Frequency of solar-like systems and of ice and gas giants beyond the snow line from high-magnification microlensing events in 2005-2008

A. Gould, Subo Dong, B. S. Gaudi, A. Udalski, I. A. Bond, J. Greenhill, R. A. Street, M. Dominik, T. Sumi, M. K. Szymański, C. Han, W. Allen, G. Bolt, M. Bos, G. W. Christie, D. L. DePoy, J. Drummond, J. D. Eastman, A. Gal-Yam, D. HigginsJ. Janczak, S. Kaspi, S. Kozllowski, C. U. Lee, F. Mallia, A. Maury, D. Maoz, J. McCormick, L. A G Monard, D. Moorhouse, N. Morgan, T. Natusch, E. O. Ofek, B. G. Park, R. W. Pogge, D. Polishook, R. Santallo, A. Shporer, O. Spector, G. Thornley, J. C. Yee, M. Kubiak, G. Pietrzyński, I. Soszyński, O. Szewczyk, Ë Wyrzykowski, K. Ulaczyk, R. Poleski, F. Abe, D. P. Bennett, C. S. Botzler, D. Douchin, M. Freeman, A. Fukui, K. Furusawa, J. B. Hearnshaw, S. Hosaka, Y. Itow, K. Kamiya, P. M. Kilmartin, A. Korpela, W. Lin, C. H. Ling, S. Makita, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, M. Nagaya, K. Nishimoto, K. Ohnishi, T. Okumura, Y. C. Perrott, L. Philpott, N. Rattenbury, T. O. Saito, T. Sako, D. J. Sullivan, W. L. Sweatman, P. J. Tristram, E. V. Von Seggern, P. C M Yock, M. Albrow, V. Batista, J. P. Beaulieu, S. Brillant, J. Caldwell, J. J. Calitz, A. Cassan, A. Cole, K. Cook, C. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouqué, K. Hill, M. Hoffman, F. Jablonski, S. R. Kane, N. Kains, D. Kubas, J. B. Marquette, R. Martin, E. Martioli, P. Meintjes, J. Menzies, E. Pedretti, K. Pollard, K. C. Sahu, C. Vinter, J. Wambsganss, R. Watson, A. Williams, M. Zub, A. Allan, M. F. Bode, D. M. Bramich, M. J. Burgdorf, N. Clay, S. Fraser, E. Hawkins, K. Horne, E. Kerins, T. A. Lister, C. Mottram, E. S. Saunders, C. Snodgrass, I. A. Steele, Y. Tsapras, U. G. Jørgensen, T. Anguita, V. Bozza, S. Calchi Novati, K. Harpsøe, T. C. Hinse, M. Hundertmark, P. Kjærgaard, C. Liebig, L. Mancini, G. Masi, M. Mathiasen, S. Rahvar, D. Ricci, G. Scarpetta, J. Southworth, J. Surdej, C. C. Thöne

