The extreme microlensing event OGLE-2007-BLG-224: Terrestrial parallax observation of a thick-disk brown dwarf

A. Gould, A. Udalski, B. Monard, K. Horne, Subo Dong, N. Miyake, K. Sahu, D. P. Bennett, Wyrzykowski, I. Soszyński, M. K. Szymański, M. Kubiak, G. Pietrzyński, O. Szewczyk, K. Ulaczyk, W. Allen, G. W. Christie, D. L. DePoy, B. S. Gaudi, C. HanC. U. Lee, J. McCormick, T. Natusch, B. G. Park, R. W. Pogge, A. Allan, M. F. Bode, D. M. Bramich, M. J. Burgdorf, M. Dominik, S. N. Fraser, E. Kerins, C. Mottram, C. Snodgrass, I. A. Steele, R. Street, Y. Tsapras, F. Abe, I. A. Bond, C. S. Botzler, A. Fukui, K. Furusawa, J. B. Hearnshaw, Y. Itow, K. Kamiya, P. M. Kilmartin, A. Korpela, W. Lin, C. H. Ling, K. Masuda, Y. Matsubara, Y. Muraki, M. Nagaya, K. Ohnishi, T. Okumura, Y. C. Perrott, N. Rattenbury, To Saito, T. Sako, L. Skuljan, D. J. Sullivan, T. Sumi, W. L. Sweatman, P. J. Tristram, P. C M Yock, M. Albrow, J. P. Beaulieu, C. Coutures, H. Calitz, J. Caldwell, P. Fouque, R. Martin, A. Williams

Research output: Contribution to journalArticle

77 Citations (Scopus)

Abstract

Parallax is the most fundamental technique for measuring distances to astronomical objects. Although terrestrial parallax was pioneered over 2000 years ago by Hipparchus (ca. 140 B.C.E.) to measure the distance to the Moon, the baseline of the Earth is so small that terrestrial parallax can generally only be applied to objects in the Solar System. However, there exists a class of extreme gravitational microlensing events in which the effects of terrestrial parallax can be readily detected and so permit the measurement of the distance, mass, and transverse velocity of the lens. Here we report observations of the first such extreme microlensing event OGLE-2007-BLG-224, from which we infer that the lens is a brown dwarf of mass M = 0.056 ± 0.004 M , with a distance of 525 ± 40 pc and a transverse velocity of 113 ± 21 km s-1. The velocity places the lens in the thick disk, making this the lowest-mass thick-disk brown dwarf detected so far. Follow-up observations may allow one to observe the light from the brown dwarf itself, thus serving as an important constraint for evolutionary models of these objects and potentially opening a new window on substellar objects. The low a priori probability of detecting a thick-disk brown dwarf in this event, when combined with additional evidence from other observations, suggests that old substellar objects may be more common than previously assumed.

Original languageEnglish
JournalAstrophysical Journal
Volume698
Issue number2
DOIs
Publication statusPublished - 20 Jun 2009
Externally publishedYes

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parallax
extreme event
lenses
solar system
Moon
moon

Keywords

  • Astrometry
  • Gravitational lensing
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

The extreme microlensing event OGLE-2007-BLG-224 : Terrestrial parallax observation of a thick-disk brown dwarf. / Gould, A.; Udalski, A.; Monard, B.; Horne, K.; Dong, Subo; Miyake, N.; Sahu, K.; Bennett, D. P.; Wyrzykowski; Soszyński, I.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Szewczyk, O.; Ulaczyk, K.; Allen, W.; Christie, G. W.; DePoy, D. L.; Gaudi, B. S.; Han, C.; Lee, C. U.; McCormick, J.; Natusch, T.; Park, B. G.; Pogge, R. W.; Allan, A.; Bode, M. F.; Bramich, D. M.; Burgdorf, M. J.; Dominik, M.; Fraser, S. N.; Kerins, E.; Mottram, C.; Snodgrass, C.; Steele, I. A.; Street, R.; Tsapras, Y.; Abe, F.; Bond, I. A.; Botzler, C. S.; Fukui, A.; Furusawa, K.; Hearnshaw, J. B.; Itow, Y.; Kamiya, K.; Kilmartin, P. M.; Korpela, A.; Lin, W.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Nagaya, M.; Ohnishi, K.; Okumura, T.; Perrott, Y. C.; Rattenbury, N.; Saito, To; Sako, T.; Skuljan, L.; Sullivan, D. J.; Sumi, T.; Sweatman, W. L.; Tristram, P. J.; Yock, P. C M; Albrow, M.; Beaulieu, J. P.; Coutures, C.; Calitz, H.; Caldwell, J.; Fouque, P.; Martin, R.; Williams, A.

In: Astrophysical Journal, Vol. 698, No. 2, 20.06.2009.

