Table 5 - uploaded by Alain Smette
Content may be subject to copyright.
Representative measurements of the accuracy of the telluric correction in spectral ranges affected by unsaturated or moderately saturated lines.
Source publication
Context: The interaction of the light from astronomical objects with the
constituents of the Earth's atmosphere leads to the formation of telluric
absorption lines in ground-based collected spectra. Correcting for these lines,
mostly affecting the red and infrared region of the spectrum, usually relies on
observations of specific stars obtained clo...
Contexts in source publication
Context 1
... continuum was fitted locally by a low-degree polynomial on each of the two ranges of the telluric-corrected spectrum. Representative values of σ are reported in Table 5. ...
Similar publications
![Figure 1. Configuration of AO's system [5]. Figure 2. European...](publication/334862407/figure/fig1/AS:787266138025984@1564710282077/Configuration-of-AOs-system-5-Figure-2-European-Extremely-Large-Telescopes_Q320.jpg)
![Figure 3. Comparison between primary mirrors of optical telescopes [8].](publication/334862407/figure/fig2/AS:787266138038274@1564710282143/Comparison-between-primary-mirrors-of-optical-telescopes-8_Q320.jpg)
The atmospheric turbulence limits the angular resolution of telescopes of tens of meters to that of a telescope of 20 cm diameter. Large telescopes, such as the VLT and the E-ELT, have adopted the Adaptive Optics (AO) system to reduce the undesirable effects of turbulence. The implantation of the technology of “sodium-LGSs” is essential to increase...
Citations
... For each source, we downloaded the Phase 3 data products from the ESO archive. Each exposure was corrected for telluric absorption using molecfit (Kausch et al. 2015;Smette et al. 2015). Where more than one exposure was present for a source, all such observations were combined to give the best signal-to-noise ratio spectrum for each quasar. ...
Understanding the links between different phases of outflows from active galactic nuclei is a key goal in extragalactic astrophysics. Here we compare [OIII] $\lambda\lambda$4960,5008 outflow signatures in quasars with and without Broad Absorption Lines (BALs), aiming to test how the broad absorption troughs seen in the rest-frame ultraviolet are linked to the narrow line region outflows seen in the rest-frame optical. We present new near-infrared spectra from Magellan/FIRE which cover [OIII] in 12 quasars with 2.1 < z < 2.3, selected to have strong outflow signatures in CIV $\lambda$1550. Combining with data from the literature, we build a sample of 73 BAL, 115 miniBAL and 125 non-BAL QSOs with 1.5 < z < 2.6. The strength and velocity width of [OIII] correlate strongly with the CIV emission properties, but no significant difference is seen in the [OIII] emission-line properties between the BALs, non-BALs and miniBALs once the dependence on CIV emission is taken into account. A weak correlation is observed between the velocities of CIV BALs and [OIII] emission, which is accounted for by the fact that both outflow signatures correlate with the underlying CIV emission properties. Our results add to the growing evidence that BALs and non-BALs are drawn from the same parent population and are consistent with a scenario wherein BAL troughs are intermittent tracers of persistent quasar outflows, with a part of such outflow becoming optically thick along our line-of-sight for sporadic periods of time within which BALs are observed.
... Another consideration to take into account when calibrating against observed stars is whether the measured flux of these stars has been corrected or not for atmospheric telluric absorption features (e.g., Gullikson et al. 2014;Smette et al. 2015). As we shall see below, these absorption features generate uncertainty in the calibration at their wavelengths given their intrinsic variability. ...
The Physics of the Accelerating Universe (PAU) camera is an optical narrow band and broad band imaging instrument mounted at the prime focus of the William Herschel Telescope. We describe the image calibration procedure of the PAU Survey data. We rely on an external photometric catalogue to calibrate our narrow band data using stars that have been observed by both datasets. We fit stellar templates to the stellar broad band photometry of the Sloan Digital Sky Survey and synthesise narrow band photometry that we compare to the PAUS narrow band data to determine their calibration. Consequently, the PAUS data are in the AB system as inherited from its reference calibrator. We do several tests to check the performance of the calibration. We find it self-consistent when comparing repeated observations of the same objects, with a good overall accuracy to the AB system which we estimate to be at the 2\% precision level and no significant trends as a function of narrow band filter or wavelength. Repeated observations allow us to build a spatial map of the illumination pattern of the system. We also check the wavelength dependence of the calibration comparing to stellar spectra. We find that using only blue stars reduces the effects of variations in the stellar template fitting to broad-band colours, improving the overall precision of the calibration to around 1\% and its wavelength uniformity. The photometric redshift performance obtained with the PAUS data attests to the validity of our calibration to reach the PAUS science goals.