Research output: Contribution to journalArticle

200 Citations (Scopus)

Abstract

We present the first measurement of the planet frequency beyond the "snow line," for the planet-to-star mass-ratio interval-4.5 < logq <-2, corresponding to the range of ice giants to gas giants. We find d 2Np1/dlog q d log s= (0.36 ± 0.15) dex dlog q d logs at the mean mass ratio q = 5 × 10-4 with no discernible deviation from a flat (öpik's law) distribution in logprojected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification (A > 200) microlensing events during 2005-2008. The sampled host stars have a typical mass Mhost ∼ 0.5 M, and detection is sensitive to planets over a range of planet-star-projected separations (s max -1Re, s maxRE), where Re ∼ 3.5 AU(Mhost/M⊙) 1/2 is the Einstein radius and smax ∼ (q/10 -43)1/3. This corresponds to deprojected separations roughly three times the "snow line." We show that the observations of these events have the properties of a "controlled experiment," which is what permits measurement of absolute planet frequency. High-magnification events are rare, but the survey-plus-follow-up high-magnification channel is very efficient: half of all high-mag events were successfully monitored and half of these yielded planet detections. The extremely high sensitivity of high-mag events leads to a policy of monitoring them as intensively as possible, independent of whether they show evidence of planets. This is what allows us to construct an unbiased sample. The planet frequency derived from microlensing is a factor 8 larger than the one derived from Doppler studies at factor ∼25 smaller star-planet separations (i.e., periods 2-2000 days). However, this difference is basically consistent with the gradient derived from Doppler studies (when extrapolated well beyond the separations from which it is measured). This suggests a universal separation distribution across 2 dex in planet-star separation, 2 dex in mass ratio, and 0.3 dex in host mass. Finally, if all planetary systems were "analogs" of the solar system, our sample would have yielded 18.2 planets (11.4 "Jupiters," 6.4 "Saturns," 0.3 "Uranuses," 0.2 "Neptunes") including 6.1 systems with two or more planet detections. This compares to six planets including one twoplanet system in the actual sample, implying a first estimate of 1/6 for the frequency of solar-like systems.

Original languageEnglish
Pages (from-to)1073-1089
Number of pages17
JournalAstrophysical Journal
Volume720
Issue number2
DOIs
Publication statusPublished - 10 Sep 2010
Externally publishedYes

Fingerprint

snow
magnification
solar system
planets
ice
planet
gases
gas
stars
planet detection
mass ratios
Neptune (planet)
planetary systems
Saturn
Jupiter (planet)
Neptune
Jupiter
analogs
intervals
gradients

Keywords

  • Gravitational lensing: micro
  • Planetary systems

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Frequency of solar-like systems and of ice and gas giants beyond the snow line from high-magnification microlensing events in 2005-2008. / Gould, A.; Dong, Subo; Gaudi, B. S.; Udalski, A.; Bond, I. A.; Greenhill, J.; Street, R. A.; Dominik, M.; Sumi, T.; Szymański, M. K.; Han, C.; Allen, W.; Bolt, G.; Bos, M.; Christie, G. W.; DePoy, D. L.; Drummond, J.; Eastman, J. D.; Gal-Yam, A.; Higgins, D.; Janczak, J.; Kaspi, S.; Kozllowski, S.; Lee, C. U.; Mallia, F.; Maury, A.; Maoz, D.; McCormick, J.; 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.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Szewczyk, O.; Wyrzykowski, Ë; Ulaczyk, K.; Poleski, R.; Abe, F.; Bennett, D. P.; 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, S.; Masuda, K.; Matsubara, Y.; Miyake, N.; Muraki, Y.; Nagaya, M.; Nishimoto, K.; Ohnishi, K.; Okumura, T.; Perrott, Y. C.; Philpott, L.; Rattenbury, N.; Saito, T. O.; Sako, T.; Sullivan, D. J.; Sweatman, W. L.; Tristram, P. J.; Von Seggern, E. V.; Yock, P. C M; Albrow, M.; Batista, V.; Beaulieu, J. P.; Brillant, S.; Caldwell, J.; Calitz, J. J.; Cassan, A.; Cole, A.; Cook, K.; Coutures, C.; Dieters, S.; Dominis Prester, D.; Donatowicz, J.; Fouqué, P.; Hill, K.; Hoffman, M.; Jablonski, F.; Kane, S. R.; Kains, N.; Kubas, D.; 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.; Allan, A.; Bode, M. F.; Bramich, D. M.; Burgdorf, M. J.; Clay, N.; Fraser, S.; Hawkins, E.; Horne, K.; Kerins, E.; Lister, T. A.; Mottram, C.; Saunders, E. S.; Snodgrass, C.; Steele, I. A.; Tsapras, Y.; Jørgensen, U. G.; Anguita, T.; Bozza, V.; Calchi Novati, S.; Harpsøe, K.; Hinse, T. C.; Hundertmark, M.; Kjærgaard, P.; Liebig, C.; Mancini, L.; Masi, G.; Mathiasen, M.; Rahvar, S.; Ricci, D.; Scarpetta, G.; Southworth, J.; Surdej, J.; Thöne, C. C.

