26 results on '"Ricci D."'
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2. BeppoSAX and Chandra Observations of SAXJ0103.2-7209=2E0101.5-7225: a new Persistent 345s X-ray Pulsar in the SMC
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Israel, G. L., Campana, S., Covino, S., Fiume, D. Dal, Gaetz, T. J., Mereghetti, S., Oosterbroek, T., Orlandini, M., Parmar, A. N., Ricci, D., and Stella, L.
- Subjects
Astrophysics - Abstract
We report the results of a 1998 July BeppoSAX observation of a field in the SMC which led to the discovery of 345s pulsations in the X-ray flux of SAXJ0103.2-7209. The BeppoSAX X-ray spectrum is well fit by an absorbed power-law with photon index 1.0 plus a black body component with kT=0.1keV. The unabsorbed luminosity in the 2-10 keV energy range is 1.2x10^{36} erg/s. In a very recent Chandra observation the 345s pulsations are also detected. The available period measurements provide a constant period derivative of -1.7s/yr over the last three years making SAXJ0103.2-7209 one of the most rapidly spinning-up X-ray pulsars known. The BeppoSAX position is consistent with that of the Einstein source 2E0101.5-7225 and the ROSAT source RXJ0103.2-7209. This source was detected at a luminosity level of few 10^{35}-10^{36} erg/s in all datasets of past X-ray missions since 1979. The ROSAT HRI and Chandra positions are consistent with that of a m_V=14.8 Be spectral type star already proposed as the likely optical counterpart of 2E0101.5-7225. We conclude that SAXJ0103.2-7209 and 2E0101.5-7225 are the same source, a relatively young and persistent X-ray pulsar in the SMC., Comment: 4 pages. Accepted for publication in ApJ Letters. Emulateapj style used
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- 2000
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3. The 0.1-100 keV spectral shape and variability of Mkn421 in high state
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Malizia, A., Capalbi, M., Fiore, F., Giommi, P., Gandolfi, G., Tesseri, A., Antonelli, L. A., Butler, R. C., Celidonio, G., Coletta, A., Di Ciolo, L., Muller, J. M., Piro, L., Rebecchi, S., Ricci, D., Ricci, R., Smith, M., and Torroni, V.
- Subjects
Astrophysics - Abstract
The results of a BeppoSAX TOO observation of the BL Lac object Mkn421 during a high intensity state are reported and compared with monitoring X-ray data collected with the BeppoSAX Wide Field Cameras (WFC) and the RXTE All Sky Monitor(ASM). The 0.1-100 keV spectrum of Mkn421 shows continuous convex curvature that can be interpreted as the high-energy end of the synchrotron emission. The source shows significant short-term temporal and spectral variability, which can be interpreted in terms of synchrotron cooling. The comparison of our results with those of previous observations when the source was a factor 3-5 fainter shows evidence for strong spectral variability, with the maximum of the synchrotron power shifting to higher energy during high states. This behaviour suggest an increase in the number of energetic electrons during high states., Comment: 6 pages, LaTeX, plus 8 .ps figures, accepted by MNRAS
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- 1999
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4. BeppoSAX LECS background subtraction techniques
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Parmar, A. N., Oosterbroek, T., Orr, A., Guainazzi, M., Shane, N., Freyberg, M. J., Ricci, D., and Malizia, A.
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Astrophysics - Abstract
We present 3 methods for the subtraction of non-cosmic and unresolved cosmic backgrounds observed by the Low-Energy Concentrator Spectrometer (LECS) on-board BeppoSAX. Removal of these backgrounds allows a more accurate modeling of the spectral data from point and small-scale extended sources. At high (>|25| degree) galactic latitudes, subtraction using a standard background spectrum works well. At low galactic latitudes, or in complex regions of the X-ray sky, two alternative methods are presented. The first uses counts obtained from two semi-annuli near the outside of the LECS field of view to estimate the background at the source location. The second method uses ROSAT Position Sensitive Proportional Counter (PSPC) all-sky survey data to estimate the LECS background spectrum for a given pointing position. A comparison of the results from these methods provides an estimate of the systematic uncertainties. For high galactic latitude fields, all 3 methods give 3 sigma confidence uncertainties of <0.9 10^-3 count/s (0.1-10 keV), or <1.5 10^-3 count/s (0.1-2 keV). These correspond to 0.1-2.0 keV fluxes of 0.7-1.8 and 0.5-1.1 10^-13 erg/cm2/s for a power-law spectrum with a photon index of 2 and photoelectric absorption of 3 10^20 and 3 10^21 atom/cm2, respectively. At low galactic latitudes, or in complex regions of the X-ray sky, the uncertainties are a factor ~2.5 higher., Comment: 13 pages. Accepted for publication in A&AS
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- 1999
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5. The BeppoSAX High Energy Large Area Survey (HELLAS)
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Fiore, F., Giommi, P., La Franca, F., Matt, G., Perola, G. C., Comastri, A., Molendi, S., Elvis, M., Gioia, I, Tamburelli, F., Ricci, D., and Pompilio, F.
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Astrophysics - Abstract
We have surveyed about 50 deg-2 of sky in the largely unexplored 5-10 keV band using the BeppoSAX MECS instrument, finding 180 sources. After correction for the non uniform sky coverage we find about 18 sources deg-2 with F(5-10keV) >= 5E-14 cgs, and resolve 30-40 % of the hard 5-10 keV Cosmic X-ray Background (XRB). Optical identification of a first small sample of sources show that most (11 out of 14) are AGN. Six of these show evidence of absorption/extinction in X-ray/optical, thus providing support to the scenario in which the hard XRB is largely made by obscured AGN (Setti & Woltjer 1989, Comastri et al. 1995)., Comment: 6 pages, Proceeding of the first XMM workshop "Science with XMM" (30 Sep. - 2 Oct. 1998 ESTEC)
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- 1998
6. Aquila X-1 from outburst to quiescence: the onset of the propeller effect and signs of a turned-on rotation-powered pulsar
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Campana, S., Stella, L., Mereghetti, S., Colpi, M., Tavani, M., Ricci, D., Fiume, D. Dal, and Belloni, T.
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Astrophysics - Abstract
We report on the March-April 1997 BeppoSAX observations of Aql X-1, the first to monitor the evolution of the spectral and time variability properties of a neutron star soft X-ray transient from the outburst decay to quiescence. We observed a fast X-ray flux decay, which brought the source luminosity from ~10^36 to ~10^{33} erg/s in less than 10 days. The X-ray spectrum showed a power law high energy tail with photon index Gamma~2 which hardened to Gamma~1-1.5 as the source reached quiescence. These observations, together with the detection by RossiXTE of a periodicity of a few milliseconds during an X-ray burst, likely indicate that the rapid flux decay is caused by the onset of the propeller effect arising from the very fast rotation of the neutron star magnetosphere. The X-ray luminosity and hard spectrum that characterise the quiescent emission can be consistently interpreted as shock emission by a turned-on rotation-powered pulsar., Comment: 4 pages (1 figure + 2 tables). Accepted for publication in ApJLetters. Requires emulateapj.sty and timesfonts.sty (included)
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- 1998
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7. The BeppoSAX Deep Surveys
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Giommi, P., Fiore, F., Ricci, D., Molendi, S., Maccarone, M. C., and Comastri, A.
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Astrophysics - Abstract
We present the preliminary results of a survey that makes use of several deep exposures obtained with the X-Ray telescopes of the BeppoSAX satellite. The survey limiting sensitivity is 5 x 10^-14 cgs in the 2-10 keV band and 7 x 10^-14 cgs in the harder 5-10 keV band. We find that the 2-10 keV LogN-LogS is consistent with that determined in ASCA surveys. The counts in the 5-10 keV band imply either a very hard average spectral slope or the existence of a population of heavily absorbed sources that can hardly be detected in soft X-ray surveys. A sample of 83 serendipitous sources has been compiled from a systematic search in 50 MECS images. The analysis of the hardness ratio of this sample also implies very hard or heavily cutoff spectral shapes., Comment: Invited Talk, to appear in : The Active X-ray Sky: Results from BeppoSAX and Rossi-XTE, Nuclear Physics B Proceedings Supplements, L. Scarsi, H. Bradt, P. Giommi and F. Fiore (eds.), Elsevier Science B.V. 9 pages LateX and 8 ps figures, using espcrc2 and epsfig
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- 1998
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8. BeppoSAX observations of the exotic black hole candidate GX 339-4
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Chiappetti, L., Haardt, F., Treves, A., Ricci, D., Santangelo, A., Mereghetti, S., and Belloni, T.
