Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo

Ouagadougou, Burkina Faso

Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo

Ouagadougou, Burkina Faso

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Sorgho A.,University of Cape Town | Hess K.,University of Cape Town | Hess K.,Netherlands Institute for Radio Astronomy | Hess K.,University of Groningen | And 4 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2017

We map the H I distribution of galaxies in a ~1.5 × 2.5° region located at the virial radius south of the Virgo Cluster using the KAT-7 and the Westerbork Synthesis Radio Telescope interferometers. Because of the different beam sizes of the two telescopes, a similar column density sensitivity of NHI ~ 1 × 1018 atoms cm-2 was reached with the two observations over 16.5 km s-1. We pioneer a new approach to combine the observations and take advantage of their sensitivity to both the large- and small-scale structures. Out to an unprecedented extent, we detect an HI tail of ~60 kpc being stripped off NGC 4424, a peculiar spiral galaxy. The properties of the galaxy, together with the shape of the tail, suggest that NGC 4424 is a postmerger galaxy undergoing ram pressure stripping as it falls towards the centre of the Virgo Cluster.We detect a total of 14 galaxies and three HI clouds lacking optical counterparts. One of the clouds is a new detection with an HI mass of 7 × 107M⊙ and a strong HI profile with W50 = 73 km s-1. We find that 10 out of the 14 galaxies present HI deficiencies not higher than those of the cluster's late spirals, suggesting that the environmental effects are not more pronounced in the region than elsewhere in the cluster. © 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.


Randriamampandry T.H.,University of Cape Town | Combes F.,Paris Observatory | Carignan C.,University of Cape Town | Carignan C.,Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo | Deg N.,University of Cape Town
Monthly Notices of the Royal Astronomical Society | Year: 2015

The observed velocities of the gas in barred galaxies are a combination of the azimuthally averaged circular velocity and non-circular motions, primarily caused by gas streaming along the bar. These non-circular flows must be accounted for before the observed velocities can be used in mass modelling. In this work, we examine the performance of the tilted-ring method and the DISKFIT algorithm for transforming velocity maps of barred spiral galaxies into rotation curves (RCs) using simulated data. We find that the tilted-ring method, which does not account for streaming motions, under-/overestimates the circular motions when the bar is parallel/perpendicular to the projected major axis. DISKFIT, which does include streaming motions, is limited to orientations where the bar is not aligned with either the major or minor axis of the image. Therefore, we propose a method of correcting RCs based on numerical simulations of galaxies. We correct the RC derived from the tilted-ring method based on a numerical simulation of a galaxy with similar properties and projections as the observed galaxy. Using observations of NGC 3319, which has a bar aligned with the major axis, as a test case, we show that the inferred mass models from the uncorrected and corrected RCs are significantly different. These results show the importance of correcting for the non-circular motions and demonstrate that new methods of accounting for these motions are necessary as current methods fail for specific bar alignments. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.


De Denus-Baillargeon M.-M.,University of Montréal | Boissier S.,Aix - Marseille University | Carignan C.,University of Montréal | Carignan C.,Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo | And 3 more authors.
Proceedings of the International Astronomical Union | Year: 2010

The exact contribution of the stellar disk to the overall kinematics of a galaxy remains in most studies a free parameter of the mass models. With the help of chemospectrophotometric evolution models, it is now possible to have a coherent picture of the stellar population of a galaxy including its mass-to-luminosity ratio at every radius spanning a wide range of observable wavelengths. We will focus on discussing the consistency of the mass thus inferred in photometric bands ranging from the FUV to the NIR for individual galaxies and compare this to the maximum-disc hypothesis. © Copyright International Astronomical Union 2011.


