TY  - JOUR
A1  - Pena-Angulo, D.
A1  - Nadal-Romero, E.
A1  - Gonzalez-Hidalgo, J. C.
A1  - Albaladejo, J.
A1  - Andreu, V
A1  - Bagarello, V
A1  - Barhi, H.
A1  - Batalla, R. J.
A1  - Bernal, S.
A1  - Bienes, R.
A1  - Campo, J.
A1  - Campo-Bescos, M. A.
A1  - Canatario-Duarte, A.
A1  - Canton, Y.
A1  - Casali, J.
A1  - Castillo, V
A1  - Cerda, Artemi
A1  - Cheggour, A.
A1  - Cid, Patricio
A1  - Cortesi, N.
A1  - Desir, G.
A1  - Diaz-Pereira, E.
A1  - Espigares, T.
A1  - Estrany, Joan
A1  - Fernandez-Raga, M.
A1  - Ferreira, Carla S. S.
A1  - Ferro, Vito
A1  - Gallart, Francesc
A1  - Gimenez, R.
A1  - Gimeno, E.
A1  - Gomez, J. A.
A1  - Gomez-Gutierrez, A.
A1  - Gomez-Macpherson, H.
A1  - Gonzalez-Pelayo, O.
A1  - Hueso-Gonzalez, P.
A1  - Kairis, O.
A1  - Karatzas, G. P.
A1  - Klotz, S.
A1  - Kosmas, C.
A1  - Lana-Renault, Noemi
A1  - Lasanta, T.
A1  - Latron, J.
A1  - Lazaro, R.
A1  - Le Bissonnais, Y.
A1  - Le Bouteiller, C.
A1  - Licciardello, F.
A1  - Lopez-Tarazon, José Andrés
A1  - Lucia, A.
A1  - Marin, C.
A1  - Marques, M. J.
A1  - Martinez-Fernandez, J.
A1  - Martinez-Mena, M.
A1  - Martinez-Murillo, J. F.
A1  - Mateos, L.
A1  - Mathys, N.
A1  - Merino-Martin, L.
A1  - Moreno-de las Heras, M.
A1  - Moustakas, N.
A1  - Nicolau, J. M.
A1  - Novara, A.
A1  - Pampalone, V
A1  - Raclot, D.
A1  - Rodriguez-Blanco, M. L.
A1  - Rodrigo-Comino, Jesús
A1  - Romero-Diaz, A.
A1  - Roose, E.
A1  - Rubio, J. L.
A1  - Ruiz-Sinoga, J. D.
A1  - Schnabel, S.
A1  - Senciales-Gonzalez, J. M.
A1  - Simonneaux, V
A1  - Sole-Benet, A.
A1  - Taguas, E.
A1  - Taboada-Castro, M. M.
A1  - Taboada-Castro, M. T.
A1  - Todisco, Francesca
A1  - Ubeda, X.
A1  - Varouchakis, E. A.
A1  - Vericat, Damia
A1  - Wittenberg, L.
A1  - Zabaleta, A.
A1  - Zorn, M.
T1  - Spatial variability of the relationships of runoff and sediment yield with weather types throughout the Mediterranean basin
JF  - Journal of hydrology
N2  - Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) W and SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures.
KW  - Synoptic weather types
KW  - Erosion
KW  - Sediment yield
KW  - Runoff
KW  - Mediterranean basin
Y1  - 2019
U6  - https://doi.org/10.1016/j.jhydrol.2019.01.059
SN  - 0022-1694
SN  - 1879-2707
VL  - 571
SP  - 390
EP  - 405
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pena, M
A1  - Peimbert, A.
A1  - Hamann, Wolf-Rainer
A1  - Ruiz, M. T.
A1  - Peimbert, M.
