Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOGLE-2014-BLG-1112LB: A Microlensing Brown Dwarf Detected Through the Channel of a Gravitational Binary-Lens Event
70
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
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.
rate research
Read More
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.
We report the discovery of a binary composed of two brown dwarfs, based on the analysis of the microlensing event OGLE-2016-BLG-1469. Thanks to detection of both finite-source and microlens-parallax effects, we are able to measure both the masses $M_1sim 0.05 M_odot$, $M_2sim 0.01 M_odot$, and distance $D_{rm L} sim 4.5$ kpc, as well as the projected separation $a_perp sim 0.33$ au. This is the third brown-dwarf binary detected using the microlensing method, demonstrating the usefulness of microlensing in detecting field brown-dwarf binaries with separations less than 1 au.
We present the analysis of the gravitational microlensing event OGLE-2013-BLG-0102. The light curve of the event is characterized by a strong short-term anomaly superposed on a smoothly varying lensing curve with a moderate magnification $A_{rm max}sim 1.5$. It is found that the event was produced by a binary lens with a mass ratio between the components of $q = 0.13$ and the anomaly was caused by the passage of the source trajectory over a caustic located away from the barycenter of the binary. From the analysis of the effects on the light curve due to the finite size of the source and the parallactic motion of the Earth, the physical parameters of the lens system are determined. The measured masses of the lens components are $M_{1} = 0.096 pm 0.013~M_{odot}$ and $M_{2} = 0.012 pm 0.002~M_{odot}$, which correspond to near the hydrogen-burning and deuterium-burning mass limits, respectively. The distance to the lens is $3.04 pm 0.31~{rm kpc}$ and the projected separation between the lens components is $0.80 pm 0.08~{rm AU}$.
We report the discovery of a planet-mass companion to the microlens OGLE-2016-BLG-0263L. Unlike most low-mass companions that were detected through perturbations to the smooth and symmetric light curves produced by the primary, the companion was discovered through the channel of a repeating event, in which the companion itself produced its own single-mass light curve after the event produced by the primary had ended. Thanks to the continuous coverage of the second peak by high-cadence surveys, the possibility of the repeating nature due to source binarity is excluded with a $96%$ confidence level. The mass of the companion estimated by a Bayesian analysis is $M_{rm p}=4.1_{-2.5}^{+6.5} M_{rm J}$. The projected primary-companion separation is $a_perp = 6.5^{+1.3}_{-1.9}$ au. The ratio of the separation to the snow-line distance of $a_perp/a_{rm sl}sim 15.4$ corresponds to the region beyond Neptune, the outermost planet of the solar system. We discuss the importance of high-cadence surveys in expanding the range of microlensing detections of low-mass companions and future space-based microlensing surveys.
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.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