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Astrophysics - Abstract
GX 339-4 has been observed by BeppoSAX twice in spring 1997 as part of a longer monitoring program. The source was close to the highest levels (50 mCrab) of the extended low state (as measured by the XTE ASM during the last 2 years). Its spectrum was quite hard, similar to the Exosat 1984 off state, but 40 times stronger. The source is detected up to more than 120 keV, enabling the possibility to study its high energy spectrum, Comment: 4 pages, 2 figures imbedded, To appear in The Active X-ray Sky: Results from BeppoSAX and Rossi-XTE, Nuclear Physics B Proceedings Supplements, L. Scarsi, H. Bradt, P. Giommi and F. Fiore (eds.), Elsevier Science B.V
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- 1997
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9. First Results from the MECS on board BeppoSAX
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Molendi, S., Chiappetti, L., Cusumano, G., Fiume, D. Dal, Fiore, F., Frontera, F., Giommi, P., Guainazzi, M., Maccarone, C., Matteuzzi, A., Mineo, T., Perola, G. C., Piro, L., Ricci, D., and Sacco, B.
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Astrophysics - Abstract
In this contribution we discuss briefly a few calibration items relevant to the data analysis and present some preliminary scientific results. The discussion on instrumental topics focuses on the response matrix and Point Spread Function (PSF). In the scientific results section we discuss a first analysis of the two Seyferts MCG 6-30-15 and NGC 4151 and of the Cosmic X-ray Background., Comment: 6 pages LaTeX with incapsulated figures, using memsait.sty. To be published in the Proceedings of the second national meeting on AGN "From micro to mega parsecs"
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- 1997
10. EXOSAT OBSERVATIONS OF THE ULTRA-SOFT X-RAY BINARY 4U1957+11
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Ricci, D., Israel, G. L., and Stella, L.
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Astrophysics - Abstract
We present results from the analysis of the two EXOSAT observations of the low mass X-ray binary (LMXRB) 4U1957+11. The 1-20keV spectrum of the source is best fitted by a power law model with exponential cutoff, that provides an approximation of a thermal Comptonisation spectrum. The cutoff energy (~2keV), as well as the X-ray colours, are intermediate between those of ultrasoft sources containing black hole candidates (BHCs) and those of soft LMXRBs containing an old accreting neutron star. We find no evidence for a black body spectral component. During the 1985 observation, the source flux was 10% higher than in the 1983 observation, and the ME spectra provide evidence for a high energy tail (up to ~16keV), which strengthens the similarity with the spectra of high state BHCs. However the source luminosity was only ~5 10^36 ergs/s. During the 1985 observation the GSPC spectra revealed the presence of a 100eV EW iron K-line emission feature with a centroid energy of 7.06+/-0.09keV; this value is among the highest measured by {\it EXOSAT}. The ME light curves showed only a low-amplitude variability on timescales of a few hours. No evidence for a periodic modulation with periods between 0.016 and 13000~s was found., Comment: uuencoded gzipped PostScript file, 8 pages, Astronomy and Astrophysics, in press (1995). For any questions and/or Comments please contact Donatella Ricci (dona@vxrmg9.icra.it)
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- 1995
11. The Search for Black Holes in X-Ray Binaries: An Update
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Stella, L., Israel, G. L., Mereghetti, S., and Ricci, D.
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Astrophysics - Abstract
This paper reviews some of the recent observational results on stellar mass black hole candidates. Over the last decade, much of the progress in this field has been achieved through the study of transient X--ray binary sources which shine only sporadically in the X--ray sky and undergo much larger luminosity variations then most persistent sources. There are currently six stellar--mass black hole candidates for which the mass of the compact object is estimated to be well above the maximum neutron star mass. The three most recently identified black hole candidates of this kind belong to a class of transient X--ray sources with peculiar spectral properties. Several new transients of this class are being discovered and studied every year thanks to more continous monitoring of the X--ray sky. Many of them are likely to contain other black hole candidates. The growing number of candidates and the large luminosity variations (and therefore, accretion rate variations) in transient sources will allow to study the chacteristics of accreting black holes with an unprecedented detail., Comment: self-extracting uuencoded tar-compressed PostScript file, 21 pages + 4 figures available (via FAX) upon request to israel@tsmi19.sissa.it, to appear on the Proceedings of the 7th Marcel Grossmann Meeting, Stanford 1994
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- 1994
12. Estimating the parameters of globular cluster M 30 (NGC 7099) from time-series photometry (Corrigendum)
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Kains, N., Bramich, D. M., Arellano Ferro, A., Figuera Jaimes, R., Jørgensen, U. G., Giridhar, S., Penny, M. T., Alsubai, K. A., Andersen, J. M., Bozza, V., Browne, P., Burgdorf, M., Calchi Novati, S., Damerdji, Y., Diehl, C., Dodds, P., Dominik, M., Elyiv, A., Fang, X.-S., Giannini, E., Gu, S.-H., Hardis, S., Harpsøe, K., Hinse, T. C., Hornstrup, A., Hundertmark, M., Jessen-Hansen, J., Juncher, D., Kerins, E., Kjeldsen, H., Korhonen, H., Liebig, C., Lund, M. N., Lundkvist, M., Mancini, L., Martin, R., Mathiasen, M., Rabus, M., Rahvar, S., Ricci, D., Sahu, K., Scarpetta, G., Skottfelt, J., Snodgrass, C., Southworth, J., Surdej, J., Tregloan-Reed, J., Vilela, C., Wertz, O., Williams, A., and Mindstep Consortium, [No Value]
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Physics ,010504 meteorology & atmospheric sciences ,Astronomy ,Astronomy and Astrophysics ,Astrophysics ,RR Lyrae variable ,01 natural sciences ,Blue straggler ,variables: RR Lyrae [stars] ,Photometry (astronomy) ,individual: M 30 (NGC 7099) [globular clusters] ,Space and Planetary Science ,variables: general [stars] ,Globular cluster ,0103 physical sciences ,010303 astronomy & astrophysics ,addenda ,errata ,0105 earth and related environmental sciences - Abstract
Not Available
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- 2016
13. A giant planet beyond the snow line in microlensing event OGLE-2011-BLG-0251
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Kains, N., Street, R.A., Choi, J.-Y., Han, C., Udalski, A., Almeida, L.A., Jablonski, F., Tristram, P.J., Jørgensen, Uffe Gråe, Szymański, M.K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Wyrzykowski, Ł., Skowron, J., Tsapras, Y., Alsubai, K.A., Bozza, V., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dominik, M., Dreizler, S., Fang, X.-S., Grundahl, F., Gu, C.-H., Hardis, S., Harpsøe, Kennet Bomann West, Hessman, F. V., Hinse, T. C., Hornstrup, Allan, Hundertmark, M., Jessen-Hansen, Jens, Kerins, E., Liebig, C., Lund, M., Lundkvist, M., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Sahu, K.C., Scarpetta, G., Skottfelt, J., Snodgrass, C., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Bajek, D., Bramich, D.M., Horne, K., Ipatov, S., Steele, I.A., Abe, F., Bennett, D.P., Bond, I.A., Botzler, C.S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Ling, C.H., Masuda, K., Matsubara, Y, Miyake, N., Muraki, Y., Ohnishi, K., Rattenbury, N., Saito, T., Sullivan, D.J., Sumi, T., Suzuki, D., Suzuki, K., Sweatman, W.L., Takino, S., Wada, K., Yock, P.C.M., Allen, W., Batista, V., Chung, S.-J., Christie, G., Depoy, D.L., Drummond, J., Gaudi, B.S., Gould, A., Henderson, C., Jung, Y.K., Koo, J.-R., Lee, C.-U., McCormick, J., McGregor, D., Muñoz, J.A., Natusch, T., Ngan, H., Park, H., Pogge, R.W., Shin, I.-G., Yee, J., Albrow, M.D., Bachelet, E., Beaulieu, J.-P., Brillant, S., Caldwell, J.A.R., Cassan, A., Cole, A., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Kane, S.R., Kubas, D., Marquette, J.-B., Martin, R., Meintjes, P., Menzies, J., Pollard, K.R., Williams, A., Wouters, D., Zub, M., Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy
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planets and satellites: detection ,010504 meteorology & atmospheric sciences ,Satellites ,bulge [Galaxy] ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Discovery ,Gravitational microlensing ,01 natural sciences ,Galaxy: bulge ,Einstein radius ,Lens ,gravitational lensing: weak ,Settore FIS/05 - Astronomia e Astrofisica ,Planet ,Snow ,0103 physical sciences ,gravitational lensing ,weak ,planets and satellites ,detection ,planetary systems ,Galaxy ,bulge ,Binary ,QB Astronomy ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,QB ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Giant planet ,Systems ,Search ,Astronomy and Astrophysics ,Radius ,Frequency ,Planetary system ,Mass ratio ,Mass ,Light curve ,Stars ,Algorithm ,detection [Planets and satellites] ,Planetary systems ,Space and Planetary Science ,Dwarf ,Astrophysics::Earth and Planetary Astrophysics ,weak [Gravitational lensing] ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present the analysis of the gravitational microlensing event OGLE-2011-BLG-0251. This anomalous event was observed by several survey and follow-up collaborations conducting microlensing observations towards the Galactic Bulge. Based on detailed modelling of the observed light curve, we find that the lens is composed of two masses with a mass ratio q=1.9 x 10^-3. Thanks to our detection of higher-order effects on the light curve due to the Earth's orbital motion and the finite size of source, we are able to measure the mass and distance to the lens unambiguously. We find that the lens is made up of a planet of mass 0.53 +- 0.21,M_Jup orbiting an M dwarf host star with a mass of 0.26 +- 0.11 M_Sun. The planetary system is located at a distance of 2.57 +- 0.61 kpc towards the Galactic Centre. The projected separation of the planet from its host star is d=1.408 +- 0.019, in units of the Einstein radius, which corresponds to 2.72 +- 0.75 AU in physical units. We also identified a competitive model with similar planet and host star masses, but with a smaller orbital radius of 1.50 +- 0.50 AU. The planet is therefore located beyond the snow line of its host star, which we estimate to be around 1-1.5 AU., 12 pages, 7 figures, 3 tables; A&A in press
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- 2013
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14. Microlensing Discovery of a Population of Very Tight, Very Low-mass Binary Brown Dwarfs
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Choi, J.-Y., Han, C., Udalski, A., Sumi, T., Gaudi, B. S., Gould, A., Bennett, D. P., Dominik, M., Beaulieu, J.-P., Tsapras, Y., Bozza, V., Abe, F., Bond, I. A., Botzler, C. S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohnishi, K., Rattenbury, N. J., Saito, To., Sullivan, D. J., Suzuki, K., Sweatman, W. L., Suzuki, D., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., The MOA Collaboration, Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Skowron, J., Kozłowski, S., Poleski, R., Ulaczyk, K., Wyrzykowski, Ł., Pietrukowicz, P., The OGLE Collaboration, Almeida, L. A., DePoy, D. L., Dong, Subo, Gorbikov, E., Jablonski, F., Henderson, C. B., Hwang, K.-H., Janczak, J., Jung, Y.-K., Kaspi, S., Lee, C.-U., Malamud, U., Maoz, D., McGregor, D., Muñoz, J. A., Park, B.-G., Park, H., Pogge, R. W., Shvartzvald, Y., Shin, I.-G., Yee, J. C., The μFUN Collaboration, Alsubai, K. A., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Fang, X.-S., Finet, F., Glitrup, M., Grundahl, F., Gu, S.-H., Hardis, S., Harpsøe, K., Hinse, T. C., Hornstrup, A., Hundertmark, M., Jessen-Hansen, J., Jrgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, M. N., Lundkvist, M., Maier, G., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Snodgrass, C., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Zimmer, F., MiNDSTEp Consortium, The, Albrow, M. D., Bachelet, E., Batista, V., Brillant, S., Cassan, A., Cole, A. A., Coutures, C., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Kubas, D., Marquette, J.-B., Menzies, J. W., Sahu, K. C., Zub, M., The PLANET Collaboration, Bramich, D. M., Horne, K., Steele, I. A., Street, R. A., The RoboNet Collaboration, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy
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binaries: general ,gravitational lensing: micro ,010504 meteorology & atmospheric sciences ,Population ,Events ,Brown dwarf ,Minimum mass ,Binary number ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Gravitational microlensing ,01 natural sciences ,micro [Gravitational lensing] ,Settore FIS/05 - Astronomia e Astrofisica ,0103 physical sciences ,QB Astronomy ,Astrophysics::Solar and Stellar Astrophysics ,education ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,QB ,Physics ,education.field_of_study ,Galactic bulge ,general [Binaries] ,Systems ,Search ,Astronomy and Astrophysics ,Stars ,Extrasolar planets ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Low Mass ,Gravitational lens - Abstract
Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs are poorly understood. The multiplicity properties and minimum mass of the brown-dwarf mass function provide critical empirical diagnostics of these mechanisms. We present the discovery via gravitational microlensing of two very low-mass, very tight binary systems. These binaries have directly and precisely measured total system masses of 0.025 Msun and 0.034 Msun, and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field brown-dwarf binaries known. The discovery of a population of such binaries indicates that brown dwarf binaries can robustly form at least down to masses of ~0.02 Msun. Future microlensing surveys will measure a mass-selected sample of brown-dwarf binary systems, which can then be directly compared to similar samples of stellar binaries., 7 pages, 5 figures, 3 tables, ApJ submitted
- Published
- 2013
15. MOA-2010-BLG-328Lb: A SUB-NEPTUNE ORBITING VERY LATE M DWARF?
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Furusawa, K., Udalski, A., Sumi, T., Bennett, D. P., Bond, I. A., Gould, A., Jorgensen, U. G., Snodgrass, C., Prester, D. Dominis, Albrow, M. D., Abe, F., Botzler, C. S., Chote, P., Freeman, M., Fukui, A., Harris, P., Itow, Y., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohnishi, K., Rattenbury, N. J., Saito, To., Sullivan, D. J., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., Szymanski, M. K., Soszynski, I., Kubiak, M., Poleski, R., Ulaczyk, K., Pietrzynski, G., Wyrzykowski, L., Choi, J. Y., Christie, G. W., DePoy, D. L., Dong, S., Drummond, J., Gaudi, B. S., Han, C., Hung, L. -W., Jung, Y. -K., Lee, C. -U., McCormick, J., Moorhouse, D., Natusch, T., Nola, M., Ofek, E., Park, B. G., Park, H., Pogge, R. W., Shin, I. -G., Skowron, J., Thornley, G., Yee, J. C., Alsubai, K. A., Bozza, V., Browne, P., Burgdorf, M. J., Novati, S. Calchi, Dodds, P., Dominik, M., Finet, F., Gerner, T., Hardis, S., Harpsoe, K., Hinse, T. C., Hundertmark, M., Kains, N., Kerins, E., Liebig, C., Mancini, L., Mathiasen, M., Penny, M. T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Schafer, S., Schonebeck, F., Southworth, J., Surdej, J., Wambsganss, J., Street, R. A., Bramich, D. M., Steele, I. A., Tsapras, Y., Horne, K., Donatowicz, J., Sahu, K. C., Bachelet, E., Batista, V., Beatty, T. G., Beaulieu, J. -P., Bennett, C. S., Black, C., Bowens-Rubin, R., Brillant, S., Caldwell, J. A. R., Cassan, A., Cole, A. A., Corrales, E., Coutures, C., Dieters, S., Fouque, P., Greenhill, J., Henderson, C. B., Kubas, D., Marquette, J. -B., Martin, R., Menzies, J. W., Shappee, B., Williams, A., Wouters, D., van Saders, J., Zellem, R., Zub, M., Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy
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gravitational lensing: micro ,planetary systems ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Astrophysics ,Gravitational microlensing ,01 natural sciences ,micro [Gravitational lensing] ,Settore FIS/05 - Astronomia e Astrofisica ,Neptune ,Planet ,0103 physical sciences ,QB Astronomy ,010303 astronomy & astrophysics ,QC ,0105 earth and related environmental sciences ,QB ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Xallarap ,Astronomy and Astrophysics ,Planetary systems ,QC Physics ,Space and Planetary Science ,Orbital motion ,Parallax ,Event (particle physics) ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We analyze the planetary microlensing event MOA-2010-BLG-328. The best fit yields host and planetary masses of Mh = 0.11+/-0.01 M_{sun} and Mp = 9.2+/-2.2M_Earth, corresponding to a very late M dwarf and sub-Neptune-mass planet, respectively. The system lies at DL = 0.81 +/- 0.10 kpc with projected separation r = 0.92 +/- 0.16 AU. Because of the host's a-priori-unlikely close distance, as well as the unusual nature of the system, we consider the possibility that the microlens parallax signal, which determines the host mass and distance, is actually due to xallarap (source orbital motion) that is being misinterpreted as parallax. We show a result that favors the parallax solution, even given its close host distance. We show that future high-resolution astrometric measurements could decisively resolve the remaining ambiguity of these solutions., Comment: 30 pages, 6 figures. accepted for publication in ApJ. Figure 1 and 2 are updated
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- 2013
16. Possible detection of a bimodal cloud distribution in the atmosphere of HAT-P-32Ab from multiband photometry.
- Author
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Tregloan-Reed, J., Southworth, J., Mancini, L., Mollière, P., Ciceri, S., Bruni, I., Ricci, D., Ayala-Loera, C., and Henning, T.