T1  - The extraordinary planetary nebula N66 in the LMC
N2  - Morphology of the planetary nebula LMC-N66 (ionized by a [WN] star) indicates that the nebula is a multipolar object with a very narrow waist. It shows several jets, knots and filaments in opposite directions from the central star. A couple of twisted long filaments could be interpreted as due to point-symmetric type ejection. If such is the case, the progenitor would be a binary precessing system. High resolution spectroscopy shows that most of the material is approaching or receding from the star. However the line profiles are very complex, showing several components at different velocities. Our high resolution spectroscopic data show that the different structures (knots, filaments, ...) present different radial velocities spreading from 240 to more than 400 km/s. The system velocity is 300 km/s. There are high velocity knots located to the north of the central star, moving at more than 100 km/s relative to the system velocity.
Y1  - 2004
SN  - 3-12-283174-0
ER  - 
TY  - JOUR
A1  - Pena, M.
A1  - Hamann, Wolf-Rainer
A1  - Ruiz, M. T.
A1  - Peimbert, A.
A1  - Peimbert, M.
T1  - A high resolution spectroscopic study of the extraordinary planetary nebula LMC-N66
N2  - The planetary nebula N66 in the Large Magellanic Cloud is an extraordinary object, as it is the only confirmed PN where the central star is a Wolf-Rayet star of the nitrogen sequence, i.e. of type [WN]. Moreover, the star showed a dramatic brightness outburst in 1993-1994. In a previous paper (Hamann et al. 2003) we analyzed the changing stellar spectra and found evidence that the central star is most likely a binary system where a white dwarf presently accretes matter from a non-degenerate companion at a high rate. Thus the object is a candidate for a future type Ia supernova in our cosmic neighborhood. In the present paper we analyze the morphology and kinematics of the nebula, using images and high-resolution spectra obtained with the Hubble Space Telescope (HST) and the Very Large Telescope (ESO-VLT). The object presents a complex multipolar structure, dominated by very bright lobes located at both sides of the central star and separated by a narrow waist. In addition there is a pair of very extended and twisted loops, also pointing in opposite directions; their symmetry axis and collimation angle differs from those of the bright lobes. High resolution spectroscopy reveals two main velocity components, "approaching" material at an average heliocentric radial velocity Of V-rad = 248 30 km s(-1) and similarly bright "receding" material at V-rad = 331 +/- 25 km s(-1). A systemic velocity of about 300 km s(-1) is derived. Opposite lobes and loops possess opposite velocities. Furthermore there are knots and filaments of complex structure and kinematics. Close to the central star, nebular gas is found, receding at very high velocity (125 km s(-1) relative to the system). The morphology and kinematics of LMC-N66 can be explained as the result of episodic bipolar ejections with changing axis. The bipolar structures could have been produced by collimated streams ejected from a precessing central source. We suggest that the precession could have been produced by an external torque, possibly due to a binary companion. Young, fast-moving nebular knots close to the star appear slightly He- and N-richer than the main body of the nebula, but are still hydrogen-rich in contrast to the helium-dominated atmosphere of the [WN]- type central star. In the binary scenario, this nebular matter must have been accreted from the non-degenerate companion and re-ejected before it was fully burnt
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Pena, M.
A1  - Hamann, Wolf-Rainer
A1  - Koesterke, Lars
A1  - Maza, J.
A1  - Mendez, R. H.
A1  - Peimbert, M.
A1  - Ruiz, M. T.
A1  - Torres-Peimbert, S.
T1  - HST spectrophotometric data of the central star of the planetary nebula LMC-N66
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Pena, M.
A1  - Hamann, Wolf-Rainer
A1  - Koesterke, Lars
A1  - Maza, J.
A1  - Mendez, R. H.
A1  - Peimbert, M.
A1  - Ruiz, M. T.
A1  - Torres-Peimbert, S.
T1  - Spectrophotometric data of the central star of the large magellanic cloud planetary nebula N66. Quantitative analysis of its WN type spectrum
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Pena, M.
A1  - Hamann, Wolf-Rainer
A1  - Ruiz, M. T.
T1  - The LMC planetary nebula N66 revisited. Nebular kinematics and stellar models
Y1  - 2003
SN  - 1-583-81148-6
ER  - 
TY  - THES
A1  - Hamann, Wolf-Rainer
A1  - Pena, M.
A1  - Gräfener, Götz
A1  - Ruiz, M. T.
