J/AJ/170/182 Sub-Neptunes obliquities & Marroon-X TOI-1759 RVs (Polanski+, 2025)
An aligned sub-Neptune revealed with MAROON-X and a tendency toward alignment
for small planets.
Polanski A.S., Crossfield I.J.M., Seifahrt A., Bean J.L., Brande J.,
Collins K.A., Coria D.R., Fukui A., Narita N., Sturmer J., Giacalone S.,
Kasper D.
<Astron. J., 170, 182 (2025)>
=2025AJ....170..182P 2025AJ....170..182P
ADC_Keywords: Exoplanets; Radial velocities; Spectra, optical; Stars, dwarfs;
Photometry, ugriz; Stars, dwarfs; Stars, M-type; Stars, diameters;
Effective temperatures
Keywords: Radial velocity ; Transit photometry ; M dwarf stars ;
Exoplanet astronomy ; Exoplanet systems ; Mini Neptunes
Abstract:
We present the Rossiter-McLaughlin measurement of the sub-Neptune
TOI-1759A b with MAROON-X. A joint analysis with MuSCAT3 photometry
and nine additional TESS transits produces a sky-projected obliquity
of |λ|=4°±18°. We also derive a true obliquity of
ψ=24°±12° making this planet consistent with full
alignment albeit to <1σ. With a period of 18.85days and an a/R*
of 40, TOI-1759A b is the longest period single sub-Neptune to have a
measured obliquity. It joins a growing number of smaller planets which
have had this measurement made and, along with K2-25 b, is the only
single, aligned sub-Neptune known to date. We also provide an overview
of the emerging distribution of obliquity measurements for planets
with R<8R⊕. We find that these types of planets tend toward
alignment, especially the sub-Neptunes and super-Earths, implying a
dynamically cool formation history. The majority of misaligned planets
in this category have 4<R≤8R⊕ and are more likely to be
isolated than planets rather than in compact systems. We find this
result to be significant at the 3σ level, consistent with
previous studies. In addition, we conduct injection and recovery
testing on available archival radial velocity data to put limits on
the presence of massive companions in these systems. Current archival
data is insufficient for most systems to have detected a giant planet.
Description:
MAROON-X is a high-resolution spectrograph (λ/Δλ∼85000)
operating in the optical range (500-920nm) and installed on the 8.1m
Gemini North telescope atop Maunakea, Hawaii. We obtained 35 RVs of
TOI-1759A on 2021 August 16 UTC, 20 of which were in-transit. An
exposure time of 600s was chosen, which resulted in a signal-to-noise
ratio per spectral element of 215±11 and 123±9 in the red and
blue arms, respectively.
In order to pin down the mid-transit time we obtained simultaneous
multiband photometric observations of the transit of TOI-1759A b using
MuSCAT3 mounted on the 2m Faulkes Telescope North at Haleakala
Observatory in Hawaii, US. MuSCAT3 has four channels that enable
simultaneous imaging in the g, r, i, and zs bands. The exposure
times were set to 20, 14, 15, and 8s for the g, r, i, and zs bands,
respectively.
Both Martioli+2022 (J/A+A/660/A86) and Espinoza+2022 (J/AJ/163/133) used
three sectors of TESS data, sectors 16 and 17 (2019 September-November),
and 24 (2020 April-May), which included three transit events. Since
then, TESS has reobserved this system for an additional seven sectors,
56, 57, 58 (2022 September-November), 76, 77, 78 (2024 March-May), and
85 (2024 October-November), providing an additional nine transits. We
downloaded the Presearch Data Conditioning (PDC) flux time series from
the Mikulski Archive for Space Telescopes (MAST).
The current inventory of obliquity measurements for planets smaller
than 8R⊕ is limited with a query of the TEPCAT catalog
(Southworth, 2011, 2011MNRAS.417.2166S 2011MNRAS.417.2166S) returning just 36 planets with
such a measurement. additional parameters (Teff, P, a/R*) are queried
from the NASA Exoplanet Archive (as of 2025 February 25). To reduce
the heterogeneity of the sample, we pull parameters from as few
sources as possible.
