scholarly journals A weak spectral signature of water vapour in the atmosphere of HD 179949 b at high spectral resolution in the L band

2020 ◽  
Vol 494 (1) ◽  
pp. 108-119 ◽  
Author(s):  
Rebecca K Webb ◽  
Matteo Brogi ◽  
Siddharth Gandhi ◽  
Michael R Line ◽  
Jayne L Birkby ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Semimajor Axis ◽  
Spectral Lines ◽  
Lapse Rate ◽  
High Spectral Resolution ◽  
High Resolution Spectroscopy ◽  
Spectral Signature ◽  
Orbital Inclination ◽  
L Band

ABSTRACT High-resolution spectroscopy ($R\, \geqslant \, 20\, 000$) is currently the only known method to constrain the orbital solution and atmospheric properties of non-transiting hot Jupiters. It does so by resolving the spectral features of the planet into a forest of spectral lines and directly observing its Doppler shift while orbiting the host star. In this study, we analyse VLT/CRIRES ($R=100\, 000$) L-band observations of the non-transiting giant planet HD 179949 b centred around 3.5 ${\mu {m}}$. We observe a weak (3.0σ, or S/N = 4.8) spectral signature of H2O in absorption contained within the radial velocity of the planet at superior-conjunction, with a mild dependence on the choice of line list used for the modelling. Combining this data with previous observations in the K band, we measure a detection significance of 8.4 σ for an atmosphere that is most consistent with a shallow lapse-rate, solar C/O ratio, and with CO and H2O being the only major sources of opacity in this wavelength range. As the two sets of data were taken 3 yr apart, this points to the absence of strong radial-velocity anomalies due, e.g. to variability in atmospheric circulation. We measure a projected orbital velocity for the planet of KP = (145.2 ± 2.0) km s−1 (1σ) and improve the error bars on this parameter by ∼70 per cent. However, we only marginally tighten constraints on orbital inclination ($66.2^{+3.7}_{-3.1}$ deg) and planet mass ($0.963^{+0.036}_{-0.031}$ Jupiter masses), due to the dominant uncertainties of stellar mass and semimajor axis. Follow ups of radial-velocity planets are thus crucial to fully enable their accurate characterization via high-resolution spectroscopy.

Star And Planet’s Characterisation Through High Spectral Resolution

2020 ◽  
Author(s):  
Maria Chiara Maimone ◽  
Andrea Chiavassa ◽  
Jeremy Leconte ◽  
Matteo Brogi
Keyword(s):  
High Resolution ◽  
Spectral Resolution ◽  
Molecular Species ◽  
Climate Model ◽  
Global Climate Model ◽  
Spectral Lines ◽  
High Spectral Resolution ◽  
High Resolution Spectroscopy ◽  
Stellar Disk ◽  
Precise Knowledge

