Zobrazeno 1 - 10
of 31
pro vyhledávání: '"Engels, Dieter"'
We present our past and current long-term monitoring program of water masers in the circumstellar envelopes of evolved stars, augmented by occasional interferometric observations. Using as example the Mira-variable U Her, we identify three types of v
Externí odkaz:
http://arxiv.org/abs/2402.01309
Since 2013 we are performing with the Nancay Radio Telescope (NRT) a monitoring program of >100 Galactic disk OH/IR stars, having bright 1612-MHz OH maser emission. The variations of the maser emission are used to probe the underlying stellar variabi
Externí odkaz:
http://arxiv.org/abs/1811.06906
Variable OH/IR stars are Asymptotic Giant Branch (AGB) stars with an optically thick circumstellar envelope that emit strong OH 1612 MHz emission. They are commonly observed throughout the Galaxy but also in the LMC and SMC. Hence, the precise infere
Externí odkaz:
http://arxiv.org/abs/1711.09694
Autor:
Etoka, Sandra, Engels, Dieter, Imai, Hiroshi, Dawson, Joanne, Ellingsen, Simon, Sjouwerman, Lorant, van Langevelde, Huib
The intense line emission of OH masers is a perfect tracer of regions where new stars are born aswell as of evolved stars, shedding large amounts of processed matter into the interstellar medium. From SKA deep surveys at 18 cm, where the maser lines
Externí odkaz:
http://arxiv.org/abs/1501.06153
Publikováno v:
Proceedings of the International Astronomical Union. Dec2022, Vol. 18 Issue S380, p319-323. 5p.
We performed a near-IR/optical monitoring programme from 1999 to 2005 in order to study the variability properties of the 'Arecibo sample of OH/IR stars' (periods, amplitudes, and colour variations). Here we describe this multi-wavelength long-term m
Externí odkaz:
http://arxiv.org/abs/astro-ph/0610957
Autor:
Engels, Dieter
Intermediate mass stars (1-8 solar masses) evolve along the Asymptotic Giant Branch after completion of hydrogen and helium core burning. At the tip they lose for several ten to hundred thousand years copious amounts of mass and exhibit various forms
Externí odkaz:
http://arxiv.org/abs/astro-ph/0508285
Autor:
Engels, Dieter, Keil, Ralf
We have analyzed optical spectra of 473 X-ray and 235 optically selected AGNs, to study their emission line properties. We present results of an analysis of the H-beta linewidths. We find that the linewidth distribution of quasars is shifted towards
Externí odkaz:
http://arxiv.org/abs/astro-ph/0005157
Autor:
Engels, Dieter1 dengels@hs.uni-hamburg.de, López-Martí, Belen2
Publikováno v:
Proceedings of the International Astronomical Union. Dec2022, Vol. 18 Issue S380, p368-370. 3p.
Autor:
Engels, Dieter
Publikováno v:
Verwaltung und Management, 2015 May 01. 21(3), 115-124.
Externí odkaz:
https://www.jstor.org/stable/26386330