Search Publications

Investigating the role of plasma topography on chromospheric oscillations observed by TRACE

Judge, P. G.; McIntosh, S. W.; Fleck, B.

We present the results of an investigation into the interaction of the topographic structure of the solar chromospheric plasma with the wave modes manifesting themselves in the UV continua formed there. We show that there is a distinct correlation between the inferred plasma topography, the phase-differences between and suppression of oscillations…

Ground-based Near-Infrared Imaging of the HD 141569 Circumstellar Disk

Augereau, J. -C.; Boccaletti, A.; Hahn, J. +1 more

We present the first ground-based near-infrared image of the circumstellar disk around the post-Herbig Ae/Be star HD 141569A initially detected with the Hubble Space Telescope (HST). Observations were carried out in the near-IR (2.2 µm) at the Palomar 200 inch telescope using the adaptive optics system PALAO. The main large-scale asymmetric …

The Absorption and Emission Kinematics in the z=0.7450 Mg II Absorber toward Q1331+17

Ellison, Sara L.; Sawicki, Marcin; Mallén-Ornelas, Gabriela

We present a comparative analysis of the galaxy emission and quasar (QSO) absorption kinematics of a z_abs~0.7450 Mg II system and its candidate absorbing galaxy (G5) located 3.86" (28.3 h^-1₇₀ kpc) from the QSO. We have obtained a spectrum of the galaxy candidate, previously identified as a luminous edge-on disk, an…

The hydrogen ortho-to-para ratio in the stratospheres of the giant planets

Lellouch, Emmanuel; Fouchet, Thierry; Feuchtgruber, Helmut

Observations of the H ₂ S(0) and S(1) quadrupole lines in the four giant planets by the short-wavelength spectrometer of the Infrared Space Observatory are analyzed. These lines probe pressure levels located between 10 and 1 mbar and allow us to determine the stratospheric hydrogen para fraction for the first time. In Jupiter and Saturn…

Small Magellanic Cloud-Type Interstellar Dust in the Milky Way

Gordon, Karl D.; Clayton, Geoffrey C.; Valencic, Lynne A. +1 more

It is well known that the sight line toward HD 204827 in the cluster Trumpler 37 shows a UV extinction curve that does not follow the average Galactic extinction relation. However, when a dust component, foreground to the cluster, is removed, the residual extinction curve is identical to that found in the SMC within the uncertainties. The curve is…

The discovery of a new non-thermal X-ray filament near the Galactic Centre

Decourchelle, A.; Warwick, R. S.; Predehl, P. +1 more

We report the discovery by XMM-Newton and Chandra of a hard extended X-ray source (XMM J174540-2904.5) associated with a compact non-thermal radio filament (the Sgr A-E `wisp'= 1LC 359.888-0.086 = G359.88-0.07), which is located within ~4 arcmin of the Galactic Centre. The source position is also coincident with the peak of the molecular cloud M-0…

Long-term behaviour of space radiometers

Fr Hlich, C.

Revealing New Physical Structures in the Supernova Remnant N63A through Chandra Imaging Spectroscopy

Hughes, John P.; Slane, Patrick O.; Warren, Jessica S.

We present Chandra X-ray observations of the supernova remnant (SNR) N63A in the Large Magellanic Cloud (LMC). N63A, one of the brightest LMC remnants, is embedded in an H II region and is probably associated with an OB association. The optical remnant consists of three lobes of emission contained within the approximately 3 times larger X-ray remn…

The Leo I Cloud: Secular Nuclear Evolution of NGC 3379, NGC 3384, and NGC 3368?

Moiseev, A. V.; Chavushyan, V. H.; Sil'chenko, O. K. +2 more

The central regions of the three brightest members of the Leo I galaxy group-NGC 3368, NGC 3379, and NGC 3384-are investigated by means of two-dimensional spectroscopy. In all three galaxies we have found separate circumnuclear stellar and gaseous subsystems-more probably, disks-whose spatial orientations and spins are connected to the spatial ori…

Molecular Gas and the Nuclear Star Cluster in IC 342: Sufficient Inflow for Recurring Star Formation Events?

Meier, David S.; Böker, Torsten; Schinnerer, Eva

We present high spatial resolution (1.2") millimeter-interferometric observations of the ¹²CO (2-1) line emission in the central 300 pc of the late-type spiral galaxy IC 342. The data, obtained with the Owens Valley Radio Observatory, allow first-time detection of a molecular gas disk that coincides with the luminous young stellar clust…