J/AJ/159/57 HST spectroscopic LCs of Kepler 51b & 51d (Libby-Roberts+, 2020)
The featureless transmission spectra of two super-puff planets.
Libby-Roberts J.E., Berta-Thompson Z.K., Desert J.-M., Masuda K.,
Morley C.V., Lopez E.D., Deck K.M., Fabrycky D., Fortney J.J., Line M.R.,
Sanchis-Ojeda R., Winn J.N.
<Astron. J., 159, 57 (2020)>
=2020AJ....159...57L 2020AJ....159...57L
ADC_Keywords: Exoplanets; Spectra, infrared
Keywords: Atmospheric composition ; Exoplanet atmospheres ;
Exoplanet structure ; Exoplanet evolution ;
Transit timing variation method ; Transits ;
Hubble Space Telescope ; Exoplanets
Abstract:
The Kepler mission revealed a class of planets known as "super-puffs,"
with masses only a few times larger than Earth's but radii larger than
Neptune, giving them very low mean densities. All three of the known
planets orbiting the young solar-type star Kepler 51 are super-puffs.
The Kepler 51 system thereby provides an opportunity for a comparative
study of the structures and atmospheres of this mysterious class of
planets, which may provide clues about their formation and evolution.
We observed two transits each of Kepler 51b and 51d with the Wide
Field Camera 3 (WFC3) on the Hubble Space Telescope. Combining new
WFC3 transit times with reanalyzed Kepler data and updated stellar
parameters, we confirmed that all three planets have densities lower
than 0.1g/cm3. We measured the WFC3 transmission spectra to be
featureless between 1.15 and 1.63µm, ruling out any variations
greater than 0.6 scale heights (assuming a H/He-dominated atmosphere),
thus showing no significant water absorption features. We interpreted
the flat spectra as the result of a high-altitude aerosol layer
(pressure <3mbar) on each planet. Adding this new result to the
collection of flat spectra that have been observed for other
sub-Neptune planets, we find support for one of the two hypotheses
introduced by Crossfield & Kreidberg (2017AJ....154..261C 2017AJ....154..261C), that
planets with cooler equilibrium temperatures have more high-altitude
aerosols. We strongly disfavor their other hypothesis that the H/He
mass fraction drives the appearance of large-amplitude transmission
features.
Description:
We observed two transits each of Kepler 51b and 51d with the infrared
channel of Wide Field Camera 3 (WFC3) on Hubble Space Telescope (HST)
(Cycle 23, GO#14218, PI Berta-Thompson). We used the G141 grism for
all observations, providing slitless spectroscopy across the
1.1-1.7µm wavelength range. HST successfully observed transits on
2015 September 29 and 2016 June 26 for Kepler 51b and on 2015 December
31 and 2017 January 24 for Kepler 51d.
Objects:
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RA (2000) DE Designation(s) (Period)
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19 45 55.142 +49 56 15.65 Kepler51b = KOI-620.01 (P=45.154)
19 45 55.14 +49 56 15.6 Kepler51c = KOI-620.03 (P=85.313)
19 45 55.14 +49 56 15.7 Kepler51d = KOI-620.02 (P=130.184)
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File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 713 774 HST Wide Field Camera 3 (WFC3) spectroscopic light
curve data
table9.dat 203 5100 *Markov Chain Monte Carlo (MCMC) samples from our
transit timing variations (TTV) analysis
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Note on table9.dat : Planet b,c and d reffers to Kepler 51b, Kepler 51c and
Kepler 51d.
