J/AJ/168/185 HATS-38b & WASP-139b: LCs & RVs (Espinoza-Retamal+, 2024)
HATS-38 b and WASP-139 b join a growing group of hot Neptunes on polar orbits.
Espinoza-Retamal J.I., Stefansson G., Petrovich C., Brahm R., Jordan A.,
Sedaghati E., Lucero J.P., Tala Pinto M., Munoz D.J., Boyle G., Leiva R.,
Suc V.
<Astron. J., 168, 185 (2024)>
=2024AJ....168..185E 2024AJ....168..185E
ADC_Keywords: Exoplanets; Spectra, optical; Photometry; Radial velocities
Keywords: Exoplanets ; Hot Neptunes ; Exoplanet dynamics ; Planetary alignment
Abstract:
We constrain the sky-projected obliquities of two low-density hot
Neptune planets, HATS-38 b and WASP-139 b, orbiting nearby G and K
stars using Rossiter-McLaughlin (RM) observations with VLT/ESPRESSO,
yielding λ=-108-16+11deg and -85.6-4.2+7.7deg,
respectively. To model the RM effect, we use a new publicly available
code, ironman, which is capable of jointly fitting transit photometry,
Keplerian radial velocities, and RM effects. WASP-139 b has a residual
eccentricity e=0.103-0.041+0.050 while HATS-38 b has an
eccentricity of e=0.112-0.070+0.072, which is compatible with a
circular orbit given our data. Using the obliquity constraints, we
show that they join a growing group of hot and low-density Neptunes on
polar orbits. We use long-term radial velocities to rule out
companions with masses ∼0.3-50MJ within ∼10AU. We show that the
orbital architectures of the two Neptunes can be explained with
high-eccentricity migration from ≥2AU driven by an unseen distant
companion. If HATS-38 b has no residual eccentricity, its polar and
circular orbit can also be consistent with a primordial misalignment.
Finally, we perform a hierarchical Bayesian modeling of the true
obliquity distribution of Neptunes and find suggestive evidence for a
higher preponderance of polar orbits for hot Neptunes compared to
Jupiters. However, we note that the exact distribution is sensitive to
the choice of priors, highlighting the need for additional obliquity
measurements of Neptunes to robustly compare the hot Neptune obliquity
distribution to that of Jupiters.
Description:
Old observations of HATS-38 were taken from Jordan+ (2020, J/AJ/160/222)
and of WASP-139 from Hellier+ (2017, J/MNRAS/465/3693). See Section 2.
We observed a single transit of each planet, HATS-38 b and WASP-139 b,
with the ESPRESSO spectrograph at ESO's Paranal Observatory in Chile.
It covers a wavelength range of 380 to 788nm at a resolving power of
R∼140,000 in single Unit Telescope (UT) high-resolution mode.
The transit of HATS-38 b was observed on the night of 2023 April 18,
between 01:25 and 06:01 UTC. We obtained 26 spectra of the host star
during the primary transit with UT1 at an exposure time of 610s.
The transit of WASP-139 b was observed on the night of 2023 August 8,
between 05:35 and 10:04 UTC. We obtained 22 spectra of the host star
during the primary transit with UT3. We started observations with an
exposure time of 900s, and then changed it to 600s when observing
conditions improved. See Section 2.1.
HATS-38 and WASP-139 were both observed with the high-resolution
(R∼120,000) HARPS spectrograph mounted on the 3.6m telescope installed
at the ESO La Silla Observatory. Archival observations were available
through the ESO archive and we obtained two additional spectra for
each system. These new observations were performed in 2023 November
and December. For HATS-38 we used an exposure time of 1500s while for
WASP-139 we adopted an exposure time of 1800s. See Section 2.2.
Simultaneously with the ESPRESSO observations, we observed the transit
of HATS-38 b using the station of Observatoire Moana located in El
Sauce (ES) Observatory in Chile. We used a Sloan r' filter, and the
exposure time was set to 74s. See Section 2.3.
We also used all the available TESS light curves of both targets.
