scholarly journals Stellar contributions to the line profiles of high-resolution transmission spectra of exoplanets

2018 ◽  
Vol 617 ◽  
pp. A134 ◽  
Author(s):  
F. Borsa ◽  
A. Zannoni
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Transmission Spectrum ◽  
Signal To Noise Ratio ◽  
Transmission Spectra ◽  
Line Profiles ◽  
Stellar Rotation ◽  
Stellar Spectra ◽  
Exoplanetary Atmospheres ◽  
Sophisticated Analysis

Context. In-depth studies of exoplanetary atmospheres are starting to become reality. In order to unveil their properties in detail, we need spectra with a higher signal-to-noise ratio (S/N) and also more sophisticated analysis methods. Aims. With high-resolution spectrographs, we can not only detect the sodium feature in the atmosphere of exoplanets, but also characterize it by studying its line profile. After finding a clearly w-shaped sodium line profile in the transmission spectrum of HD 189733b, we investigated the possible sources of contamination given by the star and tried to correct for these spurious deformations. Methods. By analyzing the single transmission spectra of HD 189733b in the wavelength space, we show that the main sodium signal that causes the absorption in the transmission spectrum is centered on the stellar rest frame. We concentrate on two main stellar effects that contaminate the exoplanetary transmission spectrum: center-to-limb variations (CLVs) and stellar rotation. We show the effects on the line profile: while we correct for the CLV using simulated theoretical stellar spectra, we provide a new method, based directly on observational data, to correct for the Rossiter–McLaughlin contribution to the line profile of the retrieved transmission spectrum. Results. We apply the corrections to the spectra of HD 189733b. Our analysis shows line profiles of the Na D lines in the transmission spectrum that are narrower than reported previously. The correction of the sodium D2 line, which is deeper than the D1 line, is probably still incomplete since the planetary radius is larger at this wavelength. A careful detrending from spurious stellar effects followed by an inspection in the velocity space is mandatory when studying the line profile of atmospheric features in the high-resolution transmission spectrum of exoplanets. Since the line profile is used to retrieve atmospheric properties, the resulting atmospheric parameters could be incorrectly estimated when the stellar contamination is not corrected for. Data with higher S/N coupled with improved atmospheric models will allow us to adapt the magnitude of the corrections of stellar effects in an iterative way.

Revisiting the atmosphere of HD 209458b with HARPS-N, CARMENES and ESPRESSO

2020 ◽  
Author(s):  
Núria Casasayas-Barris ◽  
Enric Palle ◽  
Monika Stangret ◽  
Guo Chen ◽  
Fei Yan ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Evolution ◽  
Transmission Spectrum ◽  
State Of The Art ◽  
Signal To Noise Ratio ◽  
Light Curves ◽  
High Resolution Spectroscopy ◽  
Transmission Spectra ◽  
Signal To Noise ◽  
Transmission Spectroscopy

<p>HD 209458b was the first transiting planet discovered, and the first for which its atmosphere, in particular Na I, was detected. With time, it has become one of the most studied planets, with a large diversity of atmospheric studies using low- and high-resolution spectroscopy. Here, we present the analysis of high-resolution transmission spectroscopy of HD 209458b using a total of five transit observations with HARPS-N and CARMENES spectrographs. In contrast to previous studies where atmospheric Na I absorption is detected, we find that, for all of the nights, either individually or combined, the transmission spectra can be explained by the combination of the centre-to-limb variation and the Rossiter-McLaughlin effect. Thus, the transmission spectrum reveals no detectable Na I absorption in HD 209458b. This is also observed in the time-evolution maps and transmission light curves, but at lower signal-to-noise ratio. Other strong lines such as Hα, Ca II IRT, the Mg I triplet region, and K I D1 are analysed, and are also consistent with the modelled effects, without considering any contribution from the exoplanet atmosphere. New ESPRESSO observations, with state-of-the-art stability and considerably larger signal-to-noise, confirm the results of our study and will also be shown.</p>

scholarly journals New Progress in Mode Detection and Identification in δ Scuti Stars by the Analysis of Line Profile Variations

