Abstract
A star’s obliquity with respect to its planetary system can provide us with insight into the system’s formation and evolution, as well as hinting at the presence of additional objects in the ...system. However, M dwarfs, which are the most promising targets for atmospheric follow-up, are underrepresented in terms of obliquity characterization surveys due to the challenges associated with making precise measurements. In this paper, we use the extreme-precision radial velocity (RV) spectrograph MAROON-X to measure the obliquity of the late M dwarf TRAPPIST-1. With the Rossiter–McLaughlin effect, we measure a system obliquity of
−
2
°
−
19
◦
+
17
◦
and a stellar rotational velocity of 2.1 ± 0.3 km s
−1
. We were unable to detect stellar surface differential rotation, and we found that a model in which all planets share the same obliquity was favored by our data. We were also unable to make a detection of the signatures of the planets using Doppler tomography, which is likely a result of the both the slow rotation of the star and the low signal-to-noise ratio of the data. Overall, TRAPPIST-1 appears to have a low obliquity, which could imply that the system has a low primordial obliquity. It also appears to be a slow rotator, which is consistent with past characterizations of the system and estimates of the star’s rotation period. The MAROON-X data allow for a precise measurement of the stellar obliquity through the Rossiter–McLaughlin effect, highlighting the capabilities of MAROON-X and its ability to make high-precision RV measurements around late, dim stars.
Abstract TOI-561 is a galactic thick-disk star hosting an ultra-short-period (0.45-day-orbit) planet with a radius of 1.37 R ⊕ , making it one of the most metal-poor (Fe/H = −0.41) and oldest (≈10 ...Gyr) sites where an Earth-sized planet has been found. We present new simultaneous radial velocity (RV) measurements from Gemini-N/MAROON-X and Keck/HIRES, which we combined with literature RVs to derive a mass of M b = 2.24 ± 0.20 M ⊕ . We also used two new sectors of TESS photometry to improve the radius determination, finding R b = 1.37 ± 0.04 R ⊕ and confirming that TOI-561 b is one of the lowest-density super-Earths measured to date ( ρ b = 4.8 ± 0.5 g cm −3 ). This density is consistent with an iron-poor rocky composition reflective of the host star’s iron and rock-building element abundances; however, it is also consistent with a low-density planet with a volatile envelope. The equilibrium temperature of the planet (∼2300 K) suggests that this envelope would likely be composed of high mean molecular weight species, such as water vapor, carbon dioxide, or silicate vapor, and is likely not primordial. We also demonstrate that the composition determination is sensitive to the choice of stellar parameters and that further measurements are needed to determine whether TOI-561 b is a bare rocky planet, a rocky planet with an optically thin atmosphere, or a rare example of a nonprimordial envelope on a planet with a radius smaller than 1.5 R ⊕ .
Abstract The early K-type T-Tauri star, V1298 Tau ( V = 10 mag, age ≈ 20–30 Myr) hosts four transiting planets with radii ranging from 4.9 to 9.6 R ⊕ . The three inner planets have orbital periods of ...≈8–24 days while the outer planet’s period is poorly constrained by single transits observed with K2 and the Transiting Exoplanet Survey Satellite (TESS). Planets b, c, and d are proto–sub-Neptunes that may be undergoing significant mass loss. Depending on the stellar activity and planet masses, they are expected to evolve into super-Earths/sub-Neptunes that bound the radius valley. Here we present results of a joint transit and radial velocity (RV) modeling analysis, which includes recently obtained TESS photometry and MAROON-X RV measurements. Assuming circular orbits, we obtain a low-significance (≈2 σ ) RV detection of planet c, implying a mass of 19.8 − 8.9 + 9.3 M ⊕ and a conservative 2 σ upper limit of <39 M ⊕ . For planets b and d, we derive 2 σ upper limits of M b < 159 M ⊕ and M d < 41 M ⊕ , respectively. For planet e, plausible discrete periods of P e > 55.4 days are ruled out at the 3 σ level while seven solutions with 43.3 < P e / d < 55.4 are consistent with the most probable 46.768131 ± 000076 days solution within 3 σ . Adopting the most probable solution yields a 2.6 σ RV detection with a mass of 0.66 ± 0.26 M Jup . Comparing the updated mass and radius constraints with planetary evolution and interior structure models shows that planets b, d, and e are consistent with predictions for young gas-rich planets and that planet c is consistent with having a water-rich core with a substantial (∼5% by mass) H 2 envelope.