Objects:
-----------------------------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------------------------
21 47 24.79 +62 45 13.9 TOI-1759b = LSPM J2147+6245b
-----------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablec1.dat 174 36 Properties of systems with measured obliquity
λ (Rp<8Rgeo)
tablee1.dat 181 70 MAROON-X radial velocities for TOI-1759A
--------------------------------------------------------------------------------
See also:
J/A+A/524/A25 : Radial Velocities on 6 exoplanet host stars (Triaud+, 2010)
J/A+A/534/A16 : WASP-22 and WASP-26 photometry and velocities (Anderson+, 2011)
J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)
J/A+A/527/L11 : HAT-P-6 radial velocity curve (Hebrard+, 2011)
J/A+A/546/A27 : Radial velocity and photometry for GJ3470 (Bonfils+, 2012)
J/ApJ/801/3 : Rotation periods for Q3-Q14 KOIs (Mazeh+, 2015)
J/AJ/154/107 : California-Kepler Survey (CKS). I. 1305 stars (Petigura+, 2017)
J/A+A/619/A1 : 55 Cnc radial velocities and photometry (Bourrier+, 2018)
J/AJ/156/147 : RV and activity measurements of Kepler-1656 (Brady+, 2018)
J/A+A/610/A63 : WASP-151b, WASP-153b, WASP-156b (Demangeon+, 2018)
J/AJ/155/89 : California-Kepler Survey (CKS). IV. Planets (Petigura+, 2018)
J/AJ/157/97 : Radial velocity measurements of K2-3 & GJ3470 (Kosiarek+, 2019)
J/AJ/157/145 : HIRES RVs of three compact, multiplanet systems (Mills+, 2019)
J/A+A/642/A31 : pi Men radial velocity curves (Damasso+, 2020)
J/AJ/160/222 : RVs and RI-photometry of HATS-37 and HATS-38 (Jordan+, 2020)
J/AJ/160/192 : Photometry and RVs of K2-25b with HPF (Stefansson+, 2020)
J/MNRAS/491/5248 : Pan-Pacific Planet Search (PPPS). VIII. (Wittenmyer+, 2020)
J/AJ/161/68 : Obliquities of 150 hot Kepler hosting stars (Louden+, 2021)
J/AJ/161/70 : RVs for WASP-107 with HIRES & CORALIE (Piaulet+, 2021)
J/ApJS/255/8 : The California Legacy Surv. I. Planet cat. (Rosenthal+, 2021)
J/AJ/161/119 : The TESS-Keck survey. IV. Rvel for WASP-107 (Rubenzahl+, 2021)
J/AJ/163/160 : Properties of 170 TOI hosts and companions (Behmard+, 2022)
J/A+A/668/A31 : A CHEOPS-enhanced view of the HD3167 system (Bourrier+, 2022)
J/AJ/163/133 : VRI photometry & radial velocity of TOI-1759 (Espinoza+, 2022)
J/AJ/163/247 : HIRES, PEPSI & TRES RVs of V1298 Tau (Johnson+, 2022)
J/AJ/163/101 : TESS-Keck survey. IX. RVs of HD1919139 (Lubin+, 2022)
J/A+A/660/A86 : Detection and characterization of TOI-1759 b (Martioli+, 2022)
J/AJ/164/104 : NEID and HIRES radial velocity of TOI-1478 (Rice+, 2022)
J/ApJ/931/L15 : Obs. of two transits of GJ 3470b with NEID (Stefansson+, 2022)
J/AJ/165/88 : Radial velocity follow up of TOI-561 b (Brinkman+, 2023)
J/AJ/165/33 : HIRES TOI-1136s planets & planet b RVs (Dai+, 2023)
J/ApJ/944/L41 : In-transit sp. and phot. obs. of TOI-2076b (Frazier+, 2023)
J/AJ/167/70 : TESS-Keck Survey. XVII. TOI-1136 RVs (Beard+, 2024)
J/AJ/168/185 : HATS-38b & WASP-139b: LCs & RVs (Espinoza-Retamal+, 2024)
J/A+A/689/A302 : Multiplicity of stars with planets (Gonzalez-Payo+, 2024)
J/A+A/690/A379 : Obliquities of exoplanet host stars (Knudstrup+, 2024)
J/AJ/168/196 : HD 191939 exoplanet system radial velocities (Lubin+, 2024)
J/ApJS/272/32 : TKS. XX. Exoplanet masses & orbit parameters (Polanski+, 2024)
J/AJ/168/116 : NEID RVs of TOI-5126 and TOI-5398 (Radzom+, 2024)
J/A+A/693/A228 : CARMENES input catalogue of M dwarfs. IX. (Cifuentes+, 2025)
J/AJ/170/70 : RV & LCs of 8 gas giant systems (Espinoza-Retamal+, 2025)