2000 ◽  
Vol 176 ◽  
pp. 463-464
Author(s):  
L. Mantegazza ◽  
E. Poretti ◽  
M. Bossi ◽  
N. S. Nuñez ◽  
A. Sacchi ◽  
...  
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
High Resolution Spectroscopy ◽  
Line Profiles ◽  
Powerful Technique ◽  
Mode Detection ◽  
Detection And Identification ◽  
Scuti Stars ◽  
Δ Scuti Stars ◽  
Nonradial Pulsation

Abstractδ Sct stars are among the most promising targets to perform ground-based asteroseismology. High resolution spectroscopy offers us a powerful technique to identify radial and nonradial pulsation modes, since we can easily detect oscillations and travelling features in the line profiles.

scholarly journals The fast rotating δ Scuti pulsator V376 Per: Frequency analysis and mode identification

2013 ◽  
Vol 9 (S301) ◽  
pp. 499-500
Author(s):  
Nathalie Themessl ◽  
Veronique Fritz ◽  
Michel Breger ◽  
Sabine Karrer ◽  
Barbara G. Castanheira
Keyword(s):  
High Resolution ◽  
Line Profile ◽  
Frequency Analysis ◽  
Spectroscopic Data ◽  
Simultaneous Analysis ◽  
Stellar Spectra ◽  
Mode Identification ◽  
Pulsation Mode ◽  
Scuti Star ◽  
Fast Rotating

AbstractOur simultaneous analysis of ground-based photometric and high-resolution spectroscopic data of the δ Scuti star V376 Per revealed eight individual frequencies from 82 nights of two-color photometry and six frequencies from the line-profile variations using 769 stellar spectra. Additionally, we identified the corresponding pulsation modes and derived reliable estimates of the line profile and pulsation mode parameters.

scholarly journals Combining low- to high-resolution transit spectroscopy of HD 189733b

2018 ◽  
Vol 612 ◽  
pp. A53 ◽  
Author(s):  
Lorenzo Pino ◽  
David Ehrenreich ◽  
Aurélien Wyttenbach ◽  
Vincent Bourrier ◽  
Valerio Nascimbeni ◽  
...  
Keyword(s):  
High Resolution ◽  
Wavelength Range ◽  
Near Infrared ◽  
Theoretical Models ◽  
Apparent Size ◽  
Transmission Spectra ◽  
Infrared Transmission ◽  
Line Spread Function ◽  
Building Models ◽  
Exoplanetary Atmospheres

Space-borne low- to medium-resolution (ℛ ~ 102–103) and ground-based high-resolution spectrographs (ℛ ~ 105) are commonly used to obtain optical and near infrared transmission spectra of exoplanetary atmospheres. In this wavelength range, space-borne observations detect the broadest spectral features (alkali doublets, molecular bands, scattering, etc.), while high-resolution, ground-based observations probe the sharpest features (cores of the alkali lines, molecular lines). The two techniques differ by several aspects. (1) The line spread function of ground-based observations is ~103 times narrower than for space-borne observations; (2) Space-borne transmission spectra probe up to the base of thermosphere (P ≳ 10−6 bar), while ground-based observations can reach lower pressures (down to ~10−11 bar) thanks to their high resolution; (3) Space-borne observations directly yield the transit depth of the planet, while ground-based observations can only measure differences in the apparent size of the planet at different wavelengths. These differences make it challenging to combine both techniques. Here, we develop a robust method to compare theoretical models with observations at different resolutions. We introduce πη, a line-by-line 1D radiative transfer code to compute theoretical transmission spectra over a broad wavelength range at very high resolution (ℛ ~ 106, or Δλ ~ 0.01 Å). An hybrid forward modeling/retrieval optimization scheme is devised to deal with the large computational resources required by modeling a broad wavelength range ~0.3–2 μm at high resolution. We apply our technique to HD 189733b. In this planet, HST observations reveal a flattened spectrum due to scattering by aerosols, while high-resolution ground-based HARPS observations reveal sharp features corresponding to the cores of sodium lines. We reconcile these apparent contrasting results by building models that reproduce simultaneously both data sets, from the troposphere to the thermosphere. We confirm: (1) the presence of scattering by tropospheric aerosols; (2) that the sodium core feature is of thermospheric origin. When we take into account the presence of aerosols, the large contrast of the core of the sodium lines measured by HARPS indicates a temperature of up to ~10 000K in the thermosphere, higher than what reported in the literature. We also show that the precise value of the thermospheric temperature is degenerate with the relative optical depth of sodium, controlled by its abundance, and of the aerosol deck.

