scholarly journals Doppler shifts and spectral line profile changes in the starlight scattered from an exoplanet

2020 ◽  
Vol 493 (2) ◽  
pp. 1596-1613
Author(s):  
John B P Strachan ◽  
Guillem Anglada-Escudé
Keyword(s):  
Spectral Line ◽  
Doppler Shift ◽  
Finite Size ◽  
Flux Ratio ◽  
Software Tool ◽  
High Resolution Spectroscopy ◽  
Circular Orbits ◽  
Hot Jupiters ◽  
Doppler Shifts ◽  
Reflected Light

ABSTRACT Scattered starlight from an exoplanet, commonly called reflected light, can be used to characterize the planet including the determination of its albedo and inclination of orbit. The relatively low flux ratio between directly observed starlight and starlight scattered off hot Jupiters make these systems the prime candidates for detection of reflected light using high-resolution spectroscopy. The first detections have been claimed for 51 Peg b. In a first calculation, we derive the Doppler shift of reflected light measured by a remote observer for a planet modelled as a point-like particle in orbit around a star. We find that the Doppler shift of reflected light from planets have a different Doppler shift to that of light emitted directly from the planet with magnitude equivalent to the radial motion of the planet with respect to the star. This only occurs for non-circular orbits. Secondly, restricting our investigation to planets that are tidally locked and orbit in circular orbits we account for the finite size of the star and planet by integrating the contribution to a simulated spectral line across both their surfaces. Since exact analytical expressions cannot be easily derived as a function of all free parameters of the problem, we have developed a software tool called REflected STARlighT (restart) that produces the resulting line profiles. By applying it to study cases found in the literature, we explicitly show that hot Jupiters such as WASP-19b and 51 Peg b should show substantial broadening and asymmetric distortions compared to the nominal stellar line.

scholarly journals TOI-150b and TOI-163b: two transiting hot Jupiters, one eccentric and one inflated, revealed by TESS near and at the edge of the JWST CVZ

2019 ◽  
Vol 490 (1) ◽  
pp. 1094-1110 ◽  
Author(s):  
Diana Kossakowski ◽  
Néstor Espinoza ◽  
Rafael Brahm ◽  
Andrés Jordán ◽  
Thomas Henning ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Scale ◽  
High Resolution Spectroscopy ◽  
Spin Orbit ◽  
Eccentric Orbit ◽  
Hot Jupiters ◽  
Eclipse Observations ◽  
James Webb Space Telescope ◽  
Hot Jupiter

Abstract We present the discovery of TYC9191-519-1b (TOI-150b, TIC 271893367) and HD271181b (TOI-163b, TIC 179317684), two hot Jupiters initially detected using 30-min cadence Transiting Exoplanet Survey Satellite (TESS) photometry from Sector 1 and thoroughly characterized through follow-up photometry (CHAT, Hazelwood, LCO/CTIO, El Sauce, TRAPPIST-S), high-resolution spectroscopy (FEROS, CORALIE), and speckle imaging (Gemini/DSSI), confirming the planetary nature of the two signals. A simultaneous joint fit of photometry and radial velocity using a new fitting package juliet reveals that TOI-150b is a $1.254\pm 0.016\ \rm {R}_ \rm{J}$, massive ($2.61^{+0.19}_{-0.12}\ \rm {M}_ \rm{J}$) hot Jupiter in a 5.857-d orbit, while TOI-163b is an inflated ($R_ \rm{P}$ = $1.478^{+0.022}_{-0.029} \,\mathrm{ R}_ \rm{J}$, $M_ \rm{P}$ = $1.219\pm 0.11 \, \rm{M}_ \rm{J}$) hot Jupiter on a P = 4.231-d orbit; both planets orbit F-type stars. A particularly interesting result is that TOI-150b shows an eccentric orbit ($e=0.262^{+0.045}_{-0.037}$), which is quite uncommon among hot Jupiters. We estimate that this is consistent, however, with the circularization time-scale, which is slightly larger than the age of the system. These two hot Jupiters are both prime candidates for further characterization – in particular, both are excellent candidates for determining spin-orbit alignments via the Rossiter–McLaughlin (RM) effect and for characterizing atmospheric thermal structures using secondary eclipse observations considering they are both located closely to the James Webb Space Telescope (JWST) Continuous Viewing Zone (CVZ).

scholarly journals Molecular cross-sections for high-resolution spectroscopy of super-Earths, warm Neptunes, and hot Jupiters

2020 ◽  
Vol 495 (1) ◽  
pp. 224-237 ◽  
Author(s):  
Siddharth Gandhi ◽  
Matteo Brogi ◽  
Sergei N Yurchenko ◽  
Jonathan Tennyson ◽  
Phillip A Coles ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Sections ◽  
Cross Correlation ◽  
High Resolution Spectroscopy ◽  
High Signal ◽  
Pressure Broadening ◽  
Spectral Signatures ◽  
Hot Jupiters ◽  
Wide Range ◽  
Infrared Spectral

