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Your search keyword '"J. J. Calitz"' showing total 4 results
Start Over Author "J. J. Calitz" Topic astrophysics (astro-ph)
4 results on '"J. J. Calitz"'

1. Discovery of a cool planet of 5.5 Earth masses through gravitational microlensing

Author

M. F. Bode, Kisaku Kamiya, Ian A. Bond, P. M. Kilmartin, Yutaka Matsubara, Penny D. Sackett, C. Coutures, Igor Soszyński, Stephen R. Kane, T. Wiȩckowski, Michael D. Albrow, Andrew Williams, J. G. Greenhill, T. R. Britton, O. Szewczyk, Łukasz Wyrzykowski, D. Dominis, M. Desort, R. M. Martin, Fumio Abe, D. M. Bramich, A. C. Gilmore, J. A. R. Caldwell, M. Hoffman, Shota Nakamura, J. J. Calitz, Denis J. Sullivan, Grzegorz Pietrzyński, Susumu Sato, Iain A. Steele, K. Woller, Kailash C. Sahu, P. J. Tristram, Martin Burgdorf, Misao Sasaki, Pascal Fouqué, J. W. Menzies, A. V. Korpela, E. Corrales, D. Kubas, Martin Dominik, T. Sekiguchi, Kimiaki Masuda, David P. Bennett, Colin Snodgrass, S. Brillant, Yoshitaka Itow, C. Okada, Takashi Sako, T. Yoshioka, Philip Yock, K. R. Pollard, Joachim Wambsganss, U. G. Jørgensen, P. J. Meintjes, Bohdan Paczynski, M. Kubiak, Arnaud Cassan, J. B. Marquette, M. Motomura, Andrzej Udalski, Michał K. Szymański, C. Vinter, Kouji Ohnishi, S. Dieters, J. P. Beaulieu, Nicholas J. Rattenbury, John B. Hearnshaw, J. Donatowicz, K. H. Cook, K. M. Hill, Yasushi Muraki, Keith Horne, Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Astronomische Rechen-Institut [Heidelberg] (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg] = Heidelberg University-Universität Heidelberg [Heidelberg] = Heidelberg University, Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Universität Heidelberg [Heidelberg]-Universität Heidelberg [Heidelberg]

Subjects
FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Planetary migration, Physics, Multidisciplinary, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astrophysics (astro-ph), Giant planet, Institut für Physik und Astronomie, Astronomy, Planetary system, Exoplanet, planet, microlensing, 13. Climate action, Terrestrial planet, Astrophysics::Earth and Planetary Astrophysics, Planetary mass, Jupiter mass
Abstract

Over 170 extrasolar planets have so far been discovered, with a wide range of masses and orbital periods, but until last July no planet of Neptune's mass or less had been detected any more than 0.15 astronomical units (AU) from a normal star. (That's close — Earth is one AU from the Sun). On 11 July 2005 the OGLE Early Warning System recorded a notable event: gravitational lensing of light from a distant object by a foreground star revealed a small planet of about 5.5 Earth masses, orbiting at about 2.6 AU from the foreground star. This is the lowest known mass for an extrasolar planet orbiting a main sequence star, and its detection suggests that cool, sub-Neptune mass planets are more common than gas giants, as predicted by the favoured core accretion theory of planet formation. In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars (the most common stars in our Galaxy), this model favours the formation of Earth-mass (M⊕) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (au), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars1,2,3,4. More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 au from normal stars. Here we report the discovery of a M⊕ planetary companion at a separation of au from a M⊙ M-dwarf star, where M⊙ refers to a solar mass. (We propose to name it OGLE-2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.

Published
2006
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2. OGLE 2004-BLG-254: a K3 III Galactic Bulge Giant spatially resolved by a single microlens

Author

J. A. R. Caldwell, P. Fouque, D. Dominis, K. Zebrun, Keith Horne, Michael D. Albrow, Andrew Williams, D. Kubas, L. Wyrzykowski, R. M. Martin, H. C. Stempels, J. P. Beaulieu, J. Donatowicz, J. J. Calitz, K. H. Cook, C. Coutures, V. R. Miller, Stephane Brillant, K. R. Pollard, Martin Dominik, Arnaud Cassan, J. B. Marquette, Joachim Wambsganss, Andrzej Udalski, Michał K. Szymański, J. W. Menzies, M. Hoffman, U. G. Jørgensen, C. Vinter, Grzegorz Pietrzyński, K. Hill, M. Kubiak, P. J. Meintjes, Kailash C. Sahu, David P. Bennett, S. R. Kane, D. Heyrovsky, Igor Soszyński, J. G. Greenhill, O. Szewczyk, Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Astronomische Rechen-Institut [Heidelberg] (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg] = Heidelberg University-Universität Heidelberg [Heidelberg] = Heidelberg University, Laboratoire d'Astrophysique de l'Observatoire Midi-Pyrénées (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Universität Heidelberg [Heidelberg]-Universität Heidelberg [Heidelberg], Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
gravitational lensing, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, 01 natural sciences, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Bulge, Planet, individual: OGLE 2004-BLG-254, 0103 physical sciences, stars: atmospheres, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Spectrograph, Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Astrophysics (astro-ph), stars, Astrophysics::Instrumentation and Methods for Astrophysics, techniques: high angular resolution, Astronomy and Astrophysics, Light curve, Stars, Space and Planetary Science, Limb darkening, Astrophysics::Earth and Planetary Astrophysics, Event (particle physics)
Abstract

