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368 results on '"Ibañez R"'

7. First long-term activity study of AU Microscopii: a possible chromospheric cycle

Author

Ibañez, R. V., Buccino, A. P., Flores, M., Martinez, C. I., Maizel, D., Messina, S., and Mauas, P. J. D.

Subjects
Astrophysics - Solar and Stellar Astrophysics
Abstract

M stars are ideal targets to search for Earth-like planets. However, they usually have high levels of magnetic activity, which could affect their habitability and make difficult the detection of exoplanets orbiting around them. Unfortunately, long-term variability of dM stars has not been extensively studied, due to their low intrinsic brightness. For this reason, in 1999 we started the HKalpha project, which systematically observes the spectra of a large number of stars, in particular dM stars, at the Complejo Astronomico El Leoncito (CASLEO). In this work, we study the long-term activity of the young active dM1 star AU Microscopii. We analyze the Mount Wilson index S derived from CASLEO spectra obtained between 2004 and 2016, which we complement with the S-index derived from HARPS, FEROS and UVES public spectra. We also analyze the simultaneous photometric counterpart provided by the ASAS public database for this star between 2000 and 2009, and our own photometry. In both totally independent time series, we detect a possible activity cycle of period around 5 years. We also derived a precise rotation period for this star P rot = 4.85 days, consistent with the literature. This activity cycle reflects that an alphaOmega dynamo could be operating in this star., Comment: Accepted for publication in MNRAs

Published
2019
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20. Symplectically harmonic cohomology of nilmanifolds

Author

Ibáñez, R., Rudyak, Yu., Tralle, A., and Ugarte, L.

Subjects
Mathematics - Symplectic Geometry, 53D05, 57T15
Abstract

This paper can be considered as an extension to our paper [On symplectically harmonic forms on six-dimensional nilmanifolds, Comment. Math. Helv. 76 (2001), n 1, 89-109]. Also, it contains a brief survey of recent results on symplectically harmonic cohomology., Comment: 18 pages

Published
2001

21. Duality and modular class of a Nambu-Poisson structure

Author

Ibanez, R., de Leon, M., Lopez, B., Marrero, J. C., and Padron, E.

Subjects
Mathematics - Symplectic Geometry, Mathematical Physics, 53C15, 53D05, 81S10
Abstract

In this paper we introduce cohomology and homology theories for Nambu-Poisson manifolds. Also we study the relation between the existence of a duality for these theories and the vanishing of a particular Nambu-Poisson cohomology class, the modular class. The case of a regular Nambu-Poisson structure and some singular examples are discussed.

Published
2000
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22. On Symplectically Harmonic Forms on Six-dimensional Nilmanifolds

Author

Ibáñez, R., Rudyak, Yu., Tralle, A., and Ugarte, L.

Subjects
Mathematics - Symplectic Geometry, 53C15
Abstract

In the present paper we study the variation of the dimensions $h_k$ of spaces of symplectically harmonic cohomology classes (in the sense of Brylinski) on closed symplectic manifolds. We give a description of such variation for all 6-dimensional nilmanifolds equipped with symplectic forms. In particular, it turns out that certain 6-dimensional nilmanifolds possess families of homogeneous symplectic forms $\omega_t$ for which numbers $h_k(M,\omega_t)$ vary with respect to t. This gives an affirmative answer to a question raised by Boris Khesin and Dusa McDuff. Our result is in contrast with the case of 4-dimensional nilmanifolds which do not admit such variations by a remark of Dong Yan.

Published
2000

23. Leibniz algebroid associated with a Nambu-Poisson structure

Author

Ibanez, R., de Leon, M., Marrero, J. C., and Padron, E.

Subjects
Mathematical Physics, Mathematics - Symplectic Geometry, 53C15, 58F05, 81S10
Abstract

The notion of Leibniz algebroid is introduced, and it is shown that each Nambu-Poisson manifold has associated a canonical Leibniz algebroid. This fact permits to define the modular class of a Nambu-Poisson manifold as an appropiate cohomology class, extending the well-known modular class of Poisson manifolds.

Published
1999
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