J/AJ/170/183 Scaling K2. VIII. Sub-Neptunes & M dwarfs (Hardegree-Ullman+, 2025)
Scaling K2.
VIII. Short-period sub-Neptune occurrence rates peak around early-type M dwarfs.
Hardegree-Ullman K.K., Bergsten G.J., Christiansen J.L., Zink J.K.,
Bhure S., Boley K.M., Fernandes R.B., Giacalone S., Karpoor P.R.
<Astron. J., 170, 183 (2025)>
=2025AJ....170..183H 2025AJ....170..183H
ADC_Keywords: Exoplanets; Stars, masses; Stars, diameters; Stars, distances;
Effective temperatures; Abundances, [Fe/H]; Photometry, UBVRI;
Photometry, infrared
Keywords: Exoplanet systems ; Exoplanets ; Fundamental parameters of stars
Abstract:
We uniformly combined data from the NASA Kepler and K2 missions to
compute planet occurrence rates across the entire FGK and M-dwarf
stellar range. The K2 mission, driven by targets selected by guest
observers, monitored nine times more M dwarfs than the Kepler mission.
Combined, Kepler and K2 observed 130 short-period (P=1-40days) Earth
to Neptune-sized candidate planets orbiting M dwarfs. K2 observed
3.5 times more of these planets than Kepler for host stars below
3700K. Our planet occurrence rates show that short-period sub-Neptunes
peak at 3750-97+153K and drop for cooler M dwarfs. A peak near
this location was predicted by pebble accretion planet formation
models and confirmed here by observations for the first time.
Super-Earths continue to increase in occurrence toward cooler stars
and show no clear evidence of a peak in the host star range considered
here (3200-6900K). Our observations provide critical input to further
refine planet formation models. We strongly recommend further study of
mid-to-late M dwarfs with TESS and soon the Nancy Grace Roman Space
Telescope and PLATO to identify additional small planet trends.
Description:
In order to place Kepler and K2 targets on the same scale, we used
photometry from Gaia DR3 (I/355) and 2MASS (II/246), and probabilistic
distance measurements based on Gaia DR3 from Bailer-Jones+2021
(I/352). We started with the full Kepler and K2 target tables from
NASA Exoplanet Archive, which yielded 200,038 unique Kepler and
372,289 unique K2 targets. Next, we used the CDS crossmatch service
(Boch+2012, 2012ASPC..461..291B 2012ASPC..461..291B; Pineau+2020, 2020ASPC..522..125P 2020ASPC..522..125P) to
then further refine our sample with other criteria. These cuts left
94,422 Kepler and 90,344 unique K2 FGKM main-sequence stars.
K2 planets were selected from the full Scaling K2 planet catalog in
Zink+2021 (J/AJ/162/259) and Kepler planets were drawn from
Berger+2020b (J/AJ/159/280) based on Kepler DR25 (Thompson+2018,
J/ApJS/235/38). Since the K2 stellar radii, masses, and temperatures
were updated from the Hardegree-Ullman+2020 (J/ApJS/247/28) sample,
the planet radii and stellar incident flux were updated accordingly.
The same updates were applied to the Kepler stellar and planet samples
from Berger+2020b (J/AJ/159/280) and Berger+2020a (J/AJ/160/108).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table4.dat 197 94422 Properties of Kepler Stars
table5.dat 206 99142 Properties of K2 Stars
table6.dat 58 1385 Kepler Super-Earth and Sub-Neptune Exoplanet
Parameters
table7.dat 74 328 K2 Super-Earth and Sub-Neptune Exoplanet Parameters
--------------------------------------------------------------------------------
See also:
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010)
J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)
J/ApJ/807/45 : Potentially habitable planets orbit. M dwarfs (Dressing+, 2015)
J/ApJ/804/64 : Empirical and model parameters of 183 M dwarfs (Mann+, 2015)
J/ApJ/814/130 : Planet occurrence rates calculated for KOIs (Mulders+, 2015)
J/ApJS/224/2 : K2 EPIC stellar properties for 138600 targets (Huber+, 2016)
