Neue Artikel in Astronomy & Astrophysics Volume 689 (September 2024) vom 31.08.2024 bis 06.09.2024
von Michael Johne ·
Zwischen dem 31.08.2024 und dem 06.09.2024 wurden in der Astronomy & Astrophysics Volume 689 (September 2024) 11 neue Artikel veröffentlicht.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa49935-24/aa49935-24.html
Autoren: A. R. Costa Silva, O. D. S. Demangeon, N. C. Santos, D. Ehrenreich, C. Lovis, H. Chakraborty, M. Lendl, F. Pepe, S. Cristiani, R. Rebolo, M. R. Zapatero-Osorio, V. Adibekyan, Y. Alibert, R. Allart, C. Allende Prieto, T. Azevedo Silva, F. Borsa, V. Bourrier, E. Cristo, P. Di Marcantonio, E. Esparza-Borges, P. Figueira, J. I. González Hernández, E. Herrero-Cisneros, G. Lo Curto, C. J. A. P. Martins, A. Mehner, N. J. Nunes, E. Palle, S. Pelletier, J. V. Seidel, A. M. Silva, S. G. Sousa, A. Sozzetti, M. Steiner, A. Suárez Mascareño und S. Udry
Inhalt: 15 Seiten, 11 Abbildungen, 4 Tabellen
Kurztext: Context. Ultra hot Jupiters (gas giants with Teq > 2000 K) are intriguing exoplanets due to the extreme physics and chemistry present in their atmospheres. Their torrid daysides can be characterised using ground-based high-resolution emission spectroscopy.
Aims. We search for signatures of neutral and singly ionised iron (Fe I and Fe II, respectively) in the dayside of the ultra hot Jupiter WASP-76 b, as these species were detected via transmission spectroscopy in this exoplanet. Furthermore, we aim to confirm the existence of a thermal inversion layer, which has been reported in previous studies, and attempt to constrain its properties.
Methods. We observed WASP-76 b on four epochs with ESPRESSO at the VLT, at orbital phases shortly before and after the secondary transit, when the dayside is in view. We present the first analysis of high-resolution optical emission spectra for this exoplanet. We compare the data to synthetic templates created with petitRADTRANS, using cross-correlation function techniques.
Results. We detect a blueshifted (−4.7 ± 0.3 km s−1) Fe I emission signature on the dayside of WASP-76 b at 6.0σ. The signal is detected independently both before and after the eclipse, and it is blueshifted in both cases. The presence of iron emission features confirms the existence of a thermal inversion layer. Fe II was not detected, possibly because this species is located in the upper layers of the atmosphere, which are more optically thin. Thus the Fe II signature on the dayside of WASP-76 b is too weak to be detected with emission spectroscopy.
Conclusions. We propose that the blueshifted Fe I signature is created by material rising from the hot spot to the upper layers of the atmosphere, and discuss possible scenarios related to the position of the hotspot. This work unveils some of the dynamic processes ongoing on the dayside of the ultra hot Jupiter WASP-76 b through the analysis of the Fe I signature from its atmosphere, and complements previous knowledge obtained from transmission studies. It also highlights the ability of ESPRESSO to probe the dayside of this class of exoplanets.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa50974-24/aa50974-24.html
