Detection of OH at the evening terminator of the ultra-hot Jupiter WASP-76b

2021 ◽  
Author(s):  
Rico Landman ◽  
Alejandro Sánchez-López ◽  
Paul Mollière ◽  
Aurora Kesseli ◽  
Amy Louca ◽  
...  
Keyword(s):  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Molecular Dissociation ◽  
Molecular Absorption ◽  
M Dwarfs ◽  
Infrared Observations ◽  
Hot Jupiters ◽  
Near Infrared Spectra ◽  
Generate Model ◽  
Fast Spin

<p>Ultra-hot Jupiters have dayside temperatures similar to those of M-dwarfs. While molecular absorption from the hydroxyl radical (OH) is easily observed in near-infrared spectra of M-dwarfs, it is often not considered when studying the atmospheres of (ultra-)hot Jupiters. We use high-resolution spectroscopic near-infrared observations of a transit of WASP-76b obtained using CARMENES to assess the presence of OH. After validating the OH line list, we generate model transit spectra of WASP-76b with petitRADTRANS. The data are corrected for telluric contamination and cross-correlated with the model spectra. After combining all cross-correlation functions from the transit, a detection map is constructed. OH is detected in the atmosphere of WASP-76b with a signal-to-noise ratio of 6.1. From a Markov Chain Monte Carlo retrieval we obtain Kp=234 km/s and a blueshift of 13.9 km/s. Considering the fast spin-rotation of the planet, the OH signal is best explained with the signal mainly originating from the evening terminator and the presence of a strong day- to nightside wind. The signal appears to be broad, with a full width at half maximum of 16.2 km/s. The retrieval results in a weak constraint on the temperature of 2420-3150 K at the pressure of the OH signal. Our results demonstrate that OH is readily observable in the transit spectra of ultra-hot Jupiters. Studying this molecule can give new insights in the molecular dissociation processes in the atmospheres of such planets.</p>

scholarly journals The CARMENES search for exoplanets around M dwarfs

2020 ◽  
Vol 642 ◽  
pp. A227 ◽  
Author(s):  
C. Abia ◽  
H. M. Tabernero ◽  
S. A. Korotin ◽  
D. Montes ◽  
E. Marfil ◽  
...  
Keyword(s):  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Heavy Elements ◽  
High Signal ◽  
M Dwarfs ◽  
Chemical Enrichment ◽  
Near Infrared Spectra ◽  
Theoretical Predictions ◽  
History Of ◽  
First Time

Due to their ubiquity and very long main-sequence lifetimes, abundance determinations in M dwarfs provide a powerful and alternative tool to GK dwarfs to study the formation and chemical enrichment history of our Galaxy. In this study, abundances of the neutron-capture elements Rb, Sr, and Zr are derived, for the first time, in a sample of nearby M dwarfs. We focus on stars in the metallicity range − 0.5 ≲ [Fe/H] ≲ +0.3, an interval poorly explored for Rb abundances in previous analyses. To do this we use high-resolution, high-signal-to-noise-ratio, optical and near-infrared spectra of 57 M dwarfs observed with CARMENES. The resulting [Sr/Fe] and [Zr/Fe] ratios for most M dwarfs are almost constant at about the solar value, and are identical to those found in GK dwarfs of the same metallicity. However, for Rb we find systematic underabundances ([Rb/Fe] < 0.0) by a factor two on average. Furthermore, a tendency is found for Rb – but not for other heavy elements (Sr, Zr) – to increase with increasing metallicity such that [Rb/Fe] ≳ 0.0 is attained at metallicities higher than solar. These are surprising results, never seen for any other heavy element, and are difficult to understand within the formulation of the s- and r-processes, both contributing sources to the Galactic Rb abundance. We discuss the reliability of these findings for Rb in terms of non-LTE (local thermodynamic equilibrium) effects, stellar activity, or an anomalous Rb abundance in the Solar System, but no explanation is found. We then interpret the full observed [Rb/Fe] versus [Fe/H] trend within the framework of theoretical predictions from state-of-the-art chemical evolution models for heavy elements, but a simple interpretation is not found either. In particular, the possible secondary behaviour of the [Rb/Fe] ratio at super-solar metallicities would require a much larger production of Rb than currently predicted in AGB stars through the s-process without overproducing Sr and Zr.

