- Archaeoastronomy, Ancient Astronomy, Prehistoric Archaeology, Iconography, Cosmology (Anthropology), Mental Representation, and 10 moreRepresentations, History of Astronomy, Bronze Age Europe (Archaeology), Cognitive archaeology, Symbols, Experimental Archaeology, Megalithic Monuments, Protohistory, Nordic Bronze Age, and Alain Testartedit
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A measurement by microlensing of the planetary mass function of planets with masses ranging from 5M_E to 10M_J and orbital radii from 0.5 to 10 AU was reported recently. A strategy for extending the mass range down to (1-3)M_E is proposed... more
A measurement by microlensing of the planetary mass function of planets with masses ranging from 5M_E to 10M_J and orbital radii from 0.5 to 10 AU was reported recently. A strategy for extending the mass range down to (1-3)M_E is proposed here. This entails monitoring the peaks of a few tens of microlensing events with moderately high magnifications with 1-2m class telescopes. Planets of a few Earth masses are found to produce deviations of ~ 5% to the peaks of microlensing light curves with durations ~ (0.7-3)hr in events with magnification ~ 100 if the projected separation of the planet lies in the annular region (0.85-1.2)r_E. Similar deviations are produced by Earth mass planets in the annular region (0.95-1.05)r_E. It is possible that sub-Earths could be detected very close to the Einstein ring if they are sufficiently abundant, and also planetary systems with more than one low mass planet.
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Les nebuleuses planetaires (NP) sont le produit de l'evolution d'etoiles de masses intermediaires apres leur expansion spherique a la fin de leurs vies. Il a ete estime observationnellement que 80 % des NP ont des formes... more
Les nebuleuses planetaires (NP) sont le produit de l'evolution d'etoiles de masses intermediaires apres leur expansion spherique a la fin de leurs vies. Il a ete estime observationnellement que 80 % des NP ont des formes non-spheriques. Une fraction si elevee est deroutante et a mobilise la communaute de recherche sur les NP pendant plus de trente ans. Un scenario qui permettrait de justifier les formes observees serait que les etoiles progenitrices de noyaux de NP (NNP) ne sont pas simples, mais possedent un compagnon. Les formes des nebuleuses seraient ainsi le resultat de l'interaction avec le compagnon. La fraction si elevee de NP non-spheriques impliquerait donc une fraction elevee de NNP binaires, faisant de la parite stellaire un canal de formation privilegie pour les NP. Apres avoir presente l'etat de connaissance actuelle concernant la formation et la mise en forme des NP, je presente mes travaux visant a detecter un exces infrarouge qui serait la signature ...
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The RoboNet collaboration also followed the event with their three 2m robotic telescopes : the Faulkes Telescopes The microlensing event MOA-2009-BLG-387 was alerted North (FTN) and South (FTS) in Hawaii and Australia by the MOA... more
The RoboNet collaboration also followed the event with their three 2m robotic telescopes : the Faulkes Telescopes The microlensing event MOA-2009-BLG-387 was alerted North (FTN) and South (FTS) in Hawaii and Australia by the MOA collaboration (Microlensing Observations in (Siding Springs Observatory) respectively, and the Liverpool Astrophysics) on 24 July 2009 at 15:08 UT, HJD'=HJD-24500000=5037.13, a few days before the
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ABSTRACT During the past 20 years, the idea that non-spherical planetary nebulae, comprising 80% of the total population, might need a binary or planetary interaction to be shaped, was discussed by various authors. It is now generally... more
ABSTRACT During the past 20 years, the idea that non-spherical planetary nebulae, comprising 80% of the total population, might need a binary or planetary interaction to be shaped, was discussed by various authors. It is now generally agreed that the varied morphologies of planetary nebulae cannot currently be explained by rotation and magnetic fields in single giant stars. Observationally, more binary central stars of planetary nebula have been discovered, opening new possibilities to understand the connections between binarity and morphology. So far, 45 binary central stars of planetary nebulae have been detected, most being close systems detected via flux variability. In order to determine the actual PN binary fraction, one needs a method that can detect wider binaries. We present here early results from a survey of high precision I-band and near infrared photometry of planetary nebula central stars aimed at detecting binaries with any separation. Eventually our survey will sample most of the 2-kpc volume limited sample of Frew (2008). At that time we expect that the binary fraction will reveal whether PN derive primarily from binaries or whether the current scenario, whereby single stars somehow, can generate non spherical planetary nebulae, is more in line with observation.
