MOA-2007-BLG-197

Exploring the brown dwarf desert

C. Ranc, A. Cassan, M. D. Albrow, D. Kubas, I. A. Bond, V. Batista, J. P. Beaulieu, D. P. Bennett, M. Dominik, Subo Dong, P. Fouqué, A. Gould, J. Greenhill, U. G. Jørgensen, N. Kains, J. Menzies, T. Sumi, E. Bachelet, C. Coutures, S. Dieters & 31 others D. Dominis Prester, J. Donatowicz, B. S. Gaudi, C. Han, M. Hundertmark, K. Horne, S. R. Kane, C. U. Lee, J. B. Marquette, B. G. Park, K. R. Pollard, K. C. Sahu, R. Street, Y. Tsapras, J. Wambsganss, A. Williams, M. Zub, F. Abe, A. Fukui, Y. Itow, K. Masuda, Y. Matsubara, Y. Muraki, K. Ohnishi, N. Rattenbury, To Saito, D. J. Sullivan, W. L. Sweatman, P. J. Tristram, P. C M Yock, A. Yonehara

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We present the analysis of MOA-2007-BLG-197Lb, the first brown dwarf companion to a Sun-like star detected through gravitational microlensing. The event was alerted and followed-up photometrically by a network of telescopes from the PLANET, MOA, and μFUN collaborations, and observed at high angular resolution using the NaCo instrument at the VLT. From the modelling of the microlensing light curve, we derived basic parameters such as, the binary lens separation in Einstein radius units (s ≃ 1:13), the mass ratio q = (4:732 ± 0:020) × 10<sup>-2</sup> and the Einstein radius crossing time (t<inf>E</inf> ≃ 82d). Because of this long time scale, we took annual parallax and orbital motion of the lens in the models into account, as well as finite source effects that were clearly detected during the source caustic exit. To recover the lens system's physical parameters, we combined the resulting light curve best-fit parameters with (J, H, K<inf>s</inf>) magnitudes obtained with VLT NaCo and calibrated using IRSF and 2MASS data. From this analysis, we derived a lens total mass of 0:86 ± 0:04 M<inf>⊙</inf> and a lens distance of D<inf>L</inf> = 4:2 ± 0:3 kpc. We find that the companion of MOA-2007-BLG-197L is a brown dwarf of 41 ± 2 M<inf>J</inf> observed at a projected separation of a<inf>⊥</inf> = 4:3 ± 0:1 AU, and orbits a 0:82 ± 0:04 M<inf>⊙</inf> G-K dwarf star. We then placed the companion of MOA-2007-BLG-197L in a mass-period diagram consisting of all brown dwarf companions detected so far through different techniques, including microlensing, transit, radial velocity, and direct imaging (most of these objects orbit solar-type stars). To study the statistical properties of this population, we performed a two-dimensional, non-parametric probability density distribution fit to the data, which draws a structured brown dwarf landscape. We confirm the existence of a region that is strongly depleted in objects at short periods and intermediate masses (P ≲ 30 d, M ∼ 30-60 M<inf>J</inf>), but also find an accumulation of objects around P ∼ 500 d and M ∼ 20 M<inf>J</inf>, as well as another depletion region at long orbital periods (P ≃ 500 d) and high masses (M ≃ 50 M<inf>J</inf>). While these data provide important clues on the different physical mechanisms of formation (or destruction) that shape the brown dwarf desert, more data are needed to establish their relative importance, in particular as a function of host star mass. Future microlensing surveys should soon provide more detections, in particular for red dwarf hosts, thus uniquely complementing the solar-type host sample.

Original languageEnglish
JournalAstronomy and Astrophysics
Volume580
DOIs
Publication statusPublished - 1 Aug 2015

Fingerprint

deserts
desert
lenses
stars
light curve
K stars
solar orbits
orbits
dwarf stars
radii
parallax
transit
angular resolution
radial velocity
mass ratios
destruction
density distribution
alkalies
sun
depletion

Keywords

  • brown dwarfs
  • gravitational lensing: micro
  • planets and satellites: detection

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Ranc, C., Cassan, A., Albrow, M. D., Kubas, D., Bond, I. A., Batista, V., ... Yonehara, A. (2015). MOA-2007-BLG-197: Exploring the brown dwarf desert. Astronomy and Astrophysics, 580. https://doi.org/10.1051/0004-6361/201525791