J/AJ/154/109 : California-Kepler Surv (CKS). III. Planet radii (Fulton+, 2017)
J/ApJ/844/102 : KIC star plx from asteroseismology vs Gaia (Huber+, 2017)
J/ApJS/235/38 : Kepler planetary cand. VIII. DR25 reliability (Thompson+, 2018)
J/AJ/158/75 : Mid-type M dwarfs planet occur. rates (Hardegree-Ullman+, 2019)
J/ApJ/871/63 : How to constrain your M dwarf. II. Nearby binar. (Mann+, 2019)
J/AJ/160/108 : Gaia-Kepler stellar properties cat.II. Planets (Berger+, 2020)
J/AJ/159/280 : Gaia-Kepler stellar properties cat.I. KIC stars (Berger+, 2020)
J/ApJS/247/28 : K2 star parameters from Gaia & LAMOST (Hardegree-Ullman+, 2020)
J/AJ/160/19 : 827 ultracool dwarfs with K2 (Sagear+, 2020)
J/A+A/641/A170 : Ultracool dwarf K2 light curves (Sestovic+, 2020)
J/AJ/159/154 : Exoplanet candidates in Camp. 5 of the K2 mission (Zink+, 2020)
J/A+A/653/A98 : asPIC1.1 catalogue (Montalto+, 2021)
J/AJ/162/259 : Scaling K2. IV. Camp. 1-8 & 10-18 planets sample (Zink+, 2021)
J/AJ/163/179 : The California-Kepler Survey. X. (Petigura+, 2022)
J/AJ/165/267 : O2 lvl in Nearby Transiting Exoplanets (Hardegree-Ullman+, 2023)
J/AJ/165/265 : Properties of 363 M-dwarfs from TESS (Ment+, 2023)
J/AJ/165/262 : Scaling K2. VI. HIRES/isoclassify stellar param. (Zink+, 2023)
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- KIC [757450/12984422] Kepler (V/133) ID
10- 28 I19 --- GaiaDR3 Gaia DR3 (I/355) source ID
30- 45 A16 --- 2MASS 2MASS (II/249) designation (JHHMMSSss+DDMMSSs)
47- 56 F10.6 deg RAdeg Right ascension (J2000)
58- 65 F8.6 mas e_RAdeg Uncertainty in RAdeg
67- 75 F9.6 deg DEdeg Declination (J2000)
77- 84 F8.6 mas e_DEdeg Uncertainty in DEdeg
86- 96 F11.6 pc Dist [19.21/8123] Distance from Bailer-Jones+2021
(I/352)
98- 108 F11.6 pc e_Dist [6.83e-3/1234.1] Lower uncertainty on Dist
110- 120 F11.6 pc E_Dist [6.31e-3/1941.2] Upper uncertainty on Dist
122- 125 I4 K Teff [3090/7298] Surface effective temperature
127- 129 I3 K e_Teff [90/311] Uncertainty in Teff
131- 135 F5.3 [cm/s] logg [3.56/5.37] Log, surface gravity
137- 141 F5.3 [cm/s] e_logg [0.021/0.853] Uncertainty in logg
143- 148 F6.3 [-] [Fe/H] [-1.8/0.53] Metallicity
150- 154 F5.3 [-] e_[Fe/H] [0.217] Uncertainty in [Fe/H]
156- 164 F9.6 Lsun Lstar [2.17e-3/43.63] Stellar luminosity
166- 173 F8.6 Lsun e_Lstar [1.11e-4/9.53] Uncertainty in Lstar
175- 179 F5.3 Rsun Rstar [0.16/4.19] Stellar radius
181- 185 F5.3 Rsun e_Rstar [5e-3/0.982] Uncertainty in Rstar
187- 191 F5.3 Msun Mstar [0.13/7.1] Stellar mass
193- 197 F5.3 Msun e_Mstar [5e-3/3.72] Uncertainty in Mstar
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC [201048855/251634367] EPIC (IV/34) K2
identifier
11- 12 I2 --- Camp [1/18] K2 Campaign (1)
14- 32 I19 --- GaiaDR3 Gaia DR3 (I/355) source ID
34- 49 A16 --- 2MASS 2MASS (II/246) designation (JHHMMSSss+DDMMSSs)
51 A1 --- Comp Binary component, A or B
53- 62 F10.6 deg RAdeg Right ascension (J2000)
64- 71 F8.6 mas e_RAdeg Uncertainty in RAdeg
73- 82 F10.6 deg DEdeg Declination (J2000)
84- 91 F8.6 mas e_DEdeg Uncertainty in DEdeg
93- 104 F12.6 pc Dist [20.41/11377] Distance from Bailer-Jones+2021
(I/352)
106- 116 F11.6 pc e_Dist [0.01/6354] Lower uncertainty on Dist
118- 128 F11.6 pc E_Dist [0.01/4058] Upper uncertainty on Dist
130- 133 I4 K Teff [2992/7299] Surface effective temperature
135- 137 I3 K e_Teff [88/356] Uncertainty in Teff
139- 143 F5.3 [cm/s] logg [3.57/5.44] Log, surface gravity
145- 149 F5.3 [cm/s] e_logg [0.021/1.02] Uncertainty in logg
151- 156 F6.3 [-] [Fe/H] [-1.99/0.54] Metallicity
158- 162 F5.3 [-] e_[Fe/H] [0.217] Uncertainty in [Fe/H]
164- 172 F9.6 Lsun Lstar [1.27e-3/42.87] Stellar luminosity
174- 182 F9.6 Lsun e_Lstar [4.6e-5/31.67] Uncertainty in Lstar
184- 188 F5.3 Rsun Rstar [0.13/4.22] Stellar radius
