scholarly journals Low albedos of hot to ultra-hot Jupiters in the optical to near-infrared transition regime

2019 ◽  
Vol 624 ◽  
pp. A62 ◽  
Author(s):  
M. Mallonn ◽  
J. Köhler ◽  
X. Alexoudi ◽  
C. von Essen ◽  
T. Granzer ◽  
...  
Keyword(s):  
Near Infrared ◽  
State Of The Art ◽  
Light Curves ◽  
Transition Regime ◽  
Light Component ◽  
Hot Jupiters ◽  
Upper Limit ◽  
Reflected Light ◽  
Geometric Albedo ◽  
Hot Jupiter

The depth of a secondary eclipse contains information of both the thermally emitted light component of a hot Jupiter and the reflected light component. If the day side atmosphere of the planet is assumed to be isothermal, it is possible to disentangle both. In this work, we analyzed 11 eclipse light curves of the hot Jupiter HAT-P-32 b obtained at 0.89 μm in the z′ band. We obtained a null detection for the eclipse depth with state-of-the-art precision, −0.01 ± 0.10 ppt. We confirm previous studies showing that a non-inverted atmosphere model is in disagreement to the measured emission spectrum of HAT-P-32 b. We derive an upper limit on the reflected light component, and thus, on the planetary geometric albedo Ag. The 97.5% confidence upper limit is Ag < 0.2. This is the first albedo constraint for HAT-P-32 b, and the first z′ band albedo value for any exoplanet. This finding disfavors the influence of large-sized silicate condensates on the planetary day side. We inferred z′ band geometric albedo limits from published eclipse measurements also for the ultra-hot Jupiters WASP-12 b, WASP-19 b, WASP-103 b, and WASP-121 b, applying the same method. These values consistently point to a low reflectivity in the optical to near-infrared transition regime for hot to ultra-hot Jupiters.

scholarly journals A triple star in disarray

2020 ◽  
Vol 644 ◽  
pp. A114
Author(s):  
M. Kasper ◽  
K. K. R. Santhakumari ◽  
T. M. Herbst ◽  
R. van Boekel ◽  
F. Menard ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Near Infrared ◽  
State Of The Art ◽  
High Contrast ◽  
Compelling Evidence ◽  
T Tauri ◽  
Reflected Light ◽  
First Time ◽  
Triple Star ◽  
Outflow System

Aims. T Tauri remains an enigmatic triple star for which neither the evolutionary state of the stars themselves, nor the geometry of the complex outflow system is completely understood. Eight-meter class telescopes equipped with state-of-the-art adaptive optics provide the spatial resolution necessary to trace tangential motion of features over a timescale of a few years, and they help to associate them with the different outflows. Methods. We used J-, H-, and K-band high-contrast coronagraphic imaging with VLT-SPHERE recorded between 2016 and 2018 to map reflection nebulosities and obtain high precision near-infrared (NIR) photometry of the triple star. We also present H2 emission maps of the ν = 1-0 S(1) line at 2.122 μm obtained with LBT-LUCI during its commissioning period at the end of 2016. Results. The data reveal a number of new features in the system, some of which are seen in reflected light and some are seen in H2 emission; furthermore, they can all be associated with the main outflows. The tangential motion of the features provides compelling evidence that T Tauri Sb drives the southeast–northwest outflow. T Tauri Sb has recently faded probably because of increased extinction as it passes through the southern circumbinary disk. While Sb is approaching periastron, T Tauri Sa instead has brightened and is detected in all our J-band imagery for the first time.

scholarly journals Secondary eclipse of the hot Jupiter WASP-121b at 2 μm

2019 ◽  
Vol 625 ◽  
pp. A80 ◽  
Author(s):  
Géza Kovács ◽  
Tamás Kovács
Keyword(s):  
Near Infrared ◽  
Infrared Emission ◽  
Current Data ◽  
Emission Analysis ◽  
Hot Jupiters ◽  
Occultation Data ◽  
The One ◽  
Near Infrared Emission ◽  
Absorption Features ◽  
Hot Jupiter

