J/AcA/68/351 Predicted Microlensing Events by nearby VLM objects (Nielsen+ 2018)
Predicted Microlensing Events by Nearby Very-Low-Mass Objects:
Pan-STARRS DR1 vs. Gaia DR2.
Nielsen M.B., Bramich D.M.
<Acta Astron., 68, 351-370 (2018)>
=2018AcA....68..351N 2018AcA....68..351N (SIMBAD/NED BibCode)
ADC_Keywords: Gravitational lensing ; Positional data ; Stars, nearby
Keywords: gravitational lensing: micro - methods: data analysis -
catalogs - astrometry - stars: fundamental parameters
Abstract:
Microlensing events can be used to directly measure the masses of
single field stars to a precision of ∼1-10%. The majority of direct
mass measurements for stellar and sub-stellar objects typically only
come from observations of binary systems. Hence microlensing provides
an important channel for direct mass measurements of single stars. The
Gaia satellite has observed ∼1.7 billion objects, and analysis of the
second data release has recently yielded numerous event predictions
for the next few decades. However, the Gaia catalog is incomplete for
nearby very-low-mass objects such as brown dwarfs for which mass
measurements are most crucial. We employ a catalog of very-low-mass
objects from Pan-STARRS data release 1 (PDR1) as potential lens stars,
and we use the objects from Gaia data release 2 (GDR2) as potential
source stars. We then search for future microlensing events up to the
year 2070. The Pan-STARRS1 objects are first cross-matched with GDR2
to remove any that are present in both catalogs. This leaves a sample
of 1718 possible lenses. We fit MIST isochrones to the Pan-STARRS1,
AllWISE and 2MASS photometry to estimate their masses. We then compute
their paths on the sky, along with the paths of the GDR2 source
objects, until the year 2070, and search for potential microlensing
events. Source-lens pairs that will produce a microlensing signal with
an astrometric amplitude of greater than 0.131mas, or a photometric
amplitude of greater than 0.4mmag, are retained.
Description:
Characteristics of 27 microlensing events.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
events.dat 612 27 Characteristics of 27 microlensing events
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
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)
Byte-by-byte Description of file: events.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Event Event Name (MENNN)
7- 15 A9 --- SpTypeL Lens spectral type
17- 41 A25 --- Disc Lens discovery ID
43- 59 A17 --- PS1L Lens PS1 DR1 ID
61- 79 I19 --- GDR2L ?=- Lens GDR2 ID
81- 90 F10.6 deg RALdeg Lens right ascension (ICRS) at epoch epL
92-101 F10.6 deg DELdeg Lens Declination (ICRS) at epoch epL
103-112 F10.5 yr EpL Lens epoch (Julian year)
114-119 F6.1 mas/yr pmRA*L Lens proper motion along RA, pmRA*cosDE
121-123 F3.1 mas/yr e_pmRA*L Error on lens proper motion along RA
125-131 F7.1 mas/yr pmDEL Lens proper motion along DE
133-135 F3.1 mas/yr e_pmDEL Error on lens proper motion along DE
137-142 F6.2 mas PlxL Lens parallax
144-148 F5.2 mas e_PlxL Error on lens Parallax
150-154 F5.2 mag gmagL ?=- Lens g_P1 magnitude
156-159 F4.2 mag e_gmagL ?=- Error on lens g_P1 magnitude
161-165 F5.2 mag rmagL ?=- Lens r_P1 magnitude
167-170 F4.2 mag e_rmagL ?=- Error on lens r_P1 magnitude
172-176 F5.2 mag imagL ?=- Lens i_P1 magnitude
178-181 F4.2 mag e_imagL ?=- Error on lens i_P1 magnitude
183-187 F5.2 mag zmagL ?=- Lens z_P1 magnitude
189-192 F4.2 mag e_zmagL ?=- Error on lens z_P1 magnitude
194-198 F5.2 mag ymagL ?=- Lens y_P1 magnitude