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/331/81 : Hyades membership (Perryman+ 1998)
J/AJ/142/112 : KIC photometric calibration (Brown+, 2011)
J/ApJ/736/19 : Kepler planetary candidates. II. (Borucki+, 2011)
J/ApJ/747/35 : HST/WFC3 transit observation of GJ1214b (Berta+, 2012)
J/ApJ/750/113 : Kepler TTVs. II. Confirmed multiplanet systems (Ford+, 2012)
J/ApJ/775/L11 : Stellar rotation periods for KOIs (McQuillan+, 2013)
J/ApJS/210/19 : Kepler planetary candidates. IV. 22 months (Burke+, 2014)
J/ApJS/214/25 : Rosseland & Planck gaseous mean opacities (Freedman+, 2014)
J/ApJ/785/15 : Transit times for Kepler-79's planets (Jontof-Hutter+, 2014)
J/ApJS/217/31 : Kepler planetary candidates. VI. 4yr Q1-Q16 (Mullally+, 2015)
J/AJ/154/5 : Transit timing variations of 145 Kepler planets (Hadden+, 2017)
J/AJ/154/108 : California-Kepler Survey (CKS). II. Properties (Johnson+, 2017)
J/AJ/153/142 : Radial velocities systems hosting sub-Saturns (Petigura+, 2017)
J/AJ/156/264 : California-Kepler Survey. VII. Planet radius gap (Fulton+,2018)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/AJ/157/174 : Transiting planets Kepler-47 circumbinary system (Orosz+, 2019)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 16 F16.8 d BJD [2457294/2457780] Barycentric Julian date
at TDB of mid-exposure
18- 31 F14.12 --- F1152-1176 [0.986/1.009] Relative spectrum flux from
1.152-1.176µm
33- 48 F16.14 --- e_F1152-1176 [0.002/0.003] Relative spectrum flux
uncertainty from 1.152-1.176µm
50- 63 F14.12 --- F1176-1200 [0.986/1.007] Relative spectrum flux from
1.176-1.200µm
65- 80 F16.14 --- e_F1176-1200 [0.002/0.003] Relative spectrum flux
uncertainty from 1.176-1.200µm
82- 95 F14.12 --- F1200-1223 [0.985/1.008] Relative spectrum flux from
1.200-1.223µm
97-112 F16.14 --- e_F1200-1223 [0.001/0.003] Relative spectrum flux
uncertainty from 1.200-1.223µm
114-127 F14.12 --- F1223-1247 [0.986/1.007] Relative spectrum flux from
1.223-1.247µm
129-144 F16.14 --- e_F1223-1247 [0.001/0.002] Relative spectrum flux
uncertainty from 1.223-1.247µm
146-159 F14.12 --- F1247-1271 [0.985/1.009] Relative spectrum flux from
1.247-1.271µm
161-176 F16.14 --- e_F1247-1271 [0.001/0.002] Relative spectrum flux
uncertainty from 1.247-1.271µm
178-191 F14.12 --- F1271-1294 [0.987/1.008] Relative spectrum flux from
1.271-1.294µm
193-208 F16.14 --- e_F1271-1294 [0.001/0.002] Relative spectrum flux
uncertainty from 1.271-1.294µm
210-223 F14.12 --- F1294-1318 [0.985/1.008] Relative spectrum flux from
1.294-1.318µm
225-240 F16.14 --- e_F1294-1318 [0.001/0.002] Relative spectrum flux
uncertainty from 1.294-1.318µm
242-255 F14.12 --- F1318-1342 [0.986/1.008] Relative spectrum flux from
1.318-1.342µm
257-272 F16.14 --- e_F1318-1342 [0.001/0.002] Relative spectrum flux
uncertainty from 1.318-1.342µm
274-287 F14.12 --- F1342-1366 [0.986/1.007] Relative spectrum flux from
1.342-1.366µm
289-304 F16.14 --- e_F1342-1366 [0.001/0.002] Relative spectrum flux
uncertainty from 1.342-1.366µm
306-319 F14.12 --- F1366-1389 [0.985/1.008] Relative spectrum flux from
1.366-1.389um
321-336 F16.14 --- e_F1366-1389 [0.001/0.002] Relative spectrum flux
uncertainty from 1.366-1.389µm
338-351 F14.12 --- F1389-1413 [0.986/1.008] Relative spectrum flux from
1.389-1.413µm
353-368 F16.14 --- e_F1389-1413 [0.001/0.002] Relative spectrum flux
uncertainty from 1.389-1.413µm
370-383 F14.12 --- F1413-1437 [0.986/1.008] Relative spectrum flux from
1.413-1.437µm
385-400 F16.14 --- e_F1413-1437 [0.001/0.002] Relative spectrum flux