scholarly journals Non-radial Pulsation Modeling of ω (28) CMa

2000 ◽  
Vol 175 ◽  
pp. 244-247 ◽  
Author(s):  
M. Maintz ◽  
Th. Rivinius ◽  
S. Tubbesing ◽  
B. Wolf ◽  
S. Štefl ◽  
...  
Keyword(s):  
Velocity Field ◽  
Line Profile ◽  
Inertial Frame ◽  
Absorption Lines ◽  
Pulsation Period ◽  
Radial Pulsation ◽  
Line Profiles ◽  
Stellar Rotation ◽  
Velocity Effect

AbstractAdopting non-radial pulsation (nrp) the line profile variability lpv of several absorption lines of different ions was modeled for ω (28) CMa. The parameters suggested by Baade (1982) to characterise the pulsation could be confirmed. The pulsation period in the inertial frame was found to be negative, i.e. an actually retrograde mode appears prograde due to the rapid stellar rotation. The line profiles could be reproduced in detail including structures like spikes and ramps. They were identified as velocity effect due to the latitudinal component of the nrp velocity field υϑ in combination with low inclination i. In spite of small photometric variations (Štefl et al. 1999) the lpv of the absorption lines can be explained by nrp entirely.

scholarly journals Probing the atmosphere of HD189733b with the Na i and K i lines

2020 ◽  
Vol 498 (1) ◽  
pp. 1023-1033
Author(s):  
E Keles ◽  
D Kitzmann ◽  
M Mallonn ◽  
X Alexoudi ◽  
L Fossati ◽  
...  
Keyword(s):  
High Resolution ◽  
High Altitude ◽  
Spectral Resolution ◽  
Absorption Lines ◽  
High Spectral Resolution ◽  
Transmission Spectra ◽  
Line Profiles ◽  
Line Broadening ◽  
Atmospheric Processes ◽  
Hot Jupiters

ABSTRACT High spectral resolution transmission spectroscopy is a powerful tool to characterize exoplanet atmospheres. Especially for hot Jupiters, this technique is highly relevant, due to their high-altitude absorption, e.g. from resonant sodium (Na i) and potassium (K i) lines. We resolve the atmospheric K i absorption on HD189733b with the aim to compare the resolved K i line and previously obtained high-resolution Na i-D line observations with synthetic transmission spectra. The line profiles suggest atmospheric processes leading to a line broadening of the order of ∼10 km/s for the Na i-D lines and only a few km/s for the K i line. The investigation hints that either the atmosphere of HD189733b lacks a significant amount of K i or the alkali lines probe different atmospheric regions with different temperature, which could explain the differences we see in the resolved absorption lines.

scholarly journals Assessing telluric correction methods for Na detections with high-resolution exoplanet transmission spectroscopy

2021 ◽  
Vol 502 (3) ◽  
pp. 4392-4404
Author(s):  
Adam B Langeveld ◽  
Nikku Madhusudhan ◽  
Samuel H C Cabot ◽  
Simon T Hodgkin
Keyword(s):  
High Resolution ◽  
Transmission Spectrum ◽  
Atmospheric Model ◽  
Atmospheric Conditions ◽  
Transmission Spectroscopy ◽  
Doublet Line ◽  
Exoplanetary Atmospheres ◽  
Planetary Transmission ◽  
Spurious Signals

ABSTRACT Using high-resolution ground-based transmission spectroscopy to probe exoplanetary atmospheres is difficult due to the inherent telluric contamination from absorption in Earth’s atmosphere. A variety of methods have previously been used to remove telluric features in the optical regime and calculate the planetary transmission spectrum. In this paper we present and compare two such methods, specifically focusing on Na detections using high-resolution optical transmission spectra: (1) calculating the telluric absorption empirically based on the airmass and (2) using a model of the Earth’s transmission spectrum. We test these methods on the transmission spectrum of the hot Jupiter HD 189733 b using archival data obtained with the HARPS spectrograph during three transits. Using models for Centre-to-Limb Variation and the Rossiter–McLaughlin effect, spurious signals which are imprinted within the transmission spectrum are reduced. We find that correcting tellurics with an atmospheric model of the Earth is more robust and produces consistent results when applied to data from different nights with changing atmospheric conditions. We confirm the detection of sodium in the atmosphere of HD 189733 b, with doublet line contrasts of $-0.64 \pm 0.07~{{\ \rm per\ cent}}$ (D2) and $-0.53 \pm 0.07~{{\ \rm per\ cent}}$ (D1). The average line contrast corresponds to an effective photosphere in the Na line located around 1.13 Rp. We also confirm an overall blueshift of the line centroids corresponding to net atmospheric eastward winds with a speed of 1.8 ± 1.2 km s−1. Our study highlights the importance of accurate telluric removal for consistent and reliable characterization of exoplanetary atmospheres using high-resolution transmission spectroscopy.