ABSTRACT High-resolution spectroscopy (HRS) has been used to detect a number of species in the atmospheres of hot Jupiters. Key to such detections is accurately and precisely modelled spectra for cross-correlation against the R ≳ 20 000 observations. There is a need for the latest generation of opacities which form the basis for high signal-to-noise detections using such spectra. In this study we present and make publicly available cross-sections for six molecular species, H2O, CO, HCN, CH4, NH3, and CO2 using the latest line lists most suitable for low- and high-resolution spectroscopy. We focus on the infrared (0.95–5 μm) and between 500 and 1500 K where these species have strong spectral signatures. We generate these cross-sections on a grid of pressures and temperatures typical for the photospheres of super-Earth, warm Neptunes, and hot Jupiters using the latest H2 and He pressure broadening. We highlight the most prominent infrared spectral features by modelling three representative exoplanets, GJ 1214 b, GJ 3470 b, and HD 189733 b, which encompass a wide range in temperature, mass, and radii. In addition, we verify the line lists for H2O, CO, and HCN with previous high-resolution observations of hot Jupiters. However, we are unable to detect CH4 with our new cross-sections from HRS observations of HD 102195 b. These high-accuracy opacities are critical for atmospheric detections with HRS and will be continually updated as new data become available.

scholarly journals Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

2020 ◽  
Vol 636 ◽  
pp. A117 ◽  
Author(s):  
S. R. Merritt ◽  
N. P. Gibson ◽  
S. K. Nugroho ◽  
E. J. W. de Mooij ◽  
M. J. Hooton ◽  
...  
Keyword(s):  
Correlation Method ◽  
Detection Limits ◽  
Temperature Inversion ◽  
High Resolution Spectroscopy ◽  
Echelle Spectrograph ◽  
Thermal Inversion ◽  
Hot Jupiters ◽  
Very Large Telescope ◽  
Excess Absorption ◽  
Rule Out

Thermal inversions have long been predicted to exist in the atmospheres of ultra-hot Jupiters. However, the detection of two species thought to be responsible – titanium oxide and vanadium oxide – remains elusive. We present a search for TiO and VO in the atmosphere of the ultra-hot Jupiter WASP-121b (Teq ≳ 2400 K), an exoplanet with evidence of VO in its atmosphere at low resolution which also exhibits water emission features in its dayside spectrum characteristic of a temperature inversion. We observed its transmission spectrum with the UV-Visual Echelle Spectrograph at the Very Large Telescope and used the cross-correlation method – a powerful tool for the unambiguous identification of the presence of atomic and molecular species – in an effort to detect whether TiO or VO were responsible for the observed temperature inversion. No evidence for the presence of TiO or VO was found at the terminator of WASP-121b. By injecting signals into our data at varying abundance levels, we set rough detection limits of [VO] ≲−7.9 and [TiO] ≲−9.3. However, these detection limits are largely degenerate with scattering properties and the position of the cloud deck. Our results may suggest that neither TiO or VO are the main drivers of the thermal inversion in WASP-121b; however, until a more accurate line list is developed for VO, we cannot conclusively rule out its presence. Future works will consist of a search for other strong optically-absorbing species that may be responsible for the excess absorption in the red-optical.

scholarly journals Hot Jupiter secondary eclipses measured by Kepler

2010 ◽  
Vol 6 (S276) ◽  
pp. 475-476
Author(s):  
Brice-Olivier Demory ◽  
Sara Seager
Keyword(s):  
Thermal Emission ◽  
Giant Planet ◽  
Absorption Bands ◽  
Hot Jupiters ◽  
Reflected Light ◽  
Upper Limits ◽  
Visible Wavelengths ◽  
Light Components ◽  
Outstanding Quality

AbstractHot-Jupiters are known to be dark in visible bandpasses, mainly because of the alkali metal absorption lines and TiO and VO molecular absorption bands. The outstanding quality of the Kepler mission photometry allows a detection (or non-detection upper limits on) giant planet secondary eclipses at visible wavelengths. We present such measurements on published planets from Kepler Q1 data. We then explore how to disentangle between the planetary thermal emission and the reflected light components that can both contribute to the detected signal in the Kepler bandpass. We finally mention how different physical processes can lead to a wide variety of hot-Jupiters albedos.

scholarly journals Multi-frequency observations of E-region HF radar aurora

2003 ◽  
Vol 21 (3) ◽  
pp. 761-777 ◽  
Author(s):  
S. E. Milan ◽  
M. Lester ◽  
N. Sato
Keyword(s):  
Doppler Shift ◽  
Hf Radar ◽  
Low Flow ◽  
Wave Number ◽  
Electron Drift ◽  
Doppler Shifts ◽  
Ion Acoustic ◽  
E Region ◽  
Coherent Backscatter ◽  
Acoustic Speed