- Subjects
PHOTOMETRY ,PLANETARY systems ,ASTRONOMICAL observations ,ASTROPHYSICS ,EXTRASOLAR planets - Abstract
We present high-precision photometry of eight separate transit events in the HAT-P-32 planetary system. One transit event was observed simultaneously by two telescopes of which one obtained a simultaneous multiband light curve in three optical bands, giving a total of 11 transit light curves. Due to the filter selection and in conjunction with using the defocused photometry technique, we were able to obtain an extremely high-precision, ground-based transit in the u band (350 nm), with an rms scatter of ≈1 mmag. All 11 transits were modelled using prism and gemc, and the physical properties of the system calculated. We find the mass and radius of the host star to be 1.182 ± 0.041 M
⊙ and 1.225 ± 0.015 R⊙ , respectively. For the planet, we find a mass of 0.80 ± 0.14 MJup , a radius of 1.807 ± 0.022 RJup , and a density of 0.126 ± 0.023 ρJup . These values are consistent with those found in the literature. We also obtain a new orbital ephemeris for the system T0 = BJD/TDB 2 454 420.447187(96) + 2.15000800(10) × E. We measured the transmission spectrum of HAT-P-32 A b and compared it to theoretical transmission spectra. Our results indicate a bimodal cloud particle distribution consisting of Rayleigh-like haze and grey absorbing cloud particles within the atmosphere of HAT-P-32 A b. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
17. Microlensing Binaries with Candidate Brown Dwarf Companions
- Author
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Shin, I.-G., Han, C., Gould, A., Udalski, A., Sumi, T., Dominik, M., Beaulieu, J.-P., Tsapras, Y., Bozza, V., Szymański, M. K., Kubiak, M., Soszyński, I., Pietrzyński, G., Poleski, R., Ulaczyk, K., Pietrukowicz, P., Kozłowski, S., Skowron, J., Wyrzykowski, Ł., The OGLE Collaboration, Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Freeman, M., Fukui, A., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Kobara, S., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Omori, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., The MOA Collaboration, Christie, G. W., Depoy, D. L., Dong, S., Gal-Yam, A., Gaudi, B. S., Hung, L.-W., Janczak, J., Kaspi, S., Maoz, D., McCormick, J., McGregor, D., Moorhouse, D., Muñoz, J. A., Natusch, T., Nelson, C., Pogge, R. W., Tan, T.-G., Polishook, D., Shvartzvald, Y., Shporer, A., Thornley, G., Malamud, U., Yee, J. C., Choi, J.-Y., Jung, Y.-K., Park, H., Lee, C.-U., Park, B.-G., Koo, J.-R., The μFUN Collaboration, Bajek, D., Bramich, D. M., Browne, P., Horne, K., Ipatov, S., Snodgrass, C., Steele, I., Street, R., Alsubai, K. A., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Fang, X.-S., Grundahl, F., Gu, C.-H., Hardis, S., Harpsøe, Kennet Bomann West, Hinse, T. C., Hundertmark, M., Jessen-Hansen, J., Jørgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, Mikkel Nørup, Lundkvist, M., Mancini, L., Mathiasen, M., Hornstrup, A., Penny, M. T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, Jesper Fælling, Southworth, J., Surdej, J., Tregloan-Reed, J., Wertz, O., Zimmer, F., Albrow, M. D., Batista, V., Brillant, S., Caldwell, J. A. R., Calitz, J. J., Cassan, A., Cole, A., Cook, K. H., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Hill, K., Hoffman, M., Kane, S. R., Kubas, D., Marquette, J.-B., Martin, R., Meintjes, P., Menzies, J., Pollard, K. R., Sahu, K. C., Wambsganss, J., Williams, A., Vinter, Christian, and Zub, M.
- Subjects
Physics ,010308 nuclear & particles physics ,Brown dwarf ,FOS: Physical sciences ,Astronomy and Astrophysics ,gravitational lensing: micro ,Astrophysics ,Light curve ,Gravitational microlensing ,01 natural sciences ,Einstein radius ,Stars ,binaries: general ,Settore FIS/05 - Astronomia e Astrofisica ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Planet ,0103 physical sciences ,brown dwarfs ,Parallax ,Low Mass ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation history. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing events discovered during 2004 - 2011 observation seasons. Based on the low mass ratio criterion of q < 0.2, we found 7 candidate events, including OGLE-2004-BLG-035, OGLE-2004-BLG-039, OGLE-2007-BLG-006, OGLE-2007-BLG-399/MOA-2007-BLG-334, MOA-2011-BLG-104/OGLE-2011-BLG-0172, MOA-2011-BLG-149, and MOA-201-BLG-278/OGLE-2011-BLG-012N. Among them, we are able to confirm that the companions of the lenses of MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149 are brown dwarfs by determining the mass of the lens based on the simultaneous measurement of the Einstein radius and the lens parallax. The measured mass of the brown dwarf companions are (0.02 +/- 0.01) M_Sun and (0.019 +/- 0.002) M_Sun for MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149, respectively, and both companions are orbiting low mass M dwarf host stars. More microlensing brown dwarfs are expected to be detected as the number of lensing events with well covered light curves increases with new generation searches., 10 pages, 9 figures, 4 tables
- Published
- 2012
18. MOA-2010-BLG-477Lb: constraining the mass of a microlensing planet from microlensing parallax, orbital motion and detection of blended light
- Author
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Bachelet, E., Shin, I.-G., Han, C., Fouqué, P., Gould, A., Menzies, J.W., Beaulieu, J.-P., Bennett, D.P., Bond, I.A., Dong, Subo, Heyrovský, D., Marquette, J.-B., Marshall, J., Skowron, J., Street, R.A., Sumi, T., Udalski, A., Abe, L., Agabi, K., Albrow, M.D., Allen, W., Bertin, E., Bos, M., Bramich, D.M., Chavez, J., Christie, G.W., Cole, A.A., Crouzet, N., Dieters, S., Dominik, M., Drummond, J., Greenhill, J., Guillot, T., Henderson, C.B., Hessman, F.V., Horne, K., Hundertmark, M., Johnson, J.A., Jørgensen, U.G., Kandori, R., Liebig, C., Mékarnia, D., McCormick, J., Moorhouse, D., Nagayama, T., Nataf, D., Natusch, T., Nishiyama, S., Rivet, J.P., Sahu, K.C., Shvartzvald, Y., Thornley, G., Tomczak, A.R., Tsapras, Y., Yee, J.C., Batista, V., Bennett, C.S., Brillant, S., Caldwell, J.A.R., Cassan, A., Corrales, E., Coutures, C., Dominis Prester, D., Donatowicz, J., Kubas, D., Martin, Roland, Williams, A., Zub, M., The PLANET Collaboration, De Almeida, L., Depoy, D.L., Gaudi, B.S., Hung, L.-W., Jablonski, F., Kaspi, S., Klein, N., Lee, C.-U., Lee, Y., Koo, J.-R., Maoz, D., Muñoz, J.A., Pogge, R.W., Polishook, D., Shporer, A., The FUN Collaboration, Abe, F., Botzler, C.S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Harris, P., Itow, Y., Kobara, S., Ling, C.H., Masuda, K., Matsubara, Y., Miyake, N., Ohmori, K., Ohnishi, K., Rattenbury, N.J., Saito, To., Sullivan, D.J., Suzuki, D., Sweatman, W.L., Tristram, P.J., Wada, K., Yock, P.C.M., The MOA Collaboration, Szymanski, M.K., Soszynski, I., Kubiak, M., Poleski, R., Ulaczyk, K., Pietrzynski, G., Wyrzykowski, L., The OGLE Collaboration, Kains, N., Snodgrass, C., Steele, I.A., The RoboNet Collaboration, Alsubai, K.A., Bozza, V., Browne, P., Burgdorf, M.J., Calchi Novati, S., Dodds, P., Dreizler, S., Finet, F., Gerner, T., Hardis, S., Harpsøe, K., Hinse, T.C., Kerins, E., Mancini, L., Mathiasen, M., Penny, M.T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Schäfer, S., Schönebeck, F., Southworth, J., Surdej, J., Wambsganss, J., The MiNDSTEp Consortium, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE)