<p>The study of exoplanets atmospheres is one of the most intriguing challenges in exoplanet field nowadays and the High Resolution Spectroscopy (HRS) has recently emerged as one of the leading methods for detecting atomic and molecular species in their atmospheres. In terms of numbers, if we define the resolution power R,<span class="Apple-converted-space">  </span>where λ is the wavelength and Δλ is the spectral resolution:</p> <p><span class="Apple-converted-space">     R= λ/Δλ</span></p> <p>then, “High Resolution Spectroscopy” means R > 50 000.</p> <p>Nevertheless extraordinary results have been achieved (Birkby, 2018), High Resolution Spectroscopy alone is not enough. 1D models of the host star have been coupled to HRS observations, but they do not reproduce the complexity of stellar convection mechanism (Chiavassa & Brogi, 2019). On the contrary,<span class="Apple-converted-space">  </span>3D Radiative Hydrodynamical simulations (3D RHS) take it into account intrinsically, allowing us to correctly reproduce asymmetric and blue-shifted spectral lines due to the granulation pattern of the stellar disk, which is a very important source of uncertainties at this resolution level (Chiavassa et al. 2017).</p> <p>However, numerical simulations have been computed independently for star and planet so far, while the acquired spectra are an entanglement of both the signals. In particular, some molecular species (e.g, CO) form in the same region of the spectrum, thus planetary and stellar spectral lines are completely mixed and overlapped.<span class="Apple-converted-space"> </span></p> <p>Therefore, a next step forward is needed: computing stellar and planetary models <em>together.</em></p> <p>With our work, we aim at upgrading the already-in-place 3D radiative transfer code Optim3D (Chiavassa et al. 2009) —largely used for stellar purposes so far — to taking into account also the exoplanetary contribution.<span class="Apple-converted-space"> </span>We propose to use simultaneously 3D RHS, performed for stars, and the innovative Global Climate Model (GCM), drawn up for exoplanets, in order to generate unprecedented precise synthetic spectra. As a springboard to test the code, we are carrying out the analysis of CO and H2O molecules on the well-know benchmark HD189733. Indeed, to disentangle those star’s and its companion’s signals due to the same molecules is one of the most challenging problems. In the end, we will be able to compute a complete dynamic characterisation: on one side, a precise knowledge of the stellar dynamic (i.e. convection-related surface structures) would allow to extract unequivocally the planetary signal; on the other one, a well-modelled dynamic of the planet (i.e. depth, shape, and position of spectral lines) would provide us with considerable information about the planetary atmospheric circulation.</p>

scholarly journals A non-iterative linear retrieval for infrared high-resolution limb sounders

2013 ◽  
Vol 6 (5) ◽  
pp. 1381-1396
Author(s):  
L. Millán ◽  
A. Dudhia
Keyword(s):  
High Resolution ◽  
Computing Time ◽  
Michelson Interferometer ◽  
High Spectral Resolution ◽  
Radiative Transfer Model ◽  
Spectral Signature ◽  
Transfer Model ◽  
Concentration Difference ◽  
Error Margin ◽  
Retrieval Scheme

Abstract. Currently, most of the high-spectral-resolution infrared limb sounders use subsets of the recorded spectra (microwindows) in their retrieval schemes to reduce the computing time of rerunning the radiative transfer model. A fast linear retrieval scheme is described which allows the whole spectral signature of the target molecule to be used. We determine that pressure and temperature retrievals can be treated linearly up to a 20% difference between the atmospheric state and the linearisation point for a 3% error margin and up to 10 K "difference" for a 3 K error margin near the stratopause and less than 0.5 K elsewhere. Assuming perfect pT knowledge, CH4 retrievals can be be treated linearly up to a 20% CH4 concentration "difference" for a 2% error margin. As an example, this technique is implemented for the Michelson Interferometer for Passive Atmospheric Sounding instrument, but it is applicable to any high-resolution limb sounder.

scholarly journals The Structure of the HH39 Region

1987 ◽  
Vol 115 ◽  
pp. 340-341
Author(s):  
J. R. Walsh
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Proper Motion ◽  
High Velocity ◽  
Velocity Structure ◽  
The Other ◽  
Emission Lines ◽  
High Resolution Spectroscopy ◽  
Bow Shocks ◽  
Hh Objects

HH39 is the group of Herbig-Haro (HH) objects associated with the young semi-stellar object R Monocerotis (R Mon) and the variable reflection nebula NGC 2261. An R CCD frame and a B prime focus plate of the region show a filament connecting NGC 2261 with HH39, confirming the association between R Mon and the HH objects. This filament is probably composed of emission material. The southern knot in HH39 has brightened over the last 20 years; its proper motion has been determined and is similar to that of the other knots. A total of 8 knots can be distinguished in HH39 surrounded by diffuse nebulosity. High resolution spectroscopy of the Hα and [N II] emission lines shows the spatial variation of the radial velocity structure over the largest knots (HH39 A and C). Distinct differences in excitation and velocity structure between the knots are apparent. The observations are compatible with the knots being high velocity ejecta from R Mon, decelerated by interaction with ambient material and with bow shocks on their front surfaces.

