Journal ArticleDOI
MACHO Alert 95-30: First Real-Time Observation of Extended Source Effects in Gravitational Microlensing
Charles Alcock,Charles Alcock,W. H. Allen,R. A. Allsman,David R. Alves,David R. Alves,Tim Axelrod,T. S. Banks,S. F. Beaulieu,Andrew C. Becker,Andrew C. Becker,Robert H. Becker,Robert H. Becker,David P. Bennett,David P. Bennett,David P. Bennett,Ian A. Bond,B. S. Carter,Kem H Cook,Kem H Cook,R. J. Dodd,Kenneth C. Freeman,Michael D. Gregg,Michael D. Gregg,Kim Griest,Kim Griest,John B. Hearnshaw,Ana Heller,Morihiro Honda,Jun Jugaku,S. Kabe,Shai Kaspi,P. M. Kilmartin,P. M. Kilmartin,A. Kitamura,O. Kovo,Matthew J. Lehner,Matthew J. Lehner,T. E. Love,T. E. Love,D. Maoz,S. L. Marshall,Yutaka Matsubara,Dante Minniti,M. Miyamoto,Jon A. Morse,Yasushi Muraki,Takashi Nakamura,Bruce A. Peterson,M. M. Phillips,M. R. Pratt,M. R. Pratt,M. R. Pratt,Peter J. Quinn,I. N. Reid,M. Reid,David J Reiss,A. Retter,A. W. Rodgers,Wallace L. W. Sargent,Hiroshi Sato,Masaki Sekiguchi,Peter B. Stetson,Christopher W. Stubbs,Denis J. Sullivan,William J. Sutherland,A. B. Tomaney,T. Vandehei,Yoshiyuki Watase,Douglas L. Welch,T. Yanagisawa,M. Yoshizawa,Philip Yock +72 more
TLDR
In this article, the authors present an analysis of MACHO Alert 95-30, a dramatic microlensing event toward the Galactic bulge whose peak magnification departs significantly from the standard point-source micro-lensing model.Abstract:
We present analysis of MACHO Alert 95-30, a dramatic gravitational microlensing event toward the Galactic bulge whose peak magnification departs significantly from the standard point-source microlensing model Alert 95-30 was observed in real time by the Global Microlensing Alert Network (GMAN), which obtained densely sampled photometric and spectroscopic data throughout the event We interpret the light-curve fine structure as indicating transit of the lens across the extended face of the source star This signifies resolution of a star several kiloparsecs distant We find a lens angular impact parameter θmin/θsource = 0715 ± 0003 This information, along with the radius and distance of the source, provides an additional constraint on the lensing system Spectroscopic and photometric data indicate the source is a M4 III star of radius 61 ± 12 R☉, located on the far side of the bulge at ~9 kpc We derive a lens angular velocity, relative to the source, of 215 ± 29 km s-1 kpc-1, where the error is dominated by uncertainty in the angular size of the source star Likelihood analysis yields a median lens mass of 067 -->+ 253−046 M☉, located with 80% probability in the Galactic bulge at a distance of 693 -->+ 156−225 kpc If the lens is a main-sequence star, we can include constraints on the lens luminosity This modifies our estimates to Mlens=053 -->+ 052−035 M☉ and Dlens=657 -->+ 099−225 kpc Spectra taken during the event show that the absorption-line equivalent widths of Hα and the TiO bands near 6700 A vary, as predicted for microlensing of an extended source This is most likely due to center-to-limb variation in the stellar spectral lines The observed spectral changes further support our microlensing interpretation These data demonstrate the feasibility of using microlensing limb crossings as a tool to probe stellar atmospheres directlyread more
Citations
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Journal ArticleDOI
Ogle-2003-blg-262: finite-source effects from a point-mass lens
Jaiyul Yoo,Darren L. DePoy,Avishay Gal-Yam,B. S. Gaudi,Andrew Gould,C. Han,Y. M. Lipkin,D. Maoz,Eran O. Ofek,Byeong-Gon Park,Richard W. Pogge,Andrzej Udalski,Igor Soszyński,Łukasz Wyrzykowski,M. Kubiak,Michał K. Szymański,Grzegorz Pietrzyński,O. Szewczyk,K. Żebruń +18 more
TL;DR: The OGLE-2003-BLG-262 microlensing event as mentioned in this paper, a relatively short (tE ¼ 12:5 � 0:1 day) microlens event generated by a point-mass lens transiting the face of a K giant source in the Galactic bulge, is the only published event to date in which the lens transits the source.
