Search Publications
On the source of the flaring activity in AB Doradus: the UV spectral signatures
Gómez de Castro, Ana I.
AB Dor is a young, 30-Myr-old, low-mass star with a short rotation period and strong flaring activity. In this work, a detailed analysis of the flaring activity is carried out based on ultraviolet spectral tracers of hot (T ~105 ) plasma, namely HST /GHRS profiles of the Civ[uv1] and Siiv[uv1] lines. The quiescent component has been sub…
Mrk 1014: an AGN-dominated ultraluminous infrared galaxy
Lutz, D.; Sturm, E.; Boller, Th. +1 more
In this paper we report on an XMM-Newton observation of the ultraluminous infrared QSO Mrk 1014. The X-ray observation reveals a power-law-dominated (Γ~ 2.2) spectrum with a slight excess in the soft energy range. Active galactic nucleus (AGN) and starburst emission models fit the soft excess emission equally well, however, the most plausible expl…
The origin of the strings in the outer regions of η Carinae
Redman, M. P.; Meaburn, J.; Holloway, A. J.
The narrow optical filaments (`strings' or `spikes') emerging from the Homunculus of η Carinae are modelled as resulting from the passage of ballistic `bullets' of material through the dense circumstellar environment. In this explanation, the string is the decelerating flow of ablated gas from the bullet. An archive Hubble Space Telescope image an…
Bulk flow velocities in the solar corona at solar maximum
Simnett, G. M.; Lewis, D. J.
We present velocity estimates of bulk motions seen in the solar corona by the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft. These estimates reflect the mass-weighted mean outflow of all coronal mass ejections (CMEs) seen during a 1-yr period on the approach to solar maximum. The par…
XMM-Newton observes flaring in the polar UZ For during a low state
Pandel, Dirk; Córdova, France A.
During an XMM-Newton observation, the eclipsing polar UZ For was found in a peculiar state with an extremely low X-ray luminosity and occasional X-ray and ultraviolet (UV) flaring. For most of the observation, UZ For was only barely detected in X-rays and ~800 times fainter than during a high state previously observed with ROSAT. A transient event…
Correlated multiwavelength emission from the X-ray-bright Seyfert galaxy III Zw 2
Page, M. J.; Stevens, J. A.; Mason, K. O. +8 more
The X-ray-bright Seyfert 1 galaxy III Zw 2 was observed with XMM-Newton in 2000 July. Its X-ray spectrum can be described by a power law of photon index Γ= 1.7 and an extremely broad (FWHM~ 140 000 km s-1) Fe Kα line at 6.44 keV. The iron line has an equivalent width of ~800 eV. To study the long-term X-ray behaviour of the source we ha…
Relationship between horizontal flow velocity and cell size for supergranulation using SOHO Dopplergrams
Singh, Jagdev; Paniveni, U.; Krishan, V. +1 more
A study of 90 supergranular cells obtained from SOHO Dopplergrams was undertaken in order to investigate a possible relation between the sizes and peak horizontal velocities of the cells. For the sample obtained, the two parameters are found to be correlated with a relation: horizontal velocity ~(size)1/3. This is in agreement with the …
The pulsational behaviour of the rapidly oscillating Ap star HD 122970 during two photometric multisite campaigns
Granzer, T.; Handler, G.; Garrido, R. +11 more
We undertook two time-series photometric multisite campaigns for the rapidly oscillating Ap star HD 122970. The first one, conducted in 1998, resulted in 119h of data and in the detection of three pulsation frequencies. The presence of possible further modes which held the promise of deriving a mode identification motivated a second worldwide camp…
The orientation of the Seyfert nucleus in Markarian 348
Browne, I. W. A.; Thean, A. H. C.; Pedlar, A. +1 more
Multi-frequency observations of Mrk 348 are presented consisting of two epochs of MERLIN data at 5 GHz, ISOPHOT data at 170, 90, 60 and 25 µm, Nordic Optical Telescope images in the U, B, R and I bands and data at 1350 µm from the archive for SCUBA. The new optical images reveal a disrupted arm that ends towards the eastern companion o…
Spectroscopy of SN 1987A at 0.9-2.4µm: days 1348-3158
Spyromilio, J.; Meikle, W. P. S.; Fassia, A.
We present near-infrared spectroscopic observations of SN 1987A covering the period 1358 to 3158 d post explosion. This is the first time that IR spectra of a supernova have been obtained to such late epochs. The spectra comprise emission from both the ejecta and the bright, ring-shaped circumstellar medium (CSM). The most prominent CSM emission l…