J/AJ/161/126 I-band LC of the microlensing event KMT-2017-BLG-2820 (Ryu+, 2021)
KMT-2017-BLG-2820 and the nature of the free-floating planet population.
Ryu Y.-H., Mroz P., Gould A., Hwang K.-H., Kim H.-W., Yee J.C., Albrow M.D.,
Chung S.-J., Jung Y.K., Shin I.-G., Shvartzvald Y., Zang W., Cha S.-M.,
Kim D.-J., Kim S.-L., Lee C.-U., Lee D.-J., Lee Y., Park B.-G., Han C.,
Pogge R.W., Udalski A., Poleski R., Skowron J., Szymanski M.K.,
Soszynski I., Pietrukowicz P., Kozlowski S., Ulaczyk K., Rybicki K.A.,
Iwanek P.
<Astron. J., 161, 126 (2021)>
=2021AJ....161..126R 2021AJ....161..126R
ADC_Keywords: Gravitational lensing; Photometry, RI
Keywords: Gravitational microlensing
Abstract:
We report a new free-floating planet (FFP) candidate,
KMT-2017-BLG-2820, with Einstein radius θE∼6µas, lens-source
relative proper motion µrel∼8mas/yr, and Einstein timescale
tE=6.5hr. It is the third FFP candidate found in an ongoing study of
giant-source finite-source point-lens (FSPL) events in the KMTNet
database and the sixth FSPL FFP candidate overall. We find no
significant evidence for a host. Based on their timescale
distributions and detection rates, we argue that five of these six
FSPL FFP candidates are drawn from the same population as the six
point-source point-lens (PSPL) FFP candidates found by Mroz et al. in
the OGLE-IV database. The θE distribution of the FSPL FFPs
implies that they are either sub- Jovian planets in the bulge or
super-Earths in the disk. However, the apparent "Einstein desert"
(10≲θE/µas≲30) would argue for the latter. Whether each of
the 12 (six FSPL and six PSPL) FFP candidates is truly an FFP or
simply a very wide-separation planet can be determined at first
adaptive optics (AO) light on 30m telescopes, and earlier for some. If
the latter, a second epoch of AO observations could measure the
projected planet- host separation with a precision of O(10au). At the
present time, the balance of evidence favors the unbound-planet
hypothesis.
Description:
KMT-2017-BLG-2820 (in KMT field BLG14) was observed with KMT's three
observatories at the Cerro Tololo Interamerican Observatory (KMTC),
South African Astronomical Observatory (KMTS), and Siding Springs
Observatory (KMTA). Each facility has a 1.6m telescope equipped with a
2x2° camera. Most observations were in Cousins I. In 2017, every
10th I-band observation from KMTC was complemented by an observation
in the Johnson V band, while this applied to only every 20th
observation from KMTS and KMTA.
The event also lies in OGLE field BLG653, which was observed in the
Cousins I band with a cadence of 0.17/hr from OGLE's 1.3m telescope at
Las Campanas Observatory, which is equipped with a 1.4deg2 camera.
Objects:
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RA (2000) DE Designation(s)
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17 34 58.25 -28 32 51.2 KMT-2017-BLG-2820 = KMT-2017-BLG-2820
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig1.dat 35 2006 Light curve of KMT-2017-BLG-2820
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See also:
J/AcA/50/421 : OGLE-II DIA BUL_SC1 field (Wozniak, 2000)
J/A+A/549/A147 : Abundances of microlensed bulge dwarf stars. V. (Bensby+,2013)
J/A+A/618/A44 : Predicted microlensing events from Gaia DR2 (Bramich, 2018)
J/AcA/68/183 : Predicted Microlensing Events for 21st Century (Bramich+, 2018)
J/AJ/159/98 : I-band LC of microlensing event KMT-2016-BLG-1836 (Yang+, 2020)
J/AJ/159/262 : OGLE/KMTnet VI bands photo. of OGLE-2019-BLG-0551 (Mroz+, 2020)
Byte-by-byte Description of file: fig1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Tel Observatory identifier (KMTA, KMTC, KMTS and OGLE)
6- 16 F11.6 d HJD [7792/8045] Heliocentric Julian Date; HJD-24500000
18- 26 F9.6 mag Imag [16.33/17.29] Apparent I band magnitude
28- 35 F8.6 mag e_Imag [0.005/0.08] Uncertainty in Imag
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 26-Apr-2021