- Subjects
gravitational lensing: micro ,planetary systems ,FOS: Physical sciences ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Gravitational microlensing ,01 natural sciences ,7. Clean energy ,Einstein radius ,Settore FIS/05 - Astronomia e Astrofisica ,Planet ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010306 general physics ,010303 astronomy & astrophysics ,ComputingMilieux_MISCELLANEOUS ,Astrophysics::Galaxy Astrophysics ,Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Giant planet ,Astronomy and Astrophysics ,Mass ratio ,Light curve ,Orbit ,13. Climate action ,Space and Planetary Science ,Orbital motion ,micro [gravitational lensing] ,gravitational lensing: micro, planetary systems ,Astrophysics::Earth and Planetary Astrophysics ,[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Microlensing detections of cool planets are important for the construction of an unbiased sample to estimate the frequency of planets beyond the snow line, which is where giant planets are thought to form according to the core accretion theory of planet formation. In this paper, we report the discovery of a giant planet detected from the analysis of the light curve of a high-magnification microlensing event MOA-2010-BLG-477. The measured planet-star mass ratio is $q=(2.181\pm0.004)\times 10^{-3}$ and the projected separation is $s=1.1228\pm0.0006$ in units of the Einstein radius. The angular Einstein radius is unusually large $\theta_{\rm E}=1.38\pm 0.11$ mas. Combining this measurement with constraints on the "microlens parallax" and the lens flux, we can only limit the host mass to the range $0.13, Comment: 3 Tables, 12 Figures, accepted in ApJ
- Published
- 2012
19. Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars
- Author
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Choi, J.-Y., Shin, I.-G., Park, S.-Y., Han, C., Gould, A., Sumi, T., Udalski, A., Beaulieu, J.-P., Street, R., Dominik, M., Allen, W., Almeida, L. A., Bos, M., Christie, G. W., Depoy, D. L., Dong, S., Drummond, J., Gal-Yam, A., Gaudi, B. S., Henderson, C. B., Hung, L.-W., Jablonski, F., Janczak, J., Lee, C.-U., Mallia, F., Maury, A., McCormick, J., McGregor, D., Monard, L. A. G., Moorhouse, D., Muñoz, J. A., Natusch, T., Nelson, C., Park, B.-G., Pogge, R. W., 'TG\\' Tan, T.-G., Thornley, G., Yee, J. C., The μFUN Collaboration, Abe, F., Barnard, E., Baudry, J., Bennett, D. P., Bond, I. A., Botzler, C. S., Freeman, M., Fukui, A., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Kobara, S., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Omori, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Suzuki, D., Suzuki, K., Sweatman, W. L., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., The MOA Collaboration, Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Ulaczyk, K., Wyrzykowski, Ł., Kozłowski, S., Pietrukowicz, P., The OGLE Collaboration, Albrow, M. D., Bachelet, E., Batista, V., Bennett, C. S., Bowens-Rubin, R., Brillant, S., Cassan, A., Cole, A., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Kane, S. R., Menzies, J., Sahu, K. C., Wambsganss, J., Williams, A., Zub, M., The PLANET Collaboration, Allan, A., Bramich, D. M., Browne, P., Clay, N., Fraser, S., Horne, K., Kains, N., Mottram, C., Snodgrass, C., Steele, I., Tsapras, Y., The RoboNet Collaboration, Alsubai, K. A., Bozza, V., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Finet, F., Gerner, T., Glitrup, M., Grundahl, F., Hardis, S., Harpsøe, K., Hinse, T. C., Hundertmark, M., Jørgensen, U. G., Kerins, E., Liebig, C., Maier, G., Mancini, L., Mathiasen, M., Penny, M. T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Schäfer, S., Schönebeck, F., Skottfelt, Jesper Fælling, Surdej, J., Southworth, J., Zimmer, F., and MiNDSTEp Consortium, The
- Subjects
Physics ,010308 nuclear & particles physics ,Brown dwarf ,FOS: Physical sciences ,Astronomy and Astrophysics ,gravitational lensing: micro ,Astrophysics ,Mass ratio ,Light curve ,Gravitational microlensing ,01 natural sciences ,Galaxy: bulge ,Galaxy: bulge, gravitational lensing: micro ,Einstein radius ,law.invention ,Lens (optics) ,Stars ,Astrophysics - Solar and Stellar Astrophysics ,Settore FIS/05 - Astronomia e Astrofisica ,Space and Planetary Science ,law ,0103 physical sciences ,Surface brightness ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) - Abstract
We present the analysis of the light curves of 9 high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For 7 events, we measure the Einstein radii and the lens-source relative proper motions. Among them, 5 events are found to have Einstein radii less than 0.2 mas, making the lenses candidates of very low-mass stars or brown dwarfs. For MOA-2011-BLG-274, especially, the small Einstein radius of $\theta_{\rm E}\sim 0.08$ mas combined with the short time scale of $t_{\rm E}\sim 2.7$ days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of $\sim 0.84\ M_\odot$ is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we find planetary signals for none of events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio., Comment: 14 pages, 12 figures, 5 tables
- Published
- 2012
20. Characterizing Low-Mass Binaries From Observation of Long Time-scale Caustic-crossing Gravitational Microlensing Events
- Author
-
Shin, I.-G, Han, C., Choi, J.-Y, Udalski, A., Sumi, T., Gould, A., Bozza, V., Dominik, M., Fouque´, P., Horne, K., Szyman´ski, M. K., Kubiak, M., Soszyn´ski, I., Pietrzyn´ski, G., Poleski, R., Ulaczyk, K., Pietrukowicz, P., Kozłowski, S., Skowron, J., Wyrzykowski, Ł., Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Kobara, S., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohmori, K., Ohnishi, K., Rattenbury, N. J., Saito, To, Sullivan, D. J., Suzuki, D., Suzuki, K., Sweatman, W. L., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., MOA Collaboration, Bramich, D. M., Snodgrass, C., Steele, I. A., Street, R. A., Tsapras, Y., RoboNet Collaboration, Alsubai, K. A., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Fang, X.-S, Grundahl, Frank, Gu, C.-H, Hardis, S., Harpsøe, Kennet Bomann West, Hinse, T. C., Hornstrup, Allan, Hundertmark, M., Jessen-Hansen, Jens, Jørgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, M., Lunkkvist, M., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Almeida, L. A., Batista, V., Christie, G., DePoy, D. L., Dong, Subo, Gaudi, B. S., Henderson, C., Jablonski, F., Lee, C.-U, McCormick, J., McGregor, D., Moorhouse, D., Natusch, T., Ngan, H., Park, S.-Y., Pogge, R. W., Tan, T.-G, Thornley, G., Yee, J. C., Albrow, M. D., Bachelet, E., Beaulieu, J.-P, Brillant, S., Cassan, A., Cole, A. A., Corrales, E., Coutures, C., Dieters, S., Dominis Prester, D., Donatowicz, J., Greenhill, J., Kubas, D., Marquette, J.-B, Menzies, J. W., Sahu, K. C., and Zub, M.