In: Astrophysical Journal, Vol. 720, No. 2, 10.09.2010, p. 1073-1089.

Research output: Contribution to journalArticle

Gould, A, Dong, S, Gaudi, BS, Udalski, A, Bond, IA, Greenhill, J, Street, RA, Dominik, M, Sumi, T, Szymański, 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, CU, Mallia, F, Maury, A, Maoz, D, McCormick, J, Monard, LAG, Moorhouse, D, Morgan, N, Natusch, T, Ofek, EO, Park, BG, Pogge, RW, Polishook, D, Santallo, R, Shporer, A, Spector, O, Thornley, G, Yee, JC, Kubiak, M, Pietrzyński, G, Soszyński, I, Szewczyk, O, Wyrzykowski, Ë, 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, Fouqué, P, Hill, K, Hoffman, M, Jablonski, F, Kane, SR, Kains, N, Kubas, D, Marquette, JB, 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, Jørgensen, UG, Anguita, T, Bozza, V, Calchi Novati, S, Harpsøe, K, Hinse, TC, Hundertmark, M, Kjærgaard, P, Liebig, C, Mancini, L, Masi, G, Mathiasen, M, Rahvar, S, Ricci, D, Scarpetta, G, Southworth, J, Surdej, J & Thöne, CC 2010, 'Frequency of solar-like systems and of ice and gas giants beyond the snow line from high-magnification microlensing events in 2005-2008', Astrophysical Journal, vol. 720, no. 2, pp. 1073-1089. https://doi.org/10.1088/0004-637X/720/2/1073
Gould, A. ; Dong, Subo ; Gaudi, B. S. ; Udalski, A. ; Bond, I. A. ; Greenhill, J. ; Street, R. A. ; Dominik, M. ; Sumi, T. ; Szymański, M. K. ; Han, C. ; Allen, W. ; Bolt, G. ; Bos, M. ; Christie, G. W. ; DePoy, D. L. ; Drummond, J. ; Eastman, J. D. ; Gal-Yam, A. ; Higgins, D. ; Janczak, J. ; Kaspi, S. ; Kozllowski, S. ; Lee, C. U. ; Mallia, F. ; Maury, A. ; Maoz, D. ; McCormick, J. ; 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. ; Kubiak, M. ; Pietrzyński, G. ; Soszyński, I. ; Szewczyk, O. ; Wyrzykowski, Ë ; Ulaczyk, K. ; Poleski, R. ; Abe, F. ; Bennett, D. P. ; 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, S. ; Masuda, K. ; Matsubara, Y. ; Miyake, N. ; Muraki, Y. ; Nagaya, M. ; Nishimoto, K. ; Ohnishi, K. ; Okumura, T. ; Perrott, Y. C. ; Philpott, L. ; Rattenbury, N. ; Saito, T. O. ; Sako, T. ; Sullivan, D. J. ; Sweatman, W. L. ; Tristram, P. J. ; Von Seggern, E. V. ; Yock, P. C M ; Albrow, M. ; Batista, V. ; Beaulieu, J. P. ; Brillant, S. ; Caldwell, J. ; Calitz, J. J. ; Cassan, A. ; Cole, A. ; Cook, K. ; Coutures, C. ; Dieters, S. ; Dominis Prester, D. ; Donatowicz, J. ; Fouqué, P. ; Hill, K. ; Hoffman, M. ; Jablonski, F. ; Kane, S. R. ; Kains, N. ; Kubas, D. ; 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. ; Allan, A. ; Bode, M. F. ; Bramich, D. M. ; Burgdorf, M. J. ; Clay, N. ; Fraser, S. ; Hawkins, E. ; Horne, K. ; Kerins, E. ; Lister, T. A. ; Mottram, C. ; Saunders, E. S. ; Snodgrass, C. ; Steele, I. A. ; Tsapras, Y. ; Jørgensen, U. G. ; Anguita, T. ; Bozza, V. ; Calchi Novati, S. ; Harpsøe, K. ; Hinse, T. C. ; Hundertmark, M. ; Kjærgaard, P. ; Liebig, C. ; Mancini, L. ; Masi, G. ; Mathiasen, M. ; Rahvar, S. ; Ricci, D. ; Scarpetta, G. ; Southworth, J. ; Surdej, J. ; Thöne, C. C. / Frequency of solar-like systems and of ice and gas giants beyond the snow line from high-magnification microlensing events in 2005-2008. In: Astrophysical Journal. 2010 ; Vol. 720, No. 2. pp. 1073-1089.