Abstract M-dwarf stars provide us with an ideal opportunity to study nearby small planets. The HUnting for M Dwarf Rocky planets Using MAROON-X (HUMDRUM) survey uses the MAROON-X spectrograph, which ...is ideally suited to studying these stars, to measure precise masses of a volume-limited (<30 pc) sample of transiting M-dwarf planets. TOI-1450 is a nearby (22.5 pc) binary system containing a M3 dwarf with a roughly 3000 K companion. Its primary star, TOI-1450A, was identified by the Transiting Exoplanet Survey Satellite (TESS) to have a 2.04 days transit signal, and is included in the HUMDRUM sample. In this paper, we present MAROON-X radial velocities (RVs) which confirm the planetary nature of this signal and measure its mass at nearly 10% precision. The 2.04 days planet, TOI-1450A b, has R b = 1.13 ± 0.04 R ⊕ and M b = 1.26 ± 0.13 M ⊕ . It is the second-lowest-mass transiting planet with a high-precision RV mass measurement. With this mass and radius, the planet’s mean density is compatible with an Earth-like composition. Given its short orbital period and slightly sub-Earth density, it may be amenable to JWST follow-up to test whether the planet has retained an atmosphere despite extreme heating from the nearby star. We also discover a nontransiting planet in the system with a period of 5.07 days and a M sin i c = 1.53 ± 0.18 M ⊕ . We also find a 2.01 days signal present in the systems’s TESS photometry that likely corresponds to the rotation period of TOI-1450A’s binary companion, TOI-1450B. TOI-1450A, meanwhile, appears to have a rotation period of approximately 40 days, which is in line with our expectations for a mid-M dwarf.
Abstract
Wolf 359 (CN Leo, GJ 406, Gaia DR3 3864972938605115520) is a low-mass star in the fifth-closest neighboring system (2.41 pc). Because of its relative youth and proximity, Wolf 359 offers a ...unique opportunity to study substellar companions around M stars using infrared high-contrast imaging and radial velocity monitoring. We present the results of
Ms
-band (4.67
μ
m) vector vortex coronagraphic imaging using Keck-NIRC2 and add 12 Keck-HIRES and 68 MAROON-X velocities to the radial velocity baseline. Our analysis incorporates these data alongside literature radial velocities from CARMENES, the High Accuracy Radial velocity Planet Searcher, and Keck-HIRES to rule out the existence of a close (
a
< 10 au) stellar or brown dwarf companion and the majority of large gas giant companions. Our survey does not refute or confirm the long-period radial velocity candidate, Wolf 359 b (
P
∼ 2900 days), but rules out the candidate's existence as a large gas giant (>4
M
Jup
) assuming an age of younger than 1 Gyr. We discuss the performance of our high-contrast imaging survey to aid future observers using Keck-NIRC2 in conjunction with the vortex coronagraph in the
Ms
band and conclude by exploring the direct imaging capabilities with JWST to observe Jupiter- and Neptune-mass planets around Wolf 359.
The abundance of refractory elements in giant planets can provide key insights into their formation histories
. Owing to the low temperatures of the Solar System giants, refractory elements condense ...below the cloud deck, limiting sensing capabilities to only highly volatile elements
. Recently, ultra-hot giant exoplanets have allowed for some refractory elements to be measured, showing abundances broadly consistent with the solar nebula with titanium probably condensed out of the photosphere
. Here we report precise abundance constraints of 14 major refractory elements on the ultra-hot giant planet WASP-76b that show distinct deviations from proto-solar and a sharp onset in condensation temperature. In particular, we find nickel to be enriched, a possible sign of the accretion of the core of a differentiated object during the evolution of the planet. Elements with condensation temperatures below 1,550 K otherwise closely match those of the Sun
before sharply transitioning to being strongly depleted above 1,550 K, which is well explained by nightside cold-trapping. We further unambiguously detect vanadium oxide on WASP-76b, a molecule long suggested to drive atmospheric thermal inversions
, and also observe a global east-west asymmetry
in its absorption signals. Overall, our findings indicate that giant planets have a mostly stellar-like refractory elemental content and suggest that temperature sequences of hot Jupiter spectra can show abrupt transitions wherein a mineral species is either present or completely absent if a cold trap exists below its condensation temperature
.
