J/AJ/157/113 TESS M-dwarf exoplanetary systems (Ballard, 2019)
Predicted number, multiplicity, and orbital dynamics of TESS M-dwarf exoplanets.
Ballard S.
<Astron. J., 157, 113 (2019)>
=2019AJ....157..113B 2019AJ....157..113B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, dwarfs ; Stars, M-type ; Exoplanets ; Stars, distances ;
Effective temperatures ; Stars, masses ; Stars, diameters ; Models
Keywords: eclipses ; planetary systems ; planets and satellites: detection
Abstract:
We present a study of the M-dwarf exoplanetary systems forthcoming from
NASA's TESS mission. While the mission's footprint is too complex to be
characterized by a single detection completeness, we extract ensemble
completeness functions that recover the planet detections from previous
work for stars between 3200 and 4000 K. We employ these completeness
functions, together with a dual- population planet occurrence model that
includes compact multiple planetary systems, to infer anew the planet
yield. We predict both the number of M-dwarf planets likely from TESS
and their system architectures. We report four main findings. First,
TESS will likely detect more planets orbiting M dwarfs that previously
predicted. Around stars with effective temperatures between 3200 and
4000 K, we predict that TESS will find 1274±241 planets orbiting
1026±182 stars, a 1.2-fold increase over previous predictions. Second,
TESS will find two or more transiting planets around 20% of these host
stars, a number similar to the multiplicity yield of NASA's Kepler mission.
Third, TESS light curves in which one or more planets are detected will
often contain transits of additional planets below the detection threshold
of TESS. Among a typical set of 200 TESS hosts to one or more detected
planets, 93±17 transiting planets will be missed. Transit follow-up
efforts with the photometric sensitivity to detect an Earth or larger
around a mid-M dwarf, even with very modest period completeness, will
readily result in additional planet discoveries. Fourth, the strong
preference of TESS for systems of compact multiples indicates that TESS
planets will be dynamically cooler on average than Kepler planets, with
90% of TESS planets residing in orbits with e<0.15. We include both
(1) a predicted sample of planets detected by TESS orbiting stars between
3200 and 4000 K, including additional nontransiting planets, or transiting
and undetected planets orbiting the same star and (2) sample completeness
functions for use by the community.
Description:
To generate a realistic synthetic sample of planetary systems, we take
the following steps. We draw periods and radii for each mock planetary
system from the empirical distribution of Dressing & Charbonneau
(2015, J/ApJ/807/45). We then employ the distributions of Limbach & Turner
(2015PNAS..112...20L 2015PNAS..112...20L) to assign eccentricity. We assign planetary
masses with the relations of Zeng & Jacobsen (2017ApJ...837..164Z 2017ApJ...837..164Z) for
R<1.5 R⊕ and Wolfgang et al. (2016, J/ApJ/825/19) for
R>1.5 R⊕. Rogers (2015ApJ...801...41R 2015ApJ...801...41R) identified the cutoff
between a majority of rocky planets and a majority of icy/gaseous planets
at 1.5 R⊕, but these two relations also naturally overlap at
1.5 R⊕. We assess the stability of the system by ensuring that
planets satisfy the criterion defined in Fabrycky et al. (2012,
J/ApJ/790/146). For generating synthetic TESS planetary systems orbiting
M dwarfs, we employ four different stellar masses corresponding to four
different effective temperature ranges (from Boyajian et al. 2012,
J/ApJ/757/112): 0.25 M☉ (for stars 3200-3400 K), 0.41 M☉
(for stars 3400-3600 K), 0.50 M☉ (for stars 3600-3800 K), and
0.60 M☉ (for stars 3800-4000 K). We then assign a Boolean TTV flag
to each transiting planet. Finally, we calculate and record an independent
density for each planet using only its mutual Hill spacing from
neighboring planets.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 98 5391 Mock sample of full systems in which TESS detected
at least one transiting planet
--------------------------------------------------------------------------------
See also:
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/ApJ/790/146 : Planets in Kepler's multi-transiting systems (Fabrycky+, 2014)
J/ApJ/807/45 : Potentially habitable planets orbiting M dwarfs
(Dressing+, 2015)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)
J/ApJ/825/19 : Mass-radius relationship for planets with Rp<4
(Wolfgang+, 2016)
J/AJ/155/180 : A catalog of cool dwarf targets for the TESS (Muirhead+, 2018)
J/ApJS/239/2 : Simulated exoplanets from TESS list of targets (Barclay+, 2018)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Star [1/952] Star identifier
5- 5 I1 --- Pl [1/8] Planet identifier
7- 10 I4 K Teff [3210/3990] Star surface effective temperature
12- 15 F4.1 mag Vmag [9.7/19.2] V-band magnitude
17- 20 F4.1 mag Kmag [5.5/14.5] K-band magnitude
22- 27 F6.2 pc Dist [4.9/323.5] System distance
29- 34 F6.2 deg RAdeg [0.48/359.8] Star Right Ascension in decimal
degrees (J2000)
36- 41 F6.2 deg DEdeg [-88.2/88.73] Star Declination in decimal degrees
(J2000)
43- 48 F6.2 d Per [0.8/199.98] Orbital period
50- 54 F5.1 Rsun a [5.4/579.2] Orbital semi-major axis
56- 62 F7.3 deg i [-28.7/29.12] Inclination
64- 68 F5.2 Msun M* [0.07/16.1] Star mass
70- 72 F3.1 Rsun R* [0.5/3.9] Star radius
74- 78 F5.1 deg Omega [0.1/359.9] Longitude of the node Ω
80- 84 F5.3 --- e [0.009/0.624] Eccentricity
86- 91 F6.3 --- Hill [4.765/63.88] Hill spacing quantity Δ (1)
93- 93 I1 --- Trans [0/1]? Transit flag (2)
95- 98 I4 --- Det [-100/1]? Detected flag (3)
--------------------------------------------------------------------------------
Note (1): Defined in Equation (1): Δ=(a2-a1)/RH1,2>2sqrt(3).
Note (2): Transit flag as follows:
0 = Planet does not transit the host star;
1 = Planet transits the host star.
Note (3): Detection flag as follows:
0 = Planet transits the host star, but is undetected by TESS;
1 = Planet transits the host star and is detected by TESS;
-100 = Planet does not transit the host star.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 11-Jun-2019