... We then used molecfit 4 (Kausch et al. 2015;Smette et al. 2015) to remove telluric features. We selected telluric absorption lines away from stellar absorption lines to constrain the molecfit model, fitting for atmospheric H 2 O only. ...
... To check our systematic errors in the wavelength solution near the He triplet, we cross-correlated our stellar spectra with model spectra that combined PHOENIX stellar atmosphere models (Husser et al. 2013) with a telluric model from the molecfit 5 software (Kausch et al. 2015;Smette et al. 2015). By cross-correlating sub-sections of the spectral order, we found that the bluest wavelengths (≤ 1.087 µm) were shifted from the truth by ∼30 km s −1 for K2-100b, ∼12 km s −1 for HD 63433b and ∼-10 km s −1 for V1298 Tau c. ...
We search for excess in-transit absorption of neutral helium at 1.083 $\mu$m in the atmospheres of the young (<800 Myr) sub-Jovian (0.2-0.5 $\rm R_{J}$) planets HD 63433b, K2-100b, and V1298 Tau c using high-resolution (R~25,000) transit observations taken with Keck II/NIRSPEC. Our observations do not show evidence of helium absorption for any of the planets in our sample. We calculate 3$\sigma$ upper limits on the planets' excess helium absorption of <0.47% for HD 63433b, <0.56% for K2-100b, and <1.13% for V1298 Tau c. In terms of equivalent width, we constrain these to <2.52, <4.44, and <8.49 mA for HD 63433b, K2-100b, and V1298 Tau c, respectively. We fit our transmission spectra with one-dimensional Parker wind models to determine upper limits on the planets' mass-loss rates of <7.9$\times10^{10}$, <1.25$\times10^{11}$, and <$7.9\times10^{11}$g s$^{-1}$. Our non-detections align with expectations from one-dimensional hydrodynamic escape models, magnetic fields, and stellar wind confinement. The upper limits we measure for these planets are consistent with predicted trends in system age and He equivalent width from 1D hydrodynamic models.
... Therefore, to date, high-resolution transmission spectroscopy has predominantly been used to characterize the atmospheres of hot Jupiters. The subtraction of a telluric model, which has been used commonly in the optical, e.g., using Molecfit (Smette et al. 2015), is often not able to sufficiently isolate the planet signal in the NIR. ...
In recent years, high-resolution transmission spectroscopy in the near-infrared has led to detections of prominent molecules in several giant exoplanets on close-in orbits. This approach has traditionally relied on the large Doppler shifts of the planetary spectral lines induced by the high velocities of close-in planets, which were considered necessary for separating them from the quasi-static stellar and telluric lines. In this work, we demonstrate the feasibility of high-resolution transmission spectroscopy for chemical detections in atmospheres of temperate low-mass exoplanets around M dwarfs with low radial velocity variation during transit. We pursue this goal using model injection and recovery tests with H - and K -band high-resolution spectroscopy of the temperate sub-Neptune TOI-732 c, observed using the IGRINS spectrograph on Gemini South. We show that planetary signals in transit may be recovered when the change in the planet’s radial velocity is very small, down to subpixel velocities. This is possible due to the presence of the planetary signal in only a subset of the observed spectra. A sufficient number of out-of-transit spectra can create enough contrast between the planet signal and telluric/stellar contaminants that the planet signal does not constitute a principal component of the time-series spectra and can therefore be isolated using principal-component-analysis-based detrending without relying on a significant Doppler shift. We additionally explore novel metrics for finding such signals, and investigate trends in their detectability. Our work extends the scope of high-resolution transmission spectroscopy and creates a pathway toward the characterization of habitable sub-Neptune worlds with ground-based facilities.
... All of these indicators have observed periodogram peaks around 39 days, however, so dropping the other lines from our analysis does not affect our results. It may be interesting in the future to attempt to fit out these lines (using a package like molecfit, see Smette et al. 2015;Kausch et al. 2015) for the purposes of determining telluric-corrected activity indicators, but is unnecessary in this case due to the relatively unambigous nature of the signal in the other indices. The activity indicators give us a clear sign that the rotation period of the A star is around 40 days. ...
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.