T1  - The central star of the planetary nebula N66 in the Large Magellanic Cloud : a detailed analysis of its dramatic evolution 1983 - 2000
Y1  - 2003
SN  - 0004-6361
ER  - 
TY  - JOUR
A1  - Heringer-Walther, Silvia
A1  - Moreira, M. C. V.
A1  - Wessel, Niels
A1  - Saliba, J. L.
A1  - Silvia-Barra, J.
A1  - Pena, J. L. B.
A1  - Becker, S.
A1  - Siems, W. E.
A1  - Schultheiss, H. P.
A1  - Walther, T.
T1  - Brain natriuretic peptide predicts survival in Chagas' disease more effectively than atrial natriuretic peptide
Y1  - 2005
SN  - 1355-6037
ER  - 
TY  - JOUR
A1  - Stastinska, G.
A1  - Gräfener, Götz
A1  - Pena, M.
A1  - Hamann, Wolf-Rainer
A1  - Koesterke, Lars
A1  - Szczerba, Ryszard
T1  - Comprehensive modelling of the planetary nebula LMC-SMP 61 and its [WC]-type central star
N2  - We present a comprehensive study of the Magellanic Cloud planetary nebula SMP 61 and of its nucleus, a Wolf- Rayet type star classified [WC 5-6]. The observational material consists of HST STIS spectroscopy and imaging, together with optical and UV spectroscopic data collected from the literature and infrared fluxes measured by IRAS. We have performed a detailed spectral analysis of the central star, using the Potsdam code for expanding atmospheres in non-LTE. For the central star we determine the following parameters: L-star = 10(3.96) L-., R-star = 0.42 R-., T-star = 87.5 kK, (M) over dot = 10(-6.12) M-. yr(-1), v(infinity) = 1400 km s(-1), and a clumping factor of D = 4. The elemental abundances by mass are X-He = 0.45, X-C = 0.52, X-N < 5 x 10(-5), X-O = 0.03, and X-Fe < 1 x 10(-4). The fluxes from the model stellar atmosphere were used to compute photoionization models of the nebula. All the available observations, within their error bars, were used to constrain these models. We find that the ionizing fluxes predicted by the stellar model are consistent with the fluxes needed by the photoionization model to reproduce the nebular emission, within the error margins. However, there are indications that the stellar model overestimates the number and hardness of Lyman continuum photons. The photoionization models imply a clumped density structure of the nebular material. The observed C III] lambda1909/C II lambda4267 line ratio implies the existence of carbon-rich clumps in the nebula. Such clumps are likely produced by stellar wind ejecta, possibly mixed with the nebular material. We discuss our results with regard to the stellar and nebular post-AGB evolution. The observed Fe-deficiency for the central star indicates that the material which is now visible on the stellar surface has been exposed to s-process nucleosynthesis during previous thermal pulses. The absence of nitrogen allows us to set an upper limit to the remaining H-envelope mass after a possible AGB final thermal pulse. Finally, we infer from the total amount of carbon detected in the nebula that the strong [WC] mass- loss may have been active only for a limited period during the post-AGB evolution
Y1  - 2004
SN  - 0004-6361
ER  - 
TY  - JOUR
A1  - Pena, M.
A1  - Hamann, Wolf-Rainer
T1  - The central star of the planetary nebula LMC-N66 : a massive accreting white dwarf?
N2  - The central star of the PN LMC-N66 showed an impressive outburst in 1993 - 1994, returning to its initial conditions about 8 years later. Its spectrum resembles that of a WN4.5 star, being the only confirmed central star of planetary nebulae showing such a spectral type. Recent analysis for the central star parameters, performed by Hamann et al. (2003) is presented. They have found that the bolometric luminosity increased by a factor larger than 6, during the outburst. We discuss the possible scenarios which have been proposed to explain the exceptional stellar parameters and the outburst mechanism. The stellar characteristics and the morphology and kinematics of the planetary nebula suggest the presence of binary system (massive star with a less massive companion or, a white dwarf accreting matter in a close- binary system). These cases pose the least severe contradictions with observational constraints.
Y1  - 2003
ER  -