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During the past 20 years, the idea that non-spherical planetary nebulae, comprising 80% of the total population, might need a binary or planetary interaction to be shaped, was discussed by various authors. It is now generally agreed that... more
During the past 20 years, the idea that non-spherical planetary nebulae, comprising 80% of the total population, might need a binary or planetary interaction to be shaped, was discussed by various authors. It is now generally agreed that the varied morphologies of planetary nebulae cannot currently be explained by rotation and magnetic fields in single giant stars. Observationally, more binary central stars of planetary nebula have been discovered, opening new possibilities to understand the connections between binarity and morphology. So far, 45 binary central stars of planetary nebulae have been detected, most being close systems detected via flux variability. In order to determine the actual PN binary fraction, one needs a method that can detect wider binaries. We present here early results from a survey of high precision I-band and near infrared photometry of planetary nebula central stars aimed at detecting binaries with any separation. Eventually our survey will sample most of...
The Kepler Observatory offers unprecedented photometric precision (<1 mmag) and cadence for monitoring the central stars of planetary nebulae, allowing the detection of tiny periodic light curve variations, a possible signature of... more
The Kepler Observatory offers unprecedented photometric precision (<1 mmag) and cadence for monitoring the central stars of planetary nebulae, allowing the detection of tiny periodic light curve variations, a possible signature of binarity. With this precision free from the observational gaps dictated by weather and lunar cycles, we are able to detect companions at much larger separations and with much smaller radii than ever before. We have been awarded observing time to obtain light-curves of the central stars of the six confirmed and possible planetary nebulae in the Kepler field, including the newly discovered object Kn 61, at cadences of both 30 min and 1 min. Of these six objects, we could confirm for three a periodic variability consistent with binarity. Two others are variables, but the initial data set presents only weak periodicities. For the central star of Kn 61, Kepler data will be available in the near future.
There is growing evidence that a majority of planetary nebulae (PNe) harbor close binary central stars. If so, PNe would be a binary interaction phenomenon. If this were the case, there would be repercussions in our understanding of... more
There is growing evidence that a majority of planetary nebulae (PNe) harbor close binary central stars. If so, PNe would be a binary interaction phenomenon. If this were the case, there would be repercussions in our understanding of galactic enrichment, nebular shaping mechanisms, and the relationship between central stars of PN and other post-common envelope and strong interaction binary classes
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During the past 20 years, the idea that non-spherical planetary nebulae might need a binary or planetary interaction to be shaped was discussed by various authors. It is now generally agreed that the varied morphologies of planetary... more
During the past 20 years, the idea that non-spherical planetary nebulae might need a binary or planetary interaction to be shaped was discussed by various authors. It is now generally agreed that the varied morphologies of planetary nebulae cannot be fully explained solely by single star evolution. Observationally, more binary central stars of planetary nebulae have been discovered, opening new possibilities to understand the connections between binarity and morphology. So far, ≃45 binary central stars of planetary nebulae have been detected, most being close systems detected via flux variability. In order to determine the PN binary fraction, one needs a method that can detect wider binaries. We present here recent results concentrating on binary infrared excess observations aimed at detecting binaries of any separation.
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Having surveyed ≈ 10% of the sky, we have identified more than 130 PN candidates by surveying multicolour Digitized Sky Survey (DSS), Sloan Digitized Sky Survey (SDSS), and combined [O III], Hα and [S II] images. In a first imaging and... more
Having surveyed ≈ 10% of the sky, we have identified more than 130 PN candidates by surveying multicolour Digitized Sky Survey (DSS), Sloan Digitized Sky Survey (SDSS), and combined [O III], Hα and [S II] images. In a first imaging and spectroscopy campaign, 51 objects were identified as true and probable PNe. This work presents an additional 17 probable or possible PNe identified since that study. The majority of these candidates are situated at Galactic latitudes |b| > 5^, with the exception of seven objects located closer to the Galactic plane. Using the techniques described here that do not require any new survey data, we anticipate that many more PNe are waiting to be found, perhaps as many as 90.
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There is growing evidence that a majority of planetary nebulae (PNe) harbor close binary central stars. If so, PNe would be a binary interaction phenomenon. If this were the case, there would be repercussions in our understanding of... more
There is growing evidence that a majority of planetary nebulae (PNe) harbor close binary central stars. If so, PNe would be a binary interaction phenomenon. If this were the case, there would be repercussions in our understanding of galactic enrichment, nebular shaping mechanisms, and the relationship between central stars of PN and other post-common envelope and strong interaction binary classes