scholarly journals Scans and Narrow-Band Photometry of Late-Type Stars in the One-Micron Region

1974 ◽  
Vol 3 ◽  
pp. 285-306 ◽  
Author(s):  
R. F. Wing
Keyword(s):  
Near Infrared ◽  
Narrow Band ◽  
M Dwarfs ◽  
Mira Variables ◽  
Near Infrared Spectra ◽  
First Results ◽  
System 2 ◽  
M Stars ◽  
Band Sequence ◽  
The One

AbstractA summary is given of the molecular bands occurring in the near-infrared spectra of cool stars, especially those having sufficient strength and freedom from contamination to be measurable by narrow-band photometry. In some cases useful indices of both temperature and luminosity can be obtained from such measurements. Several bands remain unidentified, including the 9910 Å band in late M dwarfs and at least nine bands in cool S stars.Three topics of a spectroscopic nature are discussed. (1) In Mira variables, grossly different spectral types are sometimes obtained from zero-volt and excited TiO bands of the same band system. (2) A few M stars have been found to show bands of’ both VO and CN at the same time. They may be the coolest known supergiants, although there remains some doubt as to their luminosities. (3) The first results are given from a program of measuring crude C12/C13 ratios from narrow-band photometry of sensitive points on the profile of the ∆υ = + 2 band sequence of CN. The observations require only a few minutes per star, and the method can be applied to G and K giants and supergiants as well as to carbon stars.

scholarly journals Exploring the stellar properties of M dwarfs with high-resolution spectroscopy from the optical to the near-infrared

2018 ◽  
Vol 620 ◽  
pp. A180 ◽  
Author(s):  
A. S. Rajpurohit ◽  
F. Allard ◽  
S. Rajpurohit ◽  
R. Sharma ◽  
G. D. C. Teixeira ◽  
...  
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Spectral Synthesis ◽  
Model Atmosphere ◽  
High Resolution Spectroscopy ◽  
Cloud Formation ◽  
M Dwarfs ◽  
Near Infrared Spectra ◽  
The Galaxy ◽  
Stellar Properties

Context. Being the most numerous and oldest stars in the galaxy, M dwarfs are objects of great interest for exoplanet searches. The presence of molecules in their atmosphere complicates our understanding of their atmospheric properties. But great advances have recently been made in the modeling of M dwarfs due to the revision of solar abundances. Aims. We aim to determine stellar parameters of M dwarfs using high resolution spectra (R ∼ 90 000) simultaneously in the visible and the near-infrared. The high resolution spectra and broad wavelength coverage provide an unique opportunity to understand the onset of dust and cloud formation at cool temperatures. Furthermore, this study will help in understanding the physical processes which occur in a cool atmospheres, particularly, the redistribution of energy from the optical to the near-infrared. Methods. The stellar parameters of M dwarfs in our sample have been determined by comparing the high resolution spectra both in the optical and in the near-infrared simultaneously observed by CARMENES with the synthetic spectra obtained from the BT-Settl model atmosphere. The detailed spectral synthesis of these observed spectra both in the optical and in the near-infrared helps to understand the missing continuum opacity. Results. For the first time, we derive fundamental stellar parameters of M dwarfs using the high resolution optical and near-infrared spectra simultaneously. We determine Teff, log g and [M/H] for 292 M dwarfs of spectral type M0 to M9, where the formation of dust and clouds are important. The derived Teff for the sample ranges from 2300 to 4000 K, values of log g ranges from 4.5 ≤ logg ≤ 5.5 and the resulting metallicity ranges from −0.5 ≤ [M/H] ≤ +0.5. We have also explored the possible differences in Teff, log g and [M/H] by comparing them with other studies of the same sample of M dwarfs.