We present an analysis of OGLE 2004-BLG-254, a high-magnification and relatively short duration microlensing event in which the source star, a Bulge K3-giant, has been spatially resolved by a point-like lens. We have obtained dense photometric coverage of the event light curve with OGLE and PLANET telescopes, as well as a high signal-to-noise ratio spectrum taken while the source was still magnified by 20, using the UVES/VLT spectrograph. Our dense coverage of this event allows us to measure limb darkening of the source star in the I and R bands. We also compare previous measurements of linear limb-darkening coefficients involving GK-giant stars with predictions from ATLAS atmosphere models. We discuss the case of K-giants and find a disagreement between limb-darkening measurements and model predictions, which may be caused by the inadequacy of the linear limb-darkening law., Comment: 14 pages, 8 figures, accepted for publication in A&A (04/09/2006)

Published
2006
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3. The unusual optical afterglow of the gamma-ray burst GRB 021004: Color changes and short-time-scale variability

Author

D. Bersier, K. Z. Stanek, J. N. Winn, T. Grav, M. J. Holman, T. Matheson, B. Mochejska, D. Steeghs, A. R. Walker, P. M. Garnavich, J. Quinn, S. Jha, K. H. Cook, W. W. Craig, P. J. Meintjes, and J. J. Calitz

Subjects
Physics, 010308 nuclear & particles physics, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Scale (descriptive set theory), Context (language use), Astrophysics, 01 natural sciences, Power law, Afterglow, Space and Planetary Science, Color changes, 0103 physical sciences, Gamma-ray burst, 010303 astronomy & astrophysics
Abstract

We report UBVRI observations of the optical afterglow of the gamma-ray burst GRB 021004. We observed significant (10-20%) deviations from a power law decay on several time scales, ranging from a few hours down to 20-30 minutes. We also observed a significant color change starting ~1.5 days after the burst, confirming the spectroscopic results already reported by Matheson et al. (2002). We discuss these results in the context of several models that have recently been proposed to account for the anomalous photometric behavior of this event., Comment: Submitted to ApJL, 14 pages, 4 figures. Data available on anonymous ftp at ftp://cfa-ftp.harvard.edu/pub/kstanek/GRB021004

Published
2002
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4. Gravitational Microlensing Events Due to Stellar Mass Black Holes

Author

J. J. Calitz, Sun Hong Rhie, Douglas L. Welch, Charles Alcock, M. R. Pratt, Dante Minniti, S. L. Marshall, Christopher W. Stubbs, William J. Sutherland, Kem H Cook, R. A. Allsman, Bruce A. Peterson, Tim Axelrod, David R. Alves, P. C. Fragile, Andrew J. Drake, David P. Bennett, P. Popowski, C. Laws, Kenneth C. Freeman, Peter J. Quinn, Kim Griest, Stefan Keller, Andrew C. Becker, Bradley R. Johnson, J. Quinn, T. Vandehei, Matthew J. Lehner, C. A. Nelson, Austin B. Tomaney, and Marla Geha

Subjects
Physics, Stellar mass, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Compact star, Gravitational microlensing, law.invention, Lens (optics), Black hole, Stars, Space and Planetary Science, Bulge, law, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Main sequence, Astrophysics::Galaxy Astrophysics
Abstract

We present an analysis of the longest timescale microlensing events discovered by the MACHO Collaboration during a 7 year survey of the Galactic bulge. We find 6 events that exhibit very strong microlensing parallax signals due, in part, to accurate photometric data from the GMAN and MPS collaborations. The microlensing parallax fit parameters are used in a likelihood analysis, which is able to estimate the distance and masses of the lens objects based upon a standard model of the Galactic velocity distribution. This analysis indicates that the most likely masses of 5 of the 6 lenses are > 1 Msun, which suggests that a substantial fraction of the Galactic lenses may be massive stellar remnants. This could explain the observed excess of long timescale microlensing events. The lenses for events MACHO-96-BLG-5 and MACHO-98-BLG-6 are the most massive, with mass estimates of M/Msun = 6 +10/-3 and M/Msun = 6 +7/-3, respectively. The observed upper limits on the absolute brightness of main sequence stars for these lenses are < 1 Lsun, so both lenses are black hole candidates. The black hole interpretation is also favored by a likelihood analysis with a Bayesian prior using a conventional model for the lens mass function. We consider the possibility that the source stars for some of these 6 events may lie in the foreground or background of the Galactic bulge, but we find that this is unlikely. Future HST observations of these events can either confirm the black hole lens hypothesis or detect the lens stars and provide a direct measurement of their masses. Future observations of similar events by SIM or the Keck or VLTI interferometers will allow direct measurements of the lens masses for stellar remnant lenses as well., 47 pages, with 26 included postscript figures. Includes a new likelihood analysis with a mass function prior

Published
2001
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