@article{73c454be0dab45b89c8e60602ba5f7bb,
title = "Frequency of solar-like systems and of ice and gas giants beyond the snow line from high-magnification microlensing events in 2005-2008",
abstract = "We present the first measurement of the planet frequency beyond the {"}snow line,{"} for the planet-to-star mass-ratio interval-4.5 < logq <-2, corresponding to the range of ice giants to gas giants. We find d 2Np1/dlog q d log s= (0.36 ± 0.15) dex dlog q d logs at the mean mass ratio q = 5 × 10-4 with no discernible deviation from a flat ({\"o}pik's law) distribution in logprojected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification (A > 200) microlensing events during 2005-2008. The sampled host stars have a typical mass Mhost ∼ 0.5 M⊙, and detection is sensitive to planets over a range of planet-star-projected separations (s max -1Re, s maxRE), where Re ∼ 3.5 AU(Mhost/M⊙) 1/2 is the Einstein radius and smax ∼ (q/10 -43)1/3. This corresponds to deprojected separations roughly three times the {"}snow line.{"} We show that the observations of these events have the properties of a {"}controlled experiment,{"} which is what permits measurement of absolute planet frequency. High-magnification events are rare, but the survey-plus-follow-up high-magnification channel is very efficient: half of all high-mag events were successfully monitored and half of these yielded planet detections. The extremely high sensitivity of high-mag events leads to a policy of monitoring them as intensively as possible, independent of whether they show evidence of planets. This is what allows us to construct an unbiased sample. The planet frequency derived from microlensing is a factor 8 larger than the one derived from Doppler studies at factor ∼25 smaller star-planet separations (i.e., periods 2-2000 days). However, this difference is basically consistent with the gradient derived from Doppler studies (when extrapolated well beyond the separations from which it is measured). This suggests a universal separation distribution across 2 dex in planet-star separation, 2 dex in mass ratio, and 0.3 dex in host mass. Finally, if all planetary systems were {"}analogs{"} of the solar system, our sample would have yielded 18.2 planets (11.4 {"}Jupiters,{"} 6.4 {"}Saturns,{"} 0.3 {"}Uranuses,{"} 0.2 {"}Neptunes{"}) including 6.1 systems with two or more planet detections. This compares to six planets including one twoplanet system in the actual sample, implying a first estimate of 1/6 for the frequency of solar-like systems.",
