J/AJ/156/227 Photometric observations of the K2-22 system (Colon+, 2018)
A large ground-based observing campaign of the disintegrating planet K2-22b.
Colon K.D., Zhou G., Shporer A., Collins K.A., Bieryla A., Espinoza N.,
Murgas F., Pattarakijwanich P., Awiphan S., Armstrong J.D., Bailey J.,
Barentsen G., Bayliss D., Chakpor A., Cochran W.D., Dhillon V.S., Horne K.,
Ireland M., Kedziora-Chudczer L., Kielkopf J.F., Komonjinda S., Latham D.W.,
Marsh T.R., Mkrtichian D.E., Palle E., Ruffolo D., Sefako R., Tinney C.G.,
Wannawichian S., Yuma S.
<Astron. J., 156, 227 (2018)>
=2018AJ....156..227C 2018AJ....156..227C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable ; Photometry ; Optical ; Photometry, infrared ;
Stars, diameters ; Exoplanets
Keywords: planets and satellites: detection -
planets and satellites: individual (K2-22 b) - techniques: photometric
Abstract:
We present 45 ground-based photometric observations of the K2-22 system
collected between 2016 December and 2017 May, which we use to investigate
the evolution of the transit of the disintegrating planet K2-22b. Last
observed in early 2015, in these new observations we recover the transit
at multiple epochs and measure a typical depth of <1.5%. We find that
the distribution of our measured transit depths is comparable to the
range of depths measured in observations from 2014 and 2015. These new
observations also support ongoing variability in the K2-22b transit shape
and time, although the overall shallowness of the transit makes a detailed
analysis of these transit parameters difficult. We find no strong evidence
of wavelength-dependent transit depths for epochs where we have
simultaneous coverage at multiple wavelengths, although our stacked
Las Cumbres Observatory data collected over days-to-months timescales are
suggestive of a deeper transit at blue wavelengths. We encourage continued
high-precision photometric and spectroscopic monitoring of this system
in order to further constrain the evolution timescale and to aid
comparative studies with the other few known disintegrating planets.
Description:
Near-infrared light curves of K2-22 were obtained using the IRIS2 camera
on the 3.9 m AAT (Tinney et al. 2004SPIE.5492..998T 2004SPIE.5492..998T), located at Siding
Spring Observatory (SSO) in Australia. Observations were obtained on
UT 2017 March 15 (transit epoch=2669) and UT 2017 March 16 (transit
epoch=2671) with IRIS2 in the Ks band, at 30 s exposure time.
We used KeplerCam on the 1.2 m telescope at the FLWO on Mt. Hopkins,
Arizona to observe 5 transit windows of K2-22b. The observations were
made on UT 2017 March 8 (transit epoch=2650), UT 2017 March 9 (transit
epoch=2652), UT 2017 April 16 (transit epoch=2752), UT 2017 April 21
(transit epoch=2765) and UT 2017 May 22 (transit epoch=2846). All
observations were obtained in an SDSS i filter with a 120 s exposure time.
We observed three transits of K2-22 on three consecutive nights from
UT 2017 March 15 to UT 2017 March 17 (transit epochs=2669, 2672, 2674)
using the 0.7 m Thai Robotic Telescope-Gao Mei Gu Observatory (TRT-GAO),
in Lijiang, China. The observations were performed through a Cousins-I
filter with 60 s exposures.
We were awarded Director's Discretionary Time to use the OSIRIS instrument
(Cepa et al. 2000SPIE.4008..623C 2000SPIE.4008..623C) mounted on the 10.4 m GTC to observe 1
transit of K2-22b (PI: E. Palle). The data were obtained on UT 2017 May 17
(transit epoch=2835) using OSIRIS long-slit spectroscopy mode. We collected
24 light curves of K2-22 between UT 2017 March 1 and UT 2017 May 29 in
either the Sloan g or Sloan i band from multiple 1 m telescopes in the LCO
network (Brown et al. 2013PASP..125.1031B 2013PASP..125.1031B).
We collected two light curves of K2-22 on UT 2017 March 13 (transit
epoch=2663) and UT 2017 April 11 (transit epoch=2741) using the E2V
4 Kx4 K CCD at the 40 inch Swope telescope at Las Campanas Observatory.
Observations were acquired in both cases with the SDSS i filter but with
different exposure times.
At TNO, in Chiang Mai, Thailand, we conducted photometric observations
of K2-22b on the 0.5 m Thai Robotic Telescope-Thai National Observatory
(TRT-TNO) and the 2.4 m Thai National Telescope (TNT) on UT 2017 March 15
(transit epoch=2669) and UT 2017 April 13 (transit epoch=2745),
respectively.
We observed five complete transit windows of K2-22b on UT 2017 March 08
(transit epoch=2650), UT 2017 March 09 (transit epoch=2652), UT 2017
March 15 (transit epoch=2668), UT 2017 May 22 (transit epoch= 2846), and
UT 2017 May 25 (transit epoch=2854) using the ULMT located at the Mt.
Lemmon summit of Steward Observatory, AZ.
We observed one complete transit window of K2-22b on UT 2016 December 13
(transit epoch=2427) using the WIYN25 High-Resolution Infrared Camera
(WHIRC) installed on the 3.5 m WIYN telescope at Kitt Peak National
Observatory in Arizona.
Objects:
---------------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------------
11 17 55.88 +02 37 08.6 K2-22 = 2MASS J11175587+0237086
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 51 7273 Time-series photometry of K2-22
table2.dat 100 45 Summary and results of photometric observations
of K2-22
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See also:
J/A+A/579/A19 : K2 Variable Catalogue (Armstrong+, 2015)
J/ApJS/222/14 : Planetary candidates from 1st yr K2 mission (Vanderburg+, 2016)
J/ApJS/226/7 : Planet candidates discovered using K2's 1st yr
(Crossfield+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Facility Facility
14- 18 A5 --- Filter Filter
20- 33 F14.6 d BJD Barycentric Julian Date of observation
35- 42 F8.6 --- RFlux [0.947062/1.317847] Relative flux
44- 51 F8.6 --- e_RFlux [0.00044/0.049219] Uncertainty in RFlux
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 "date" Date Observation start date
12- 15 I4 --- Epoch [2427/2866] Transit epoch (1)
17- 28 A12 --- Facility Facility
30- 33 F4.1 m Aper [0.5/10.4] Telescope aperture
35- 44 A10 --- Filter Filter
46- 52 F7.4 --- b_Phase [-0.975/0.144] Phase coverage, minimum value
54- 61 F8.5 --- B_Phase [-0.191/0.695] Phase coverage, maximum value
63- 66 I4 --- Npts [22/3022] Number of data points
68- 71 F4.2 min Cad [0.1/4.56] Cadence (2)
73- 77 F5.3 % sigma [0.044/1.75] Median uncertainty in relative
flux σmedian
79- 79 A1 --- l_Rp/R* [<] Limit flag on Rp/R*
80- 85 F6.4 --- Rp/R* [0.0364/0.1793]? Measured planet-star radius
ratio
87- 92 F6.4 --- e_Rp/R* [0.0057/0.0576]? Uncertainty in Rp/R*
94- 94 A1 --- l_Rp/R*c [<] Limit flag on Rp/R*c
95-100 F6.4 --- Rp/R*c [0.0375/0.1846]? Corrected planet-star radius
ratio
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Note (1): The transit epoch is relative to the transit ephemeris given in
Sanchis-Ojeda et al. (2015ApJ...812..112S 2015ApJ...812..112S).
Note (2): The cadence is defined as the median time between data points.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 10-Apr-2019