J/AJ/168/196 HD 191939 exoplanet system radial velocities (Lubin+, 2024)
The HD 191939 exoplanet system is well aligned and flat.
Lubin J., Petigura E.A., Van Zandt J., Beard C., Dai F., Halverson S.,
Holcomb R., Howard A.W., Isaacson H., Luhn J., Robertson P.,
Rubenzahl R.A., Stefansson G., Winn J.N., Brodheim M., Deich W.,
Hill G.M., Gibson S.R., Holden B., Householder A., Laher R.R., Lanclos K.,
Payne J., Roy A., Smith R., Shaum A.P., Schwab C., Walawender J.
<Astron. J., 168, 196 (2024)>
=2024AJ....168..196L 2024AJ....168..196L
ADC_Keywords: Exoplanets; Radial velocities; Spectra, optical
Keywords: Exoplanet dynamics ; Exoplanet astronomy
Abstract:
We report the sky-projected spin-orbit angle λ for HD 191939 b,
the innermost planet in a six-planet system, using Keck/KPF to detect
the Rossiter-McLaughlin (RM) effect. Planet b is a sub-Neptune with
radius 3.4±0.8R⊕ and mass 10.0±0.7M⊕ with an RM
amplitude <1m/s. We find the planet is consistent with a well-aligned
orbit, measuring λ=3.7±5.0°. Additionally, we place new
constraints on the mass and period of the distant super-Jupiter,
planet f, finding it to be 2.88±0.26MJ on a 2898±152days orbit.
With these new orbital parameters, we perform a dynamical analysis of
the system and constrain the mutual inclination of the nontransiting
planet e to be smaller than 12° relative to the plane shared by
the inner three transiting planets. Additionally, the further planet f
is inclined off this shared plane, the greater the amplitude of
precession for the entire inner system, making it increasingly
unlikely to measure an aligned orbit for planet b. Through this
analysis, we show that this system's wide variety of planets are all
well-aligned with the star and nearly coplanar, suggesting that the
system formed dynamically cold and flat out of a well-aligned
protoplanetary disk, similar to our own solar system.
Description:
We observed HD 191939 with the Keck Planet Finder (KPF) instrument at
Keck Observatory on UT 2023 July 28. The main spectrometer has a
spectral bandpass of 445-870nm at a resolving power of R∼98,000. A
dedicated Calcium H&K spectrograph covers the 382-402nm range at
R∼17,000.
We used an exposure time of 444s. We obtained a total of 50 spectra
over an ∼8hr span of observations from UT06:58 to 14:55. Of these,
17 spectra were obtained within the 3hr transit window between 09:48UT
and 12:43UT. Before ingress, we obtained 16 spectra and after egress
we obtained another 17 spectra. Using the updated ephemeris
information from Orell-Miquel+ (2023A&A...669A..40O 2023A&A...669A..40O) and the Transit and
Ephemeris Service tool from the NASA Exoplanet Archive, we predicted
the transit midpoint to be at UT2023-07-28:11:15=BJD2460153.96875.
Since the publication of Lubin+ in 2022 (J/AJ/163/101), who reported
73 HIRES RVs and 104 APF RVs, many more RVs have been taken with
multiple instruments. First, Orell-Miquel+ (2023A&A...669A..40O 2023A&A...669A..40O) add
42 HARPS-N RVs as well as 138 CARMENES RVs. Recently,
Polanski+ (2024, J/ApJS/272/32) published an additional 37 HIRES RVs
and an additional 150 APF RVs as part of the full data release of the
TESS-Keck Survey (Chontos+, 2022AJ....163..297C 2022AJ....163..297C). Additionally, there
are two HIRES RVs taken in 2023 May and one in 2024 June that were
unpublished until this work.
With so many more additional data, we now have a total of 544 RVs
spanning a total baseline of 1301days.
Objects:
---------------------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------------------
20 08 05.75 +66 51 02.0 HD 191939 = TOI-1339
---------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 47 545 Observations
--------------------------------------------------------------------------------
See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/other/Nat/486.375 : Stellar parameters of KOI stars (Buchhave+, 2012)
J/AJ/154/109 : CKS. III. Planet radii (Fulton+, 2017)
J/AJ/155/48 : (CKS). V. Masses and radii (Weiss+, 2018)
J/AJ/155/177 : Obliquities: planetary & eclipsing binary syst. (Dai+, 2018)
J/AJ/160/192 : Photometry and RVs of K2-25b with HPF (Stefansson+, 2020)
J/AJ/161/68 : Obliquities: 150 hot Kepler hosting stars (Louden+, 2021)
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/ApJ/931/L15 : 2 transits obs. of GJ 3470b with NEID (Stefansson+, 2022)
J/ApJ/944/L41 : In-transit sp. & phot. obs. of TOI-2076b (Frazier+, 2023)
J/ApJS/272/32 : TKS. XX. Exoplanet masses & orbit param. (Polanski+, 2024)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 d BJD Barycentric Julian Date
15- 22 F8.2 m/s RVel [-9247/57] Radial velocity from Inst (RV)
24- 28 F5.2 m/s e_RVel [0.5/13.1] Uncertainty in RVel (eRV)
30- 37 A8 --- Inst Instrument used (Instrument) (1)
39- 47 A9 --- Ref Reference (Source) (2)
--------------------------------------------------------------------------------
Note (1): Observations as follows:
APF = the Automated Planet Finder at Lick Observatory (254 occurrences)
CARMENES = the Calar Alto high-Resolution search for M dwarfs with
Exoearths with Near-infrared and optical Echelle Spectrographs
at the Centro Astronomico Hispano-Aleman (CAHA) at
Calar Alto (Almeria, Spain; 138 occurrences)
HARPS-N = the High Accuracy Radial velocity Planet Searcher for the Northern
hemisphere mounted on the 3.6m Telescopio Nazionale Galileo (TNG)
in Roque de los Muchachos Observatory, La Palma (42 occurrences)
HIRES = the High Resolution Echelle Spectrometer on Keck (111 occurrences)
Note (2): Flag as follows:
A = Orell-Miquel et al. 2023A&A...669A..40O 2023A&A...669A..40O
B = Lubin et al. 2022, J/AJ/163/101
C = Polanski et al. 2024, J/ApJS/272/32
This work = These three are the only RVs used in this study that
have not been previously published.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 11-Jun-2025