190- 194 F5.3 Rsun e_Rstar [4e-3/3.86] Uncertainty in Rstar
196- 200 F5.3 Msun Mstar [0.018/7.39] Stellar mass
202- 206 F5.3 Msun e_Mstar [3e-3/3.41] Uncertainty in Mstar
--------------------------------------------------------------------------------
Note (1): Campaigns as follows:
1 = 2014-05-30 to 2014-08-21 (8260 occurrences)
2 = 2014-08-23 to 2014-11-12 (1414 occurrences)
3 = 2014-11-14 to 2015-02-03 (5015 occurrences)
4 = 2015-02-07 to 2015-04-23 (3460 occurrences)
5 = 2015-04-27 to 2015-07-10 (8395 occurrences)
6 = 2015-07-14 to 2015-09-30 (8538 occurrences)
7 = 2015-10-04 to 2015-12-26 (2170 occurrences)
8 = 2016-01-03 to 2016-03-23 (9293 occurrences)
10 = 2016-07-06 to 2016-09-20 (5950 occurrences)
11 = 2016-09-24 to 2016-12-08 (693 occurrences)
12 = 2016-12-15 to 2017-03-04 (11709 occurrences)
13 = 2017-03-08 to 2017-05-27 (3705 occurrences)
14 = 2017-05-31 to 2017-08-19 (5265 occurrences)
15 = 2017-08-23 to 2017-11-20 (4515 occurrences)
16 = 2017-12-07 to 2018-02-25 (6835 occurrences)
17 = 2018-03-01 to 2018-05-08 (6473 occurrences)
18 = 2018-05-12 to 2018-07-02 (7452 occurrences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- KIC [1026957/12834874] Kepler (V/133) ID
10- 16 F7.2 --- KOI [49.01/8082.01] Kepler Object of Interest
18- 22 F5.3 Rgeo Rp [1/3.99] Planet Radius
24- 28 F5.3 Rgeo e_Rp [0.056/2.48] Uncertainty in Rp
30- 35 F6.3 d Per [1/39.79] Planetary orbital period
37- 41 F5.3 d e_Per [0.015/2.12] Uncertainty in Per
43- 50 F8.3 Earth Sp [2.22/7791.52] Incident Flux, Earth units (Sgeo)
52- 58 F7.3 Earth e_Sp [0.12/810.19] Uncertainty in Sp
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- EPIC [201155177/251584580] EPIC (IV/34) K2 identifier
11- 12 I2 --- Camp [1/18] K2 Campaign (1)
14- 25 F12.2 --- Cand K2 planet candidate identifier
27- 31 F5.3 Rgeo Rp [1.07/3.95] Planet Radius
33- 38 F6.3 Rgeo e_Rp [0.065/16.84] Uncertainty in Rp
40- 48 F9.6 d Per [1.13/35.95] Planetary orbital period
50- 57 F8.6 d e_Per [3.4e-5/8.5e-3] Uncertainty in Per
59- 66 F8.3 Earth Sp [1.47/3019.44] Incident Flux, Earth units (Sgeo)
68- 74 F7.3 Earth e_Sp [0.049/668.71] Uncertainty in Sp
--------------------------------------------------------------------------------
Note (1): Campaigns as follows:
1 = 2014-05-30 to 2014-08-21 (17 occurrences)
2 = 2014-08-23 to 2014-11-12 (8 occurrences)
3 = 2014-11-14 to 2015-02-03 (32 occurrences)
4 = 2015-02-07 to 2015-04-23 (22 occurrences)
5 = 2015-04-27 to 2015-07-10 (38 occurrences)
6 = 2015-07-14 to 2015-09-30 (30 occurrences)
7 = 2015-10-04 to 2015-12-26 (7 occurrences)
8 = 2016-01-03 to 2016-03-23 (30 occurrences)
10 = 2016-07-06 to 2016-09-20 (4 occurrences)
11 = 2016-09-24 to 2016-12-08 (2 occurrences)
12 = 2016-12-15 to 2017-03-04 (18 occurrences)
13 = 2017-03-08 to 2017-05-27 (10 occurrences)
14 = 2017-05-31 to 2017-08-19 (16 occurrences)
15 = 2017-08-23 to 2017-11-20 (22 occurrences)
16 = 2017-12-07 to 2018-02-25 (34 occurrences)
17 = 2018-03-01 to 2018-05-08 (17 occurrences)
18 = 2018-05-12 to 2018-07-02 (21 occurrences)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
License: CC-BY-4.0
References:
Hardegree-Ullman et al. Pap I 2020ApJS..247...28H 2020ApJS..247...28H J/ApJS/247/28
Zink et al. Pap II 2020AJ....159..154Z 2020AJ....159..154Z J/AJ/159/154
Zink et al. Pap III 2020AJ....160...94Z 2020AJ....160...94Z
Zink et al. Pap IV 2021AJ....162..259Z 2021AJ....162..259Z J/AJ/162/259
Christiansen et al. Pap V 2022AJ....163..244C 2022AJ....163..244C
Zink et al. Pap VI 2023AJ....165..262Z 2023AJ....165..262Z J/AJ/165/262
Christiansen et al. Pap VII 2023AJ....166..248C 2023AJ....166..248C
Hardegree-Ullman et al. Pap VIII 2025AJ....170..183H 2025AJ....170..183H This catalog
(End) Prepared by [AAS], Robin Leichtnam [CDS] 07-Jul-2026