Research output: Contribution to journalArticle

Gould, A, Udalski, A, Monard, B, Horne, K, Dong, S, Miyake, N, Sahu, K, Bennett, DP, Wyrzykowski, Soszyński, I, Szymański, MK, Kubiak, M, Pietrzyński, G, Szewczyk, O, Ulaczyk, K, Allen, W, Christie, GW, DePoy, DL, Gaudi, BS, Han, C, Lee, CU, McCormick, J, Natusch, T, Park, BG, Pogge, RW, Allan, A, Bode, MF, Bramich, DM, Burgdorf, MJ, Dominik, M, Fraser, SN, Kerins, E, Mottram, C, Snodgrass, C, Steele, IA, Street, R, Tsapras, Y, Abe, F, Bond, IA, Botzler, CS, Fukui, A, Furusawa, K, Hearnshaw, JB, Itow, Y, Kamiya, K, Kilmartin, PM, Korpela, A, Lin, W, Ling, CH, Masuda, K, Matsubara, Y, Muraki, Y, Nagaya, M, Ohnishi, K, Okumura, T, Perrott, YC, Rattenbury, N, Saito, T, Sako, T, Skuljan, L, Sullivan, DJ, Sumi, T, Sweatman, WL, Tristram, PJ, Yock, PCM, Albrow, M, Beaulieu, JP, Coutures, C, Calitz, H, Caldwell, J, Fouque, P, Martin, R & Williams, A 2009, 'The extreme microlensing event OGLE-2007-BLG-224: Terrestrial parallax observation of a thick-disk brown dwarf', Astrophysical Journal, vol. 698, no. 2. https://doi.org/10.1088/0004-637X/698/2/L147
Gould, A. ; Udalski, A. ; Monard, B. ; Horne, K. ; Dong, Subo ; Miyake, N. ; Sahu, K. ; Bennett, D. P. ; Wyrzykowski ; Soszyński, I. ; Szymański, M. K. ; Kubiak, M. ; Pietrzyński, G. ; Szewczyk, O. ; Ulaczyk, K. ; Allen, W. ; Christie, G. W. ; DePoy, D. L. ; Gaudi, B. S. ; Han, C. ; Lee, C. U. ; McCormick, J. ; Natusch, T. ; Park, B. G. ; Pogge, R. W. ; Allan, A. ; Bode, M. F. ; Bramich, D. M. ; Burgdorf, M. J. ; Dominik, M. ; Fraser, S. N. ; Kerins, E. ; Mottram, C. ; Snodgrass, C. ; Steele, I. A. ; Street, R. ; Tsapras, Y. ; Abe, F. ; Bond, I. A. ; Botzler, C. S. ; Fukui, A. ; Furusawa, K. ; Hearnshaw, J. B. ; Itow, Y. ; Kamiya, K. ; Kilmartin, P. M. ; Korpela, A. ; Lin, W. ; Ling, C. H. ; Masuda, K. ; Matsubara, Y. ; Muraki, Y. ; Nagaya, M. ; Ohnishi, K. ; Okumura, T. ; Perrott, Y. C. ; Rattenbury, N. ; Saito, To ; Sako, T. ; Skuljan, L. ; Sullivan, D. J. ; Sumi, T. ; Sweatman, W. L. ; Tristram, P. J. ; Yock, P. C M ; Albrow, M. ; Beaulieu, J. P. ; Coutures, C. ; Calitz, H. ; Caldwell, J. ; Fouque, P. ; Martin, R. ; Williams, A. / The extreme microlensing event OGLE-2007-BLG-224 : Terrestrial parallax observation of a thick-disk brown dwarf. In: Astrophysical Journal. 2009 ; Vol. 698, No. 2.
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abstract = "Parallax is the most fundamental technique for measuring distances to astronomical objects. Although terrestrial parallax was pioneered over 2000 years ago by Hipparchus (ca. 140 B.C.E.) to measure the distance to the Moon, the baseline of the Earth is so small that terrestrial parallax can generally only be applied to objects in the Solar System. However, there exists a class of extreme gravitational microlensing events in which the effects of terrestrial parallax can be readily detected and so permit the measurement of the distance, mass, and transverse velocity of the lens. Here we report observations of the first such extreme microlensing event OGLE-2007-BLG-224, from which we infer that the lens is a brown dwarf of mass M = 0.056 ± 0.004 M ⊙, with a distance of 525 ± 40 pc and a transverse velocity of 113 ± 21 km s-1. The velocity places the lens in the thick disk, making this the lowest-mass thick-disk brown dwarf detected so far. Follow-up observations may allow one to observe the light from the brown dwarf itself, thus serving as an important constraint for evolutionary models of these objects and potentially opening a new window on substellar objects. The low a priori probability of detecting a thick-disk brown dwarf in this event, when combined with additional evidence from other observations, suggests that old substellar objects may be more common than previously assumed.",
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TY - JOUR

T1 - The extreme microlensing event OGLE-2007-BLG-224

T2 - Terrestrial parallax observation of a thick-disk brown dwarf

AU - Gould, A.