Ground-based observations of the secondary eclipse in the 2MASS K band are presented for the hot Jupiter WASP-121b. These are the first occultation observations of an extrasolar planet that were carried out with an instrument attached to a 1 m class telescope (the SMARTS 1.3 m). We find a highly significant eclipse depth of (0.228 ± 0.023)%. Together with other planet atmosphere measurements, including the Hubble Space Telescope near-infrared emission spectrum, current data support more involved atmosphere models with species producing emission and absorption features, rather than simple smooth blackbody emission. Analysis of the time difference between the primary and secondary eclipses and the durations of these events yields an eccentricity of e = 0.0207 ± 0.0153, which is consistent with the earlier estimates of low or zero eccentricity, but with a smaller error. Comparing the observed occultation depth in the K band with the one derived under the assumption of zero Bond albedo and full heat redistribution, we find that WASP-121b has a deeper observed occultation depth than predicted. Together with the sample of 31 systems with K-band occultation data, this observation lends further support to the idea of inefficient heat transport between the day and night sides for most of the hot Jupiters.

scholarly journals The GAPS Programme at TNG

2020 ◽  
Vol 638 ◽  
pp. A5 ◽  
Author(s):  
I. Carleo ◽  
L. Malavolta ◽  
A. F. Lanza ◽  
M. Damasso ◽  
S. Desidera ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Semimajor Axis ◽  
Young Stars ◽  
Homogeneous Sample ◽  
Stellar Activity ◽  
Orbital Parameters ◽  
Hot Jupiters ◽  
Multi Band ◽  
Hot Jupiter

Context. The existence of hot Jupiters is still not well understood. Two main channels are thought to be responsible for their current location: a smooth planet migration through the protoplanetary disk or the circularization of an initial highly eccentric orbit by tidal dissipation leading to a strong decrease in the semimajor axis. Different formation scenarios result in different observable effects, such as orbital parameters (obliquity and eccentricity) or frequency of planets at different stellar ages. Aims. In the context of the GAPS Young Objects project, we are carrying out a radial velocity survey with the aim of searching and characterizing young hot-Jupiter planets. Our purpose is to put constraints on evolutionary models and establish statistical properties, such as the frequency of these planets from a homogeneous sample. Methods. Since young stars are in general magnetically very active, we performed multi-band (visible and near-infrared) spectroscopy with simultaneous GIANO-B + HARPS-N (GIARPS) observing mode at TNG. This helps in dealing with stellar activity and distinguishing the nature of radial velocity variations: stellar activity will introduce a wavelength-dependent radial velocity amplitude, whereas a Keplerian signal is achromatic. As a pilot study, we present here the cases of two known hot Jupiters orbiting young stars: HD 285507 b and AD Leo b. Results. Our analysis of simultaneous high-precision GIARPS spectroscopic data confirms the Keplerian nature of the variation in the HD 285507 radial velocities and refines the orbital parameters of the hot Jupiter, obtaining an eccentricity consistent with a circular orbit. Instead, our analysis does not confirm the signal previously attributed to a planet orbiting AD Leo. This demonstrates the power of the multi-band spectroscopic technique when observing active stars.

scholarly journals An optical transmission spectrum of the ultra-hot Jupiter WASP-33 b

2019 ◽  
Vol 622 ◽  
pp. A71 ◽  
Author(s):  
C. von Essen ◽  
M. Mallonn ◽  
L. Welbanks ◽  
N. Madhusudhan ◽  
A. Pinhas ◽  
...  
Keyword(s):  
Light Curves ◽  
Atmospheric Composition ◽  
Data Sets ◽  
Hot Jupiters ◽  
High Data ◽  
Trace Species ◽  
Exoplanetary Atmospheres ◽  
Combined Data ◽  
Hot Jupiter