Kam Z.S.,University of Montréal | Carignan C.,University of Montréal | Carignan C.,Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo | Carignan C.,University of Cape Town | And 4 more authors.
Proceedings of the International Astronomical Union | Year: 2010

We performed a deep HI and Hα mapping of M31 and M33 in order to get accurate kinematical data of those two galaxies and also to make a comparison between the HI and Hα kinematics. The HI data were obtained with the DRAO interferometer and the Hα data with the Fabry-Perot system of the Observatoire du mont Mégantic using an EMCCD as a detector. These data will give us the best possible datasets to derive accurate rotation curves and mass models for those two Local Group spirals and provide some new data for the HII regions studies of these galaxies. While the HI observations are of low resolution (∼1 arcmin), the high resolution of the Hα data (∼1 arcsec) should allow us to get much more details in the central regions, allowing at the same time a much better determination of the kinematical parameters. Hence, the inner part of the rotation curve, so inportant to constraint properly the mass models, will be determined more accurately. © Copyright International Astronomical Union 2011.


Randriamampandry T.H.,University of Cape Town | Deg N.,University of Cape Town | Carignan C.,University of Cape Town | Carignan C.,Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo | And 2 more authors.
Astronomy and Astrophysics | Year: 2016

Context. We use Tree-SPH simulations from the GalMer database to characterize and quantify the non-circular motions induced by the presence of bar-like structures on the observed rotation curve of barred galaxies derived from empirical models of their line-of-sight velocity maps. The GalMer database consists of SPH simulations of galaxies spanning a wide range of morphological types and sizes. Aims. The aim is to compare the intrinsic velocities and bar properties from the simulations with those derived from pseudo-observations. This allows us to estimate the amount of non-circularity and to test the various methods used to derive the bar properties and rotation curves. Methods. The intrinsic velocities in the simulations are calculated from the gravitational forces whereas the observed rotation velocities are derived by applying the ROTCUR and DiskFit algorithms to well-resolved observations of intermediate-inclination, strongly barred galaxies. Results. Our results confirm that the tilted ring method implemented in ROTCUR systematically underestimates or overestimates the rotational velocities by up to 40 percent in the inner part of the galaxy when the bar is aligned with one of the symmetry axes for all the models. For the DiskFit analysis, we find that it produces unrealistic values for all the models used in this work when the bar is within approximately ten degrees of the major or minor axis. © ESO, 2016.


Carignan C.,University of Montréal | Carignan C.,Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo | Carignan C.,University of Cape Town | Turbide L.,University of Montréal | Koulidiati J.,Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo
Proceedings of the International Astronomical Union | Year: 2010

On the African continent, most of the activities in Astronomy are found in South Africa where full training in Astrophysics is given in a few Universities and where most of the professional astronomers and of the research instruments (from small telescopes to the 11m SALT, in the optical) can be found. In 2007, we started a full program (undergraduate and graduate) in Astrophysics at the Université de Ouagadougou and an Observatory (ODAUO), for teaching purposes, was also built. In October 2009, we put in crates the 1m Marly telescope in La Silla, Chile which will be rebuilt in 2011-12, as a full research telescope, on mount Djaogari in Burkina Faso. © Copyright International Astronomical Union 2011.


Miley G.,Leiden University | Carignan C.,University of Montréal | Carignan C.,Observatoire Dastrophysique Of Luniversite Of Ouagadougou Odauo | Carignan C.,University of Cape Town | Govender K.,South African Astronomical Observatory SAAO
Proceedings of the International Astronomical Union | Year: 2010

During the next decade the IAU intends to mobilize talented astronomers, engineers and teachers around the world, in the service of developing countries. I shall review the content of the IAU Strategic Plan 2010 - 2020 "Astronomy for the Developing World" and give you an update on its implementation. Astronomy is a unique tool for stimulating capacity building because it combines cutting-edge technology with fundamental science and has deep cultural roots. The plan envisages a substantial increase in IAU education and development activities during the next decade. These activities will be bottom-up, with a strong regional influence. An integrated approach tailored to the conditions and needs of each country will involve a mix of education at primary, secondary and tertiary levels and public outreach. As a crucial component of the strategy, the IAU together with the South African National Research Foundation will set up a small office to coordinate and plan the various global activities at the SAAO in Cape Town. © Copyright International Astronomical Union 2011.

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