Abstract
We present dayside thermal emission observations of the hottest exoplanet KELT-9b using the new MAROON-X spectrograph. We detect atomic lines in emission with a signal-to-noise ratio of 10 ...using cross-correlation with binary masks. The detection of emission lines confirms the presence of a thermal inversion in KELT-9b’s atmosphere. We also use M-dwarf stellar masks to search for TiO, which has recently been invoked to explain the unusual Hubble Space Telescope WFC3 spectrum of the planet. We find that the KELT-9b atmosphere is inconsistent with the M-dwarf masks. Furthermore, we use an atmospheric retrieval approach to place an upper limit on the TiO volume mixing ratio of 10
−8.5
(at 99% confidence). This upper limit is inconsistent with the models used to match the WFC3 data, which require at least an order of magnitude more TiO, thus suggesting the need for an alternate explanation of the space-based data. Our retrieval results also strongly prefer an inverted temperature profile and atomic/ion abundances largely consistent with the expectations for a solar composition gas in thermochemical equilibrium. The exception is the retrieved abundance of Fe
+
, which is about 1–2 orders of magnitude greater than predictions. These results highlight the growing power of high-resolution spectrographs on large ground-based telescopes to characterize exoplanet atmospheres when used in combination with new retrieval techniques.
Echelle++, a Fast Generic Spectrum Simulator Stürmer, Julian; Seifahrt, Andreas; Robertson, Zachary ...
Publications of the Astronomical Society of the Pacific,
02/2019, Volume:
131, Issue:
996
Journal Article
Peer reviewed
Open access
We present the software package, Echelle++, an open-source C++ code to simulate realistic raw spectra based on the Zemax model of any spectrograph, with a particular emphasis on cross-dispersed ...Échelle spectrographs. Echelle++ generates realistic spectra of astronomical and calibration sources, with accurate representation of optical aberrations, the shape of the point-spread function, detector characteristics, and photon noise. It produces high-fidelity spectra fast, a very important feature when testing data reduction pipelines with a large set of different input spectra, when making critical choices about order spacing in the design phase of the instrument, or while aligning the spectrograph during construction. Echelle++ also works with low-resolution, low signal-to-noise, multi-object, IFU, or long-slit spectra, for simulating a wide array of spectrographs. We chose to initially generate our own spectrograph model from the optical prescription in Zemax. Echelle++ can then be used independently, without access to commercial ray tracing software.
Echelle++, a Fast Generic Spectrum Simulator Stürmer, Julian; Seifahrt, Andreas; Robertson, Zachary ...
Publications of the Astronomical Society of the Pacific,
02/2019, Volume:
131, Issue:
996
Journal Article
Peer reviewed
We present the software package, Echelle++, an open-source C++ code to simulate realistic raw spectra based on the Zemax model of any spectrograph, with a particular emphasis on cross-dispersed ...Échelle spectrographs. Echelle++ generates realistic spectra of astronomical and calibration sources, with accurate representation of optical aberrations, the shape of the point-spread function, detector characteristics, and photon noise. It produces high-fidelity spectra fast, a very important feature when testing data reduction pipelines with a large set of different input spectra, when making critical choices about order spacing in the design phase of the instrument, or while aligning the spectrograph during construction. Echelle++ also works with low-resolution, low signal-to-noise, multi-object, IFU, or long-slit spectra, for simulating a wide array of spectrographs. We chose to initially generate our own spectrograph model from the optical prescription in Zemax. Echelle++ can then be used independently, without access to commercial ray tracing software.
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