Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOGLE-2014-BLG-0289: Precise Characterization of a Quintuple-Peak Gravitational Microlensing Event
70
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present the analysis of the binary-microlensing event OGLE-2014-BLG-0289. The event light curve exhibits very unusual five peaks where four peaks were produced by caustic crossings and the other peak was produced by a cusp approach. It is found that the quintuple-peak features of the light curve provide tight constraints on the source trajectory, enabling us to precisely and accurately measure the microlensing parallax $pi_{rm E}$. Furthermore, the three resolved caustics allow us to measure the angular Einstein radius $thetae$. From the combination of $pi_{rm E}$ and $thetae$, the physical lens parameters are uniquely determined. It is found that the lens is a binary composed of two M dwarfs with masses $M_1 = 0.52 pm 0.04 M_odot$ and $M_2=0.42 pm 0.03 M_odot$ separated in projection by $a_perp = 6.4 pm 0.5$ au. The lens is located in the disk with a distance of $D_{rm L} = 3.3 pm 0.3$~kpc. It turns out that the reason for the absence of a lensing signal in the {it Spitzer} data is that the time of observation corresponds to the flat region of the light curve.
rate research
Read More
Due to the nature depending on only the gravitational field, microlensing, in principle, provides an important tool to detect faint and even dark brown dwarfs. However, the number of identified brown dwarfs is limited due to the difficulty of the lens mass measurement that is needed to check the substellar nature of the lensing object. In this work, we report a microlensing brown dwarf discovered from the analysis of the gravitational binary-lens event OGLE-2014-BLG-1112. We identify the brown-dwarf nature of the lens companion by measuring the lens mass from the detections of both microlens-parallax and finite-source effects. We find that the companion has a mass of $(3.03 pm 0.78)times 10^{-2} M_odot$ and it is orbiting a solar-type primary star with a mass of $1.07 pm 0.28 M_odot$. The estimated projected separation between the lens components is $9.63 pm 1.33$ au and the distance to the lens is $4.84 pm 0.67$ kpc. We discuss the usefulness of space-based microlensing observations in detecting brown dwarfs through the channel of binary-lens events.
We present the analysis of the planetary microlensing event OGLE-2014-BLG-1760, which shows a strong light curve signal due to the presence of a Jupiter mass-ratio planet. One unusual feature of this event is that the source star is quite blue, with $V-I = 1.48pm 0.08$. This is marginally consistent with source star in the Galactic bulge, but it could possibly indicate a young source star in the far side of the disk. Assuming a bulge source, we perform a Bayesian analysis assuming a standard Galactic model, and this indicates that the planetary system resides in or near the Galactic bulge at $D_L = 6.9 pm 1.1 $ kpc. It also indicates a host star mass of $M_* = 0.51 pm 0.44 M_odot$, a planet mass of $m_p = 180 pm 110 M_oplus$, and a projected star-planet separation of $a_perp = 1.7pm 0.3,$AU. The lens-source relative proper motion is $mu_{rm rel} = 6.5pm 1.1$ mas/yr. The lens (and stellar host star) is predicted to be very faint, so it is most likely that it can detected only when the lens and source stars are partially resolved. Due to the relatively high relative proper motion, the lens and source will be resolved to about $sim46,$mas in 6-8 years after the peak magnification. So, by 2020 - 2022, we can hope to detect the lens star with deep, high resolution images.
We analyze the gravitational binary-lensing event OGLE-2016-BLG-0156, for which the lensing light curve displays pronounced deviations induced by microlens-parallax effects. The light curve exhibits 3 distinctive widely-separated peaks and we find that the multiple-peak feature provides a very tight constraint on the microlens-parallax effect, enabling us to precisely measure the microlens parallax $pi_{rm E}$. All the peaks are densely and continuously covered from high-cadence survey observations using globally located telescopes and the analysis of the peaks leads to the precise measurement of the angular Einstein radius $theta_{rm E}$. From the combination of the measured $pi_{rm E}$ and $theta_{rm E}$, we determine the physical parameters of the lens. It is found that the lens is a binary composed of two M dwarfs with masses $M_1=0.18pm 0.01 M_odot$ and $M_2=0.16pm 0.01 M_odot$ located at a distance $D_{rm L}= 1.35pm 0.09 {rm kpc}$. According to the estimated lens mass and distance, the flux from the lens comprises an important fraction, $sim 25%$, of the blended flux. The bright nature of the lens combined with the high relative lens-source motion, $mu=6.94pm 0.50 {rm mas} {rm yr}^{-1}$, suggests that the lens can be directly observed from future high-resolution follow-up observations.
In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with the high-quality photometry data from ground-based observations combined with the space-based {it Spitzer} observations of this long time-scale event enables us to uniquely determine the masses $M_1=0.40 pm 0.05~M_odot$ and $M_2=0.13pm 0.01~M_odot$ of the individual lens components. Because the lens-source relative parallax and the vector lens-source relative proper motion are unambiguously determined, we can likewise unambiguously predict the astrometric offset between the light centroid of the magnified images (as observed by the {it Gaia} satellite) and the true position of the source. This prediction can be tested when the individual-epoch {it Gaia} astrometric measurements are released.
The mass function and statistics of binaries provide important diagnostics of the star formation process. Despite this importance, the mass function at low masses remains poorly known due to observational difficulties caused by the faintness of the objects. Here we report the microlensing discovery and characterization of a binary lens composed of very low-mass stars just above the hydrogen-burning limit. From the combined measurements of the Einstein radius and microlens parallax, we measure the masses of the binary components of $0.10pm 0.01 M_odot$ and $0.09pm 0.01 M_odot$. This discovery demonstrates that microlensing will provide a method to measure the mass function of all Galactic populations of very low mass binaries that is independent of the biases caused by the luminosity of the population.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
