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Featured researches published by H. Riesgo.


The Astrophysical Journal | 2008

The Acceleration of the Nebular Shells in Planetary Nebulae in the Milky Way Bulge

Michael G. Richer; Jose Alberto Lopez; Margarita Pereyra; H. Riesgo; María Teresa García-Díaz; Sol-Haret Báez

We present a systematic study of line widths in the [O III] λ5007 and Hα lines for a sample of 86 planetary nebulae in the Milky Way bulge based on spectroscopy obtained at the Observatorio Astronomico Nacional in the Sierra San Pedro Martir (OAN-SPM) using the Manchester Echelle Spectrograph. The planetary nebulae were selected with the intention of simulating samples of bright extragalactic planetary nebulae. We separate the planetary nebulae into two samples containing cooler and hotter central stars, defined by the absence or presence, respectively, of the He II λ6560 line in the Hα spectra. This division separates samples of younger and more evolved planetary nebulae. The sample of planetary nebulae with hotter central stars has systematically larger line widths, larger radii, lower electron densities, and lower Hβ luminosities. The distributions of these parameters in the two samples all differ at significance levels exceeding 99%. These differences are all in agreement with the expectations from hydrodynamical models, but for the first time confirmed for a homogeneous and statistically significant sample of Galactic planetary nebulae. We interpret these differences as evidence for the acceleration of the nebular shells during the early evolution of these intrinsically bright planetary nebulae. As is the case for planetary nebulae in the Magellanic Clouds, the acceleration of the nebular shells appears to be the direct result of the evolution of the central stars.


The Astrophysical Journal | 2012

Morpho-kinematic Analysis of the Point-symmetric, Bipolar Planetary Nebulae Hb 5 and K 3-17, A Pathway to Poly-polarity

J. A. López; Ma. T. García-Díaz; W. Steffen; H. Riesgo; Michael G. Richer

The kinematics of the bipolar planetary nebulae Hb 5 and K 3-17 are investigated in detail by means of a comprehensive set of spatially resolved high spectral resolution, long-slit spectra. Both objects share particularly interesting characteristics, such as a complex filamentary, rosette-type nucleus, axial point-symmetry, and very fast bipolar outflows. The kinematic information of Hb 5 is combined with Hubble Space Telescope imagery to construct a detailed three-dimensional model of the nebula using the code SHAPE. The model shows that the large-scale lobes are growing in a non-homologous way. The filamentary loops in the core are proven to actually be secondary lobes emerging from what appears to be a randomly punctured, dense, gaseous core and the material that forms the point-symmetric structure flows within the lobes with a distinct kinematic pattern and its interaction with the lobes has had a shaping effect on them. Hb 5 and K 3-17 may represent a class of fast evolving planetary nebulae that will develop poly-polar characteristics once the nebular core evolves and expands.


The Astronomical Journal | 2005

Confirmation of a Stellar Microjet in the Rosette H II Region (NGC 2244)

J. Meaburn; J. A. López; Michael G. Richer; H. Riesgo; J. E. Dyson

A possible microjet from a low-mass but young star, which has already shed its cocoon, could be rendered observable by the Lyman photon flux in the interior of the Rosette Nebula. Outside this environment it may not have been observable at optical wavelengths. The kinematics of this proposed monopolar microjet from an F8 Ve star have been investigated by spatially resolved, long-slit, spectral observations with the Manchester Echelle Spectrometer on the San Pedro Martir telescope (Mexico). The flow is shown to be approaching to give a radial velocity difference from the host nebula of -56 km s-1. An outflow velocity of, at the most, a few hundreds of km s-1 is therefore indicated. If the flow velocity is taken as 200 km s-1, which is found in other microjets, then this jets inclination to the sky is ≈16°. The mass in the outflowing ionized gas is estimated from the surface brightness of the Hα emission as ≈6 × 1027 g to give an estimated mass-loss rate of 10-8 M⊙ yr-1, which, along with the detection of the outflow velocity, confirms its microjet identification even though an uncertain filling factor was used in these calculations. The hottest cluster star, which is also in the neighborhood of the microjet, is found alone to emit marginally sufficient Lyman photons to account for the ionization of the jet, although direct observations of the local electron density from optical line ratios are required to confirm this point conclusively.