Abstract. Multi-frequency observations of E-region coherent backscatter from decametre waves reveal that auroral echoes tend to comprise two spectral components superimposed, one at low Doppler shifts, below 250 ms-1, and the other Doppler shifted to near the ion-acoustic speed or above, up to 800 ms-1. The low Doppler shift component occurs at all look directions; Doppler shifts near the ion acoustic speed occur when looking at low flow angles along the direction of the electron drift in the electrojet, and Doppler shifts in excess of the ion acoustic speed occur at intermediate flow angles. The latter population appears most commonly at radar frequencies near 10–12 MHz, with its occurrence decreasing dramatically at higher frequencies. The velocity of the high Doppler shift echoes increases with increasing radar frequency, or irregularity wave number k. The velocity of the low Doppler shift population appears to be suppressed significantly below the line-of-sight component of the electron drift. Initial estimates of the altitude from which scatter occurs suggest that the high Doppler shift echoes originate from higher in the E-region than the low Doppler shift echoes, certainly in the eastward electrojet. We discuss these observations with reference to the theories of de/stabilization of two-stream waves by electron density gradients and electrostatic ion cyclotron waves excited by field-parallel electron drifts.Key words. Ionosphere (ionospheric irregularities)

scholarly journals Dynamic features in the solar atmosphere with unusual spectral line enhancements and Doppler-shifts

2006 ◽  
Vol 451 (3) ◽  
pp. L35-L38 ◽  
Author(s):  
J. G. Doyle ◽  
B. Ishak ◽  
M. S. Madjarska ◽  
E. O'Shea ◽  
E. Dzifćáková
Keyword(s):  
Spectral Line ◽  
Solar Atmosphere ◽  
Dynamic Features ◽  
Doppler Shifts

Doppler Shift in X-Ray Spectrum for Laser-Imploded Spherical Microshells

1988 ◽  
Vol 102 ◽  
pp. 369-371
Author(s):  
H. Fiedorowicz ◽  
S. Denus ◽  
K. Jeziak ◽  
M. Kolanowski ◽  
P. Parys ◽  
...  
Keyword(s):  
Doppler Shift ◽  
Ablation Process ◽  
X Ray ◽  
Doppler Shifts ◽  
Plasma Motion

AbstractDoppler shifts due to plasma motion have been observed in the space-resolved X-ray spectra for the laser-imploded spherical microshells. The analysis of the X-ray spectrum makes it possible to study the ablation process from the microshell surface.

scholarly journals Revisiting the eccentricities of hot Jupiters

2010 ◽  
Vol 6 (S276) ◽  
pp. 243-247
Author(s):  
Nawal Husnoo ◽  
Frédéric Pont ◽  
Tsevi Mazeh ◽  
Daniel Fabrycky ◽  
Guillaume Hébrard ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Circular Orbits ◽  
Hot Jupiters ◽  
Transiting Planets ◽  
Eccentric Orbits ◽  
Tidal Theory ◽  
Short Period ◽  
Formation And Evolution ◽  
Orbital Periods ◽  
Radial Velocity Data

AbstractMost short period transiting exoplanets have circular orbits, as expected from an estimation of the circularisation timescale using classical tidal theory. Interestingly, a small number of short period transiting exoplanets seem to have orbits with a small eccentricity. Such systems are valuable as they may indicate that some key physics is missing from formation and evolution models. We have analysed the results of a campaign of radial velocity measurements of known transiting planets with the SOPHIE and HARPS spectrographs using Bayesian methods and obtained new constraints on the orbital elements of 12 known transiting exoplanets. We also reanalysed the radial velocity data for another 42 transiting systems and show that some of the eccentric orbits reported in the Literature are compatible with a circular orbit. As a result, we show that the systems with circular and eccentric orbits are clearly separated on a plot of the planetary mass versus orbital period. We also show that planets following the trend where heavier hot Jupiters have shorter orbital periods (the “mass-period relation” of hot Jupiters), also tend to have circular orbits, with no confirmed exception to this rule so far.

scholarly journals A Note on the Role of Mean Flows in Doppler-Shifted Frequencies

2013 ◽  
Vol 43 (2) ◽  
pp. 432-441 ◽  
Author(s):  
Theo Gerkema ◽  
Leo R. M. Maas ◽  
Hans van Haren
Keyword(s):  
Doppler Shift ◽  
Wave Dispersion ◽  
The Other ◽  
Mean Flow ◽  
Fixed Position ◽  
Doppler Shifts ◽  
The Mean ◽  
The Difference ◽  
The One

Abstract The purpose of this paper is to resolve a confusion that may arise from two quite distinct definitions of “Doppler shifts”: both are used in the oceanographic literature but they are sometimes conflated. One refers to the difference in frequencies measured by two observers, one at a fixed position and one moving with the mean flow—here referred to as “quasi-Doppler shifts.” The other definition is the one used in physics, where the frequency measured by an observer is compared to that of the source. In the latter sense, Doppler shifts occur only if the source and observer move with respect to each other; a steady mean flow alone cannot create a Doppler shift. This paper rehashes the classical theory to straighten out some misconceptions. It is also discussed how wave dispersion affects the classical relations and their application.

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