There has been increasing progress toward detailed characterization of exoplanetary atmospheres, in both observations and theoretical methods. Improvements in observational facilities and data reduction and analysis techniques are enabling increasingly higher quality spectra, especially from ground-based facilities. The high data quality also necessitates concomitant improvements in models required to interpret such data. In particular, the detection of trace species such as metal oxides has been challenging. Extremely irradiated exoplanets (~3000 K) are expected to show oxides with strong absorption signals in the optical. However, there are only a few hot Jupiters where such signatures have been reported. Here we aim to characterize the atmosphere of the ultra-hot Jupiter WASP-33 b using two primary transits taken 18 orbits apart. Our atmospheric retrieval, performed on the combined data sets, provides initial constraints on the atmospheric composition of WASP-33 b. We report a possible indication of aluminum oxide (AlO) at 3.3-σ significance. The data were obtained with the long slit OSIRIS spectrograph mounted at the 10-m Gran Telescopio Canarias. We cleaned the brightness variations from the light curves produced by stellar pulsations, and we determined the wavelength-dependent variability of the planetary radius caused by the atmospheric absorption of stellar light. A simultaneous fit to the two transit light curves allowed us to refine the transit parameters, and the common wavelength coverage between the two transits served to contrast our results. Future observations with HST as well as other large ground-based facilities will be able to further constrain the atmospheric chemical composition of the planet.

scholarly journals Distinguishing the albedo of exoplanets from stellar activity

2018 ◽  
Vol 611 ◽  
pp. A8 ◽  
Author(s):  
L. M. Serrano ◽  
S. C. C. Barros ◽  
M. Oshagh ◽  
N. C. Santos ◽  
J. P. Faria ◽  
...  
Keyword(s):  
Gaussian Process ◽  
Noise Level ◽  
Light Curves ◽  
Phase Curve ◽  
Stellar Rotation ◽  
Stellar Activity ◽  
Light Component ◽  
Instrumental Noise ◽  
Reflected Light ◽  
Planetary Albedo

Context. Light curves show the flux variation from the target star and its orbiting planets as a function of time. In addition to the transit features created by the planets, the flux also includes the reflected light component of each planet, which depends on the planetary albedo. This signal is typically referred to as phase curve and could be easily identified if there were no additional noise. As well as instrumental noise, stellar activity, such as spots, can create a modulation in the data, which may be very difficult to distinguish from the planetary signal. Aims. We analyze the limitations imposed by the stellar activity on the detection of the planetary albedo, considering the limitations imposed by the predicted level of instrumental noise and the short duration of the obervations planned in the context of the CHEOPS mission. Methods. As initial condition, we have assumed that each star is characterized by just one orbiting planet. We built mock light curves that included a realistic stellar activity pattern, the reflected light component of the planet and an instrumental noise level, which we have chosen to be at the same level as predicted for CHEOPS. We then fit these light curves to try to recover the reflected light component, assuming the activity patterns can be modeled with a Gaussian process. Results. We estimate that at least one full stellar rotation is necessary to obtain a reliable detection of the planetary albedo. This result is independent of the level of noise, but it depends on the limitation of the Gaussian process to describe the stellar activity when the light curve time-span is shorter than the stellar rotation. As an additional result, we found that with a 6.5 magnitude star and the noise level of CHEOPS, it is possible to detect the planetary albedo up to a lower limit of Rp = 0.03 R*. Finally, in presence of typical CHEOPS gaps in the simulations, we confirm that it is still possible to obtain a reliable albedo.

scholarly journals A transition between the hot and the ultra-hot Jupiter atmospheres

2020 ◽  
Vol 639 ◽  
pp. A36 ◽  
Author(s):  
Claire Baxter ◽  
Jean-Michel Désert ◽  
Vivien Parmentier ◽  
Mike Line ◽  
Jonathan Fortney ◽  
...  
Keyword(s):  
Near Infrared ◽  
Thermal Structure ◽  
Emission Spectra ◽  
Equilibrium Temperature ◽  
Hot Jupiters ◽  
Brightness Temperatures ◽  
Eclipse Observations ◽  
Theoretical Predictions ◽  
The Difference ◽  
Hot Jupiter

