Variation of the stellar color in high-magnification and caustic-crossing microlensing events

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Context. To a first approximation, the microlensing phenomenon is achromatic and great advancements have been achieved with regard to the interpretation of the achromatic signals, leading to the discovery and characterization of well above 100 new exoplanets. At a higher order accuracy in the observations, microlensing has a chromatic component (a color term) that has thus far been explored to a much lesser extent.

Aims. Here, we analyze the chromatic microlensing effect of four different physical phenomena, which have the potential to contribute key knowledge of the stellar properties that is not easily achievable with other methods of observation. Our simulation is limited to the case of main-sequence source stars.

Methods. Microlensing is particularly sensitive to giant and sub-giant stars near the Galactic center. While this population can be studied in short snapshots by the largest telescopes in the world, a general monitoring and characterization of the population can be achieved by use of more accessible medium-sized telescopes with specialized equipment via dual-color monitoring from observatories at sites with excellent seeing. We limit the results of this study to what will be achievable from the Danish 1.54 m telescope at La Silla observatory based on the use of the existing dual-color lucky imaging camera. Such potential monitoring programs of the bulge population from medium-sized telescopes include the characterization of starspots, limb-darkening, the frequency of close-in giant planet companions, and gravity darkening for blended source stars.

Results. We conclude our simulations with quantifying the likelihood of detecting these different phenomena per object where they are present to be similar to 60 and similar to 30% for the above-mentioned phenomena when monitored during both high-magnification and caustic crossings, respectively.

Original languageEnglish
Article numberA16
JournalAstronomy & Astrophysics
Volume657
Number of pages17
ISSN0004-6361
DOIs
Publication statusPublished - 21 Dec 2021

    Research areas

  • gravitational lensing: micro, instrumentation: photometers, methods: numerical, planets and satellites: general, starspots, stars: early-type, BLANKETED MODEL ATMOSPHERES, PLANETARY SYSTEMS, GALACTIC BULGE, STARS, SPOTS, CHROMATICITY, POLARIZATION, GENERATION, SIGNATURES, ALGORITHM

ID: 289233702