HATS-38 was observed in Sector 9 (Year 1, 2019) at a cadence of 30min,
in Sectors 35 and 36 (Year 3) at a cadence of 10min, and in Sector 62
(Year 5, 2023) at a cadence of 2min. WASP-139 was observed by TESS in
Sectors 3 and 4 (Year 1) and 31 and 32 (Year 3) at a cadence of 2min.
See Section 2.4.
Objects:
------------------------------------------------------------------
RA (2000) DE Designation(s) (Period)
------------------------------------------------------------------
10 17 05.07 -25 16 34.5 HATS-38 b = HATS-38b (P=4.37504)
03 18 14.94 -41 18 07.6 WASP-139 b = TOI-265b (P=5.9242705)
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File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
fig1lc.dat 43 2176 Light curves of HATS-38 (Data behind figure 1)
fig1rv.dat 43 65 Radial velocities of HATS-38 (Data behind figure 1)
fig2lc.dat 47 3990 Light curves of WASP-139 (Data behind figure 2)
fig2rv.dat 46 64 Radial velocities of WASP-139 (Data behind figure 2)
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See also:
VI/151 : Search for radio emission from giant exoplanets (Griessmeier, 2016)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
J/ApJ/757/18 : RVs for 16 hot Jupiter host stars (Albrecht+, 2012)
J/ApJS/204/24 : Kepler planetary candidates. III. (Batalha+, 2013)
J/AJ/148/81 : APASS BVgri photometry of RAVE stars. I.Data (Munari+, 2014)
J/MNRAS/465/3693 : 7 WASP-South transiting exoplanets (Hellier+, 2017)
J/AJ/155/255 : RVs and activity measurements of HAT-P-11 (Yee+, 2018)
J/AJ/158/45 : TESS light curve & RVs for HD 1397 (Brahm+, 2019)
J/other/Nat/586.528 : Properties of exoplanet host stars (Winter+, 2020)
J/AJ/160/192 : Photometry and RVs of K2-25b with HPF (Stefansson+, 2020)
J/AJ/160/222 : RVs and RI-photometry of HATS-37 and HATS-38 (Jordan+, 2020)
J/A+A/646/A77 : Chromospheric activity: AMBRE-HARPS (Gomes da Silva+, 2021)
J/AJ/161/70 : RVs for WASP-107 with HIRES & CORALIE (Piaulet+, 2021)
J/AJ/161/119 : The TESS-Keck survey. IV. RV for WASP-107 (Rubenzahl+, 2021)
J/AJ/164/15 : Exoplanets considered as Ariel's targets (Edwards+, 2022)
J/ApJ/921/24 : Planetary masses and radii (Schlaufman+, 2021)
J/ApJS/259/62 : TESS transit timing of hot Jupiters (Ivshina+, 2022)
J/ApJ/931/L15 : Obs. of 2 transits of GJ 3470b with NEID (Stefansson+, 2022)
J/AJ/168/116 : NEID RVs of TOI-5126 and TOI-5398 (Radzom+, 2024)
J/ApJS/270/14 : Transit times of hot Jupiters from TESS (Wang+, 2024)
http://heasarc.gsfc.nasa.gov/docs/tess/ : NASA TESS Science Support Center
Byte-by-byte Description of file: fig1lc.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD [2457790/2460500] Barycentric Julian Date
16- 25 F10.5 --- Flux [0.97/1.02] Relative flux
27- 34 F8.5 --- e_Flux [3e-4/3e-3] Uncertainty in flux
36- 43 A8 --- Inst Instrument used (1)
--------------------------------------------------------------------------------
Note (1): Instrument used as follows:
CHAT = the Chilean-Hungarian Automated Telescope 0.7m telescope at
Las Campanas Observatory, Chile; Jordan+ 2020, J/AJ/160/222
(146 occurrences)
LCO/CTIO = 1m telescopes from the Las Cumbres Observatory (LCO) network,
Cerro Tololo Inter-American Observatory in Chile;
Jordan+ 2020, J/AJ/160/222 (118 occurrences)
LCO/SAAO = 1m telescopes from the Las Cumbres Observatory (LCO) network,
South African Astronomical Observatory at Sutherland, South Africa;