A key hypothesis in the field of exoplanet atmospheres is the trend of atmospheric thermal structure with planetary equilibrium temperature. We explore this trend and report here the first statistical detection of a transition in the near-infrared atmospheric emission between hot and ultra-hot Jupiters. We measure this transition using secondary eclipse observations and interpret this phenomenon as changes in atmospheric properties, and more specifically in terms of transition from non-inverted to inverted thermal profiles. We examine a sample of 78 hot Jupiters with secondary eclipse measurements at 3.6 and 4.5 μm measured with Spitzer Infrared Array Camera. We calculate the planetary brightness temperatures using PHOENIX models to correct for the stellar flux. We measure the deviation of the data from the blackbody, which we define as the difference between the observed 4.5 μm eclipse depth and that expected at this wavelength based on the brightness temperature measured at 3.6 μm. We study how the deviation between 3.6 and 4.5 μm changes with theoretical predictions with equilibrium temperature and incoming stellar irradiation. We reveal a clear transition in the observed emission spectra of the hot Jupiter population at 1660 ± 100 K in the zero albedo, full redistribution equilibrium temperature. We find the hotter exoplanets have even hotter daysides at 4.5 μm compared to 3.6 μm, which manifests as an exponential increase in the emitted power of the planets with stellar insolation. We propose that the measured transition is a result of seeing carbon monoxide in emission due to the formation of temperature inversions in the atmospheres of the hottest planets. These thermal inversions could be caused by the presence of atomic and molecular species with high opacities in the optical and/or the lack of cooling species. Our findings are in remarkable agreement with a new grid of 1D radiative and convective models varying metallicity, carbon to oxygen ratio (C/O), surface gravity, and stellar effective temperature. We find that the population of hot Jupiters statistically disfavors high C/O planets (C/O ≥ 0.85).

scholarly journals τ Boo b: Not so bright, but just as heavy

2004 ◽  
Vol 202 ◽  
pp. 75-77 ◽  
Author(s):  
Andrew Collier Cameron ◽  
Keith Horne ◽  
David James ◽  
Alan Penny ◽  
Meir Semel
Keyword(s):  
Monte Carlo ◽  
Orbital Motion ◽  
Flux Ratio ◽  
Monte Carlo Analysis ◽  
Upper Limit ◽  
Reflected Light ◽  
The Mean ◽  
Data Yield ◽  
New Evidence ◽  
Geometric Albedo

We present new results derived from high-resolution optical spectra of the τ Boo system, secured in March-May 2000. The results do not show the same feature reported by Cameron et al (1999) as a candidate reflected-light signature from the planet. Together with earlier results from the 1998 and 1999 seasons, the new data yield a 99.9% upper limit on the opposition planet/star flux ratio ∊ < 3.5 × 10−5 between 387.4 and 586.3 nm, a factor 3 deeper than the upper limit of Charbonneau et al (1999). For an assumed planet radius Rp = 1.2RJ, the upper limit on the mean geometric albedo is p < 0.22, 40% that of Jupiter. We find new evidence that the star's rotation is synchronised with the planet's orbital motion. Using a Monte Carlo analysis we infer that the planet's mass must lie in the range 5.5 to 10 times the mass of Jupiter.

scholarly journals Polarization of hot Jupiter systems: a likely detection of stellar activity and a possible detection of planetary polarization

2021 ◽  
Vol 502 (2) ◽  
pp. 2331-2345
Author(s):  
Jeremy Bailey ◽  
Kimberly Bott ◽  
Daniel V Cotton ◽  
Lucyna Kedziora-Chudczer ◽  
Jinglin Zhao ◽  
...  
Keyword(s):  
False Alarm ◽  
Linear Polarization ◽  
False Alarm Probability ◽  
Magnetic Activity ◽  
Light Polarization ◽  
Polarization Signal ◽  
Hot Jupiters ◽  
Reflected Light ◽  
Instrument Sensitivity ◽  
Hot Jupiter

ABSTRACT We present high-precision linear polarization observations of four bright hot Jupiter systems (τ Boo, HD 179949, HD 189733, and 51 Peg) and use the data to search for polarized reflected light from the planets. The data for 51 Peg are consistent with a reflected light polarization signal at about the level expected with 2.8σ significance and a false alarm probability of 1.9 per cent. More data will be needed to confirm a detection of reflected light in this system. HD 189733 shows highly variable polarization that appears to be most likely the result of magnetic activity of the host star. This masks any polarization due to reflected light, but a polarization signal at the expected level of ∼20 ppm cannot be ruled out. τ Boo and HD 179949 show no evidence for polarization due to reflected light. The results are consistent with the idea that many hot Jupiters have low geometric albedos. Conclusive detection of polarized reflected light from hot Jupiters is likely to require further improvements in instrument sensitivity.

scholarly journals Mapping the Pressure-dependent Day–Night Temperature Contrast of a Strongly Irradiated Atmosphere with HST Spectroscopic Phase Curve