keywords = "Gravitational lensing: micro, Planetary systems",
author = "A. Gould and Subo Dong and Gaudi, {B. S.} and A. Udalski and Bond, {I. A.} and J. Greenhill and Street, {R. A.} and M. Dominik and T. Sumi and Szymański, {M. K.} and C. Han and W. Allen and G. Bolt and M. Bos and Christie, {G. W.} and DePoy, {D. L.} and J. Drummond and Eastman, {J. D.} and A. Gal-Yam and D. Higgins and J. Janczak and S. Kaspi and S. Kozllowski and Lee, {C. U.} and F. Mallia and A. Maury and D. Maoz and J. McCormick and Monard, {L. A G} and D. Moorhouse and N. Morgan and T. Natusch and Ofek, {E. O.} and Park, {B. G.} and Pogge, {R. W.} and D. Polishook and R. Santallo and A. Shporer and O. Spector and G. Thornley and Yee, {J. C.} and M. Kubiak and G. Pietrzyński and I. Soszyński and O. Szewczyk and {\"E} Wyrzykowski and K. Ulaczyk and R. Poleski and F. Abe and Bennett, {D. P.} and Botzler, {C. S.} and D. Douchin and M. Freeman and A. Fukui and K. Furusawa and Hearnshaw, {J. B.} and S. Hosaka and Y. Itow and K. Kamiya and Kilmartin, {P. M.} and A. Korpela and W. Lin and Ling, {C. H.} and S. Makita and K. Masuda and Y. Matsubara and N. Miyake and Y. Muraki and M. Nagaya and K. Nishimoto and K. Ohnishi and T. Okumura and Perrott, {Y. C.} and L. Philpott and N. Rattenbury and Saito, {T. O.} and T. Sako and Sullivan, {D. J.} and Sweatman, {W. L.} and Tristram, {P. J.} and {Von Seggern}, {E. V.} and Yock, {P. C M} and M. Albrow and V. Batista and Beaulieu, {J. P.} and S. Brillant and J. Caldwell and Calitz, {J. J.} and A. Cassan and A. Cole and K. Cook and C. Coutures and S. Dieters and {Dominis Prester}, D. and J. Donatowicz and P. Fouqu{\'e} and K. Hill and M. Hoffman and F. Jablonski and Kane, {S. R.} and N. Kains and D. Kubas and Marquette, {J. B.} and R. Martin and E. Martioli and P. Meintjes and J. Menzies and E. Pedretti and K. Pollard and Sahu, {K. C.} and C. Vinter and J. Wambsganss and R. Watson and A. Williams and M. Zub and A. Allan and Bode, {M. F.} and Bramich, {D. M.} and Burgdorf, {M. J.} and N. Clay and S. Fraser and E. Hawkins and K. Horne and E. Kerins and Lister, {T. A.} and C. Mottram and Saunders, {E. S.} and C. Snodgrass and Steele, {I. A.} and Y. Tsapras and J{\o}rgensen, {U. G.} and T. Anguita and V. Bozza and {Calchi Novati}, S. and K. Harps{\o}e and Hinse, {T. C.} and M. Hundertmark and P. Kj{\ae}rgaard and C. Liebig and L. Mancini and G. Masi and M. Mathiasen and S. Rahvar and D. Ricci and G. Scarpetta and J. Southworth and J. Surdej and Th{\"o}ne, {C. C.}",
year = "2010",
month = "9",
day = "10",
doi = "10.1088/0004-637X/720/2/1073",
language = "English",
volume = "720",
pages = "1073--1089",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - Frequency of solar-like systems and of ice and gas giants beyond the snow line from high-magnification microlensing events in 2005-2008

