An anomaly detector with immediate feedback to hunt for planets of Earth mass and below by microlensing

M. Dominik, N. J. Rattenbury, A. Allan, S. Mao, D. M. Bramich, M. J. Burgdorf, E. Kerins, Y. Tsapras, Wyrzykowski

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

ABSTRACT The discovery of OGLE 2005-BLG-390Lb, the first cool rocky/icy exoplanet, impressively demonstrated the sensitivity of the microlensing technique to extrasolar planets below 10 M. A planet of 1 M instead of the expected 5 M for OGLE 2005-BLG-390Lb (with an uncertainty factor of 2) in the same spot would have provided a detectable deviation with an amplitude of ∼3 per cent and a duration of ∼12 h. While a standard sampling interval of 1.5-2.5 h for microlensing follow-up observations appears to be insufficient for characterizing such light curve anomalies and thereby claiming the discovery of the planets that caused these, an early detection of a deviation could trigger higher-cadence sampling which would have allowed the discovery of an Earth-mass planet in this case. Here, we describe the implementation of an automated anomaly detector, embedded into the eSTAR system, that profits from immediate feedback provided by the robotic telescopes that form the RoboNet-1.0 network. It went into operation for the 2007 microlensing observing season. As part of our discussion about an optimal strategy for planet detection, we shed some new light on whether concentrating on highly magnified events is promising and planets in the 'resonant' angular separation equal to the angular Einstein radius are revealed most easily. Given that sub-Neptune mass planets can be considered being common around the host stars probed by microlensing (preferentially M and K dwarfs), the higher number of events that can be monitored with a network of 2-m telescopes and the increased detection efficiency for planets below 5 M arising from an optimized strategy gives a common effort of current microlensing campaigns a fair chance to detect an Earth-mass planet (from the ground) ahead of the COROT or Kepler missions. The detection limit of gravitational microlensing extends even below 0.1 M, but such planets are not very likely to be detected from current campaigns. However, these will be within the reach of high-cadence monitoring with a network of wide-field telescopes or a space-based telescope.

Original languageEnglish
Pages (from-to)792-804
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Volume380
Issue number2
DOIs
Publication statusPublished - 1 Sep 2007
Externally publishedYes

Fingerprint

planets
planet
anomalies
anomaly
detectors
telescopes
extrasolar planets
sampling
Kepler mission
planet detection
deviation
Neptune (planet)
detector
concentrating
robotics
Neptune
light curve
actuators
intervals
stars

Keywords

  • Gravitational lensing
  • Methods: observational
  • Planetary systems

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

An anomaly detector with immediate feedback to hunt for planets of Earth mass and below by microlensing. / Dominik, M.; Rattenbury, N. J.; Allan, A.; Mao, S.; Bramich, D. M.; Burgdorf, M. J.; Kerins, E.; Tsapras, Y.; Wyrzykowski.

In: Monthly Notices of the Royal Astronomical Society, Vol. 380, No. 2, 01.09.2007, p. 792-804.

Research output: Contribution to journalArticle

Dominik, M. ; Rattenbury, N. J. ; Allan, A. ; Mao, S. ; Bramich, D. M. ; Burgdorf, M. J. ; Kerins, E. ; Tsapras, Y. ; Wyrzykowski. / An anomaly detector with immediate feedback to hunt for planets of Earth mass and below by microlensing. In: Monthly Notices of the Royal Astronomical Society. 2007 ; Vol. 380, No. 2. pp. 792-804.
@article{1f7a3f76729d462fba935a6f95d743b3,
title = "An anomaly detector with immediate feedback to hunt for planets of Earth mass and below by microlensing",
abstract = "ABSTRACT The discovery of OGLE 2005-BLG-390Lb, the first cool rocky/icy exoplanet, impressively demonstrated the sensitivity of the microlensing technique to extrasolar planets below 10 M⊕. A planet of 1 M⊕ instead of the expected 5 M⊕ for OGLE 2005-BLG-390Lb (with an uncertainty factor of 2) in the same spot would have provided a detectable deviation with an amplitude of ∼3 per cent and a duration of ∼12 h. While a standard sampling interval of 1.5-2.5 h for microlensing follow-up observations appears to be insufficient for characterizing such light curve anomalies and thereby claiming the discovery of the planets that caused these, an early detection of a deviation could trigger higher-cadence sampling which would have allowed the discovery of an Earth-mass planet in this case. Here, we describe the implementation of an automated anomaly detector, embedded into the eSTAR system, that profits from immediate feedback provided by the robotic telescopes that form the RoboNet-1.0 network. It went into operation for the 2007 microlensing observing season. As part of our discussion about an optimal strategy for planet detection, we shed some new light on whether concentrating on highly magnified events is promising and planets in the 'resonant' angular separation equal to the angular Einstein radius are revealed most easily. Given that sub-Neptune mass planets can be considered being common around the host stars probed by microlensing (preferentially M and K dwarfs), the higher number of events that can be monitored with a network of 2-m telescopes and the increased detection efficiency for planets below 5 M⊕ arising from an optimized strategy gives a common effort of current microlensing campaigns a fair chance to detect an Earth-mass planet (from the ground) ahead of the COROT or Kepler missions. The detection limit of gravitational microlensing extends even below 0.1 M⊕, but such planets are not very likely to be detected from current campaigns. However, these will be within the reach of high-cadence monitoring with a network of wide-field telescopes or a space-based telescope.",
keywords = "Gravitational lensing, Methods: observational, Planetary systems",
author = "M. Dominik and Rattenbury, {N. J.} and A. Allan and S. Mao and Bramich, {D. M.} and Burgdorf, {M. J.} and E. Kerins and Y. Tsapras and Wyrzykowski",
year = "2007",
month = "9",
day = "1",
doi = "10.1111/j.1365-2966.2007.12124.x",
language = "English",
volume = "380",
pages = "792--804",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "2",