J/AJ/169/109 : Radial velocities of TOI-1266 from MAROON-X (Tyler+, 2025)
Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- System System
15- 57 A43 --- Ref References (1)
59 I1 --- nStar [1/3] System stellar multiplicity
61 I1 --- nPl [1/7] System planet multiplicity
63- 68 F6.1 deg lambda [-110/173] Sky-projected obliquity
70- 73 F4.1 deg E_lambda [2.7/50] Upper uncertainty for Lambda
75- 78 F4.1 deg e_lambda [2.6/53] Lower uncertainty for Lambda
80- 84 F5.2 --- lamErr [2.65/49] Mean obliquity error
86- 89 I4 K Teff [2566/6354] Stellar effective temperature
91- 93 I3 K E_Teff [18/120] Upper uncertainty for Teff
95- 97 I3 K e_Teff [18/130] Lower uncertainty for Teff
99- 104 F6.4 Rgeo Rp [0.92/7.4] Planet radius
106- 110 F5.3 Rgeo E_Rp [0.013/0.53] Upper uncertainty for Rp
112- 116 F5.3 Rgeo e_Rp [0.012/0.53] Lower uncertainty for Rp
118- 129 F12.9 d Per [0.73/31.58] Planet orbital period, days
131- 142 F12.9 d E_Per [3.4e-8/10.4]? Upper uncertainty for Per
144- 155 F12.9 d e_Per [3.4e-8/10.4]? Lower uncertainty for Per
157- 162 F6.3 --- a/R* [3.52/69.55] Orbital semi-major axis in units
of stellar radius
164- 168 F5.3 --- E_a/R* [0.01/5.8] Upper uncertainty for a/R*
170- 174 F5.3 --- e_a/R* [0.01/5.8] Lower uncertainty for a/R*
--------------------------------------------------------------------------------
Note (1): References as follows:
Algol2021 = Algol+2021 (2021PSJ.....2....1A 2021PSJ.....2....1A)
BadenasAgusti2020 = BadenasAgusti+2020 (2020AJ....160..113B 2020AJ....160..113B)
Barros2017 = Barros+2017 (2017A&A...608A..25B 2017A&A...608A..25B)
Basilicata2024 = Basilicata+2024 (2024A&A...686A.127B 2024A&A...686A.127B)
Benomar2014 = Benomar+2014 (2014PASJ...66...94B 2014PASJ...66...94B)
Bourrier2018 = Bourrier+2018 (J/A+A/619/A1)
Bourrier2021 = Bourrier+2021 (2021A&A...654A.152B 2021A&A...654A.152B)
Bourrier2022a = Bourrier+2022a (2022A&A...663A.160B 2022A&A...663A.160B)
Bourrier2022b = Bourrier+2022b (J/A+A/668/A31)
Bourrier2023 = Bourrier+2023 (2023A&A...669A..63B 2023A&A...669A..63B)
Brady2018 = Brady+2018 (J/AJ/156/147)
Capistrant2024 = Capistrant+2024 (2024AJ....167...54C 2024AJ....167...54C)
Carleo2021 = Carleo+2021 (2021A&A...645A..71C 2021A&A...645A..71C)
CastroGonzlez2022 = CastroGonzlez+2022 (2022MNRAS.509.1075C 2022MNRAS.509.1075C)
Dai2023 = Dai+2023 (J/AJ/165/33)
Damasso2020 = Damasso+2020 (J/A+A/642/A31)
Demangeon2018 = Demangeon+2018 (J/A+A/610/A63)
Doyle2022 = Doyle+2022 (2022MNRAS.516..298D 2022MNRAS.516..298D)
EspinozaRetamal2024 = EspinozaRetamal+2024 (J/AJ/168/185)
Fairnington2024 = Fairnington+2024 (2024MNRAS.527.8768F 2024MNRAS.527.8768F)
Feinstein2021 = Feinstein+2021 (2021AJ....162..213F 2021AJ....162..213F)
Frazier2023 = Frazier+2023 (J/ApJ/944/L41)
Hellier2019 = Hellier+2019 (2019MNRAS.488.3067H 2019MNRAS.488.3067H)
Hirano2020a = Hirano+2020a (2020ApJ...890L..27H 2020ApJ...890L..27H)
Hirano2020b = Hirano+2020b (2020ApJ...899L..13H 2020ApJ...899L..13H)
Hirano2024 = Hirano+2024 (2024MNRAS.530.3117H 2024MNRAS.530.3117H)
Hjorth2019 = Hjorth+2019 (2019MNRAS.484.3522H 2019MNRAS.484.3522H)
Hjorth2021 = Hjorth+2021 (2021PNAS..11817418H 2021PNAS..11817418H)
Jordan2020 = Jordan+2020 (J/AJ/160/222)
Kosiarek2019 = Kosiarek+2019 (J/AJ/157/97)
Kunovac2021 = Kunovac+2021 (2021MNRAS.502.2893K 2021MNRAS.502.2893K)
LibbyRoberts2023 = LibbyRoberts+2023 (2023AJ....165..249L 2023AJ....165..249L)
Lubin2024 = Lubin+2024 (J/AJ/168/196)