- Subjects
binaries: general ,gravitational lensing: micro ,010504 meteorology & atmospheric sciences ,Binary number ,FOS: Physical sciences ,Astrophysics ,Gravitational microlensing ,01 natural sciences ,Einstein radius ,micro [Gravitational lensing] ,Settore FIS/05 - Astronomia e Astrofisica ,0103 physical sciences ,Binary star ,binaries: general, gravitational lensing: micro ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences ,Orbital elements ,Physics ,general [Binaries] ,Observational techniques ,Astronomy and Astrophysics ,Light curve ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Low Mass - Abstract
Despite astrophysical importance of binary star systems, detections are limited to those located in small ranges of separations, distances, and masses and thus it is necessary to use a variety of observational techniques for a complete view of stellar multiplicity across a broad range of physical parameters. In this paper, we report the detections and measurements of 2 binaries discovered from observations of microlensing events MOA-2011-BLG-090 and OGLE-2011-BLG-0417. Determinations of the binary masses are possible by simultaneously measuring the Einstein radius and the lens parallax. The measured masses of the binary components are 0.43 $M_{\odot}$ and 0.39 $M_{\odot}$ for MOA-2011-BLG-090 and 0.57 $M_{\odot}$ and 0.17 $M_{\odot}$ for OGLE-2011-BLG-0417 and thus both lens components of MOA-2011-BLG-090 and one component of OGLE-2011-BLG-0417 are M dwarfs, demonstrating the usefulness of microlensing in detecting binaries composed of low-mass components. From modeling of the light curves considering full Keplerian motion of the lens, we also measure the orbital parameters of the binaries. The blended light of OGLE-2011-BLG-0417 comes very likely from the lens itself, making it possible to check the microlensing orbital solution by follow-up radial-velocity observation. For both events, the caustic-crossing parts of the light curves, which are critical for determining the physical lens parameters, were resolved by high-cadence survey observations and thus it is expected that the number of microlensing binaries with measured physical parameters will increase in the future., Comment: 8 pages, 5 figures, 4 tables
- Published
- 2012
21. Microlensing Binaries Discovered through High-Magnification Channel
- Author
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Shin, I.-G., Choi, J.-Y., Park, S.-Y., Han, C., Gould, A., Sumi, T., Udalski, A., Beaulieu, J.-P., Dominik, M., Allen, W., Bos, M., Christie, G. W., Depoy, D. L., Dong, S., Drummond, J., Gal-Yam, A., Gaudi, B. S., Hung, L.-W., Janczak, J., Kaspi, S., Lee, C.-U., Mallia, F., Maoz, D., Maury, A., McCormick, J., Monard, L. A. G., Moorhouse, D., Muñoz, J. A., Natusch, T., Nelson, C., Park, B.-G., Pogge, R. W., Polishook, D., Shvartzvald, Y., Shporer, A., Thornley, G., Yee, J. C., μFUN Collaboration, Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Fukui, A., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Kobara, S., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Omori, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., MOA Collaboration, Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Ulaczyk, K., Wyrzykowski, Ł., Kozłowski, S., Pietrukowicz, P., OGLE Collaboration, Albrow, M. D., Batista, V., Bramich, D. M., Brillant, S., Caldwell, J. A. R., Calitz, J. J., Cassan, A., Cole, A., Cook, K. H., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Hoffman, M., Jørgensen, U. G., Kane, S. R., Kubas, D., Marquette, J.-B., Martin, R., Meintjes, P., Menzies, J., Pollard, K. R., Sahu, K. C., Wambsganss, J., Williams, A., Vinter, Christian, Zub, M., PLANET Collaboration, Allan, A., Browne, P., Horne, K., Snodgrass, C., Steele, I., Street, R., Tsapras, Y., RoboNet Collaboration, Alsubai, K. A., Bozza, V., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Finet, F., Gerner, T., Glitrup, M., Grundahl, F., Hardis, S., Harpsøe, Kennet Bomann West, Hessman, F. V., Hinse, T. C., Hundertmark, M., Kains, N., Kerins, E., Liebig, C., Maier, G., Mancini, L., Mathiasen, M., Penny, M. T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Schäfer, S., Schönebeck, F., Skottfelt, Jesper Fælling, Surdej, J., Southworth, J., Zimmer, F., and MiNDSTEp Consortium
- Subjects
binaries: general ,gravitational lensing: micro ,Binary number ,FOS: Physical sciences ,Astrophysics ,Gravitational microlensing ,01 natural sciences ,law.invention ,Settore FIS/05 - Astronomia e Astrofisica ,Planet ,law ,0103 physical sciences ,binaries: general, gravitational lensing: micro ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,Physics ,010308 nuclear & particles physics ,Astronomy and Astrophysics ,Mass ratio ,Light curve ,3. Good health ,Lens (optics) ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Degeneracy (mathematics) ,Event (particle physics) - Abstract
Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of 8 binary lensing events detected through the channel of high-magnification events during the seasons from 2007 to 2010. The perturbations, which are confined near the peak of the light curves, can be easily distinguished from the central perturbations caused by planets. However, the degeneracy between close and wide binary solutions cannot be resolved with a $3\sigma$ confidence level for 3 events, implying that the degeneracy would be an important obstacle in studying binary distributions. The dependence of the degeneracy on the lensing parameters is consistent with a theoretic prediction that the degeneracy becomes severe as the binary separation and the mass ratio deviate from the values of resonant caustics. The measured mass ratio of the event OGLE-2008-BLG-510/MOA-2008-BLG-369 is $q\sim 0.1$, making the companion of the lens a strong brown-dwarf candidate., Comment: 10 figures, 6 tables, 26 pages
- Published
- 2011
22. A sub-Saturn mass planet, MOA-2009-BLG-319Lb
- Author
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Miyake, N., Sumi, T., Dong, Subo, Street, R., Mancini, L., Gould, A., Bennett, D. P., Tsapras, Y., Yee, J. C., Albrow, M. D., Bond, I. A., Fouque, P., Browne, P., Han, C., Snodgrass, C., Finet, F., Furusawa, K., Harpsoe, K., Allen, W., Hundertmark, M., Freeman, M., Suzuki, D., Abe, F., Botzler, C. S., Douchin, D., Fukui, A., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Muraki, Y., Nagayama, T., Nishimoto, K., Ohnishi, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., Collaboration, The MOA, Bolt, G., Bos, M., Christie, G. W., DePoy, D. L., Drummond, J., Gal-Yam, A., Gaudi, B. S., Gorbikov, E., Higgins, D., Janczak, K. -H. Hwang J., Kaspi, S., Lee, C. -U., Koo, J. -R., lowski, S. Koz, Lee, Y., Mallia, F., Maury, A., Maoz, D., McCormick, J., Monard, L. A. G., Moorhouse, D., Mu~noz, J. A., Natusch, T., Ofek, E. O., Pogge, R. W., Polishook, D., Santallo, R., Shporer, A., Spector, O., Thornley, G., Collaboration, The Micro FUN, Allan, A., Bramich, D. M., Horne, K., Kains, N., Steele, I., Collaboration, The RoboNet, Bozza, V., Burgdorf, M. J., Novati, S. Calchi, Dominik, M., Dreizler, S., Glitrup, M., Hessman, F. V., Hinse, T. C., Jorgensen, U. G., Liebig, C., Maier, G., Mathiasen, M., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J., Wambsganss, J., Zimmer, F., Consortium, The MiNDSTEp, Batista, V., Beaulieu, J. P., Brillant, S., Cassan, A., Cole, A., Corrales, E., Coutures, Ch., Dieters, S., Greenhill, J., Kubas, D., Menzies, J., and Collaboration, The PLANET