... The Tellfit synthetic model is limited to wavelengths below 5 m, and therefore the telluric reference model for the calibration of the reddest order (5.13-5.21 m), is generated by Molecfit (Smette et al. 2015). Calibration is also tested with Molecfit providing the stable telluric reference for all orders, but the generated models show a sub-optimal match to our data at shorter wavelengths. ...
High-resolution cross-correlation spectroscopy (HRCCS) combined with adaptive optics has been enormously successful in advancing our knowledge of exoplanet atmospheres, from chemistry to rotation and atmospheric dynamics. This powerful technique now drives major science cases for ELT instrumentation including METIS/ELT, GMTNIRS/GMT and MICHI/TMT, targeting biosignatures on rocky planets at 3-5 $\mu$m, but remains untested beyond 3.5 $\mu$m where the sky thermal background begins to provide the dominant contribution to the noise. We present 3.51-5.21 $\mu$m M-band CRIRES+/VLT observations of the archetypal young directly imaged gas giant $\beta$ Pictoris b, detecting CO absorption at S/N = 6.6 at 4.73 $\mu$m and H$_2$O at S/N = 5.7, and thus extending the use of HRCCS into the thermal background noise dominated infrared. Using this novel spectral range to search for more diverse chemistry we report marginal evidence of SiO at S/N = 4.3, potentially indicative that previously proposed magnesium-silicate clouds in the atmosphere are either patchy, transparent at M-band wavelengths, or possibly absent on the planetary hemisphere observed. The molecular detections are rotationally broadened by the spin of $\beta$ Pic b, and we infer a planetary rotation velocity of $v$sin(i) = 22$\pm$2 km s$^{-1}$ from the cross-correlation with the H$_2$O model template, consistent with previous K-band studies. We discuss the observational challenges posed by the thermal background and telluric contamination in the M-band, the custom analysis procedures required to mitigate these issues, and the opportunities to exploit this new infrared window for HRCCS using existing and next-generation instrumentation.
... Stare mode was used for the first two epochs, while nod on slit was used for the last epoch, so the spectra from the near-IR (NIR) arm can be extracted. We used the standard ESO data reduction pipeline esoreflex (Freudling et al. 2013) and molecfit (Kausch et al. 2015;Smette et al. 2015). The complete spectrum of Gaia J0611−6931 is shown in Figure 1. ...
The chemical composition of an extrasolar planet is fundamental to its formation, evolution, and habitability. In this study, we explore a new way to measure the chemical composition of the building blocks of extrasolar planets by measuring the gas composition of the disrupted planetesimals around white dwarf stars. As a first attempt, we used the photoionization code Cloudy to model the circumstellar gas emission around white dwarf Gaia J0611−6931 under some simplified assumptions. We found that most of the emission lines are saturated, and the line ratios approach the ratios of thermal emission; therefore, only lower limits to the number density can be derived. Silicon is the best-constrained element in the circumstellar gas, and we derived a lower limit of 10 10.3 cm ⁻³ . In addition, we placed a lower limit on the total amount of gas to be 1.8 × 10 ¹⁹ g. Further study is needed to better constrain the parameters of the gas disk and connect it to other white dwarfs with circumstellar gas absorption.
... Not only does the telluric absorption shape the nonflat continuum near the coronal line, it may also attenuate a portion of the coronal line itself. In astronomy, multiple telluric calibration strategies have been advanced (see, e.g., Smette et al. 2015), which also have a similar applicability to the solar case. These can include the use of atlases of telluric absorption spectra; calibration measurements of standard sources, which for the Sun is the disk-center or integrated quiet-Sun spectra; or synthetic modeling of the telluric absorption. ...
... Figure 5, in particular, demonstrates the results attainable from DKIST and Cryo-NIRSP even when humidity conditions fluctuate, provided one carefully accounts for the impacts of telluric absorption during the background-removal process. The method introduced here (Section 4.2) bypasses the need for a direct modeling of the entire telluric absorption profile, which, as in Smette et al. (2015), requires more detailed knowledge of the local atmospheric profile during the observations. Instead, we only model the fluctuations in the water absorbance between the science observations and the flatfield calibration measurements using a single constant-property slab model. ...
We report commissioning observations of the Si x 1430 nm solar coronal line observed coronagraphically with the Cryogenic Near-Infrared Spectropolarimeter at the National Science Foundation’s Daniel K. Inouye Solar Telescope. These are the first known spatially resolved observations of this spectral line, which has strong potential as a coronal magnetic field diagnostic. The observations target a complex active region located on the solar northeast limb on 2022 March 4. We present a first analysis of these data that extracts the spectral line properties through a careful treatment of the variable atmospheric transmission that is known to impact this spectral window. Rastered images are created and compared with extreme-UV observations from the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) instrument. A method for estimating the electron density from the Si x observations is then demonstrated that makes use of the forbidden line density-sensitive emissivity and an emission-measure analysis of the SDO/AIA bandpass observations. In addition, we derive an effective temperature and nonthermal line width across the region. This study informs the calibration approaches required for more routine observations of this promising diagnostic line.