scholarly journals The CARMENES search for exoplanets around M dwarfs

2018 ◽  
Vol 612 ◽  
pp. A49 ◽  
Author(s):  
A. Reiners ◽  
M. Zechmeister ◽  
J. A. Caballero ◽  
I. Ribas ◽  
J. C. Morales ◽  
...  
Keyword(s):  
High Resolution ◽  
Wavelength Range ◽  
Near Infrared ◽  
Signal To Noise Ratio ◽  
Rotation Velocity ◽  
Atmospheric Models ◽  
M Dwarfs ◽  
Low Mass Stars ◽  
Low Mass ◽  
M Dwarf

The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520–1710 nm at a resolution of at least R >80 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700–900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s−1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3–4 m s−1.

scholarly journals Elemental abundances of M dwarfs based on high-resolution near-infrared spectra: Verification by binary systems

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Hiroyuki Tako Ishikawa ◽  
Wako Aoki ◽  
Takayuki Kotani ◽  
Masayuki Kuzuhara ◽  
Masashi Omiya ◽  
...  
Keyword(s):  
High Resolution ◽  
Measurement Errors ◽  
Binary Systems ◽  
Near Infrared ◽  
M Dwarfs ◽  
Chemical Abundances ◽  
Elemental Abundances ◽  
Analysis Process ◽  
Near Infrared Spectra ◽  
Atomic Lines

ABSTRACT M dwarfs are prominent targets of planet search projects, and their chemical composition is crucial to understanding the formation process or interior of orbiting exoplanets. However, measurements of elemental abundances of M dwarfs have been limited due to difficulties in the analysis of their optical spectra. We conducted a detailed chemical analysis of five M dwarfs (Teff ∼ 3200–3800 K), which form binary systems with G/K-type stars, by performing a line-by-line analysis based on high-resolution (R ∼ 80000) near-infrared (960–1710 nm) spectra obtained with CARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Échelle Spectrographs). We determined the chemical abundances of eight elements (Na, Mg, K, Ca, Ti, Cr, Mn, and Fe), which are in agreement with those of the primary stars within measurement errors (∼0.2 dex). Through the analysis process, we investigated the unique behavior of atomic lines in a cool atmosphere. Most atomic lines are sensitive to changes in the abundance of not only the corresponding elements but also other elements, especially dominant electron donors such as Na and Ca. The Ti i lines show a negative correlation with the overall metallicity at Teff &lt; 3400 K due to the consumption of neutral titanium by the formation of TiO molecules. These findings indicate that to estimate the overall metallicity or the abundance of any element correctly, we need to determine the abundances of other individual elements consistently.

Optical and Near-infrared Observations of Supernova 1987A

1991 ◽  
Vol 9 (1) ◽  
pp. 8-12 ◽  
Author(s):  
Jason Spyromilio
Keyword(s):  
Interstellar Medium ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Infrared Observations ◽  
Supernova 1987A ◽  
Near Infrared Spectra

AbstractWe present observational results obtained during the first three years following the explosion of Supernova 1987 A. We discuss aspects of the optical and near infrared spectra as well as results from spectropolarimetric observations. The observations of the circumstellar and interstellar medium are also briefly discussed.

scholarly journals Scientific Goals of the Kunlun Infrared Sky Survey (KISS)

2016 ◽  
Vol 33 ◽  
Author(s):  
Michael G. Burton ◽  
Jessica Zheng ◽  
Jeremy Mould ◽  
Jeff Cooke ◽  
Michael Ireland ◽  
...  
Keyword(s):  
Gamma Ray ◽  
M Dwarfs ◽  
Infrared Observations ◽  
Antarctic Plateau ◽  
Reverberation Mapping ◽  
Hot Jupiters ◽  
Ice Surface ◽  
Sky Survey ◽  
Infrared Background ◽  
Fast Transients