AU - Gould, A.

AU - Dong, Subo

AU - Gaudi, B. S.

AU - Udalski, A.

AU - Bond, I. A.

AU - Greenhill, J.

AU - Street, R. A.

AU - Dominik, M.

AU - Sumi, T.

AU - Szymański, M. K.

AU - Han, C.

AU - Allen, W.

AU - Bolt, G.

AU - Bos, M.

AU - Christie, G. W.

AU - DePoy, D. L.

AU - Drummond, J.

AU - Eastman, J. D.

AU - Gal-Yam, A.

AU - Higgins, D.

AU - Janczak, J.

AU - Kaspi, S.

AU - Kozllowski, S.

AU - Lee, C. U.

AU - Mallia, F.

AU - Maury, A.

AU - Maoz, D.

AU - McCormick, J.

AU - Monard, L. A G

AU - Moorhouse, D.

AU - Morgan, N.

AU - Natusch, T.

AU - Ofek, E. O.

AU - Park, B. G.

AU - Pogge, R. W.

AU - Polishook, D.

AU - Santallo, R.

AU - Shporer, A.

AU - Spector, O.

AU - Thornley, G.

AU - Yee, J. C.

AU - Kubiak, M.

AU - Pietrzyński, G.

AU - Soszyński, I.

AU - Szewczyk, O.

AU - Wyrzykowski, Ë

AU - Ulaczyk, K.

AU - Poleski, R.

AU - Abe, F.

AU - Bennett, D. P.

AU - Botzler, C. S.

AU - Douchin, D.

AU - Freeman, M.

AU - Fukui, A.

AU - Furusawa, K.

AU - Hearnshaw, J. B.

AU - Hosaka, S.

AU - Itow, Y.

AU - Kamiya, K.

AU - Kilmartin, P. M.

AU - Korpela, A.

AU - Lin, W.

AU - Ling, C. H.

AU - Makita, S.

AU - Masuda, K.

AU - Matsubara, Y.

AU - Miyake, N.

AU - Muraki, Y.

AU - Nagaya, M.

AU - Nishimoto, K.

AU - Ohnishi, K.

AU - Okumura, T.

AU - Perrott, Y. C.

AU - Philpott, L.

AU - Rattenbury, N.

AU - Saito, T. O.

AU - Sako, T.

AU - Sullivan, D. J.

AU - Sweatman, W. L.

AU - Tristram, P. J.

AU - Von Seggern, E. V.

AU - Yock, P. C M

AU - Albrow, M.

AU - Batista, V.

AU - Beaulieu, J. P.

AU - Brillant, S.

AU - Caldwell, J.

AU - Calitz, J. J.

AU - Cassan, A.

AU - Cole, A.

AU - Cook, K.

AU - Coutures, C.

AU - Dieters, S.

AU - Dominis Prester, D.

AU - Donatowicz, J.

AU - Fouqué, P.

AU - Hill, K.

AU - Hoffman, M.

AU - Jablonski, F.

AU - Kane, S. R.

AU - Kains, N.

AU - Kubas, D.

AU - Marquette, J. B.

AU - Martin, R.

AU - Martioli, E.

AU - Meintjes, P.

AU - Menzies, J.

AU - Pedretti, E.

AU - Pollard, K.

AU - Sahu, K. C.

AU - Vinter, C.

AU - Wambsganss, J.

AU - Watson, R.

AU - Williams, A.

AU - Zub, M.

AU - Allan, A.

AU - Bode, M. F.

AU - Bramich, D. M.

AU - Burgdorf, M. J.

AU - Clay, N.

AU - Fraser, S.

AU - Hawkins, E.

AU - Horne, K.

AU - Kerins, E.

AU - Lister, T. A.

AU - Mottram, C.

AU - Saunders, E. S.

AU - Snodgrass, C.

AU - Steele, I. A.

AU - Tsapras, Y.

AU - Jørgensen, U. G.

AU - Anguita, T.

AU - Bozza, V.

AU - Calchi Novati, S.

AU - Harpsøe, K.

AU - Hinse, T. C.

AU - Hundertmark, M.

AU - Kjærgaard, P.

AU - Liebig, C.

AU - Mancini, L.

AU - Masi, G.

AU - Mathiasen, M.

AU - Rahvar, S.

AU - Ricci, D.

AU - Scarpetta, G.

AU - Southworth, J.

AU - Surdej, J.

AU - Thöne, C. C.