2021 ◽  
Vol 163 (1) ◽  
pp. 8
Author(s):  
Ben W. P. Lew ◽  
Dániel Apai ◽  
Yifan Zhou ◽  
Mark Marley ◽  
L. C. Mayorga ◽  
...  
Keyword(s):  
White Dwarf ◽  
Near Infrared ◽  
Brown Dwarfs ◽  
Phase Curve ◽  
Brown Dwarf ◽  
Night Temperature ◽  
Flux Variation ◽  
Hot Jupiters ◽  
Temperature Contrast ◽  
Hot Jupiter

Abstract Many brown dwarfs are on ultrashort-period and tidally locked orbits around white dwarf hosts. Because of these small orbital separations, the brown dwarfs are irradiated at levels similar to hot Jupiters. Yet, they are easier to observe than hot Jupiters because white dwarfs are fainter than main-sequence stars at near-infrared wavelengths. Irradiated brown dwarfs are, therefore, ideal hot Jupiter analogs for studying the atmospheric response under strong irradiation and fast rotation. We present the 1.1–1.67 μm spectroscopic phase curve of the irradiated brown dwarf (SDSS1411-B) in the SDSS J141126.20 + 200911.1 brown dwarf–white dwarf binary with the near-infrared G141 grism of the Hubble Space Telescope Wide Field Camera 3. SDSS1411-B is a 50M Jup brown dwarf with an irradiation temperature of 1300 K and has an orbital period of 2.02864 hr. Our best-fit model suggests a phase-curve amplitude of 1.4% and places an upper limit of 11° for the phase offset from the secondary eclipse. After fitting the white dwarf spectrum, we extract the phase-resolved brown dwarf emission spectra. We report a highly wavelength-dependent day–night spectral variation, with a water-band flux variation of about 360% ± 70% and a comparatively small J-band flux variation of 37% ± 2%. By combining the atmospheric modeling results and the day–night brightness temperature variations, we derive a pressure-dependent temperature contrast. We discuss the difference in the spectral features of SDSS1411-B and hot Jupiter WASP-43b, as well as the lower-than-predicted day–night temperature contrast of J4111-BD. Our study provides the high-precision observational constraints on the atmospheric structures of an irradiated brown dwarf at different orbital phases.

scholarly journals Light-curve properties of SN 2017fgc and HV SNe Ia

2021 ◽  
Vol 502 (3) ◽  
pp. 4112-4124
Author(s):  
Umut Burgaz ◽  
Keiichi Maeda ◽  
Belinda Kalomeni ◽  
Miho Kawabata ◽  
Masayuki Yamanaka ◽  
...  
Keyword(s):  
Light Curve ◽  
Near Infrared ◽  
Light Curves ◽  
Normal Velocity ◽  
External Effects ◽  
Band Maximum ◽  
Bolometric Luminosity ◽  
V Band ◽  
Photometric And Spectroscopic Observations ◽  
Type Ia

ABSTRACT Photometric and spectroscopic observations of Type Ia supernova (SN) 2017fgc, which cover the period from −12 to + 137 d since the B-band maximum are presented. SN 2017fgc is a photometrically normal SN Ia with the luminosity decline rate, Δm15(B)true  = 1.10 ± 0.10 mag. Spectroscopically, it belongs to the high-velocity (HV) SNe Ia group, with the Si ii λ6355 velocity near the B-band maximum estimated to be 15 200 ± 480 km s−1. At the epochs around the near-infrared secondary peak, the R and I bands show an excess of ∼0.2-mag level compared to the light curves of the normal velocity (NV) SNe Ia. Further inspection of the samples of HV and NV SNe Ia indicates that the excess is a generic feature among HV SNe Ia, different from NV SNe Ia. There is also a hint that the excess is seen in the V band, both in SN 2017fgc and other HV SNe Ia, which behaves like a less prominent shoulder in the light curve. The excess is not obvious in the B band (and unknown in the U band), and the colour is consistent with the fiducial SN colour. This might indicate that the excess is attributed to the bolometric luminosity, not in the colour. This excess is less likely caused by external effects, like an echo or change in reddening but could be due to an ionization effect, which reflects an intrinsic, either distinct or continuous, difference in the ejecta properties between HV and NV SNe Ia.

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