Proceedings of the International Astronomical Union | 2011

The SPM kinematic catalogue of Galactic planetary nebulae

J. A. López; Michael G. Richer; Maria-Teresa García-Díaz; D. M. Clark; John Meaburn; H. Riesgo; W. Steffen; M. Lloyd

The San Pedro Martir kinematic catalogue of galactic planetary nebulae provides spatially resolved, long-slit, Echelle spectra for about 600 planetary nebulae, representing 55 observing runs and about 4000 individual integrations to date in this first release. The project is ongoing and will continue adding spectra to the database. The data are presented wavelength calibrated and corrected for heliocentric motion. This is the most extensive and homogeneous single source of data concerning the internal kinematics of the ionized nebular material in planetary nebulae. The catalogue is available through the world wide web at http://kincatpn.astrosen.unam.mx and an article will a full description of the catalogue will soon appear in the RevMexAA.


Proceedings of the International Astronomical Union | 2006

The SPM Kinematic Catalogue of Planetary Nebulae

J. A. López; Michael G. Richer; H. Riesgo; W. Steffen; Guillermo Garcia-Segura; J. Meaburn; M. Bryce

The San Pedro Mártir Kinematic Catalogue of Planetary Nebulae aims at providing detailed kinematic information for galactic planetary nebulae (PNe) and bright PNe in the Local Group. The database provides long-slit, Echelle spectra and images where the location of the slits on the nebula are indicated. As a tool to help interpret the 2D line profiles or position-velocity data, an atlas of synthetic emission line spectra accompanies the Catalogue. The atlas has been produced with the code SHAPE and contains synthetic spectra for all the main morphological groups for a wide range of spatial orientations and slit locations over the nebula.


Proceedings of the International Astronomical Union | 2006

Morpho-Kinematic Analysis of PNe with Intense [N II ] and [S II ] Emission Lines

H. Riesgo; J. A. López; Michael G. Richer

From the sample of 613 PNe used in the paper ‘Revised Diagnostic Diagrams for Planetary Nebulae’ (Riesgo & Lopez, 2006) we have isolated a subsample of 51 PNe defined by log [H


Revista Mexicana De Astronomia Y Astrofisica | 2012

THE SAN PEDRO MÀRTIR KINEMATIC CATALOGUE OF GALACTIC PLANETARY NEBULAE

J. A. López; Michael G. Richer; Maria-Teresa García-Díaz; D. M. Clark; J. Meaburn; H. Riesgo; W. Steffen; M. Lloyd

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Revista Mexicana De Astronomia Y Astrofisica | 2006

Revised diagnostic diagrams for planetary nebulae

H. Riesgo; J. A. López

/[N II ]]


Revista Mexicana De Astronomia Y Astrofisica | 2010

The San Pedro Mártir Planetary Nebula Kinematic Catalogue: Extragalactic Planetary Nebulae

Michael G. Richer; J. A. López; E. Díaz-Méndez; H. Riesgo; S. H. Báez; Ma. T. García-Díaz; J. Meaburn; D. M. Clark; R. M. Calderón Olvera; G. López Soto; O. Toledano Rebolo

and log [H


Revista Mexicana De Astronomia Y Astrofisica | 2005

H 2-12, A MISIDENTIFIED PLANETARY NEBULA IN KEPLER SNR

H. Riesgo; J. A. López

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J. A. López

National Autonomous University of Mexico

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Michael G. Richer

National Autonomous University of Mexico

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W. Steffen

National Autonomous University of Mexico

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D. M. Clark

National Autonomous University of Mexico

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J. Meaburn

University of Manchester

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Ma. T. García-Díaz

National Autonomous University of Mexico

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Maria-Teresa García-Díaz

National Autonomous University of Mexico

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J. Meaburn

University of Manchester

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S. H. Báez

Universidad Veracruzana

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John Meaburn

University of Manchester

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