PY - 2010/9/10

Y1 - 2010/9/10

N2 - We present the first measurement of the planet frequency beyond the "snow line," for the planet-to-star mass-ratio interval-4.5 < logq <-2, corresponding to the range of ice giants to gas giants. We find d 2Np1/dlog q d log s= (0.36 ± 0.15) dex dlog q d logs at the mean mass ratio q = 5 × 10-4 with no discernible deviation from a flat (öpik's law) distribution in logprojected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification (A > 200) microlensing events during 2005-2008. The sampled host stars have a typical mass Mhost ∼ 0.5 M⊙, and detection is sensitive to planets over a range of planet-star-projected separations (s max -1Re, s maxRE), where Re ∼ 3.5 AU(Mhost/M⊙) 1/2 is the Einstein radius and smax ∼ (q/10 -43)1/3. This corresponds to deprojected separations roughly three times the "snow line." We show that the observations of these events have the properties of a "controlled experiment," which is what permits measurement of absolute planet frequency. High-magnification events are rare, but the survey-plus-follow-up high-magnification channel is very efficient: half of all high-mag events were successfully monitored and half of these yielded planet detections. The extremely high sensitivity of high-mag events leads to a policy of monitoring them as intensively as possible, independent of whether they show evidence of planets. This is what allows us to construct an unbiased sample. The planet frequency derived from microlensing is a factor 8 larger than the one derived from Doppler studies at factor ∼25 smaller star-planet separations (i.e., periods 2-2000 days). However, this difference is basically consistent with the gradient derived from Doppler studies (when extrapolated well beyond the separations from which it is measured). This suggests a universal separation distribution across 2 dex in planet-star separation, 2 dex in mass ratio, and 0.3 dex in host mass. Finally, if all planetary systems were "analogs" of the solar system, our sample would have yielded 18.2 planets (11.4 "Jupiters," 6.4 "Saturns," 0.3 "Uranuses," 0.2 "Neptunes") including 6.1 systems with two or more planet detections. This compares to six planets including one twoplanet system in the actual sample, implying a first estimate of 1/6 for the frequency of solar-like systems.

AB - We present the first measurement of the planet frequency beyond the "snow line," for the planet-to-star mass-ratio interval-4.5 < logq <-2, corresponding to the range of ice giants to gas giants. We find d 2Np1/dlog q d log s= (0.36 ± 0.15) dex dlog q d logs at the mean mass ratio q = 5 × 10-4 with no discernible deviation from a flat (öpik's law) distribution in logprojected separation s. The determination is based on a sample of six planets detected from intensive follow-up observations of high-magnification (A > 200) microlensing events during 2005-2008. The sampled host stars have a typical mass Mhost ∼ 0.5 M⊙, and detection is sensitive to planets over a range of planet-star-projected separations (s max -1Re, s maxRE), where Re ∼ 3.5 AU(Mhost/M⊙) 1/2 is the Einstein radius and smax ∼ (q/10 -43)1/3. This corresponds to deprojected separations roughly three times the "snow line." We show that the observations of these events have the properties of a "controlled experiment," which is what permits measurement of absolute planet frequency. High-magnification events are rare, but the survey-plus-follow-up high-magnification channel is very efficient: half of all high-mag events were successfully monitored and half of these yielded planet detections. The extremely high sensitivity of high-mag events leads to a policy of monitoring them as intensively as possible, independent of whether they show evidence of planets. This is what allows us to construct an unbiased sample. The planet frequency derived from microlensing is a factor 8 larger than the one derived from Doppler studies at factor ∼25 smaller star-planet separations (i.e., periods 2-2000 days). However, this difference is basically consistent with the gradient derived from Doppler studies (when extrapolated well beyond the separations from which it is measured). This suggests a universal separation distribution across 2 dex in planet-star separation, 2 dex in mass ratio, and 0.3 dex in host mass. Finally, if all planetary systems were "analogs" of the solar system, our sample would have yielded 18.2 planets (11.4 "Jupiters," 6.4 "Saturns," 0.3 "Uranuses," 0.2 "Neptunes") including 6.1 systems with two or more planet detections. This compares to six planets including one twoplanet system in the actual sample, implying a first estimate of 1/6 for the frequency of solar-like systems.

KW - Gravitational lensing: micro

KW - Planetary systems

UR - http://www.scopus.com/inward/record.url?scp=77957128317&partnerID=8YFLogxK

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U2 - 10.1088/0004-637X/720/2/1073

DO - 10.1088/0004-637X/720/2/1073

M3 - Article

AN - SCOPUS:77957128317

VL - 720

SP - 1073

EP - 1089

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

ER -