Journal ArticleDOI
Frequency of solar-like systems and of ice and gas giants beyond the snow line from high-magnification microlensing events in 2005-2008
Andrew Gould,Subo Dong,B. S. Gaudi,Andrzej Udalski,Ian A. Bond,J. G. Greenhill,Rachel Street,Martin Dominik,Takahiro Sumi,Michał K. Szymański,C. Han,William H. Allen,Greg Bolt,M. Bos,G. W. Christie,Darren L. DePoy,Jack D. Drummond,Jason D. Eastman,Avishay Gal-Yam,D. Higgins,J. Janczak,Shai Kaspi,Szymon Kozłowski,C.-U. Lee,F. Mallia,Anaëlle Maury,D. Maoz,Jennie McCormick,L. A. G. Monard,D. Moorhouse,N. D. Morgan,Tim Natusch,Eran O. Ofek,Byeong-Gon Park,Richard W. Pogge,David Polishook,R. Santallo,Avi Shporer,O. Spector,G. Thornley,Jennifer C. Yee,M. Kubiak,Grzegorz Pietrzyński,Igor Soszyński,O. Szewczyk,Łukasz Wyrzykowski,Krzysztof Ulaczyk,Radosław Poleski,Fumio Abe,David P. Bennett,C. S. Botzler,D. Douchin,M. Freeman,Akihiko Fukui,K. Furusawa,John B. Hearnshaw,S. Hosaka,Yoshitaka Itow,K. Kamiya,P. M. Kilmartin,A. Korpela,W. Lin,C. H. Ling,S. Makita,Kimiaki Masuda,Yutaka Matsubara,N. Miyake,Yasushi Muraki,M. Nagaya,K. Nishimoto,Kouji Ohnishi,Teppei Okumura,Y. C. Perrott,L. Philpott,Nicholas J. Rattenbury,To. Saito,Takashi Sako,Denis J. Sullivan,W. L. Sweatman,P. J. Tristram,E. von Seggern,P. C. M. Yock,Michael D. Albrow,V. Batista,J. P. Beaulieu,S. Brillant,J. Caldwell,J. J. Calitz,Arnaud Cassan,Andrew A. Cole,K. W. Cook,C. Coutures,S. Dieters,D. Dominis Prester,J. Donatowicz,Pascal Fouqué,K. Hill,M. Hoffman,Francisco Jablonski,Stephen R. Kane,N. Kains,D. Kubas,J.-B. Marquette,R. M. Martin,Eder Martioli,P. J. Meintjes,J. Menzies,Ettore Pedretti,K. R. Pollard,K. C. Sahu,C. Vinter,J. Wambsganss,R. A. Watson,Andrew Williams,M. Zub,Alasdair Allan,M. F. Bode,D. M. Bramich,Martin Burgdorf,N. Clay,S. Fraser,E. Hawkins,Keith Horne,E. Kerins,T. A. Lister,C. Mottram,E. S. Saunders,Colin Snodgrass,Iain A. Steele,Yiannis Tsapras,U. G. Jørgensen,Timo Anguita,Valerio Bozza,S. Calchi Novati,K. Harpsøe,Tobias C. Hinse,M. Hundertmark,P. Kjærgaard,C. Liebig,C. Liebig,Luigi Mancini,G. Masi,M. Mathiasen,Sohrab Rahvar,Davide Ricci,Gaetano Scarpetta,John Southworth,Jean Surdej,Christina C. Thöne,Christina C. Thöne +149 more
TL;DR: In this paper, the authors presented the first measurement of the planet frequency beyond the "snow line," for the planet-to-star mass-ratio interval during 2005-2008 microlensing events during the survey-plus-follow-up high-magnification channel.
Journal ArticleDOI
A Natural Formalism for Microlensing
TL;DR: This paper recast the basic formalism of microlensing in light of this more natural geometry and in terms of observables, and then found that the relations between observable and physical quantities assume an exceptionally simple form.
Journal ArticleDOI
The MACHO Project: Microlensing Optical Depth Toward the Galactic Bulge from Difference Image Analysis
Charles Alcock,Charles Alcock,R. A. Allsman,David R. Alves,Tim Axelrod,Andrew C. Becker,David P. Bennett,David P. Bennett,Kem H Cook,Kem H Cook,Andrew J. Drake,Andrew J. Drake,Kenneth C. Freeman,Marla Geha,Kim Griest,Kim Griest,Matthew J. Lehner,S. L. Marshall,S. L. Marshall,Dante Minniti,C. A. Nelson,C. A. Nelson,Bruce A. Peterson,P. Popowski,M. R. Pratt,Peter J. Quinn,Christopher W. Stubbs,Christopher W. Stubbs,Christopher W. Stubbs,William J. Sutherland,A. B. Tomaney,T. Vandehei,Douglas L. Welch +32 more
TL;DR: In this paper, the authors presented the microlensing optical depth toward the Galactic bulge based on the detection of 99 events found in our Difference Image Analysis (DIA) survey.
Journal ArticleDOI
Detecting Earth-Mass Planets with Gravitational Microlensing
TL;DR: In this paper, it was shown that Earth mass planets orbiting stars in the Galactic disk and bulge can be detected by monitoring microlensed stars in a Galactic bulge, and that the planetary signal remains detectable for planetary masses as small as an Earth mass when realistic source star sizes are included in the lightcurve calculation.
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