Ground-based detection of sodium in the transmission spectrum of exoplanet HD209458b

By I. Snellen, A. S, Mooij E J W, L. Poole. 2008

204 citations recorded by the source corpus.

Context. The first detection of an atmosphere around an extrasolar planet was presented by Charbonneau and collaborators in 2002. In the optical transmission spectrum of the transiting exoplanet HD 209458b, an absorption signal from sodium was measured at a level of 0.023 ± 0.006%, using the STIS spectrograph on the Hubble Space Telescope. Despite several attempts, so far only upper limits to the Na D absorption have been obtained using telescopes from the ground, and the HST result has yet to be confirmed. Aims. The aims of this paper are to re-analyse data taken with the High Dispersion Spectrograph on the Subaru telescope, to correct for systematic effects dominating the data quality, and to improve on previous results presented in the literature. Methods. The data reduction process was altered in several places, most importantly allowing for small shifts in the wavelength solution. The relative depth of all lines in the spectra, including the two sodium D lines, are found to correlate strongly with the continuum count level in the spectra. These variations are attributed to non-linearity effects in the CCDs. After removal of this empirical relation the uncertainties in the line depths are only a fraction above that expected from photon statistics. Results. The sodium absorption due to the planet's atmosphere is detected at > 5 σ , at a level of 0.056 ± 0.007% (2 $\times$ 3.0 A band), 0.070 ± 0.011% (2 $\times$ 1.5 A band), and 0.135 ± 0.017% (2 $\times$0.75 Aband). There is no evidence that the planetary absorption signal is shifted with respect to the stellar absorption, as recently claimed for HD 189733b. Conclusions. The STIS/HST measurements are confirmed. The measurements of the Na D absorption in the two most narrow bands indicate that some signal is being resolved. Due to variations in the instrumental resolution and intrinsic variations in the stellar lines due to the Rossiter-McLauglin effect, it will be challenging to probe the planetary absorption on spectral scales smaller than the stellar absorption using conventional transmission spectroscopy.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2304f0889cfb8f348b08952fd195c077b7d3a000

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Atomic and Molecular Physics, and Optics

In Instrumentation

Citations in the corpus

TRANSMISSION SPECTRA OF THREE-DIMENSIONAL HOT JUPITER MODEL ATMOSPHERES (2009, result): “Neutral atomic sodium was first discovered by Charbonneau et al. (2000), and later confirmed by other authors (Snellen et al. 2008; Sing et al. 2008a; Langland-Shula et al. 2009).”
DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b (2011, unknown): “…in the planets’ upper atmospheres (Charbonneau et al. 2002; Vidal-Madjar et al. 2003, 2004, 2008; Ben-Jaffel 2007, 2008; Ballester et al. 2007; Snellen et al. 2008; Redfield et al. 2008; Sing et al. 2008a; Ehrenreich et al. 2008; Langland-Shula et al. 2009; Linsky et al. 2010; Ben-Jaffel…”
Transit spectrophotometry of the exoplanet HD189733b. I. Searching for water but finding haze with HST NICMOS (2009, background): “The atmospheric Na signature has also been confirmed by ground based observations (Snellen et al. 2008).”
Hubble Space Telescope transmission spectroscopy of the exoplanet HD 189733b: high‐altitude atmospheric haze in the optical and near‐ultraviolet with STIS (2011, result): “Sodium was later confirmed from ground-based spectrographs which measured similar absorption levels as the revised STIS data (Snellen et al. 2008; Sing et al. 2008a).”
DETECTION OF AN ATMOSPHERE AROUND THE SUPER-EARTH 55 CANCRI E (2015, background): “…molecular features in the atmospheres of exoplanets, both from the ground (e.g. Redfield et al. 2008; Swain et al. 2010; Waldmann et al. 2012; Snellen et al. 2008, 2010, 2014; Bean et al. 2010, 2013) and from space (e.g. Charbonneau et al. 2002, 2005; Deming et al. 2005, 2011; Knutson et al.…”
Temperature–pressure profile of the hot Jupiter HD 189733b from HST sodium observations: detection of upper atmospheric heating (2012, methodology): “Further analysis of transit observations of HD 209458b by Vidal-Madjar et al. (2011b) and Vidal-Madjar et al. (2011a), combining archive Hubble Space Telescope (HST) and ground-based measurements (Snellen et al. 2008), allowed a temperature-pressure (T -”
Extremely Irradiated Hot Jupiters: Non-oxide Inversions, H− Opacity, and Thermal Dissociation of Molecules (2018, methodology): “…resolution by spectroscopically separating the planet’s flux contribution from its host star and telluric lines in a way very similar to techniques used to detect spectroscopic binary stars (e.g., Snellen et al. 2008; Birkby et al. 2013; de Kok et al. 2013; Brogi et al. 2014; Schwarz et al. 2015).”
HD 209458b in new light: evidence of nitrogen chemistry, patchy clouds and sub-solar water (2017, unknown): “We confirm previous detections of Na (Charbonneau et al. 2002; Snellen et al. 2008) and H2O (Deming et al. 2013) in the transmission spectrum of HD 209458b.”
Hubble Space Telescope hot Jupiter transmission spectral survey: a detection of Na and strong optical absorption in HAT-P-1b (2013, background): “In particular, the optical transmission spectrum of HD 209458b shows broad sodium feature and a lack of potassium (Charbonneau et al. 2002; Sing et al. 2008b; Snellen et al. 2008; Narita et al. 2005).”
A NEW APPROACH TO ANALYZING HST SPATIAL SCANS: THE TRANSMISSION SPECTRUM OF HD 209458 b (2015, background): “…been identified both with ground-based and space-based instruments (e.g. Charbonneau et al. 2002; Vidal-Madjar et al. 2003; Redfield et al. 2008; Snellen et al. 2008; Swain et al. 2009a,b; Linsky et al. 2010; Swain et al. 2010; Tinetti et al. 2010; Crouzet et al. 2012; Majeau et al. 2012;…”
An HST optical-to-near-IR transmission spectrum of the hot Jupiter WASP-19b: detection of atmospheric water and likely absence of TiO (2013, result): “…so far have had mixed results, with HD 209458b showing some of these features (Charbonneau et al. 2002; Narita et al. 2005; Sing et al. 2008; Snellen et al. 2008) while the spectrum of HD 189733b is instead dominated by a slope of increasing planetary radius with decreasing wavelength,…”
Spectrally resolved detection of sodium in the atmosphere of HD 189733b with the HARPS spectrograph (2015, methodology): “Even if the telluric sodium undergoes seasonal variations and possibly does not follow the water absorption levels, we assume that within a night, this telluric sodium absorption behaves and can be corrected for as other telluric features (Snellen et al. 2008; Zhou & Bayliss 2012).”