Luque2023 = Luque+2023 (2023Natur.623..932L 2023Natur.623..932L)
Maciejewski2014 = Maciejewski+2014 (2014AcA....64..323M 2014AcA....64..323M)
Mann2016 = Mann+2016 (2016AJ....152...61M 2016AJ....152...61M)
Mann2020 = Mann+2020 (2020AJ....160..179M 2020AJ....160..179M)
Martioli2022 = Martioli+2022 (J/A+A/660/A86)
Mills2019 = Mills+2019 (J/AJ/157/145)
OrellMiqual2023 = OrellMiqual+2023 (2023A&A...669A..40O 2023A&A...669A..40O)
Radzom2024 = Radzom+2024 (J/AJ/168/116)
Rubenzahl2024 = Rubenzahl+2024 (2024ApJ...971L..40R 2024ApJ...971L..40R)
SanchisOjeda2012 = SanchisOjeda+2012 (2012Natur.487..449S 2012Natur.487..449S)
SanchisOjeda2013 = SanchisOjeda+2013 (2013ApJ...775...54S 2013ApJ...775...54S)
SaurezMascareno2022 = SaurezMascareno+2022 (2022NatAs...6..232S 2022NatAs...6..232S)
Stefansson2020 = Stefansson+2020 (J/AJ/160/192)
Stefansson2022 = Stefansson+2022 (J/ApJ/931/L15)
Teng2024 = Teng+2024 (2024AJ....168..194T 2024AJ....168..194T)
Wirth2021 = Wirth+2021 (2021ApJ...917L..34W 2021ApJ...917L..34W)
Wittrock2023 = Wittrock+2023 (2023AJ....166..232W 2023AJ....166..232W)
Yu2018 = Yu+2018 (2018AJ....156..127Y 2018AJ....156..127Y)
Yu2025 = Yu+2025 (2025MNRAS.536.2046Y 2025MNRAS.536.2046Y)
Zak2024 = Zak+2024 (2024A&A...687L...2Z 2024A&A...687L...2Z)
Zhao2023 = Zhao+2023 (2023NatAs...7..198Z 2023NatAs...7..198Z)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablee1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 F15.7 d BJD [2459442/2459444] Barycentric Julian date
17- 21 F5.2 m/s RVel [-2.66/3.76] Radial velocity, in the MAROON-X
arm
23- 26 F4.2 m/s e_RVel [0.86/1.58] Uncertainty in RVel
28- 30 I3 --- SNR [107/232] Peak signal to noise ratio
32- 34 I3 s ExpTime [600] Exposure time
36- 39 F4.2 m/s Drift [0.27/0.32] Radial velocity drift correction
41- 44 F4.2 km/s BERV [9.42/9.76] Barycentric correction from
SERVAL
46- 49 F4.2 km/s fw-BERV [9.42/9.76] Flux-weighted midpoint
barycentric correction
51- 54 F4.2 km/s nom-BERV [9.43/9.76] Geometric midpoint barycentric
correction
56- 61 F6.2 km/s Vref [-61.33] System velocity
63- 66 F4.2 --- AM [1.37/2.04] Airmass of observation
68- 71 F4.1 --- dLW [0.7/11.1] Differential line width
73- 75 F3.1 --- e_dLW [1.3/2.6] Uncertainty in dLW
77- 81 F5.1 --- CRX [-59.5/24.1] Chromatic index
83- 86 F4.1 --- e_CRX [8.0/45.5] Uncertainty in CRX
88- 94 F7.5 --- IRT1 [0.56/0.58]? Ca II infrared triplet indicator
at 849.8nm
96- 102 F7.5 --- e_IRT1 [5.8e-4/7.4e-4]? Uncertainty in IRT1
104- 110 F7.5 --- IRT2 [0.5/0.52]? Ca II infrared triplet indicator
at 854.2nm
112- 118 F7.5 --- e_IRT2 [6.4e-4/8.1e-4]? Uncertainty in IRT2
120- 126 F7.5 --- IRT3 [0.47/0.49]? Ca II infrared triplet indicator
at 866.2nm
128- 134 F7.5 --- e_IRT3 [6.2e-4/7.9e-4]? Uncertainty in IRT3
136- 141 F6.4 --- Halpha [0.43/0.46]? Hydrogen alpha indicator at
656.4nm
143- 148 F6.4 --- e_Halpha [1.6e-3/2.1e-3]? Uncertaiunty in Halpha
150- 155 F6.4 --- NaD1 [0.182/0.191]? Na D indicator at 589.0nm
157- 162 F6.4 --- e_NaD1 [8e-4/1.9e-3]? Uncertainty in NaD1
164- 169 F6.4 --- NaD2 [0.2/0.22]? Na D indicator at 589.6nm
171- 176 F6.4 --- e_NaD2 [9e-4/1.9e-3]? Uncertainty in NaD2
178- 181 A4 --- Arm Arm of MAROON-X (1)
--------------------------------------------------------------------------------
Note (1): Arm as follows:
blue = 491-670nm; 35 occurrences
red = 649-920nm; 35 occurrences
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Robin Leichtnam [CDS] 06-Jul-2026