}

TY - JOUR

T1 - An anomaly detector with immediate feedback to hunt for planets of Earth mass and below by microlensing

AU - Dominik, M.

AU - Rattenbury, N. J.

AU - Allan, A.

AU - Mao, S.

AU - Bramich, D. M.

AU - Burgdorf, M. J.

AU - Kerins, E.

AU - Tsapras, Y.

AU - Wyrzykowski,

PY - 2007/9/1

Y1 - 2007/9/1

N2 - ABSTRACT The discovery of OGLE 2005-BLG-390Lb, the first cool rocky/icy exoplanet, impressively demonstrated the sensitivity of the microlensing technique to extrasolar planets below 10 M⊕. A planet of 1 M⊕ instead of the expected 5 M⊕ for OGLE 2005-BLG-390Lb (with an uncertainty factor of 2) in the same spot would have provided a detectable deviation with an amplitude of ∼3 per cent and a duration of ∼12 h. While a standard sampling interval of 1.5-2.5 h for microlensing follow-up observations appears to be insufficient for characterizing such light curve anomalies and thereby claiming the discovery of the planets that caused these, an early detection of a deviation could trigger higher-cadence sampling which would have allowed the discovery of an Earth-mass planet in this case. Here, we describe the implementation of an automated anomaly detector, embedded into the eSTAR system, that profits from immediate feedback provided by the robotic telescopes that form the RoboNet-1.0 network. It went into operation for the 2007 microlensing observing season. As part of our discussion about an optimal strategy for planet detection, we shed some new light on whether concentrating on highly magnified events is promising and planets in the 'resonant' angular separation equal to the angular Einstein radius are revealed most easily. Given that sub-Neptune mass planets can be considered being common around the host stars probed by microlensing (preferentially M and K dwarfs), the higher number of events that can be monitored with a network of 2-m telescopes and the increased detection efficiency for planets below 5 M⊕ arising from an optimized strategy gives a common effort of current microlensing campaigns a fair chance to detect an Earth-mass planet (from the ground) ahead of the COROT or Kepler missions. The detection limit of gravitational microlensing extends even below 0.1 M⊕, but such planets are not very likely to be detected from current campaigns. However, these will be within the reach of high-cadence monitoring with a network of wide-field telescopes or a space-based telescope.

AB - ABSTRACT The discovery of OGLE 2005-BLG-390Lb, the first cool rocky/icy exoplanet, impressively demonstrated the sensitivity of the microlensing technique to extrasolar planets below 10 M⊕. A planet of 1 M⊕ instead of the expected 5 M⊕ for OGLE 2005-BLG-390Lb (with an uncertainty factor of 2) in the same spot would have provided a detectable deviation with an amplitude of ∼3 per cent and a duration of ∼12 h. While a standard sampling interval of 1.5-2.5 h for microlensing follow-up observations appears to be insufficient for characterizing such light curve anomalies and thereby claiming the discovery of the planets that caused these, an early detection of a deviation could trigger higher-cadence sampling which would have allowed the discovery of an Earth-mass planet in this case. Here, we describe the implementation of an automated anomaly detector, embedded into the eSTAR system, that profits from immediate feedback provided by the robotic telescopes that form the RoboNet-1.0 network. It went into operation for the 2007 microlensing observing season. As part of our discussion about an optimal strategy for planet detection, we shed some new light on whether concentrating on highly magnified events is promising and planets in the 'resonant' angular separation equal to the angular Einstein radius are revealed most easily. Given that sub-Neptune mass planets can be considered being common around the host stars probed by microlensing (preferentially M and K dwarfs), the higher number of events that can be monitored with a network of 2-m telescopes and the increased detection efficiency for planets below 5 M⊕ arising from an optimized strategy gives a common effort of current microlensing campaigns a fair chance to detect an Earth-mass planet (from the ground) ahead of the COROT or Kepler missions. The detection limit of gravitational microlensing extends even below 0.1 M⊕, but such planets are not very likely to be detected from current campaigns. However, these will be within the reach of high-cadence monitoring with a network of wide-field telescopes or a space-based telescope.

KW - Gravitational lensing

KW - Methods: observational

KW - Planetary systems

UR - http://www.scopus.com/inward/record.url?scp=34548394641&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34548394641&partnerID=8YFLogxK

U2 - 10.1111/j.1365-2966.2007.12124.x

DO - 10.1111/j.1365-2966.2007.12124.x

M3 - Article

VL - 380

SP - 792

EP - 804

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -