Search

A star's spin-orbit angle can give us insight into a system's formation and dynamical history. In this paper, we use MAROON-X observations of the Rossiter-McLaughlin (RM) effect to measure the projected obliquity of the LP 261-75 (also known as TOI-1779) system, focusing on the fully-convective M dwarf LP 261-75A and the transiting brown dwarf LP 261-75C. This is the first obliquity constraint of a brown dwarf orbiting an M dwarf and the seventh obliquity constraint of a brown dwarf overall. We measure a projected obliquity of $5^{+11}_{-10}$ degrees and a true obliquity of $14^{+8}_{-7}$ degrees for the system, meaning that the system is well-aligned and that the star is rotating very nearly edge-on, with an inclination of $90^o\,\pm\,11^o$. The system thus follows along with the trends observed in transiting brown dwarfs around hotter stars, which typically have low obliquities. The tendency for brown dwarfs to be aligned may point to some enhanced obliquity damping in brown dwarf systems, but there is also a possibility that the LP 261-75 system was simply formed aligned. In addition, we note that the brown dwarf's radius ($R_C\,=\,0.9$ R$_J$) is not consistent with the youth of the system or radius trends observed in other brown dwarfs, indicating that LP 261-75C may have an unusual formation history., Comment: 16, pages, 7 figures. Accepted in AJ

Hundreds of exoplanets between 1-1.8 times the size of the Earth have been discovered on close in orbits. However, these planets show such a diversity in densities that some appear to be made entirely of iron, while others appear to host gaseous envelopes. To test this diversity in composition, we update the masses of 5 rocky exoplanets (HD 93963 A b, Kepler-10 b, Kepler-100 b, Kepler-407 b, and TOI-1444 b) and present the confirmation of a new planet (TOI-1011) using 187 high precision RVs from Gemini/MAROON-X and Keck/KPF. Our updated planet masses suggest compositions closer to that of the Earth than previous literature values for all planets in our sample. In particular, we report that two previously identified ``super-Mercuries'' (Kepler-100 b and HD 93963 A b) have lower masses that suggest less iron-rich compositions. We then compare the ratio of iron to rock-building species to the abundance ratios of those elements in their host stars. These updated planet compositions do not suggest a steep relationship between planet and host star compositions, contradictory to previous results, and suggest that planets and host stars have similar abundance ratios., Comment: Submitted to AJ 09/30/2024

GHOST is a newly operational optical fiber-fed high-resolution spectrograph at the Gemini South 8.1m telescope. It currently offers the choice of two resolution modes captured by one (or two) input IFUs with a FOV of 1.2'' and a spectral resolving power of 56,000 and 76,000 for the unbinned CCDs. At the high-resolution mode, one can also instigate a simultaneous ThXe calibration lamp, which along with a simultaneous pseudo-slit profile constructed from reformatting the input IFU image will allow for precision radial velocity measurements. Here we talk about the proposed roadmap towards full queue operations, potential upgrades, and the error terms contributing to the final on-sky RV precision, which is estimated to be in the 1-10 m s$^{-1}$ range., Comment: Proceedings of SPIE Astronomical Telescopes+Instrumentation, 2024, Yokohama, Japan; 5 pages, 5 figures

The sub-Jovian desert is a region in the mass-period and radius-period parameter space, typically encompassing short-period ranges between super-Earths and hot Jupiters, that exhibits an intrinsic dearth of planets. This scarcity is likely shaped by photoevaporation caused by the stellar irradiation received by giant planets that have migrated inward. We report the detection and characterization of TOI-3568 b, a transiting super-Neptune with a mass of $26.4\pm1.0$ M$_\oplus$, a radius of $5.30\pm0.27$ R$_\oplus$, a bulk density of $0.98\pm0.15$ g cm$^{-3}$, and an orbital period of 4.417965(5) d situated in the vicinity of the sub-Jovian desert. This planet orbiting a K dwarf star with solar metallicity, was identified photometrically by TESS. It was characterized as a planet by our high-precision radial velocity monitoring program using MAROON-X at Gemini North, supplemented by additional observations from the SPICE large program with SPIRou at CFHT. We performed a Bayesian MCMC joint analysis of the TESS and ground-based photometry, MAROON-X and SPIRou radial velocities, to measure the orbit, radius, and mass of the planet, as well as a detailed analysis of the high-resolution flux and polarimetric spectra to determine the physical parameters and elemental abundances of the host star. Our results reveal TOI-3568 b as a hot super-Neptune, rich in hydrogen and helium with a core of heavier elements with a mass between 10 and 25 M$_\oplus$. We analyzed the photoevaporation status of TOI-3568 b and found that it experiences one of the highest EUV luminosities among planets with a mass M$_{\rm p}$ $<2$ M$_{\rm Nep}$, yet it has an evaporation lifetime exceeding 5 Gyr. Positioned in the transition between two significant populations of exoplanets on the mass-period and energy diagrams, this planet presents an opportunity to test theories concerning the origin of the sub-Jovian desert., Comment: Accepted for publication in A&A on September 4, 2024

Transiting giant exoplanets around M-dwarf stars (GEMS) are rare, owing to the low-mass host stars. However, the all-sky coverage of TESS has enabled the detection of an increasingly large number of them to enable statistical surveys like the \textit{Searching for GEMS} survey. As part of this endeavour, we describe the observations of six transiting giant planets, which includes precise mass measurements for two GEMS (K2-419Ab, TOI-6034b) and statistical validation for four systems, which includes validation and mass upper limits for three of them (TOI-5218b, TOI-5616b, TOI-5634Ab), while the fourth one -- TOI-5414b is classified as a `likely planet'. Our observations include radial velocities from the Habitable-zone Planet Finder on the Hobby-Eberly Telescope, and MAROON-X on Gemini-North, along with photometry and high-contrast imaging from multiple ground-based facilities. In addition to TESS photometry, K2-419Ab was also observed and statistically validated as part of the K2 mission in Campaigns 5 and 18, which provides precise orbital and planetary constraints despite the faint host star and long orbital period of $\sim 20.4$ days. With an equilibrium temperature of only 380 K, K2-419Ab is one of the coolest known well-characterized transiting planets. TOI-6034 has a late F-type companion about 40\arcsec~away, making it the first GEMS host star to have an earlier main-sequence binary companion. These confirmations add to the existing small sample of confirmed transiting GEMS., Comment: Accepted in AJ

Measuring the obliquities of stars hosting giant planets may shed light on the dynamical history of planetary systems. Significant efforts have been made to measure the obliquities of FGK stars with hot Jupiters, mainly based on observations of the Rossiter-McLaughlin effect. In contrast, M dwarfs with hot Jupiters have hardly been explored, because such systems are rare and often not favorable for such precise observations. Here, we report the first detection of the Rossiter-McLaughlin effect for an M dwarf with a hot Jupiter, TOI-4201, using the Gemini-North/MAROON-X spectrograph. We find TOI-4201 to be well-aligned with its giant planet, with a sky-projected obliquity of $\lambda=-3.0_{-3.2}^{+3.7}\ ^{\circ}$ and a true obliquity of $\psi=21.3_{-12.8}^{+12.5}\ ^{\circ}$ with an upper limit of $40^{\circ}$ at a 95% confidence level. The result agrees with dynamically quiet formation or tidal obliquity damping that realigned the system. As the first hot Jupiter around an M dwarf with its obliquity measured, TOI-4201b joins the group of aligned giant planets around cool stars ($T_{\rm eff}<6250\ K$), as well as the small but growing sample of planets with relatively high planet-to-star mass ratio ($M_p/M_\ast\gtrsim 3\times 10^{-3}$) that also appear to be mostly aligned., Comment: 12 pages, 5 figures, 3 tables, accepted to ApJL

We present an updated characterization of the TOI-1685 planetary system, which consists of a P$_{\rm{b}}$ = 0.69\,day USP super-Earth planet orbiting a nearby ($d$ = 37.6\,pc) M2.5V star (TIC 28900646, 2MASS J04342248+4302148). This planet was previously featured in two contemporaneous discovery papers, but the best-fit planet mass, radius, and bulk density values were discrepant allowing it to be interpreted either as a hot, bare rock or a 50\% H$_{2}$O / 50\% MgSiO$_{3}$ water world. TOI-1685 b will be observed in three independent JWST cycle two programs, two of which assume the planet is a water world while the third assumes that it is a hot rocky planet. Here we include a refined stellar classification with a focus on addressing the host star's metallicity, an updated planet radius measurement that includes two sectors of TESS data and multi-color photometry from a variety of ground-based facilities, and a more accurate dynamical mass measurement from a combined CARMENES, IRD, and MAROON-X radial velocity data set. We find that the star is very metal-rich ([Fe/H] $\simeq$ +0.3) and that the planet is systematically smaller, lower mass, and higher density than initially reported, with new best-fit parameters of \Rpl = 1.468 $^{+0.050}_{-0.051}$ \Rearth\ and \Mpl = 3.03$^{+0.33}_{-0.32}$ \Mearth. These results fall in between the previously derived values and suggest that TOI-1685 b is a hot, rocky, planet with an Earth-like density (\Rhopl = 5.3 $\pm$ 0.8 g cm$^{-3}$, or 0.96 \rhoearth), high equilibrium temperature (T$_{\rm{eq}}$ = 1062 $\pm$ 27 K) and negligible volatiles, rather than a water world., Comment: 20 pages, 9 Figures, accepted for publication in ApJL. Datasets and software available via Zenodo and GitHub links found in the paper

M dwarf stars provide us with an ideal opportunity to study nearby small planets. The HUMDRUM (HUnting for M Dwarf Rocky planets Using MAROON-X) 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 $TESS$ to have a 2.04d transit signal, and is included in the HUMDRUM sample. In this paper, we present MAROON-X radial velocities which confirm the planetary nature of this signal and measure its mass at a nearly 10% precision. The 2.04d planet, TOI-1450Ab, has $R_b\,=\,1.13\,\pm\,0.04\,R_\oplus$ and $M_b\,=\,1.26\,\pm\,0.13\,M_\oplus$. 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 non-transiting planet in the system with a period of 5.07 days and a $M\mathrm{sin}i_c\,=\,1.53\,\pm\,0.18\,M_\oplus$. We also find a 2.01d 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., Comment: 31 pages, 17 figures, accepted in AJ

Exoplanets in the ultra-hot Jupiter regime provide an excellent laboratory for testing the impact of stellar irradiation on the dynamics and chemical composition of gas giant atmospheres. In this study, we observed two transits of the ultra-hot Jupiter WASP-189 b with MAROON-X/Gemini-North to probe its high-altitude atmospheric layers, using strong absorption lines. We derived posterior probability distributions for the planetary and stellar parameters by calculating the stellar spectrum behind the planet at every orbital phase during the transit. This was used to correct the Rossiter-McLaughlin imprint on the transmission spectra. Using differential transmission spectroscopy, we detect strong absorption lines of Ca+, Ba+, Na, H$\alpha$, Mg, Fe, and Fe+, providing an unprecedented and detailed view of the atmospheric chemical composition. Ca+ absorption is particularly well suited for analysis through time-resolved narrow-band spectroscopy, owing to its transition lines formed in high-altitude layers. The spectral absorption lines show no significant blueshifts that would indicate high-altitude day-to-night winds, and further analysis is needed to investigate the implications for atmospheric dynamics. These high signal-to-noise observations provide a benchmark data set for testing high-resolution retrievals and the assumptions of atmospheric models. We also simulate observations of WASP-189 b with ANDES/ELT, and show that ANDES will be highly sensitive to the individual absorption lines of a myriad of elements and molecules, including TiO and CO., Comment: 34 pages, 31 figures, accepted for publication in A&A on 16 February 2024

The two known planets in the planetary system of Teegarden's Star are among the most Earth-like exoplanets currently known. Revisiting this nearby planetary system with two planets in the habitable zone aims at a more complete census of planets around very low-mass stars. A significant number of new radial velocity measurements from CARMENES, ESPRESSO, MAROON-X, and HPF, as well as photometry from TESS motivated a deeper search for additional planets. We confirm and refine the orbital parameters of the two know planets Teegarden's Star b and c. We also report the detection of a third planet d with an orbital period of 26.13+-0.04 d and a minimum mass of 0.82+-0.17 M_Earth. A signal at 96 d is attributed to the stellar rotation period. The interpretation of a signal at 172 d remains open. The TESS data exclude transiting short-period planets down to about half an Earth radius. We compare the planetary system architecture of very low-mass stars. In the currently known configuration, the planetary system of Teegarden's star is dynamically quite different from that of TRAPPIST-1, which is more compact, but dynamically similar to others such as GJ 1002., Comment: Astronomy & Astrophysics, accepted; 21 pages, 18 figures

TOI-732 is an M dwarf hosting two transiting planets, which are located on the two opposite sides of the radius valley. By doubling the number of available space-based observations and increasing the number of radial velocity (RV) measurements, we aim at refining the parameters of TOI-732 b and c. We also aim at using the results to study the slope of both the radius valley and the density valley for a well characterised sample of M dwarf exoplanets. We performed a global MCMC analysis by jointly modelling ground-based light curves, CHEOPS and TESS observations, along with RV time series both taken from the literature and obtained with the MAROON-X spectrograph. The slopes of the M dwarf valleys were quantified via a Support Vector Machine (SVM) procedure. TOI-732 b is an ultra short period planet ($P\sim0.77$ d) with a radius $R_b=1.325_{-0.058}^{+0.057}$ $R_{\oplus}$ and a mass $M_b=2.46\pm0.19$ $M_{\oplus}$ (mean density $\rho_b=5.8_{-0.8}^{+1.0}$ g cm$^{-3}$), while the outer planet at $P\sim12.25$ d has $R_c=2.39_{-0.11}^{+0.10}$ $R_{\oplus}$, $M_c=8.04_{-0.48}^{+0.50}$ $M_{\oplus}$, and thus $\rho_c=3.24_{-0.43}^{+0.55}$ g cm$^{-3}$. Also considering our interior structure calculations TOI-732 b is a super-Earth and TOI-732 c is a mini-Neptune. Following the SVM approach, we quantified $\mathrm{d}\log{R_{p,{\mathrm{valley}}}}/\mathrm{d}\log{P}=-0.065_{-0.013}^{+0.024}$, which is flatter than for Sun-like stars. In line with former analyses, we noted a more filled radius valley for M-planets and we further quantified the density valley slope as $\mathrm{d}\log{\hat{\rho}_{\mathrm{valley}}}/\mathrm{d}\log{P}=-0.02_{-0.04}^{+0.12}$. Compared to FGK stars, the weaker dependence of the position of the radius valley with orbital period might indicate a heavier influence of formation relative to evolution mechanisms in shaping the radius valley around M-dwarfs., Comment: 28 pages (17 in the main text), 18 figures (9 in the main text), 11 tables (7 in the main text). Accepted for publication in A&A

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 $\mu$m) vector vortex coronagraphic imaging using Keck-NIRC2 and add 12 Keck-HIRES velocities and 68 MAROON-X velocities to the radial velocity baseline. Our analysis incorporates these data alongside literature radial velocities from CARMENES, HARPS, 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 ($P\sim2900$ d) 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-mass and Neptune-mass planets around Wolf 359.

Close-in lava planets represent an extreme example of terrestrial worlds, but their high temperatures may allow us to probe a diversity of crustal compositions. The brightest and most well-studied of these objects is 55 Cancri e, a nearby super-Earth with a remarkably short 17-hour orbit. However, despite numerous studies, debate remains about the existence and composition of its atmosphere. We present upper limits on the atmospheric pressure of 55 Cnc e derived from high-resolution time-series spectra taken with Gemini-N/MAROON-X. Our results are consistent with current crustal evaporation models for this planet which predict a thin $\sim$ 100 mbar atmosphere. We conclude that, if a mineral atmosphere is present on 55 Cnc e, the atmospheric pressure is below 100 mbar., Comment: Accepted to the AJ. 7 pages, 5 figures

Ultra-hot Jupiters are tidally locked with their host stars dividing their atmospheres into a hot dayside and a colder nightside. As the planet moves through transit, different regions of the atmosphere rotate into view revealing different chemical regimes. High-resolution spectrographs can observe asymmetries and velocity shifts, and offer the possibility for time-resolved spectroscopy. In this study, we search for other atoms and molecules in the planet`s transmission spectrum and investigate asymmetric signals. We analyse and combine eight transits of the ultra-hot Jupiter WASP-189 b taken with the HARPS, HARPS-N, ESPRESSO and MAROON-X high-resolution spectrographs. Using the cross-correlation technique, we search for neutral and ionised atoms, and oxides and compare the obtained signals to model predictions. We report significant detections for H, Na, Mg, Ca, Ca+, Ti, Ti+, TiO, V, Cr, Mn, Fe, Fe+, Ni, Sr, Sr+, and Ba+. Of these, Sr, Sr+, and Ba+ are detected for the first time in the transmission spectrum of WASP-189 b. In addition, we robustly confirm the detection of titanium oxide based on observations with HARPS and HARPS-N using the follow-up observations performed with MAROON-X and ESPRESSO. By fitting the orbital traces of the detected species by means of time-resolved spectroscopy using a Bayesian framework, we infer posterior distributions for orbital parameters as well as lineshapes. Our results indicate that different species must originate from different regions of the atmosphere to be able to explain the observed time dependence of the signals. Throughout the course of the transit, most signal strengths are expected to increase due to the larger atmospheric scale height at the hotter trailing terminator. For some species, however, the signals are instead observed to weaken due to ionisation for atoms and their ions, or the dissociation of molecules on the dayside., Comment: 38 pages, 34 figures, published in A&A on October 24, 2023

The abundance of refractory elements in giant planets can provide key insights into their formation histories. Due to the Solar System giants' low temperatures, 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 likely 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 a differentiated object's core during the planet's evolution. 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, well explained by nightside cold-trapping. We further unambiguously detect vanadium oxide on WASP-76b, a molecule long hypothesized 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., Comment: Published online in Nature on June 14, 2023

The early K-type T-Tauri star, V1298 Tau ($V=10\,{\rm mag}$, ${\rm age}\approx20-30\,{\rm Myr}$) hosts four transiting planets with radii ranging from $4.9-9.6\,R_\oplus$. The three inner planets have orbital periods of $\approx8-24\,{\rm d}$ while the outer planet's period is poorly constrained by single transits observed with \emph{K2} and \emph{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) modelling analysis, which includes recently obtained \emph{TESS} photometry and MAROON-X RV measurements. Assuming circular orbits, we obtain a low-significance ($\approx2\sigma$) RV detection of planet c implying a mass of $19.8_{-8.9}^{+9.3}\,M_\oplus$ and a conservative $2\sigma$ upper limit of $<39\,M_\oplus$. For planets b and d, we derive $2\sigma$ upper limits of $M_{\rm b}<159\,M_\oplus$ and $M_{\rm d}<41\,M_\oplus$. For planet e, plausible discrete periods of $P_{\rm e}>55.4\,{\rm d}$ are ruled out at a $3\sigma$ level while seven solutions with $43.3

One of the main scientific goals of the TESS mission is the discovery of transiting small planets around the closest and brightest stars in the sky. Here, using data from the CARMENES, MAROON-X, and HIRES spectrographs, together with TESS, we report the discovery and mass determination of a planetary system around the M1.5 V star GJ 806 (TOI-4481). GJ 806 is a bright (V=10.8 mag, J=7.3 mag) and nearby (d=12 pc) M dwarf that hosts at least two planets. The innermost planet, GJ 806 b, is transiting and has an ultra-short orbital period of 0.93 d, a radius of 1.331+-0.023 Re, a mass of 1.90+-0.17 Me, a mean density of 4.40+-0.45 g/cm3, and an equilibrium temperature of 940+-10 K. We detect a second, non-transiting, super-Earth planet in the system, GJ 806c, with an orbital period of 6.6 d, a minimum mass of 5.80+-0.30 Me, and an equilibrium temperature of 490+-5 K. The radial velocity data also shows evidence for a third periodicity at 13.6 d, although the current dataset does not provide sufficient evidence to unambiguously distinguish between a third super-Earth mass (Msin(i)=8.50+-0.45 Me) planet or stellar activity. Additionally, we report one transit observation of GJ 806 b taken with CARMENES in search for a possible extended atmosphere of H or He, but we can only place upper limits to its existence. This is not surprising as our evolutionary models support the idea that any possible primordial H/He atmosphere that GJ 806 b might have had, would long have been lost. However, GJ 806b's bulk density makes it likely that the planet hosts some type of volatile atmosphere. In fact, with a transmission spectroscopy metrics (TSM) of 44 and an emission spectroscopy metrics (ESM) of 24, GJ 806 b the third-ranked terrestrial planet around an M dwarf suitable for transmission spectroscopy studies, and the most promising terrestrial planet for emission spectroscopy studies., Comment: Under second review in A&A. This paper is NOT yet accepted, but it is made openly available to the community due to the approaching JWST deadline

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 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 $-2^{+17}_{-19}$ degrees and a stellar rotational velocity of 2.1 $\pm$ 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 current data. We were 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 SNR 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., Comment: 18 pages, 6 figures, submitted to AJ

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$_{\oplus}$, making it one of the most metal-poor ([Fe/H] = -0.41) and oldest ($\sim$10 Gyr) sites where an Earth-sized planet has been found. We present new simultaneous radial velocity measurements (RVs) from Gemini-N/MAROON-X and Keck/HIRES, which we combined with literature RVs to derive a mass of M$_{b}$=2.24 $\pm$ 0.20 M$_{\oplus}$. We also used two new Sectors of TESS photometry to improve the radius determination, finding R$_{b}$=$1.37 \pm 0.04 R_\oplus$, and confirming that TOI-561 b is one of the lowest-density super-Earths measured to date ($\rho_b$= 4.8 $\pm$ 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 ($\sim$2300 K) suggests that this envelope would likely be composed of high mean molecular weight species, such as water vapor, carbon dioxide, or silicate vapor, and is likely not primordial. We also demonstrate that the composition determination is sensitive to the choice of stellar parameters, and that further measurements are needed to determine if TOI-561 b is a bare rocky planet, a rocky planet with an optically thin atmosphere, or a rare example of a non-primordial envelope on a planet with a radius smaller than 1.5 R$_{\oplus}$., Comment: Accepted to AJ on 11/28/2022

MAROON-X is a fiber-fed, optical EPRV spectrograph at the 8-m Gemini North Telescope on Mauna Kea, Hawai'i. MAROON-X was commissioned as a visiting instrument in December 2019 and is in regular use since May 2020. Originally designed for RV observations of M-dwarfs, the instrument is used for a broad range of exoplanet and stellar science cases and has transitioned to be the second-most requested instrument on Gemini North over a number of semesters. We report here on the first two years of operations and radial velocity observations. MAROON-X regularly achieves sub-m/s RV performance on sky with a short-term instrumental noise floor at the 30 cm/s level. We will discuss various technical aspects in achieving this level of precision and how to further improve long-term performance

We report the discovery and characterization of two small transiting planets orbiting the bright M3.0V star TOI-1468 (LSPM J0106+1913), whose transit signals were detected in the photometric time series in three sectors of the TESS mission. We confirm the e planetary nature of both of them using precise radial velocity measurements from the CARMENES and MAROON-X spectrographs, and supplement them with ground-based transit photometry. A joint analysis of all these data reveals that the shorter-period planet, TOI-1468 b ($P_{\rm b}$ = 1.88 d), has a planetary mass of $M_{\rm b} = 3.21\pm0.24$ $M_{\oplus}$ and a radius of $R_{\rm b} =1.280^{+0.038}_{-0.039} R_{\oplus}$, resulting in a density of $\rho_{\rm b} = 8.39^{+ 1.05}_{- 0.92}$ g cm$^{-3}$, which is consistent with a mostly rocky composition. For the outer planet, TOI-1468 c ($P_{\rm c} = 15.53$ d), we derive a mass of $M_{\rm c} = 6.64^{+ 0.67}_{- 0.68}$ $M_{\oplus}$, a radius of $R_{\rm c} = 2.06\pm0.04\,R_{\oplus}$, and a bulk density of $\rho_{c} = 2.00^{+ 0.21}_{- 0.19}$ g cm$^{-3}$, which corresponds to a rocky core composition with a H/He gas envelope. These planets are located on opposite sides of the radius valley, making our system an interesting discovery as there are only a handful of other systems with the same properties. This discovery can further help determine a more precise location of the radius valley for small planets around M dwarfs and, therefore, shed more light on planet formation and evolution scenarios., Comment: 26 pages, 15 figures

We present high-resolution dayside thermal emission observations of the exoplanet KELT-20b/MASCARA-2b using the MAROON-X spectrograph. Applying the cross-correlation method with both empirical and theoretical masks and a retrieval analysis, we confirm previous detections of Fe\,\textsc{i} emission lines and we detect Ni\,\textsc{i} for the first time in the planet (at 4.7$\sigma$ confidence). We do not see evidence for additional species in the MAROON-X data, including notably predicted thermal inversion agents TiO and VO, their atomic constituents Ti\,\textsc{i} and V\,\textsc{i}, and previously claimed species Fe\,\textsc{ii} and Cr\,\textsc{i}. We also perform a joint retrieval with existing \textit{Hubble Space Telescope}/WFC3 spectroscopy and \textit{Spitzer}/IRAC photometry. This allows us to place bounded constraints on the abundances of Fe\,\textsc{i}, H$_2$O, and CO, and to place a stringent upper limit on the TiO abundance. The results are consistent with KELT-20b having a solar to slightly super-solar composition atmosphere in terms of the bulk metal enrichment, and the carbon-to-oxygen and iron-to-oxygen ratios. However, the TiO volume mixing ratio upper limit (10$^{-7.6}$ at 99\% confidence) is inconsistent with this picture, which, along with the non-detection of Ti\,\textsc{i}, points to sequestration of Ti species, possibly due to nightside condensation. The lack of TiO but the presence of a large H$_2$O emission feature in the WFC3 data is challenging to reconcile within the context of 1D self-consistent, radiative-convective models., Comment: 14 pages, 9 figures, 2 tables

The Gl 486 system consists of a very nearby, relatively bright, weakly active M3.5 V star at just 8 pc with a warm transiting rocky planet of about 1.3 R_Terra and 3.0 M_Terra that is ideal for both transmission and emission spectroscopy and for testing interior models of telluric planets. To prepare for future studies, we collected light curves of seven new transits observed with the CHEOPS space mission and new radial velocities obtained with MAROON-X/Gemini North and CARMENES/Calar Alto telescopes, together with previously published spectroscopic and photometric data from the two spectrographs and TESS. We also performed interferometric observations with the CHARA Array and new photometric monitoring with a suite of smaller telescopes. From interferometry, we measure a limb-darkened disc angular size of the star Gl 486. Together with a corrected Gaia EDR3 parallax, we obtain a stellar radius. We also measure a stellar rotation period at P_rot ~ 49.9 d, an upper limit to its XUV (5-920 AA) flux with new Hubble/STIS data, and, for the first time, a variety of element abundances (Fe, Mg, Si, V, Sr, Zr, Rb) and C/O ratio. Besides, we impose restrictive constraints on the presence of additional components, either stellar or substellar, in the system. With the input stellar parameters and the radial-velocity and transit data, we determine the radius and mass of the planet Gl 486 b at R_p = 1.343+/0.063 R_Terra and M_p = 3.00+/-0.13 M_Terra. From the planet parameters and the stellar element abundances, we infer the most probable models of planet internal structure and composition, which are consistent with a relatively small metallic core with respect to the Earth, a deep silicate mantle, and a thin volatile upper layer. With all these ingredients, we outline prospects for Gl 486 b atmospheric studies, especially with forthcoming James Webb Space Telescope observations (abridged)., Comment: A&A, in press. See https://carmenes.caha.es/ext/pressreleases/GJ486/Exoearth.Video.mp4

We present the validation of a transiting low-density exoplanet orbiting the M2.5 dwarf TOI 620 discovered by the NASA TESS mission. We utilize photometric data from both TESS and ground-based follow-up observations to validate the ephemerides of the 5.09-day transiting signal and vet false positive scenarios. High-contrast imaging data are used to resolve the stellar host and exclude stellar companions at separations $\gtrsim 0.2''$. We obtain follow-up spectroscopy and corresponding precise radial velocities (RVs) with multiple PRV spectrographs to confirm the planetary nature of the transiting exoplanet. We calculate a 5$\sigma$ upper limit of $M_P < 7.1$ M$_\oplus$ and $\rho_P < 0.74$ g cm$^{-3}$, and we identify a non-transiting 17.7-day candidate. We also find evidence for a substellar (1-20 M$_{\rm J}$) companion with a projected separation $\lesssim 20$ au from a combined analysis of Gaia, AO imaging, and RVs. With the discovery of this outer companion, we carry out a detailed exploration of the possibilities that TOI 620 b might instead be a circum-secondary planet or a pair of eclipsing binary stars orbiting the host in a hierarchical triple system. We find, under scrutiny, that we can exclude both of these scenarios from the multi-wavelength transit photometry, thus validating TOI 620 b as a low-density exoplanet transiting the central star in this system. The low density of TOI 620 b makes it one of the most amenable exoplanets for atmospheric characterization, such as with JWST and Ariel, validated or confirmed by the TESS mission to date., Comment: 64 pages, 34 figures, 22 tables. Accepted for publication in the Astronomical Journal

A high spectral resolution investigation of diffuse interstellar bands (DIBs) in the near-infrared ($YJ$ band) is conducted to test new methods, to confirm and improve existing parameters, and to search for new DIBs. Methods: The CRyogenic high-resolution InfraRed Echelle Spectrograph (CRIRES) on the European Southern Observatory's Very Large Telescope was employed to obtain spectra of four reddened background supergiant stars (HD 183143, HD 165784, HD 92207, HD 111613) and an unreddened comparison star (HD 87737) at the highest resolution of $R \approx 100000$ currently achievable at near-infrared wavelengths. The correction for telluric absorption was performed by a modelling approach. Non-local thermodynamic equilibrium spectral modelling of available optical and the new near-infrared spectra facilitated a comprehensive characterisation of the atmospheric properties of the background stars. A more precise and accurate determination of the reddening law along the sight lines could be achieved than feasible before by comparison of the observed and model spectral energy distributions. For DIBs that overlap with stellar lines the DIB profile shapes could be recovered. Results: Seventeen known near-infrared DIBs were confirmed, and 12 previously unknown and generally weaker DIBs were identified in the $YJ$ band. Three DIBs that show uniform profiles along all sight lines were identified, possibly connected to transitions from a common lower state of the same carrier. The divergent extinction curve towards the frequently discussed DIB standard star HD 183143 could be reproduced for the first time, requiring extra absorption by $\sim$3.5 mag due to polycyclic aromatic hydrocarbons (PAHs) to match the ultraviolet extinction bump. This extra absorption probably stems from a circumstellar bubble lying in front of the star which is intersected tangentially by the line of sight., Comment: 17 pages, 14 figures, Accepted for publication in Astronomy & Astrophysics, Data: https://doi.org/10.5281/zenodo.6461585

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 \textit{HST}/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 thermochemcial 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., Comment: 8 pages, 4 figures, accepted to ApJL

LTT 1445 is a hierarchical triple M-dwarf star system located at a distance of 6.86 parsecs. The primary star LTT 1445A (0.257 M_Sun) is known to host the transiting planet LTT 1445Ab with an orbital period of 5.4 days, making it the second closest known transiting exoplanet system, and the closest one for which the host is an M dwarf. Using TESS data, we present the discovery of a second planet in the LTT 1445 system, with an orbital period of 3.1 days. We combine radial velocity measurements obtained from the five spectrographs ESPRESSO, HARPS, HIRES, MAROON-X, and PFS to establish that the new world also orbits LTT 1445A. We determine the mass and radius of LTT 1445Ab to be 2.87+/-0.25 M_Earth and 1.304^{+0.067}_{-0.060} R_Earth, consistent with an Earth-like composition. For the newly discovered LTT 1445Ac, we measure a mass of 1.54^{+0.20}_{-0.19} M_Earth and a minimum radius of 1.15 R_Earth, but we cannot determine the radius directly as the signal-to-noise of our light curve permits both grazing and non-grazing configurations. Using MEarth photometry and ground-based spectroscopy, we establish that star C (0.161 M_Sun) is likely the source of the 1.4-day rotation period, and star B (0.215 M_Sun) has a likely rotation period of 6.7 days. We estimate a probable rotation period of 85 days for LTT 1445A. Thus, this triple M-dwarf system appears to be in a special evolutionary stage where the most massive M dwarf has spun down, the intermediate mass M dwarf is in the process of spinning down, while the least massive stellar component has not yet begun to spin down., Comment: Accepted to the Astronomical Journal. 4 tables, 10 figures; RV table available upon request

Precise mass measurements of exoplanets discovered by the direct imaging or transit technique are required to determine planet bulk properties and potential habitability. Furthermore, it is generally acknowledged that, for the foreseeable future, the Extreme Precision Radial Velocity (EPRV) measurement technique is the only method potentially capable of detecting and measuring the masses and orbits of habitable-zone Earths orbiting nearby F, G, and K spectral-type stars from the ground. In particular, EPRV measurements with a precision of better than approximately 10 cm/s (with a few cm/s stability over many years) are required. Unfortunately, for nearly a decade, PRV instruments and surveys have been unable to routinely reach RV accuracies of less than roughly 1 m/s. Making EPRV science and technology development a critical component of both NASA and NSF program plans is crucial for reaching the goal of detecting potentially habitable Earthlike planets and supporting potential future exoplanet direct imaging missions such as the Habitable Exoplanet Observatory (HabEx) or the Large Ultraviolet Optical Infrared Surveyor (LUVOIR). In recognition of these facts, the 2018 National Academy of Sciences (NAS) Exoplanet Science Strategy (ESS) report recommended the development of EPRV measurements as a critical step toward the detection and characterization of habitable, Earth-analog planets. In response to the NAS-ESS recommendation, NASA and NSF commissioned the EPRV Working Group to recommend a ground-based program architecture and implementation plan to achieve the goal intended by the NAS. This report documents the activities, findings, and recommendations of the EPRV Working Group., Comment: Full report: 103 pages. Executive summary: 7 pages. More information about the NASA-NSF Exoplanet Observational Research (NN-EXPLORE) program, including the NASA-NSF Extreme Precision Radial Velocity Initiative, can be found here: https://exoplanets.nasa.gov/exep/NNExplore/

MAROON-X is a fiber-fed, red-optical, high precision radial velocity spectrograph recently commissioned at the Gemini North telescope on Mauna Kea, Hawai'i. With a resolving power of 85,000 and a wavelength coverage of 500-920 nm, it delivers radial velocity measurements for late K and M dwarfs with sub-50 cm s$^{-1}$ precision. MAROON-X is currently the only optical EPRV spectrograph on a 8m-class telescope in the northern hemisphere and the only EPRV instrument on a large telescope with full access by the entire US community. We report here on the results of the commissioning campaign in December 2019 and early science results., Comment: 21 pages, 14 figures

Spectroscopy of transiting exoplanets can be used to investigate their atmospheric properties and habitability. Combining radial velocity (RV) and transit data provides additional information on exoplanet physical properties. We detect a transiting rocky planet with an orbital period of 1.467 days around the nearby red dwarf star Gliese 486. The planet Gliese 486 b is 2.81 Earth masses and 1.31 Earth radii, with uncertainties of 5%, as determined from RV data and photometric light curves. The host star is at a distance of ~8.1 parsecs, has a J-band magnitude of ~7.2, and is observable from both hemispheres of Earth. On the basis of these properties and the planet's short orbital period and high equilibrium temperature, we show that this terrestrial planet is suitable for emission and transit spectroscopy., Comment: Published in Science

Precise wavelength calibration is a critical issue for high-resolution spectroscopic observations. The ideal calibration source should be able to provide a very stable and dense grid of evenly distributed spectral lines of constant intensity. A new method which satisfies all mentioned conditions has been developed by our group. The approach is to actively measure the exact position of a single spectral line of a Fabry-Perot etalon with very high precision with a wavelength-tuneable laser and compare it to an extremely stable wavelength standard. The ideal choice of standard is the D2 absorption line of Rubidium, which has been used as an optical frequency standard for decades. With this technique, the problem of stable wavelength calibration of spectrographs becomes a problem of how reliably we can measure and anchor one etalon line to the Rb transition. In this work we present our self-built module for Rb saturated absorption spectroscopy and discuss its stability., Comment: SPIE ANZCOP conference, Melbourne 2019

MAROON-X is a red-optical, high precision radial velocity spectrograph currently nearing completion and undergoing extensive performance testing at the University of Chicago. The instrument is scheduled to be installed at Gemini North in the first quarter of 2019. MAROON-X will be the only RV spectrograph on a large telescope with full access by the entire US community. In these proceedings we discuss the latest addition of the red wavelength arm and the two science grade detector systems, as well as the design and construction of the telescope front end. We also present results from ongoing RV stability tests in the lab. First results indicate that MAROON-X can be calibrated at the sub-m/s level, and perhaps even much better than that using a simultaneous reference approach., Comment: 10 pages, 9 figures, submitted for SPIE Astronomical Telescopes + Instrumentation 2018

Context. High resolution stellar spectral atlases are valuable resources to astronomy. They are rare in the $1 - 5\,\mu$m region for historical reasons, but once available, high resolution atlases in this part of the spectrum will aid the study of a wide range of astrophysical phenomena. Aims. The aim of the CRIRES-POP project is to produce a high resolution near-infrared spectral library of stars across the H-R diagram. The aim of this paper is to present the fully reduced spectrum of the K giant 10 Leo that will form the basis of the first atlas within the CRIRES-POP library, to provide a full description of the data reduction processes involved, and to provide an update on the CRIRES-POP project. Methods. All CRIRES-POP targets were observed with almost 200 different observational settings of CRIRES on the ESO Very Large Telescope, resulting in a basically complete coverage of its spectral range as accessible from the ground. We reduced the spectra of 10 Leo with the CRIRES pipeline, corrected the wavelength solution and removed telluric absorption with Molecfit, then resampled the spectra to a common wavelength scale, shifted them to rest wavelengths, flux normalised, and median combined them into one final data product. Results. We present the fully reduced, high resolution, near-infrared spectrum of 10 Leo. This is also the first complete spectrum from the CRIRES instrument. The spectrum is available online. Conclusions. The first CRIRES-POP spectrum has exceeded our quality expectations and will form the centre of a state-of-the-art stellar atlas. This first CRIRES-POP atlas will soon be available, and further atlases will follow. All CRIRES-POP data products will be freely and publicly available online., Comment: 12 pages, 12 figures, accepted to A&A

We report on the construction and testing of a vacuum-gap Fabry-P\'erot etalon calibrator for high precision radial velocity spectrographs. Our etalon is traced against a rubidium frequency standard to provide a cost effective, yet ultra-precise wavelength reference. We describe here a turn-key system working at 500 nm to 900 nm, ready to be installed at any current and next generation radial velocity spectrograph that requires calibration over a wide spectral bandpass. Where appropriate, we have used off-the-shelf, commercial components with demonstrated long-term performance to accelerate the development timescale of this instrument. Our system combines for the first time the advantages of passively stabilized etalons for optical and near-infrared wavelengths with the laser-locking technique demonstrated for single-mode fiber etalons. We realize uncertainties in the position of one etalon line at the 10 cm/s level in individual measurements taken at 4 Hz. When binning the data over 10 s, we are able to trace the etalon line with a precision of better than 3 cm/s . We present data obtained during a week of continuous operation where we detect (and correct for) the predicted, but previously unobserved shrinking of the etalon Zerodur spacer corresponding to a shift of 13 cm/s per day., Comment: 17 pages, 6 figures, accepted by JATIS May 11, 2017

We report on the scrambling performance and focal-ratio-degradation (FRD) of various octagonal and rectangular fibers considered for MAROON-X. Our measurements demonstrate the detrimental effect of thin claddings on the FRD of octagonal and rectangular fibers and that stress induced at the connectors can further increase the FRD. We find that fibers with a thick, round cladding show low FRD. We further demonstrate that the scrambling behavior of non-circular fibers is often complex and introduce a new metric to fully capture non-linear scrambling performance, leading to much lower scrambling gain values than are typically reported in the literature (<1000 compared to 10,000 or more). We find that scrambling gain measurements for small-core, non-circular fibers are often speckle dominated if the fiber is not agitated., Comment: 10 pages, 8 figures, submitted to SPIE Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation 2016 (9912-185)

Optical fibers are a key component for high-resolution spectrographs to attain high precision in radial velocity measurements. We present a custom fiber with a novel core geometry - a 'D'-shape. From a theoretical standpoint, such a fiber should provide superior scrambling and modal noise mitigation, since unlike the commonly used circular and polygonal fiber cross sections, it shows chaotic scrambling. We report on the fabrication process of a test fiber and compare the optical properties, scrambling performance, and modal noise behavior of the D-fiber with those of common polygonal fibers., Comment: 7 pages, 6 figures, submitted to SPIE Astronomical Telescopes & Instrumentation 2016 (9912-192)

We report on the design and construction of a microlens-array (MLA)-based pupil slicer and double scrambler for MAROON-X, a new fiber-fed, red-optical, high-precision radial-velocity spectrograph for one of the twin 6.5m Magellan Telescopes in Chile. We have constructed a 3X slicer based on a single cylindrical MLA and show that geometric efficiencies of >85% can be achieved, limited by the fill factor and optical surface quality of the MLA. We present here the final design of the 3x pupil slicer and double scrambler for MAROON-X, based on a dual MLA design with (a)spherical lenslets. We also discuss the techniques used to create a pseudo-slit of rectangular core fibers with low FRD levels., Comment: 9 pages, 6 figures, submitted to SPIE Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation 2016 (9912-61)

We report on the development and construction of a new fiber-fed, red-optical, high-precision radial-velocity spectrograph for one of the twin 6.5m Magellan Telescopes in Chile. MAROON-X will be optimized to find and characterize rocky planets around nearby M dwarfs with an intrinsic per measurement noise floor below 1 m/s. The instrument is based on a commercial echelle spectrograph customized for high stability and throughput. A microlens array based pupil slicer and double scrambler, as well as a rubidium-referenced etalon comb calibrator will turn this spectrograph into a high-precision radial-velocity machine. MAROON-X will undergo extensive lab tests in the second half of 2016., Comment: 14 pages, 10 figures, submitted to SPIE Astronomical Telescopes & Instrumentation 2016 (9908-45)

We surveyed the 25 Ori association for direct-imaging companions. This association has an age of only few million years. Among other targets, we observed CVSO 30, which has recently been identified as the first T Tauri star found to host a transiting planet candidate. We report on photometric and spectroscopic high-contrast observations with the Very Large Telescope, the Keck telescopes, and the Calar Alto observatory. They reveal a directly imaged planet candidate close to the young M3 star CVSO 30. The JHK-band photometry of the newly identified candidate is at better than 1 sigma consistent with late-type giants, early-T and early-M dwarfs, and free-floating planets. Other hypotheses such as galaxies can be excluded at more than 3.5 sigma. A lucky imaging z' photometric detection limit z'= 20.5 mag excludes early-M dwarfs and results in less than 10 MJup for CVSO 30 c if bound. We present spectroscopic observations of the wide companion that imply that the only remaining explanation for the object is that it is the first very young (< 10 Myr) L-T-type planet bound to a star, meaning that it appears bluer than expected as a result of a decreasing cloud opacity at low effective temperatures. Only a planetary spectral model is consistent with the spectroscopy, and we deduce a best-fit mass of 4-5 Jupiter masses (total range 0.6-10.2 Jupiter masses). This means that CVSO 30 is the first system in which both a close-in and a wide planet candidate are found to have a common host star. The orbits of the two possible planets could not be more different: they have orbital periods of 10.76 hours and about 27000 years. The two orbits may have formed during a mutual catastrophic event of planet-planet scattering., Comment: 15 pages, 16 figures, accepted for publication in A&A

Close-in extrasolar giant planets are expected to cool their thermospheres by producing H3+ emission in the near-infrared (NIR), but simulations predict H3+ emission intensities that differ in the resulting intensity by several orders of magnitude. We want to test the observability of H3+ emission with CRIRES at the Very Large Telescope (VLT), providing adequate spectral resolution for planetary atmospheric lines in NIR spectra. We search for signatures of planetary H3+ emission in the L` band, using spectra of HD 209458 obtained during and after secondary eclipse of its transiting planet HD 209458 b. We searched for H3+ emission signatures in spectra containing the combined light of the star and, possibly, the planet. With the information on the ephemeris of the transiting planet, we derive the radial velocities at the time of observation and search for the emission at the expected line positions and search for planetary signals and use a shift and add technique combining all observed spectra taken after sec. eclipse to calculate an upper emission limit. We do not find signatures of atmospheric H3+ emission in the spectra containing the combined light of HD 209458 and planet b. We calculate the emission limit for the H3+ line at 3953.0 nm (Q(1, 0)) to be 8.32 E18W and a limit of 5.34E18 W for the line at 3985.5 nm (Q(3, 0)). Comparing our emission limits to the theoretical predictions suggests that we lack 1 to 3 magnitudes of sensitivity to measure H3+ emission in our target object. We show that under more favorable weather conditions the data quality can be improved significantly, reaching 5 E16W for star-planet systems that are close to Earth. We estimate that pushing the detection limit down to 1E15W will be possible with ground-based observations with future instrumentation, for example, the E-ELT., Comment: 7 pages, Astronomy & Astrophysics accepted

The characterization of a physically-diverse set of transiting exoplanets is an important and necessary step towards establishing the physical properties linked to the production of obscuring clouds or hazes. It is those planets with identifiable spectroscopic features that can most effectively enhance our understanding of atmospheric chemistry and metallicity. The newly-commissioned LDSS-3C instrument on Magellan provides enhanced sensitivity and suppressed fringing in the red optical, thus advancing the search for the spectroscopic signature of water in exoplanetary atmospheres from the ground. Using data acquired by LDSS-3C and the Spitzer Space Telescope, we search for evidence of water vapor in the transmission spectrum of the Neptune-mass planet HAT-P-26b. Our measured spectrum is best explained by the presence of water vapor, a lack of potassium, and either a high-metallicity, cloud-free atmosphere or a solar-metallicity atmosphere with a cloud deck at ~10 mbar. The emergence of multi-scale-height spectral features in our data suggests that future observations at higher precision could break this degeneracy and reveal the planet's atmospheric chemical abundances. We also update HAT-P-26b's transit ephemeris, t_0 = 2455304.65218(25) BJD_TDB, and orbital period, p = 4.2345023(7) days., Comment: 9 pages, 8 figures, Accepted for publication in ApJ

Context. Several new techniques to determine the metallicity of M dwarfs with better precision have been developed over the last decades. However, most of these studies were based on empirical methods. In order to enable detailed abundance analysis, standard methods established for warmer solar-like stars, i.e. model-dependent methods using fitting of synthetic spectra, still need to be used. Aims. In this work we continue the reliability confirmation and development of metallicity determinations of M dwarfs using high- resolution infrared spectra. The reliability was confirmed though analysis of M dwarfs in four binary systems with FGK dwarf companions and by comparison with previous optical studies of the FGK dwarfs. Methods. The metallicity determination was based on spectra taken in the J band (1.1-1.4 {\mu}m) with the CRIRES spectrograph. In this part of the infrared, the density of stellar molecular lines is limited, reducing the amount of blends with atomic lines enabling an accurate continuum placement. Lines of several atomic species were used to determine the stellar metallicity. Results. All binaries show excellent agreement between the derived metallicity of the M dwarf and its binary companion. Our results are also in good agreement with values found in the literature. Furthermore, we propose an alternative way to determine the effective temperature of M dwarfs of spectral types later than M2 through synthetic spectral fitting of the FeH lines in our observed spectra. Conclusions. We have confirmed that a reliable metallicity determination of M dwarfs can be achieved using high-resolution infrared spectroscopy. We also note that metallicites obtained with photometric metallicity calibrations available for M dwarfs only partly agree with the results we obtain from high-resolution spectroscopy., Comment: 18 pages

We present an exposure-time calculator (ETC) for the Immersion Grating Infrared Spectrograph (IGRINS). The signal and noise values are calculated by taking into account the telluric background emission and absorption, the emission and transmission of the telescope and instrument optics, and the dark current and read noise of the infrared detector arrays. For the atmospheric transmission, we apply models based on the amount of precipitable water vapor along the line of sight to the target. The ETC produces the expected signal-to-noise ratio (S/N) for each resolution element, given the exposure-time and number of exposures. In this paper, we compare the simulated continuum S/N for the early-type star HD 124683 and the late-type star GSS 32, and the simulated emission line S/N for the H2 rovibrational transitions from the Iris Nebula NGC 7023 with the observed IGRINS spectra. The simulated S/N from the ETC is overestimated by 40-50% for the sample continuum targets., Comment: 27 pages, 11 figures, Accepted to be published in Advances in Space Research (JASR)

In 2010 a sub-stellar companion to the solar analog pre-main sequence star PZ Tel and member of the about 12 Myr old Beta Pic moving group was found by high-contrast direct imaging independently by two teams. In order to determine the basic parameters of this companion more precisely and independent of evolutionary models, hence age independent, we obtained follow-up spectroscopic observations of primary and companion. We use the Spectrograph for INtegral Field Observations in the Near Infrared (SINFONI) at the Very Large Telescope Unit 4/YEPUN of ESO's Paranal Observatory in H+K band and process the data using the spectral deconvolution technique. The resulting spectrum of the companion is then compared to a grid of Drift-Phoenix synthetic model spectra, a combination of a general-purpose model atmosphere code with a non-equilibrium, stationary cloud and dust model, using a chi^2 minimization analysis. We find a best fitting spectral type of G6.5 for PZ Tel A. The extracted spectrum of the sub-stellar companion, at a spatial position compatible with earlier orbit estimates, yields a temperature Teff= 2500 +138-115 K, a visual extinction A_V= 0.53 +0.84-0.53 mag, a surface gravity of log g= 3.50 +0.51-0.30 dex, and a metallicity at the edge of the grid of [M/H]= 0.30 -0.30 dex. We derive a luminosity of log(Lbol/Lsun)= -2.66 +0.06-0.08, a radius of R= 2.42 +0.28-0.34 R_Jup and a mass of M= 7.5 +16.9-4.3 M_Jup for the PZ Tel companion, being consistent with most earlier estimates using photometry alone. Combining our results with evolutionary models, we find a best fitting mass of about 21 Jupiter masses at an age corresponding to the recently determined lithium depletion age of 7 +4-2 Myr. Hence, the PZ Tel companion is most likely a wide brown dwarf companion in the 12 +8-4 Myr old Beta Pic moving group., Comment: 7 pages, 6 figures, accepted for publication in A&A

The onset of the asymmetry in planetary nebulae (PNe) occurs during the short transition between the end of the asymptotic giant branch (AGB) phase and the beginning of the PN phase. Sources in this transition phase are compact and emit intensely in infrared wavelengths, making high spatial resolution observations in the infrared mandatory to investigate the shaping process of PNe. Interferometric VLTI IR observations have revealed compelling evidence of disks at the cores of PNe, but the limited sensitivity, strong observational constraints, and limited spatial coverage place severe limits on the universal use of this technique. Inspired by the successful detection of proto-planetary disks using spectro-astrometric observations, we apply here for the first time this technique to search for sub-arcsecond structures in PNe. Our exploratory study using CRIRES (CRyogenic high-resolution Infra-Red Echelle Spectrograph) commissioning data of the proto-PN IRAS 17516-2525 and the young PN SwSt 1 has revealed small-sized structures after the spectro-astrometric analysis of the two sources. In IRAS 17516-2525, the spectro-astrometric signal has a size of only 12 mas, as detected in the Brackett-gamma line, whereas the structures found in SwSt 1 have sizes of 230 mas in the [Fe III] line and 130 mas in the Brackett-gamma line. The spectroscopic observations required to perform spectro-astrometry of sources in the transition towards the PN phase are less time consuming and much more sensitive than VLTI IR observations. The results presented here open a new window in the search of the small-sized collimating agents that shape the complex morphologies of extremely axisymmetric PNe., Comment: 6 pages, 4 figures