MOA-2007-BLG-197 : Exploring the brown dwarf desert. / Ranc, C.; Cassan, A.; Albrow, M. D.; Kubas, D.; Bond, I. A.; Batista, V.; Beaulieu, J. P.; Bennett, D. P.; Dominik, M.; Dong, Subo; Fouqué, P.; Gould, A.; Greenhill, J.; Jørgensen, U. G.; Kains, N.; Menzies, J.; Sumi, T.; Bachelet, E.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Gaudi, B. S.; Han, C.; Hundertmark, M.; Horne, K.; Kane, S. R.; Lee, C. U.; Marquette, J. B.; Park, B. G.; Pollard, K. R.; Sahu, K. C.; Street, R.; Tsapras, Y.; Wambsganss, J.; Williams, A.; Zub, M.; Abe, F.; Fukui, A.; Itow, Y.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Ohnishi, K.; Rattenbury, N.; Saito, To; Sullivan, D. J.; Sweatman, W. L.; Tristram, P. J.; Yock, P. C M; Yonehara, A.

In: Astronomy and Astrophysics, Vol. 580, 01.08.2015.

Research output: Contribution to journalArticle

Ranc, C, Cassan, A, Albrow, MD, Kubas, D, Bond, IA, Batista, V, Beaulieu, JP, Bennett, DP, Dominik, M, Dong, S, Fouqué, P, Gould, A, Greenhill, J, Jørgensen, UG, Kains, N, Menzies, J, Sumi, T, Bachelet, E, Coutures, C, Dieters, S, Dominis Prester, D, Donatowicz, J, Gaudi, BS, Han, C, Hundertmark, M, Horne, K, Kane, SR, Lee, CU, Marquette, JB, Park, BG, Pollard, KR, Sahu, KC, Street, R, Tsapras, Y, Wambsganss, J, Williams, A, Zub, M, Abe, F, Fukui, A, Itow, Y, Masuda, K, Matsubara, Y, Muraki, Y, Ohnishi, K, Rattenbury, N, Saito, T, Sullivan, DJ, Sweatman, WL, Tristram, PJ, Yock, PCM & Yonehara, A 2015, 'MOA-2007-BLG-197: Exploring the brown dwarf desert', Astronomy and Astrophysics, vol. 580. https://doi.org/10.1051/0004-6361/201525791
Ranc C, Cassan A, Albrow MD, Kubas D, Bond IA, Batista V et al. MOA-2007-BLG-197: Exploring the brown dwarf desert. Astronomy and Astrophysics. 2015 Aug 1;580. https://doi.org/10.1051/0004-6361/201525791
Ranc, C. ; Cassan, A. ; Albrow, M. D. ; Kubas, D. ; Bond, I. A. ; Batista, V. ; Beaulieu, J. P. ; Bennett, D. P. ; Dominik, M. ; Dong, Subo ; Fouqué, P. ; Gould, A. ; Greenhill, J. ; Jørgensen, U. G. ; Kains, N. ; Menzies, J. ; Sumi, T. ; Bachelet, E. ; Coutures, C. ; Dieters, S. ; Dominis Prester, D. ; Donatowicz, J. ; Gaudi, B. S. ; Han, C. ; Hundertmark, M. ; Horne, K. ; Kane, S. R. ; Lee, C. U. ; Marquette, J. B. ; Park, B. G. ; Pollard, K. R. ; Sahu, K. C. ; Street, R. ; Tsapras, Y. ; Wambsganss, J. ; Williams, A. ; Zub, M. ; Abe, F. ; Fukui, A. ; Itow, Y. ; Masuda, K. ; Matsubara, Y. ; Muraki, Y. ; Ohnishi, K. ; Rattenbury, N. ; Saito, To ; Sullivan, D. J. ; Sweatman, W. L. ; Tristram, P. J. ; Yock, P. C M ; Yonehara, A. / MOA-2007-BLG-197 : Exploring the brown dwarf desert. In: Astronomy and Astrophysics. 2015 ; Vol. 580.
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title = "MOA-2007-BLG-197: Exploring the brown dwarf desert",
abstract = "We present the analysis of MOA-2007-BLG-197Lb, the first brown dwarf companion to a Sun-like star detected through gravitational microlensing. The event was alerted and followed-up photometrically by a network of telescopes from the PLANET, MOA, and μFUN collaborations, and observed at high angular resolution using the NaCo instrument at the VLT. From the modelling of the microlensing light curve, we derived basic parameters such as, the binary lens separation in Einstein radius units (s ≃ 1:13), the mass ratio q = (4:732 ± 0:020) × 10-2 and the Einstein radius crossing time (tE ≃ 82d). Because of this long time scale, we took annual parallax and orbital motion of the lens in the models into account, as well as finite source effects that were clearly detected during the source caustic exit. To recover the lens system's physical parameters, we combined the resulting light curve best-fit parameters with (J, H, Ks) magnitudes obtained with VLT NaCo and calibrated using IRSF and 2MASS data. From this analysis, we derived a lens total mass of 0:86 ± 0:04 M⊙ and a lens distance of DL = 4:2 ± 0:3 kpc. We find that the companion of MOA-2007-BLG-197L is a brown dwarf of 41 ± 2 MJ observed at a projected separation of a⊥ = 4:3 ± 0:1 AU, and orbits a 0:82 ± 0:04 M⊙ G-K dwarf star. We then placed the companion of MOA-2007-BLG-197L in a mass-period diagram consisting of all brown dwarf companions detected so far through different techniques, including microlensing, transit, radial velocity, and direct imaging (most of these objects orbit solar-type stars). To study the statistical properties of this population, we performed a two-dimensional, non-parametric probability density distribution fit to the data, which draws a structured brown dwarf landscape. We confirm the existence of a region that is strongly depleted in objects at short periods and intermediate masses (P ≲ 30 d, M ∼ 30-60 MJ), but also find an accumulation of objects around P ∼ 500 d and M ∼ 20 MJ, as well as another depletion region at long orbital periods (P ≃ 500 d) and high masses (M ≃ 50 MJ). While these data provide important clues on the different physical mechanisms of formation (or destruction) that shape the brown dwarf desert, more data are needed to establish their relative importance, in particular as a function of host star mass. Future microlensing surveys should soon provide more detections, in particular for red dwarf hosts, thus uniquely complementing the solar-type host sample.",
keywords = "brown dwarfs, gravitational lensing: micro, planets and satellites: detection",
author = "C. Ranc and A. Cassan and Albrow, {M. D.} and D. Kubas and Bond, {I. A.} and V. Batista and Beaulieu, {J. P.} and Bennett, {D. P.} and M. Dominik and Subo Dong and P. Fouqu{\'e} and A. Gould and J. Greenhill and J{\o}rgensen, {U. G.} and N. Kains and J. Menzies and T. Sumi and E. Bachelet and C. Coutures and S. Dieters and {Dominis Prester}, D. and J. Donatowicz and Gaudi, {B. S.} and C. Han and M. Hundertmark and K. Horne and Kane, {S. R.} and Lee, {C. U.} and Marquette, {J. B.} and Park, {B. G.} and Pollard, {K. R.} and Sahu, {K. C.} and R. Street and Y. Tsapras and J. Wambsganss and A. Williams and M. Zub and F. Abe and A. Fukui and Y. Itow and K. Masuda and Y. Matsubara and Y. Muraki and K. Ohnishi and N. Rattenbury and To Saito and Sullivan, {D. J.} and Sweatman, {W. L.} and Tristram, {P. J.} and Yock, {P. C M} and A. Yonehara",
year = "2015",
month = "8",
day = "1",
doi = "10.1051/0004-6361/201525791",
language = "English",
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journal = "Astronomy and Astrophysics",
issn = "0004-6361",
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TY - JOUR

