TY - JOUR

T1 - Variation of the stellar color in high-magnification and caustic-crossing microlensing events

AU - Sajadian, S.

AU - Jorgensen, U. G.

PY - 2021/12/21

Y1 - 2021/12/21

N2 - 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.

AB - 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.

KW - gravitational lensing: micro

KW - instrumentation: photometers

KW - methods: numerical

KW - planets and satellites: general

KW - starspots

KW - stars: early-type

KW - BLANKETED MODEL ATMOSPHERES

KW - PLANETARY SYSTEMS

KW - GALACTIC BULGE

KW - STARS

KW - SPOTS

KW - CHROMATICITY

KW - POLARIZATION

KW - GENERATION

KW - SIGNATURES

KW - ALGORITHM

U2 - 10.1051/0004-6361/202141623

DO - 10.1051/0004-6361/202141623

M3 - Journal article

VL - 657

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A16

ER -