- Subjects
Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Planetary system ,Mass ratio ,Gravitational microlensing ,Light curve ,01 natural sciences ,Einstein radius ,Settore FIS/05 - Astronomia e Astrofisica ,Space and Planetary Science ,Planet ,Saturn ,0103 physical sciences ,Astrophysics::Earth and Planetary Astrophysics ,010306 general physics ,010303 astronomy & astrophysics ,Planetary mass ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K or M-dwarf star in the inner Galactic disk or Galactic bulge. The high cadence observations of the MOA-II survey discovered this microlensing event and enabled its identification as a high magnification event approximately 24 hours prior to peak magnification. As a result, the planetary signal at the peak of this light curve was observed by 20 different telescopes, which is the largest number of telescopes to contribute to a planetary discovery to date. The microlensing model for this event indicates a planet-star mass ratio of q = (3.95 +/- 0.02) x 10^{-4} and a separation of d = 0.97537 +/- 0.00007 in units of the Einstein radius. A Bayesian analysis based on the measured Einstein radius crossing time, t_E, and angular Einstein radius, \theta_E, along with a standard Galactic model indicates a host star mass of M_L = 0.38^{+0.34}_{-0.18} M_{Sun} and a planet mass of M_p = 50^{+44}_{-24} M_{Earth}, which is half the mass of Saturn. This analysis also yields a planet-star three-dimensional separation of a = 2.4^{+1.2}_{-0.6} AU and a distance to the planetary system of D_L = 6.1^{+1.1}_{-1.2} kpc. This separation is ~ 2 times the distance of the snow line, a separation similar to most of the other planets discovered by microlensing., Comment: accepted to ApJ, 28 pages, 6 figures, 3 tables
- Published
- 2011
23. MOA-2009-BLG-387Lb: A massive planet orbiting an M dwarf
- Author
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Batista, V., Gould, A., Dieters, S., Dong, S., Bond, I., Beaulieu, J. P., Maoz, D., Monard, B., Christie, G. W., Mccormick, J., Albrow, M. D., Horne, K., Tsapras, Y., Burgdorf, M. J., Calchi Novati, S., Skottfelt, J., Caldwell, J., Kozłowski, S., Kubas, D., Gaudi, B. S., Han, C., Bennett, D. P., An, J., Abe, F., Botzler, C. S., Douchin, D., Freeman, M., Fukui, A., Furusawa, K., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Makita, B. S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Perrott, Y. C., Rattenbury, N., Saito, T. o., Sullivan, D. J., Sumi, T., Sweatman, W. L., Tristram, P. J., von Seggern, E., Yock, P. C. M., Brillant, S., Calitz, J. J., Cassan, A., Cole, A., Cook, K., Coutures, C., Dominis Prester, D., Donatowicz, J., Greenhill, J., Hoffman, M., Jablonski, F., Kane, S. R., Kains, N., Marquette, J. B., Martin, R., Martioli, E., Meintjes, P., Menzies, J., Pedretti, E., Pollard, K., Sahu, K. C., Vinter, C., Wambsganss, J., Watson, R., Williams, A., Zub, M., Allen, W., Bolt, G., Bos, M., Depoy, D. L., Drummond, J., Eastman, J. D., Gal Yam, A., Gorbikov, E., Higgins, D., Janczak, J., Kaspi, S., Lee, C. U., Mallia, F., Maury, A., Monard, L. A. G., Moorhouse, D., Morgan, N., Natusch, T., Ofek, E. O., Park, B. G., Pogge, R. W., Polishook, D., Santallo, R., Shporer, A., Spector, O., Thornley, G., Yee, J. C., Bozza, Valerio, Browne, P., Dominik, M., Dreizler, S., Finet, F., Glitrup, M., Grundahl, F., Harpsøe, K., Hessman, F. V., Hinse, T. C., Hundertmark, M., Jørgensen, U. G., Liebig, C., Maier, G., Mancini, L., Mathiasen, M., Rahvar, S., Ricci, D., Scarpetta, Gaetano, Southworth, J., Surdej, J., Zimmer, F., Allan, A., Bramich, D. M., Snodgrass, C., Steele, I. A., and Street, R. A.
- Subjects
Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,010308 nuclear & particles physics ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Mass ratio ,Gravitational microlensing ,01 natural sciences ,Einstein radius ,Jupiter ,Settore FIS/05 - Astronomia e Astrofisica ,13. Climate action ,Space and Planetary Science ,Planet ,0103 physical sciences ,Orbital motion ,High Energy Physics::Experiment ,gravitational lensing ,micro methods ,data analysis ,planets ,satellites ,detection ,methods ,numerical ,instrumentation ,adaptive optics ,photometers ,Astrophysics::Earth and Planetary Astrophysics ,010303 astronomy & astrophysics ,Planetary mass ,Astrophysics::Galaxy Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We report the discovery of a planet with a high planet-to-star mass ratio in the microlensing event MOA-2009-BLG-387, which exhibited pronounced deviations over a 12-day interval, one of the longest for any planetary event. The host is an M dwarf, with a mass in the range 0.07 M_sun < M_host < 0.49M_sun at 90% confidence. The planet-star mass ratio q = 0.0132 +- 0.003 has been measured extremely well, so at the best-estimated host mass, the planet mass is m_p = 2.6 Jupiter masses for the median host mass, M = 0.19 M_sun. The host mass is determined from two "higher order" microlensing parameters. One of these, the angular Einstein radius ��_E = 0.31 +- 0.03 mas, is very well measured, but the other (the microlens parallax ��_E, which is due to the Earth's orbital motion) is highly degenate with the orbital motion of the planet. We statistically resolve the degeneracy between Earth and planet orbital effects by imposing priors from a Galactic model that specifies the positions and velocities of lenses and sources and a Kepler model of orbits. The 90% confidence intervals for the distance, semi-major axis, and period of the planet are 3.5 kpc < D_L < 7.9 kpc, 1.1 AU < a < 2.7AU, and 3.8 yr < P < 7.6 yr, respectively., 20 pages including 8 figures. A&A 529 102 (2011)
- Published
- 2011
- Full Text
- View/download PDF
24. OGLE-2009-BLG-092/MOA-2009-BLG-137: A Dramatic Repeating Event with the Second Perturbation Predicted by Real-time Analysis
- Author
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Ryu, Y. H., Han, C., Hwang, K. H., Street, R., Udalski, A., Sumi, T., Fukui, A., Beaulieu, J. P., Gould, A., Dominik, M., Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nishimoto, K., Ohnishi, K., Perrott, Y. C., Rattenbury, N., Saito, T. o., Skuljan, L., Sullivan, D. J., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., Szymański, M. K., Kubiak, M., Pietrzyński, G., Poleski, R., Soszyński, I., Szewczyk, O., Wyrzykowski, Ł., Ulaczyk, K., Bos, M., Christie, G. W., Depoy, D. L., Gal Yam, A., Gaudi, B. S., Kaspi, S., Lee, C. U., Maoz, D., Mccormick, J., Monard, B., Moorhouse, D., Pogge, R. W., Polishook, D., Shvartzvald, Y., Shporer, A., Thornley, G., Yee, J. C., Albrow, M. D., Batista, V., Brillant, S., Cassan, A., Cole, A., Corrales, E., Coutures, C. h., Dieters, S., Fouque, P., Greenhill, J., Menzies, J., Allan, A., Bramich, D. M., Browne, P., Horne, K., Kains, N., Snodgrass46, C., Steele, I., Tsapras, Y., Bozza, Valerio, Burgdorf, M. J., CALCHI NOVATI, Sebastiano, Dreizler, S., Finet, F., Glitrup, M., Grundahl, F., Harpsøe, K., Hessman, F. V., Hinse, T. C., Hundertmark, M., Jørgensen, U. G., Liebig, C., Maier, G., Mancini, Luigi, Mathiasen, M., Rahvar, S., Ricci, D., Scarpetta, Gaetano, Skottfelt, J., Surdej, J., Southworth, J., Wambsganss, J., and Zimmer, F.