T1 - MOA-2007-BLG-197

T2 - Exploring the brown dwarf desert

AU - Ranc, C.

AU - Cassan, A.

AU - Albrow, M. D.

AU - Kubas, D.

AU - Bond, I. A.

AU - Batista, V.

AU - Beaulieu, J. P.

AU - Bennett, D. P.

AU - Dominik, M.

AU - Dong, Subo

AU - Fouqué, P.

AU - Gould, A.

AU - Greenhill, J.

AU - Jørgensen, U. G.

AU - Kains, N.

AU - Menzies, J.

AU - Sumi, T.

AU - Bachelet, E.

AU - Coutures, C.

AU - Dieters, S.

AU - Dominis Prester, D.

AU - Donatowicz, J.

AU - Gaudi, B. S.

AU - Han, C.

AU - Hundertmark, M.

AU - Horne, K.

AU - Kane, S. R.

AU - Lee, C. U.

AU - Marquette, J. B.

AU - Park, B. G.

AU - Pollard, K. R.

AU - Sahu, K. C.

AU - Street, R.

AU - Tsapras, Y.

AU - Wambsganss, J.

AU - Williams, A.

AU - Zub, M.

AU - Abe, F.

AU - Fukui, A.

AU - Itow, Y.

AU - Masuda, K.

AU - Matsubara, Y.

AU - Muraki, Y.

AU - Ohnishi, K.

AU - Rattenbury, N.

AU - Saito, To

AU - Sullivan, D. J.

AU - Sweatman, W. L.

AU - Tristram, P. J.

AU - Yock, P. C M

AU - Yonehara, A.

PY - 2015/8/1

Y1 - 2015/8/1

N2 - We present the analysis of MOA-2007-BLG-197Lb, the first brown dwarf companion to a Sun-like star detected through gravitational microlensing. The event was alerted and followed-up photometrically by a network of telescopes from the PLANET, MOA, and μFUN collaborations, and observed at high angular resolution using the NaCo instrument at the VLT. From the modelling of the microlensing light curve, we derived basic parameters such as, the binary lens separation in Einstein radius units (s ≃ 1:13), the mass ratio q = (4:732 ± 0:020) × 10-2 and the Einstein radius crossing time (tE ≃ 82d). Because of this long time scale, we took annual parallax and orbital motion of the lens in the models into account, as well as finite source effects that were clearly detected during the source caustic exit. To recover the lens system's physical parameters, we combined the resulting light curve best-fit parameters with (J, H, Ks) magnitudes obtained with VLT NaCo and calibrated using IRSF and 2MASS data. From this analysis, we derived a lens total mass of 0:86 ± 0:04 M⊙ and a lens distance of DL = 4:2 ± 0:3 kpc. We find that the companion of MOA-2007-BLG-197L is a brown dwarf of 41 ± 2 MJ observed at a projected separation of a⊥ = 4:3 ± 0:1 AU, and orbits a 0:82 ± 0:04 M⊙ G-K dwarf star. We then placed the companion of MOA-2007-BLG-197L in a mass-period diagram consisting of all brown dwarf companions detected so far through different techniques, including microlensing, transit, radial velocity, and direct imaging (most of these objects orbit solar-type stars). To study the statistical properties of this population, we performed a two-dimensional, non-parametric probability density distribution fit to the data, which draws a structured brown dwarf landscape. We confirm the existence of a region that is strongly depleted in objects at short periods and intermediate masses (P ≲ 30 d, M ∼ 30-60 MJ), but also find an accumulation of objects around P ∼ 500 d and M ∼ 20 MJ, as well as another depletion region at long orbital periods (P ≃ 500 d) and high masses (M ≃ 50 MJ). While these data provide important clues on the different physical mechanisms of formation (or destruction) that shape the brown dwarf desert, more data are needed to establish their relative importance, in particular as a function of host star mass. Future microlensing surveys should soon provide more detections, in particular for red dwarf hosts, thus uniquely complementing the solar-type host sample.

AB - We present the analysis of MOA-2007-BLG-197Lb, the first brown dwarf companion to a Sun-like star detected through gravitational microlensing. The event was alerted and followed-up photometrically by a network of telescopes from the PLANET, MOA, and μFUN collaborations, and observed at high angular resolution using the NaCo instrument at the VLT. From the modelling of the microlensing light curve, we derived basic parameters such as, the binary lens separation in Einstein radius units (s ≃ 1:13), the mass ratio q = (4:732 ± 0:020) × 10-2 and the Einstein radius crossing time (tE ≃ 82d). Because of this long time scale, we took annual parallax and orbital motion of the lens in the models into account, as well as finite source effects that were clearly detected during the source caustic exit. To recover the lens system's physical parameters, we combined the resulting light curve best-fit parameters with (J, H, Ks) magnitudes obtained with VLT NaCo and calibrated using IRSF and 2MASS data. From this analysis, we derived a lens total mass of 0:86 ± 0:04 M⊙ and a lens distance of DL = 4:2 ± 0:3 kpc. We find that the companion of MOA-2007-BLG-197L is a brown dwarf of 41 ± 2 MJ observed at a projected separation of a⊥ = 4:3 ± 0:1 AU, and orbits a 0:82 ± 0:04 M⊙ G-K dwarf star. We then placed the companion of MOA-2007-BLG-197L in a mass-period diagram consisting of all brown dwarf companions detected so far through different techniques, including microlensing, transit, radial velocity, and direct imaging (most of these objects orbit solar-type stars). To study the statistical properties of this population, we performed a two-dimensional, non-parametric probability density distribution fit to the data, which draws a structured brown dwarf landscape. We confirm the existence of a region that is strongly depleted in objects at short periods and intermediate masses (P ≲ 30 d, M ∼ 30-60 MJ), but also find an accumulation of objects around P ∼ 500 d and M ∼ 20 MJ, as well as another depletion region at long orbital periods (P ≃ 500 d) and high masses (M ≃ 50 MJ). While these data provide important clues on the different physical mechanisms of formation (or destruction) that shape the brown dwarf desert, more data are needed to establish their relative importance, in particular as a function of host star mass. Future microlensing surveys should soon provide more detections, in particular for red dwarf hosts, thus uniquely complementing the solar-type host sample.

KW - brown dwarfs

KW - gravitational lensing: micro

KW - planets and satellites: detection

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