... Nor does redness appear to correlate with the delivered image quality (IQ). Low-level variations in atmospheric transmission may occur on timescales of minutes at λ > 0.65 μm because changes to the precipitable water wavor (PWV) present in Earth's atmosphere along an observer's line of sight can drive variations in the strength of telluric water absorption bands (see Smette et al. 2015). Although variation in PWV could be a convenient explanation for the observed variation in the spectrum of 2004 GV 9 , it is not monitored by Gemini South, precluding checks for causal links between PWV and the redness of 2004 GV 9 at λ > 0.65 μm. ...
... Here we elaborate on the selection process for the binning factor of each spectrum. For a given spectrum, we selected an appropriate binning factor through a process of iterative trialand-error testing of different binning factors and comparative visual inspection of the binned spectrum, the unbinned 2D spectroscopic frames mapping the location of sky emission lines, and published maps of optical-NIR telluric absorption bands (Smette et al. 2015). ...
We present new optical reflectance spectra of three potentially silicate-rich trans-Neptunian objects (TNOs). These spectra were obtained with the aim of confirming past hints and detections of λ ∼ 0.7 μ m absorption features associated with the presence of iron-bearing phyllosilicates. Our new spectrum of 120216 (2004 EW 95 ) presents clearly detected absorption features that are similar in shape to hydrated mineral absorption bands present in the spectra of aqueously altered outer main belt asteroids. Four new reflectance spectra of 208996 (2003 AZ 84 ) obtained at separate epochs all appear featureless, but they vary significantly in spectral gradient (between ∼3.5%/0.1 μ m and ∼8.5%/0.1 μ m) on a timescale consistent with this object’s nominal rotational period. We report the first four optical reflectance spectra of 90568 (2004 GV 9 ), finding them all to be featureless but consistent with colors previously reported for this object. We speculate that impacts are the only mechanism capable of delivering, excavating, or forming hydrated minerals at the surfaces of TNOs in detectable concentrations; as a result, any deposits of hydrated minerals on TNOs are predicted to be localized and associated with impact sites. Globally altered TNOs (as observationally suggested for 2004 EW 95 ) plausibly formed more easily at smaller heliocentric distances ( r H < 15 au) before being transplanted into the current trans-Neptunian population.
... The quantification of these bands may allow for simultaneous observations of CO and CO + emission around ∼4.7 μm, which could provide constraints on the CO/CO + abundance and shed light on the production mechanisms of CO + in distant comets (Womack, Sarid & Wierzchos 2017 ). Ho we ver, the detectability of these features is not known at this time, and there exists possible overlap with known H 2 O and O 3 telluric absorption features (Smette et al. 2015 ). ...
A new CO+ fluorescence emission model for analyzing cometary spectra is presented herein. Accurate line lists are produced using the PGOPHER software for all transitions between the three electronic states (X 2Σ, A 2Π, B 2Σ) with vibrational states up to vmax = 9, 8, 6, respectively, and maximum rotational states with rotational quantum numbers N ≤ 20. As a result of improved molecular constants and theoretical transition rates, an expansion of the utilized solar spectrum into the infrared, and the substantial expansion of the included rovibronic states, the model provides an update of the fluorescence efficiencies of the CO+ cation. The dependencies on heliocentric velocity and distance are explicitly included. We report, for the first time, quantification of the fluorescence efficiencies for the ground state rovibrational transitions of CO+ and predict the positions and relative intensities of CO+ lines in windows accessible to both ground- and space-based observatories. The computed fluorescence efficiencies show excellent agreement with UV/optical observations of both C/2016 R2 (Pan-STARRS) and 29P/Schwassmann-Wachmann 1. The updated fluorescence efficiencies allow for revised N2/CO abundances for comets 1P/Halley, C/1987 P1 (Bradfield), and C/2016 R2 (Pan-STARRS), which can change by up to 30% when accounting for recent improvements to CO+ and N$_2^+$ fluorescence efficiencies. The model code, input files, and fluorescence efficiencies are publicly available and distributed on permanent archives for future uses in cometary analyses.