scholarly journals A non-iterative linear retrieval for infrared high resolution limb sounders

2013 ◽  
Vol 6 (1) ◽  
pp. 721-766
Author(s):  
L. Millán ◽  
A. Dudhia
Keyword(s):  
High Resolution ◽  
Computing Time ◽  
Michelson Interferometer ◽  
High Spectral Resolution ◽  
Radiative Transfer Model ◽  
Spectral Signature ◽  
Transfer Model ◽  
Gas Concentration ◽  
Atmospheric Sounding ◽  
Retrieval Scheme

Abstract. Currently most of the high spectral resolution infrared limb sounders use subsets of the recorded spectra (microwindows) in their retrieval schemes to reduce the computing time of rerunning the radiative transfer model. A fast linear retrieval scheme is described which allows the whole spectral signature of the target molecule to be used. We determine how close the linearisation point needs to be to the solution in order to fall in the linear regime and also suggest an adjustment to the forward model and Jacobians to propagate the change in pressure and temperature on the gas concentration retrievals. As an example, this technique is implemented for the Michelson Interferometer for Passive Atmospheric Sounding instrument, but it is applicable to any high resolution limb sounder.

scholarly journals Radial velocity follow-up for confirmation and characterization of transiting exoplanets

2008 ◽  
Vol 4 (S253) ◽  
pp. 129-139 ◽  
Author(s):  
François Bouchy ◽  
Claire Moutou ◽  
Didier Queloz ◽  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Space Mission ◽  
High Resolution Spectroscopy

AbstractRadial Velocity follow-up is essential to establish or exclude the planetary nature of a transiting companion as well as to accurately determine its mass. Here we present some elements of an efficient Doppler follow-up strategy, based on high-resolution spectroscopy, devoted to the characterization of transiting candidates. Some aspects and results of the radial velocity follow-up of the CoRoT space mission are presented in order to illustrate the strategy used to deal with the zoo of transiting candidates.

scholarly journals Transit Search for Exoplanets with the Vulcan Camera

2004 ◽  
Vol 202 ◽  
pp. 69-71
Author(s):  
Douglas A. Caldwell ◽  
W. J. Borucki ◽  
J. M. Jenkins ◽  
D. G. Koch ◽  
L. Webster ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Data Reduction ◽  
Extrasolar Planets ◽  
Galactic Plane ◽  
Variable Stars ◽  
Current Data ◽  
Eclipsing Binaries ◽  
High Resolution Spectroscopy ◽  
Nasa Ames Research

The NASA Ames Research Center's Vulcan photometer is being used in a search for close–in giant extrasolar planets. With our current data reduction system we achieve 0.2–0.8% hour–to–hour relative photometric precision on ∽ 6000 stars brighter than 13th magnitude. Three Galactic-plane fields have so far yielded hundreds of variable stars, including ∽ 50 eclipsing or interacting binaries per field. Several candidate detections have been followed up with radial velocity observations. High-resolution spectroscopy revealed many of the strongest candidates to be grazing eclipsing binaries.

scholarly journals The inhomogeneous wind of the LBV candidate Cyg OB2 No.12

2010 ◽  
Vol 6 (S272) ◽  
pp. 400-401
Author(s):  
Valentina G. Klochkova ◽  
Eugene L. Chentsov ◽  
Anatoly S. Miroshnichenko
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Stellar Atmosphere ◽  
Time Variable ◽  
High Resolution Spectroscopy ◽  
Spectral Features ◽  
Velocity Data ◽  
Absorption Component ◽  
Hα Emission ◽  
Radial Velocity Data

AbstractWe present the results of high-resolution spectroscopy of the extremely luminous star Cyg OB2 No. 12. We identified about 200 spectral features in the range 4552–7939 Å, including the interstellar Na I, K I lines and numerous very strong DIBs, along with the He I, C II, and Si II lines. An MK spectral type we derived for the object is B4.5±0.5 Ia+. Our analysis of the radial velocity data shows the presence of a gradient in the stellar atmosphere, caused by both atmospheric expansion and matter infall onto the star. The Hα emission displays broad Thompson wings, a slightly blue-shifted P Cyg type absorption component and a time-variable core absorption. We conclude that the wind is variable in time.