200-203 F4.2 mag e_ymagL ?=- Error on lens y_P1 magnitude
205-209 F5.2 mag JmagL Lens 2MASS J magnitude
211-214 F4.2 mag e_JmagL Error on lens 2MASS J magnitude
216-220 F5.2 mag HmagL ?=- Lens 2MASS H magnitude
222-225 F4.2 mag e_HmagL ?=- Error on lens 2MASS H magnitude
227-231 F5.2 mag KsmagL ?=- Lens 2MASS K_S magnitude
233-236 F4.2 mag e_KsmagL ?=- Error on lens 2MASS K_S magnitude
238-242 F5.2 mag W1magL ?=- Lens AllWISE W1 magnitude
244-247 F4.2 mag e_W1magL ?=- Error on lens AllWISE W1 magnitude
249-253 F5.2 mag W2magL ?=- Lens AllWISE W2 magnitude
255-258 F4.2 mag e_W2magL ?=- Error on lens AllWISE W2 magnitude
260-264 F5.2 mag W3magL ?=- Lens AllWISE W3 magnitude
266-269 F4.2 mag e_W3magL ?=- Error on lens AllWISE W3 magnitude
271-274 F4.2 mag W4magL ?=- Lens AllWISE W4 magnitude
276-279 F4.2 mag e_W4magL ?=- Error on lens AllWISE W4 magnitude
281-284 F4.2 Msun MassL Lens mass
286-304 I19 --- GDR2 Source GDR2 ID (source_id)
306-319 F14.10 deg RAdeg Source right ascension (ICRS) at epoch 2015.5
321-326 F6.3 mas e_RAdeg Error on Source RA
328-341 F14.10 deg DEdeg Source declination (ICRS) at epoch 2015.5
343-348 F6.3 mas e_DEdeg Error on Source DE
350-355 F6.1 yr Ep [2015.5] Source Epoch (Julian year)
357-362 F6.3 mas/yr pmRA* ?=- Source proper motion along RA,
pmRA*cosDE
364-368 F5.3 mas/yr e_pmRA* ?=- Error on Source proper motion along RA
370-376 F7.3 mas/yr pmDE ?=- Source proper motion along DE
378-382 F5.3 mas/yr e_pmDE ?=- Error on Source proper motion along DE
384-389 F6.3 mas Plx ?=- Source absolute parallax
391-395 F5.3 mas e_Plx ?=- Error on source absolute Parallax
397-403 F7.4 mag Gmag Source G mean magnitude
405-410 F6.4 mag e_Gmag Error on Source G mean magnitude
412-418 F7.4 mag BPmag ?=- Source G_BP mean magnitude
420-425 F6.4 mag e_BPmag ?=- Error on Source G_BP mean magnitude
427-433 F7.4 mag RPmag ?=- Source G_RP mean magnitude
435-440 F6.4 mag e_RPmag ?=- Error on Source G_RP mean magnitude
442-447 F6.3 mas thetaE Median theta_E
449-453 F5.3 mas e_thetaE Error on theta_E
455-459 F5.2 --- u0t Minimum normalised source-lens separation
u_0 in theta_E units (theta_E)
461-465 F5.2 --- e_u0t 15.9 percentile of the minimum normalised
source-lens separation u_0 (theta_E)
467-472 F6.2 --- E_u0t 84.1 percentile of the minimum normalised
source-lens separation u_0 (theta_E)
474-480 F7.2 mas u0 Minimum source-lens separation u_0
482-487 F6.2 mas e_u0 15.9 percentile of the minimum source-lens
separation u_0
489-495 F7.2 mas E_u0 84.1 percentile of the minimum source-lens
separation u_0
497-506 F10.5 yr t0 Median t_0 (Julian year)
508-517 F10.5 yr e_t0 15.9 Percentile t_0 (Julian year)
519-528 F10.5 yr E_t0 84.1 Percentile t_0 (Julian year)
530-535 F6.4 mag dAA1 Median {DELTA}(A,A1)
537-542 F6.4 mag e_dAA1 15.9 Percentile {DELTA}(A,A1))
544-549 F6.4 mag E_dAA1 84.1 Percentile {DELTA}(A,A1))
551-556 F6.2 d TdAA1 Median T[{DELTA}(A,A1))]
558-563 F6.2 d e_TdAA1 15.9 Percentile T[{DELTA}(A,A1))]
565-570 F6.2 d E_TdAA1 84.1 Percentile T[{DELTA}(A,A1))]
572-576 F5.3 mas dmth2 Median {DELTA}(δmic,θ2)
578-582 F5.3 mas e_dmth2 15.9 Percentile
{DELTA}(δmic,θ2)
584-588 F5.3 mas E_dmth2 84.1 Percentile
{DELTA}(δmic,θ2)
590-596 F7.2 d Tdmth2 Median T[{DELTA}(δmic,θ2)]
598-604 F7.2 d e_Tdmth2 15.9 Percentile
T[{DELTA}(δmic,θ2)]
606-612 F7.2 d E_Tdmth2 84.1 Percentile
T[{DELTA}(δmic,θ2)]
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Acknowledgements:
Dan Bramich, dan.bramich(at)hotmail.co.uk
(End) Dan Bramich [NYUAD, UAE], Patricia Vannier [CDS] 09-May-2019