Jordan+ 2020, J/AJ/160/222 (83 occurrences)
MOANA/ES = Observatoire Moana located in El Sauce (ES) Observatory in Chile;
this work (233 occurrences)
TESS-Y1 = TESS Year 1 (2019; all sectors combined); this work (45 occurrences)
TESS-Y2 = TESS Year 3 (2021; all sectors combined); this work
(418 occurrences)
TESS-Y3 = TESS Year 5 (2023; all sectors combined); this work
(1133 occurrences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig1rv.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD [2457708/2460300] Barycentric Julian Date
16- 25 F10.5 m/s RVel [-2.2e1/4.2e3] Radial velocity
27- 34 F8.5 m/s e_RVel [1.41/15] Uncertainty in radial velocity
36- 43 A8 --- Inst Instrument used (1)
--------------------------------------------------------------------------------
Note (1): Instrument as follows:
ESPRESSO = ESPRESSO spectrograph installed at the incoherent combined Coude
focus of ESO's Paranal Observatory in Chile;
this work (26 occurrences)
HARPS = HARPS spectrograph mounted on the 3.6m telescope installed at
the ESO La Silla Observatory; Jordan+ 2020, J/AJ/160/222 except
two extra HARPS measurements, see Section 2.2. (24 occurrences)
FEROS = the Fiber-fed Extended Range Optical Spectrograph on the ESO/MPG
2.2m telescope, La Silla; Jordan+ 2020, J/AJ/160/222
(10 occurrences)
PFS = the "Planet Finding Spectrometer" on the Magellan 6.5m;
Jordan+ 2020, J/AJ/160/222 (5 occurrences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig2lc.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD [2456876/2459170] Barycentric Julian Date
16- 27 F12.5 --- Flux [0.97/1.01] Relative flux
29- 36 F8.5 --- e_Flux [7.2e-4/3.3e-3] Uncertainty in relative flux
38- 47 A10 --- Inst Instrument used (1)
--------------------------------------------------------------------------------
Note (1): Instrument as follows:
TESS-Y1 = TESS Year 1 (2019; all sectors combined); this work
(1314 occurrences)
TESS-Y3 = TESS Year 3 (2021; all sectors combined); this work
(1362 occurrences)
TRAPPIST-1 = the robotic 0.6-m TRAPPIST photometer on 2014-Aug-6;
Hellier+ 2017, J/MNRAS/465/3693 (498 occurrences)
TRAPPIST-2 = the robotic 0.6-m TRAPPIST photometer on 2015-Sep-7;
Hellier+ 2017, J/MNRAS/465/3693 (624 occurrences)
EULER = EulerCAM; Hellier+ 2017, J/MNRAS/465/3693 (192 occurrences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig2rv.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD [2454750/2460281] Barycentric Julian Date
16- 27 F12.5 m/s RVel [-1.31e4/-1.29e4] Radial velocity
29- 34 F6.3 m/s e_RVel [1.55/41.3] Uncertainty in radial velocity
38- 46 A9 --- Inst Instrument used (1)
--------------------------------------------------------------------------------
Note (1): Instrument as follows:
ESPRESSO = ESPRESSO spectrograph installed at the incoherent combined Coude
focus of ESO's Paranal Observatory in Chile;
this work (18 occurrences)
HARPS = HARPS spectrograph mounted on the 3.6m telescope installed at
the ESO La Silla Observatory; Hellier+ 2017, J/MNRAS/465/3693
except two extra HARPS measurements, see Section 2.2
(23 occurrences)
CORALIE-1 = the 1.2-m Euler/CORALIE spectrograph pre-update data;
Hellier+ 2017, J/MNRAS/465/3693 (16 occurrences)
CORALIE-2 = CORALIE post-update data; Hellier+ 2017, J/MNRAS/465/3693
(7 occurrences)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 04-Jun-2025