scholarly journals Stellar activity of planetary host star HD 189733

2008 ◽  
Vol 4 (S253) ◽  
pp. 462-465
Author(s):  
I. Boisse ◽  
C. Moutou ◽  
A. Vidal-Madjar ◽  
F. Bouchy ◽  
F. Pont ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
High Precision ◽  
Velocity Gradient ◽  
Orbital Motion ◽  
Spectral Lines ◽  
Stellar Surface ◽  
Stellar Activity ◽  
Orbital Parameters

AbstractExoplanet search programs need to study how to disentangle radial-velocity (RV) variations due to Doppler motion and the noise induced by stellar activity. We monitored the active K2V HD 189733 with the high-resolution SOPHIE spectrograph (OHP, France). We refined the orbital parameters of HD 189733b and put limitations on the eccentricity and on a long-term velocity gradient. We subtracted the orbital motion of the planet and compared the variability of activity spectroscopic indices (HeI, Hα, Ca II H&K lines) to the evolution of the RV residuals and the shape of spectral lines. All are in agreement with an active stellar surface in rotation. We used such correlations to correct for the RV jitter due to stellar activity. This results in achieving a high precision on the orbital parameters, with a semi-amplitude: K=200.56±0.88m⋅s−1 and a derived planet mass of MP=1.13±0.03 MJup.

scholarly journals Modeling the High-resolution Emission Spectra of Clear and Cloudy Nontransiting Hot Jupiters

2021 ◽  
Vol 923 (1) ◽  
pp. 62
Author(s):  
Isaac Malsky ◽  
Emily Rauscher ◽  
Eliza M.-R. Kempton ◽  
Michael Roman ◽  
Deryl Long ◽  
...  
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
Emission Spectra ◽  
Spectral Lines ◽  
Orbital Inclination ◽  
Hot Jupiters ◽  
Cloud Coverage ◽  
Doppler Shifts ◽  
Dimensional Models ◽  
Three Dimensional Models

Abstract The advent of high-resolution spectroscopy (R ≳ 25,000) as a method for characterization of exoplanet atmospheres has expanded our capability to study nontransiting planets, vastly increasing the number of planets accessible for observation. Many of the most favorable targets for atmospheric characterization are hot Jupiters, where we expect large spatial variation in physical conditions such as temperature, wind speed, and cloud coverage, making viewing geometry important. Three-dimensional models have generally simulated observational properties of hot Jupiters assuming edge-on viewing, which can be compared to observations of transiting planets, but neglected the large fraction of planets without nearly edge-on orbits. As the first investigation of how orbital inclination manifests in high-resolution emission spectra from three-dimensional models, we use a general circulation model to simulate the atmospheric structure of Upsilon Andromedae b, a typical nontransiting hot Jupiter with high observational interest, due the brightness of its host star. We compare models with and without clouds, and find that cloud coverage intensifies spatial variations by making colder regions dimmer and relatedly enhancing emission from the clear, hotter regions. This increases both the net Doppler shifts and the variation of the continuum flux amplitude over the course of the planet’s orbit. In order to accurately capture scattering from clouds, we implement a generalized two-stream radiative transfer routine for inhomogeneous multiple scattering atmospheres. As orbital inclination decreases, four key features of the high-resolution emission spectra also decrease in both the clear and cloudy models: (1) the average continuum flux level, (2) the amplitude of the variation in continuum with orbital phase, (3) net Doppler shifts of spectral lines, and (4) Doppler broadening in the spectra. Models capable of treating inhomogeneous cloud coverage and different viewing geometries are critical in understanding results from high-resolution emission spectra, enabling an additional avenue to investigate these extreme atmospheres.

Sign in / Sign up

Export Citation Format

Share Document