
We confirm the reality of the recently discovered Milky Way stellar cluster Gaia 1 using spectra acquired with the HERMES and AAOmega spectrographs of the Anglo-Australian Telescope. This cluster had been previously undiscovered due to its close angular proximity to Sirius, the brightest star in the sky at visual wavelengths. Our observations iden…
Dynamics of non-spherical dust in the coma of 67P/Churyumov- Gerasimenko constrained by GIADA and ROSINA data
Fulle, M.; Bieler, A.; Fougere, N. +6 more
Among the comet 67P/Churyumov-Gerasimenko (67P/C-G) in situ measurements, the closest that have ever been performed at a comet nucleus, are also those of speed, mass, and cross-section of cometary grains performed by the Grain Impact Analyser and Dust Accumulator (GIADA) instrument. To interpret GIADA data, we performed dust dynamical numerical si…
Detection of the high-energy cut-off from the Seyfert 1.5 galaxy NGC 5273
Misra, R.; Dewangan, G. C.; McHardy, I. M. +2 more
We perform the NuSTAR and Swift/XRT joint energy spectral fitting of simultaneous observations from the broad-line Seyfert 1.5 galaxy NGC 5273. When fitted with the combination of an exponential cut-off power law and a reflection model, a high-energy cut-off is detected at 143^{+96}_{-40} keV with 2σ significance. Existence of such cut-off is also…
A 1.4 deg2 blind survey for C II], C III] and C IV at z ∼ 0.7-1.5 - I. Nature, morphologies and equivalent widths
Sobral, David; Matthee, Jorryt; Stroe, Andra +2 more
While traditionally associated with active galactic nuclei (AGN), the properties of the C II] (λ = 2326 Å), C III] (λ, λ = 1907, 1909 Å) and C IV (λ, λ = 1549, 1551 Å) emission lines are still uncertain as large, unbiased samples of sources are scarce. We present the first blind, statistical study of C II], C III] and C IV emitters at z ∼ 0.68, 1.…
The ultraluminous X-ray source HoII X-1: kinematic evidence of its escape from a cluster
Egorov, Oleg V.; Lozinskaya, Tatiana A.; Moiseev, Alexei V.
We analyse the structure and kinematics of ionized gas in the vicinity of the ultraluminous X-ray source (ULX) HoII X-1 in the Holmberg II galaxy using observational data obtained with a scanning Fabry-Perot interferometer in the Hα, [S II] and [O III] emission lines at the Russian 6-m telescope. Decomposition of the line profiles allows us to ide…
Nature of the warm absorber outflow in NGC 4051
Ebisawa, Ken; Mizumoto, Misaki
The narrow-line Seyfert 1 galaxy NGC 4051 is known to exhibit significant X-ray spectral/flux variations and have a number of emission/absorption features. X-ray observations have revealed that these absorption features are blueshifted, which indicates that NGC 4051 has warm absorber outflow. In order to constrain physical parameters of the warm a…
Fluxgate magnetometer offset vector determination by the 3D mirror mode method
Dougherty, M. K.; Glassmeier, K. -H.; Volwerk, M. +5 more
Fluxgate magnetometers on-board spacecraft need to be regularly calibrated in flight. In low fields, the most important calibration parameters are the three offset vector components, which represent the magnetometer measurements in vanishing ambient magnetic fields. In case of three-axis stabilized spacecraft, a few methods exist to determine offs…
Quantitative spectroscopy of extreme helium stars Model atmospheres and a non-LTE abundance analysis of BD+10°2179
Butler, K.; Heber, U.; Przybilla, N. +3 more
Extreme helium stars (EHe stars) are hydrogen-deficient supergiants of spectral type A and B. They are believed to result from mergers in double degenerate systems. In this paper, we present a detailed quantitative non-LTE spectral analysis for BD+10°2179, a prototype of this rare class of stars, using UV-Visual Echelle Spectrograph and Fiber-fed …