AbstractThe high Antarctic plateau provides exceptional conditions for infrared observations on account of the cold, dry and stable atmosphere above the ice surface. This paper describes the scientific goals behind the first program to examine the time-varying universe in the infrared from Antarctica — the Kunlun Infrared Sky Survey (KISS). This will employ a 50cm telescope to monitor the southern skies in the 2.4μmKdark window from China's Kunlun station at Dome A, on the summit of the Antarctic plateau, through the uninterrupted 4-month period of winter darkness. An earlier paper discussed optimisation of the Kdark filter for sensitivity (Li et al. 2016). This paper examines the scientific program for KISS. We calculate the sensitivity of the camera for the extrema of observing conditions that will be encountered. We present the parameters for sample surveys that could then be carried out for a range of cadences and sensitivities. We then discuss several science programs that could be conducted with these capabilities, involving star formation, brown dwarfs and hot Jupiters, exoplanets around M dwarfs, the terminal phases of stellar evolution, fast transients, embedded supernova searches, reverberation mapping of AGN, gamma ray bursts and the detection of the cosmic infrared background.

scholarly journals Seeing above the clouds with high-resolution spectroscopy

2020 ◽  
Vol 498 (1) ◽  
pp. 194-204
Author(s):  
Siddharth Gandhi ◽  
Matteo Brogi ◽  
Rebecca K Webb
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Chemical Species ◽  
Compositional Analysis ◽  
Chemical Diversity ◽  
High Resolution Spectroscopy ◽  
Infrared Observations ◽  
Hot Jupiters ◽  
Doppler Spectroscopy ◽  
Cloud Top Pressure

ABSTRACT In the last decade, ground-based high-resolution Doppler spectroscopy (HRS) has detected numerous species in transiting and non-transiting hot Jupiters, and is ideally placed for atmospheric characterization of warm Neptunes and super Earths. Many of these cooler and smaller exoplanets have shown cloudy atmospheres from low-resolution near-infrared observations, making constraints on chemical species difficult. We investigate how HRS can improve on these given its sensitivity to spectral line cores which probe higher altitudes above the clouds. We model transmission spectra for the warm Neptune GJ 3470b and determine the detectability of H2O with the CARMENES, GIANO, and SPIRou spectrographs. We also model a grid of spectra for another warm Neptune, GJ 436b, over a range of cloud-top pressure and H2O abundance. We show H2O is detectable for both planets with modest observational time and that the high H2O abundance-high cloud deck degeneracy is broken with HRS. However, meaningful constraints on abundance and cloud-top pressure are only possible in the high-metallicity scenario. We also show that detections of CH4 and NH3 are possible from cloudy models of GJ 436b. Lastly, we show how the presence of the Earth’s transmission spectrum hinders the detection of H2O for the most cloudy scenarios given that telluric absorption overlaps with the strongest H2O features. The constraints possible with HRS on the molecular species can be used for compositional analysis and to study the chemical diversity of such planets in the future.

scholarly journals Characterizing stellar parameters from high-resolution spectra of main sequence cool stars. I. The G2V–K2V stars

2019 ◽  
Vol 487 (1) ◽  
pp. 1335-1362
Author(s):  
Logithan Kulenthirarajah ◽  
Jean-François Donati ◽  
Gaitee Hussain ◽  
Julien Morin ◽  
France Allard
Keyword(s):  
High Resolution ◽  
Main Sequence ◽  
Near Infrared ◽  
Absolute Accuracy ◽  
Spectral Library ◽  
M Dwarfs ◽  
Near Infrared Spectra ◽  
Cool Stars ◽  
Error Bars ◽  
Good Agreement

Abstract The goal of the present study is to construct, test, and validate a high-resolution synthetic spectral library using PHOENIX model atmospheres and develop a reliable tool to estimate stellar parameters from high-resolution optical and/or near-infrared spectra of M dwarfs. We report here the preliminary results of tests characterizing main sequence G–K stars from high-resolution spectra. We anchored the atomic line-list using the stellar standards Sun, ξ Boo A, and ϵ Eri to ensure the synthetic spectra computed with PHOENIX reproduce their observed counterparts. These stars were chosen because their parameters are very well characterized, and on which the absolute accuracy of our method depends on. We successfully estimated the stellar parameters with associated error bars for 17 stars. Using a pseudo Monte Carlo statistical analysis, we present overall improved uncertainties on the stellar parameters compared to those in the literature (on average 9 K, 0.014 dex, and 0.008 dex for the effective temperature, the surface gravity, and the metallicity, respectively). Our estimated stellar parameters are also in good agreement with values found in the literature.

Sign in / Sign up

Export Citation Format

Share Document