AU - Udalski, A.

AU - Monard, B.

AU - Horne, K.

AU - Dong, Subo

AU - Miyake, N.

AU - Sahu, K.

AU - Bennett, D. P.

AU - Wyrzykowski,

AU - Soszyński, I.

AU - Szymański, M. K.

AU - Kubiak, M.

AU - Pietrzyński, G.

AU - Szewczyk, O.

AU - Ulaczyk, K.

AU - Allen, W.

AU - Christie, G. W.

AU - DePoy, D. L.

AU - Gaudi, B. S.

AU - Han, C.

AU - Lee, C. U.

AU - McCormick, J.

AU - Natusch, T.

AU - Park, B. G.

AU - Pogge, R. W.

AU - Allan, A.

AU - Bode, M. F.

AU - Bramich, D. M.

AU - Burgdorf, M. J.

AU - Dominik, M.

AU - Fraser, S. N.

AU - Kerins, E.

AU - Mottram, C.

AU - Snodgrass, C.

AU - Steele, I. A.

AU - Street, R.

AU - Tsapras, Y.

AU - Abe, F.

AU - Bond, I. A.

AU - Botzler, C. S.

AU - Fukui, A.

AU - Furusawa, K.

AU - Hearnshaw, J. B.

AU - Itow, Y.

AU - Kamiya, K.

AU - Kilmartin, P. M.

AU - Korpela, A.

AU - Lin, W.

AU - Ling, C. H.

AU - Masuda, K.

AU - Matsubara, Y.

AU - Muraki, Y.

AU - Nagaya, M.

AU - Ohnishi, K.

AU - Okumura, T.

AU - Perrott, Y. C.

AU - Rattenbury, N.

AU - Saito, To

AU - Sako, T.

AU - Skuljan, L.

AU - Sullivan, D. J.

AU - Sumi, T.

AU - Sweatman, W. L.

AU - Tristram, P. J.

AU - Yock, P. C M

AU - Albrow, M.

AU - Beaulieu, J. P.

AU - Coutures, C.

AU - Calitz, H.

AU - Caldwell, J.

AU - Fouque, P.

AU - Martin, R.

AU - Williams, A.

PY - 2009/6/20

Y1 - 2009/6/20

N2 - Parallax is the most fundamental technique for measuring distances to astronomical objects. Although terrestrial parallax was pioneered over 2000 years ago by Hipparchus (ca. 140 B.C.E.) to measure the distance to the Moon, the baseline of the Earth is so small that terrestrial parallax can generally only be applied to objects in the Solar System. However, there exists a class of extreme gravitational microlensing events in which the effects of terrestrial parallax can be readily detected and so permit the measurement of the distance, mass, and transverse velocity of the lens. Here we report observations of the first such extreme microlensing event OGLE-2007-BLG-224, from which we infer that the lens is a brown dwarf of mass M = 0.056 ± 0.004 M ⊙, with a distance of 525 ± 40 pc and a transverse velocity of 113 ± 21 km s-1. The velocity places the lens in the thick disk, making this the lowest-mass thick-disk brown dwarf detected so far. Follow-up observations may allow one to observe the light from the brown dwarf itself, thus serving as an important constraint for evolutionary models of these objects and potentially opening a new window on substellar objects. The low a priori probability of detecting a thick-disk brown dwarf in this event, when combined with additional evidence from other observations, suggests that old substellar objects may be more common than previously assumed.

AB - Parallax is the most fundamental technique for measuring distances to astronomical objects. Although terrestrial parallax was pioneered over 2000 years ago by Hipparchus (ca. 140 B.C.E.) to measure the distance to the Moon, the baseline of the Earth is so small that terrestrial parallax can generally only be applied to objects in the Solar System. However, there exists a class of extreme gravitational microlensing events in which the effects of terrestrial parallax can be readily detected and so permit the measurement of the distance, mass, and transverse velocity of the lens. Here we report observations of the first such extreme microlensing event OGLE-2007-BLG-224, from which we infer that the lens is a brown dwarf of mass M = 0.056 ± 0.004 M ⊙, with a distance of 525 ± 40 pc and a transverse velocity of 113 ± 21 km s-1. The velocity places the lens in the thick disk, making this the lowest-mass thick-disk brown dwarf detected so far. Follow-up observations may allow one to observe the light from the brown dwarf itself, thus serving as an important constraint for evolutionary models of these objects and potentially opening a new window on substellar objects. The low a priori probability of detecting a thick-disk brown dwarf in this event, when combined with additional evidence from other observations, suggests that old substellar objects may be more common than previously assumed.

KW - Astrometry

KW - Gravitational lensing

KW - Stars: low-mass, brown dwarfs

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