scholarly journals Planned Observations of Hot Gas in the LISM

1997 ◽  
Vol 166 ◽  
pp. 95-98
Author(s):  
R. McLean ◽  
J.C. Green ◽  
K.S. Gunderson
Keyword(s):  
High Resolution ◽  
Column Density ◽  
Signal To Noise Ratio ◽  
Gas Absorption ◽  
Line Profiles ◽  
Local Interstellar Medium ◽  
Local Bubble ◽  
Hot Gas ◽  
Production Models ◽  
Oxygen Profiles

AbstractWe plan to observe hot gas in the local interstellar medium (LISM) at high resolution using a rocket-borne spectrograph that can simultaneously observe OVI, NV and CIV at resolutions of 1 – 2kms−1. Data from a single flight will have sufficient signal to noise ratio to detect a broad 50kms−1 component down to a column density of N ≥ 0.5 × 1013cm−2. High-velocity components as fast as 300kms−1 can be detected. New high resolution observations of hot gas absorption line profiles will probe the kinematics of the local bubble, and comparison between the carbon, nitrogen and oxygen profiles will allow discrimination between the various production models.

scholarly journals Is there Na I in the atmosphere of HD 209458b?

2020 ◽  
Vol 635 ◽  
pp. A206 ◽  
Author(s):  
N. Casasayas-Barris ◽  
E. Pallé ◽  
F. Yan ◽  
G. Chen ◽  
R. Luque ◽  
...  
Keyword(s):  
High Resolution ◽  
Signal To Noise Ratio ◽  
Planetary Atmospheres ◽  
Light Curves ◽  
High Resolution Spectroscopy ◽  
Transmission Spectra ◽  
Spin Orbit ◽  
Velocity Data ◽  
Signal To Noise ◽  
Radial Velocity Data

HD 209458b was the first transiting planet discovered, and the first for which an atmosphere, in particular Na I, was detected. With time, it has become one of the most frequently studied planets, with a large diversity of atmospheric studies using low- and high-resolution spectroscopy. Here, we present transit spectroscopy observations of HD 209458b using the HARPS-N and CARMENES spectrographs. We fit the Rossiter-McLaughlin effect by combining radial velocity data from both instruments (nine transits in total), measuring a projected spin-orbit angle of − 1.6 ± 0.3 deg. We also present the analysis of high-resolution transmission spectroscopy around the Na I region at 590 nm, using a total of five transit observations. In contrast to previous studies where atmospheric Na I absorption is detected, we find that for all of the nights, whether individually or combined, the transmission spectra can be explained by the combination of the centre-to-limb variation and the Rossiter-McLaughlin effect. This is also observed in the time-evolution maps and transmission light curves, but at lower signal-to-noise ratio. Other strong lines such as Hα, Ca II IRT, the Mg I triplet region, and K I D1 are analysed, and are also consistent with the modelled effects, without considering any contribution from the exoplanet atmosphere. Thus, the transmission spectrum reveals no detectable Na I absorption in HD 209458b. We discuss how previous pioneering studies of this benchmark object may have overlooked these effects. While for some star–planet systems these effects are small, for other planetary atmospheres the results reported in the literature may require revision.

scholarly journals Theoretical Narrow Emission-Line Profiles of Active Galactic Nuclei

1989 ◽  
Vol 134 ◽  
pp. 318-319
Author(s):  
M. Contini ◽  
S.M. Viegas-Aldrovandi
Keyword(s):  
High Resolution ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
Line Profile ◽  
Galactic Nuclei ◽  
Line Profiles ◽  
Narrow Emission

In recent years, a large number of high resolution observations of active galactic nuclei (AGN) have become available. Most of them show the [OIII]5007 line profile (Heckman, Miley and Green 1984, Vrtilek and Carleton 1985, Whittle 1985a,b).

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