uncertainty from 1.413-1.437µm
402-415 F14.12 --- F1437-1460 [0.987/1.008] Relative spectrum flux from
1.437-1.460µm
417-432 F16.14 --- e_F1437-1460 [0.001/0.003] Relative spectrum flux
uncertainty from 1.437-1.460µm
434-447 F14.12 --- F1460-1484 [0.987/1.007] Relative spectrum flux from
1.460-1.484µm
449-464 F16.14 --- e_F1460-1484 [0.001/0.003] Relative spectrum flux
uncertainty from 1.460-1.484µm
466-479 F14.12 --- F1484-1508 [0.986/1.009] Relative spectrum flux from
1.484-1.508µm
481-496 F16.14 --- e_F1484-1508 [0.001/0.003] Relative spectrum flux
uncertainty from 1.484-1.508µm
498-511 F14.12 --- F1508-1531 [0.984/1.01] Relative spectrum flux from
1.508-1.531µm
513-528 F16.14 --- e_F1508-1531 [0.002/0.003] Relative spectrum flux
uncertainty from 1.508-1.531µm
530-543 F14.12 --- F1531-1555 [0.985/1.008] Relative spectrum flux from
1.531-1.555µm
545-560 F16.14 --- e_F1531-1555 [0.002/0.003] Relative spectrum flux
uncertainty from 1.531-1.555µm
562-575 F14.12 --- F1555-1579 [0.985/1.01] Relative spectrum flux from
1.555-1.579µm
577-592 F16.14 --- e_F1555-1579 [0.002/0.003] Relative spectrum flux
uncertainty from 1.555-1.579µm
594-607 F14.12 --- F1579-1602 [0.98/1.1] Relative spectrum flux from
1.579-1.602µm
609-624 F16.14 --- e_F1579-1602 [0.002/0.003] Relative spectrum flux
uncertainty from 1.579-1.602µm
626-639 F14.12 --- F1602-1625 [0.986/1.009] Relative spectrum flux from
1.602-1.625µm
641-656 F16.14 --- e_F1602-1625 [0.002/0.003] Relative spectrum flux
uncertainty from 1.602-1.625µm
658-669 F12.10 ct/pix/s Sky [0.73/1.9] Sky background,
in photoelectrons/pixel/s
671-683 F13.10 pix Ypos [-0.24/0.26] Vertical centroid of the
spectral trace on the detector
685-696 F12.10 --- Slope [0.007/0.01] Slope of the spectral trace on
the detectors; in pixels/pixel units
698-709 F12.10 pix Width [0.72/0.78] Width of the spectral trace on
the detector
711-711 A1 --- ID [bd] Planet identifier (1)
713-713 I1 --- Nvis [1/2] Visit Number
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Note (1): Identifier as follows:
b = Kepler 51b (308 occurrences)
d = Kepler 51d (466 occurrences)
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Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 E13.8 --- Mb/M* Planet "b" to star mass ratio
15- 27 E13.8 d Perb [45.1528/45.156] Orbital period, planet "b"
29- 40 E12.7 --- ecoswb [-0.21/0.03] Sqrt(eb)Cos(ωb),
planet "b" (1)
42- 53 E12.7 --- esinwb [-0.3/0.05] Sqrt(eb)Sin(ωb),
planet "b" (1)
55- 67 E13.8 d T0b [159.1/159.2] Time, first inferior
conjunction, planet "b" (2)
69- 81 E13.8 --- Mc/M* Planet "c" to star mass ratio
83- 95 E13.8 d Perc [85.3/85.321] Orbital period, planet "c"
97-108 E12.7 --- ecoswc [-0.173/0.235] Sqrt(ec)Cos(ωc),
planet "c" (1)
110-121 E12.7 --- esinwc [-0.312/0.19] Sqrt(ec)Sin(ωc),
planet "c" (1)
123-135 E13.8 d T0c [295.309/295.332] Time, first inferior
conjunction, planet "c" (2)
137-149 E13.8 --- Md/M* Planet "d" to star mass ratio
151-163 E13.8 d Perd [130.1819/130.188] Orbital Period, planet "d"
165-176 E12.7 --- ecoswd [-0.17/0.21] Sqrt(ed)Cos(ωd),
planet "d" (1)
178-189 E12.7 --- esinwd [-0.282/0.17] Sqrt(ed)Sin(ωd),
planet "d" (1)
191-203 E13.8 d T0d [212.021/212.0261] Time, first inferior
conjunction, planet "d" (2)
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Note (1): With "e" the eccentricity and "ω" the argument of periastron of
the planet.
Note (2): T0 is the time of first inferior conjunction assuming a Keplerian
orbit (BJD-2454833).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 19-Mar-2020