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Physics ,010504 meteorology & atmospheric sciences ,FOS: Physical sciences ,Binary number ,Perturbation (astronomy) ,Astronomy and Astrophysics ,Astrophysics ,Light curve ,Gravitational microlensing ,01 natural sciences ,Stars ,Settore FIS/05 - Astronomia e Astrofisica ,Astrophysics - Solar and Stellar Astrophysics ,Space and Planetary Science ,Bulge ,0103 physical sciences ,Orbital motion ,Real time analysis ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,0105 earth and related environmental sciences - Abstract
We report the result of the analysis of a dramatic repeating gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137, for which the light curve is characterized by two distinct peaks with perturbations near both peaks. We find that the event is produced by the passage of the source trajectory over the central perturbation regions associated with the individual components of a wide-separation binary. The event is special in the sense that the second perturbation, occurring $\sim 100$ days after the first, was predicted by the real-time analysis conducted after the first peak, demonstrating that real-time modeling can be routinely done for binary and planetary events. With the data obtained from follow-up observations covering the second peak, we are able to uniquely determine the physical parameters of the lens system. We find that the event occurred on a bulge clump giant and it was produced by a binary lens composed of a K and M-type main-sequence stars. The estimated masses of the binary components are $M_1=0.69 \pm 0.11\ M_\odot$ and $M_2=0.36\pm 0.06\ M_\odot$, respectively, and they are separated in projection by $r_\perp=10.9\pm 1.3\ {\rm AU}$. The measured distance to the lens is $D_{\rm L}=5.6 \pm 0.7\ {\rm kpc}$. We also detect the orbital motion of the lens system., 18 pages, 5 figures, 1 table
- Published
- 2010
25. Frequency of Solar-Like Systems and of Ice and Gas Giants Beyond the Snow Line from High-Magnification Microlensing Events in 2005-2008
- Author
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Gould, A, Dong, S, Gaudi, Bs, Udalski, A, Bond, Ia, Greenhill, J, Street, Ra, Dominik, M, Sumi, T, Szymanski, Mk, Han, C, Allen, W, Bolt, G, Bos, M, Christie, Gw, Depoy, Dl, Drummond, J, Eastman, Jd, Gal-Yam, A, Higgins, D, Janczak, J, Kaspi, S, Kozllowski, S, Lee, C, Mallia, F, Maury, A, Maoz, D, Mccormick, J, Monard, Lag, Moorhouse, D, Morgan, N, Natusch, T, Ofek, Eo, Park, B, Pogge, Rw, Polishook, D, Santallo, R, Shporer, A, Spector, O, Thornley, G, Yee, Jc, Kubiak, M, Pietrzynski, G, Soszynski, I, Szewczyk, O, Wyrzykowski, E, Ulaczyk, K, Poleski, R, Abe, F, Bennett, Dp, Botzler, Cs, Douchin, D, Freeman, M, Fukui, A, Furusawa, K, Hearnshaw, Jb, Hosaka, S, Itow, Y, Kamiya, K, Kilmartin, Pm, Korpela, A, Lin, W, Ling, Ch, Makita, S, Masuda, K, Matsubara, Y, Miyake, N, Muraki, Y, Nagaya, M, Nishimoto, K, Ohnishi, K, Okumura, T, Perrott, Yc, Philpott, L, Rattenbury, N, Saito, To, Sako, T, Sullivan, Dj, Sweatman, Wl, Tristram, Pj, Von Seggern, Ev, Yock, Pcm, Albrow, M, Batista, V, Beaulieu, Jp, Brillant, S, Caldwell, J, Calitz, Jj, Cassan, A, Cole, A, Cook, K, Coutures, C, Dieters, S, Dominis Prester, D, Donatowicz, J, Fouque, P, Hill, K, Hoffman, M, Jablonski, F, Kane, Sr, Kains, N, Kubas, D, Marquette, J, Martin, R, Martioli, E, Meintjes, P, Menzies, J, Pedretti, E, Pollard, K, Sahu, Kc, Vinter, C, Wambsganss, J, Watson, R, Williams, A, Zub, M, Allan, A, Bode, Mf, Bramich, Dm, Burgdorf, Mj, Clay, N, Fraser, S, Hawkins, E, Horne, K, Kerins, E, Lister, Ta, Mottram, C, Saunders, Es, Snodgrass, C, Steele, Ia, Tsapras, Y, Jorgensen, Ug, Anguita, T, Bozza, V, Calchi Novati, S, Harpsoe, K, Hinse, Tc, Hundertmark, M, Kjaergaard, P, Liebig, C, Mancini, L, Masi, G, Mathiasen, M, Rahvar, S, Ricci, D, Scarpetta, G, Southworth, J, Surdej, J, and Thone, Cc
- Subjects
Physics ,Earth and Planetary Astrophysics (astro-ph.EP) ,Solar System ,010504 meteorology & atmospheric sciences ,Gas giant ,FOS: Physical sciences ,Astronomy and Astrophysics ,Astrophysics ,Planetary system ,Mass ratio ,Gravitational microlensing ,01 natural sciences ,Einstein radius ,Stars ,Settore FIS/05 - Astronomia e Astrofisica ,13. Climate action ,Space and Planetary Science ,Planet ,0103 physical sciences ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Astrophysics - Earth and Planetary Astrophysics - Abstract
We present the first measurement of planet frequency beyond the "snow line" for planet/star mass-ratios[-4.5200) microlensing events during 2005-8. The sample host stars have typical mass M_host 0.5 Msun, and detection is sensitive to planets over a range of projected separations (R_E/s_max,R_E*s_max), where R_E 3.5 AU sqrt(M_host/Msun) is the Einstein radius and s_max (q/5e-5)^{2/3}, corresponding to deprojected separations ~3 times the "snow line". Though frenetic, the observations constitute a "controlled experiment", which permits measurement of absolute planet frequency. High-mag events are rare, but the high-mag channel is efficient: half of high-mag events were successfully monitored and half of these yielded planet detections. The planet frequency derived from microlensing is a factor 7 larger than from RV studies at factor ~25 smaller separations [2, Comment: 42 pages, 10 figures
- Published
- 2010
- Full Text
- View/download PDF
26. A NEW TYPE OF AMBIGUITY IN THE PLANET AND BINARY INTERPRETATIONS OF CENTRAL PERTURBATIONS OF HIGH-MAGNIFICATION GRAVITATIONAL MICROLENSING EVENTS
- Author
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Choi, J.-Y, Shin, I.-G, Han, C., Udalski, A., Sumi, T., Gould, A., Bozza, V., Dominik, M., Fouque´, P., Horne, K., Szyman´ski, M. K., Kubiak, M., Soszyn´ski, I., Pietrzyn´ski, G., Poleski, R., Ulaczyk, K., Pietrukowicz, P., Kozłowski, S., Skowron, J., Wyrzykowski, Ł., OGLE Collaboration, Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Kobara, S., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohmori, K., Ohnishi, K., Rattenbury, N. J., Saito, To, Sullivan, D. J., Suzuki, D., Suzuki, K., Sweatman, W. L., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., MOA Collaboration, Bramich, D. M., Snodgrass, C., Steele, I. A., Street, R. A., Tsapras, Y., RoboNet Collaboration, Alsubai, K. A., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Fang, X.-S, Grundahl, F., Gu, C.-H, Hardis, S., Harpsøe, K., Hinse, T. C., Hornstrup, Allan, Hundertmark, M., Jessen-Hansen, J., Jørgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, M., Lunkkvist, M., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Almeida, L. A., Batista, V., Christie, G., DePoy, D. L., Dong, Subo, Gaudi, B. S., Henderson, C., Jablonski, F., Lee, C.-U, McCormick, J., McGregor, D., Moorhouse, D., Natusch, T., Ngan, H., Pogge, R. W., Tan, T.-G, Thornley, G., Yee, J. C., Albrow, M. D., Bachelet, E., Beaulieu, J.-P, Brillant, S., Cassan, A., Cole, A. A., Corrales, E., Coutures, C., Dieters, S., Dominis Prester, D., Donatowicz, J., Greenhill, J., Kubas, D., Marquette, J.-B, Menzies, J. W., Sahu, K. C., and Zub, M.
- Subjects
media_common.quotation_subject ,FOS: Physical sciences ,Binary number ,Perturbation (astronomy) ,gravitational lensing: micro ,Astrophysics ,Gravitational microlensing ,01 natural sciences ,Galaxy: bulge ,Settore FIS/05 - Astronomia e Astrofisica ,Planet ,0103 physical sciences ,010306 general physics ,010303 astronomy & astrophysics ,Solar and Stellar Astrophysics (astro-ph.SR) ,media_common ,Earth and Planetary Astrophysics (astro-ph.EP) ,Physics ,Binary Independence Model ,Astronomy and Astrophysics ,Ambiguity ,Light curve ,Galaxy: bulge, gravitational lensing: micro ,Astrophysics - Solar and Stellar Astrophysics ,13. Climate action ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,Caustic (optics) ,Astrophysics - Earth and Planetary Astrophysics - Abstract
High-magnification microlensing events provide an important channel to detect planets. Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion. It is known that central perturbations induced by both types of companions can be generally distinguished due to the basically different magnification pattern around caustics. In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations. The peak of a lensing light curve affected by this perturbation appears to be blunt and flat. For a planetary case, this perturbation occurs when the source trajectory passes the negative perturbation region behind the back end of an arrowhead-shaped central caustic. For a binary case, a similar perturbation occurs for a source trajectory passing through the negative perturbation region between two cusps of an astroid-shaped caustic. We demonstrate the degeneracy for 2 high-magnification events of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011-BLG-336. For OGLE-2011-BLG-0526, the $\chi^2$ difference between the planetary and binary model is $\sim$ 3, implying that the degeneracy is very severe. For OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is formally excluded with $\Delta \chi^2 \sim$ 105 and the planetary model is preferred. However, it is difficult to claim a planet discovery because systematic residuals of data from the planetary model are larger than the difference between the planetary and binary models. Considering that 2 events observed during a single season suffer from such a degeneracy, it is expected that central perturbations experiencing this type of degeneracy is common., Comment: 8 pages, 8 figures
- Published
- 2012
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