47 research outputs found
Wind structure of late B supergiants I. Multi-line analyses of near-surface and wind structure in HD 199 478 (B8 Iae)
We provide a quantitative analysis of time-variable phenomena in the
photospheric, near-star, and outflow regions of the late-B supergiant (SG) HD
199478. The analysis is based primarily on optical spectroscopic datasets
secured between 1999 and 2000 from the Bulgarian NAO, Tartu, and Ritter
Observatories. The temporal behaviour of HD 199478 is characterised by three
key empirical properties: (i) systematic central velocity shifts in the
photospheric absorption lines, including C II and He I, over a characteristic
time-scale of abou 20 days; (ii) extremely strong, variable H alpha emission
with no clear modulation signal, and (iii) the occurrence in 2000 of a (rare)
high-velocity absorption (HVA) event in H alpha, which evolved over about 60
days, showing the clear signature of mass infall and outflows. In these
properties HD 199478 resembles few other late-B SGs with peculiar emission and
HVAs in H alpha (HD 91619, HD 34085, HD 96919). Non-LTE line synthesis
modelling is conducted using FASTWIND for these late-B SGs to constrain and
compare their fundamental parameters within the context of extreme behaviour in
the H alpha lines. Our analysis indicate that at the cooler temperature edge of
B SGs, there are objects whose wind properties, as traced by H alpha, are
inconsistent with the predictions of the smooth, spherically symmetric wind
approximation. This discordance is still not fully understood and may highlight
the role of a non-spherical, disk-like, geometry, which may result from
magnetically-driven equatorial compression of the gas. Ordered dipole magnetic
fields may also lead to confined plasma held above the stellar surface, which
ultimately gives rise to transient HVA events.Comment: 12 pages. To be published in Astronomy and AStrophysic
Correcting for a Density Distribution: Particle Size Analysis of Core–Shell Nanocomposite Particles Using Disk Centrifuge Photosedimentometry
The outspan : tales of South Africa
The original document was digitized with financial support from Media24.The outspan -- Soltké -- Induna Nairn -- Cassidy -- The pool -- Two Christmas days.http://explore.up.ac.za/record=b171608
Unie : een pleidooi voor een nieuw begin ; the Union : a plea for a fresh start
Dutch text followed by English text.The original document was digitized with financial support from Media24.by J. Percy Fitzpatrickhttp://explore.up.ac.za/record=172871
South African memories
Rhodes and Alfred Beit -- Kimberley memories -- Early days on the goldfields -- Rhodes and the goldfields -- Premier mine -- Lord Milner and the Diamond Law -- Meeting with Mr Balfour -- Battle of Colenso -- Apprehension of war after the Raid -- Capitalist negotiations in the Transvaal -- "The Transvaal from within" -- General J.H. de la Rey -- Shooting of De la Rey -- Story of a great diamond -- Pretoria forts -- Lord Cromer -- Jock of the bushveld -- Recollections of RhodesThe original document was digitized with financial support from Media24.by J. Percy Fitzpatrick ; prepared for the press from the manuscript of the author by G.H. Wilson.http://explore.up.ac.za/record=b166210
The Transvaal from within; a private record of public affairs,
Map mounted on front fly-leaf.Mode of access: Internet
Jock of the bushveld /
First issue, with the incorrect drawing of the beetle pushing with its forlegs on p. 65. Subsequently recalled and reissued. Cf. Wolff, R.L. 19th cent. fiction.Osborne Coll.,Wolff, R.L. 19th cent. fiction,Mode of access: Internet
The Transvaal from within; a private record of public affairs,
Map mounted on front fly-leaf.Mode of access: Internet.Photocopy