Autoren: L. Borsato, D. Degen, A. Leleu, M. J. Hooton, J. A. Egger, A. Bekkelien, A. Brandeker, A. Collier Cameron, M. N. Günther, V. Nascimbeni, C. M. Persson, A. Bonfanti, T. G. Wilson, A. C. M. Correia, T. Zingales, T. Guillot, A. H. M. J. Triaud, G. Piotto, D. Gandolfi, L. Abe, Y. Alibert, R. Alonso, T. Bárczy, D. Barrado Navascues, S. C. C. Barros, W. Baumjohann, T. Beck, P. Bendjoya, W. Benz, N. Billot, C. Broeg, M.-D. Busch, Sz. Csizmadia, P. E. Cubillos, M. B. Davies, M. Deleuil, A. Deline, L. Delrez, O. D. S. Demangeon, B.-O. Demory, A. Derekas, B. Edwards, D. Ehrenreich, A. Erikson, A. Fortier, L. Fossati, M. Fridlund, K. Gazeas, M. Gillon, M. Güdel, A. Heitzmann, Ch. Helling, S. Hoyer, K. G. Isaak, L. L. Kiss, J. Korth, K. W. F. Lam, J. Laskar, A. Lecavelier des Etangs, M. Lendl, D. Magrin, L. Marafatto, P. F. L. Maxted, M. Mecina, D. Mékarnia, C. Mordasini, D. Mura, G. Olofsson, R. Ottensamer, I. Pagano, E. Pallé, G. Peter, D. Pollacco, D. Queloz, R. Ragazzoni, N. Rando, F. Ratti, H. Rauer, I. Ribas, S. Salmon, N. C. Santos, G. Scandariato, D. Ségransan, A. E. Simon, A. M. S. Smith, S. G. Sousa, M. Stalport, O. Suarez, S. Sulis, Gy. M. Szabó, S. Udry, V. Van Grootel, J. Venturini, E. Villaver, N. A. Walton und D. Wolter
Inhalt: 21 Seiten, 10 Abbildungen, 3 Tabellen
Kurztext: Context. Among the thousands of exoplanets discovered to date, approximately a few hundred gas giants on short-period orbits are classified as ‘lonely’ and only a few are in a multi-planet system with a smaller companion on a close orbit. The processes that formed multi-planet systems hosting gas giants on close orbits are poorly understood, and only a few examples of this kind of system have been observed and well characterised.
Aims. Within the contest of a multi-planet system hosting a gas giant on short orbits, we characterise the TOI-1130 system by measuring masses and orbital parameters. This is a two-transiting planet system with a Jupiter-like planet (c) on a 8.35 days orbit and a Neptune-like planet (b) on an inner (4.07 days) orbit. Both planets show strong anti-correlated transit timing variations (TTVs). Furthermore, radial velocity (RV) analysis showed an additional linear trend, a possible hint of a non-transiting candidate planet on a far outer orbit.
Methods. Since 2019, extensive transit and radial velocity observations of the TOI-1130 have been acquired using TESS and various ground-based facilities. We present a new photo-dynamical analysis of all available transit and RV data, with the addition of new CHEOPS and ASTEP+ data, which achieve the best precision to date on the planetary radii and masses and on the timings of each transit.
Results. We were able to model interior structure of planet b constraining the presence of a gaseous envelope of H/He, while it was not possible to assess the possible water content. Furthermore, we analysed the resonant state of the two transiting planets, and we found that they lie just outside the resonant region. This could be the result of the tidal evolution that the system underwent. We obtained both masses of the planets with a precision of less than 1.5%, and radii with a precision of about 1% and 3% for planet b and c, respectively.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa50717-24/aa50717-24.html
Autoren: O. Balsalobre-Ruza, J. Lillo-Box, D. Barrado, A. C. M. Correia, J. P. Faria, P. Figueira, A. Leleu, P. Robutel, N. Santos und E. Herrero-Cisneros
Inhalt: 19 Seiten, 9 Abbildungen, 6 Tabellen
Kurztext: Context. Co-orbital objects, also known as trojans, are frequently found in simulations of planetary system formation. In these configurations, a planet shares its orbit with other massive bodies. It is still unclear why there have not been any co-orbitals discovered thus far in exoplanetary systems (exotrojans) or even pairs of planets found in such a 1:1 mean motion resonance. Reconciling observations and theory is an open subject in the field.
Aims. The main objective of the 𝒯ℛ𝒪𝒴 project is to conduct an exhaustive search for exotrojans using diverse observational techniques. In this work, we analyze the radial velocity time series informed by transits, focusing the search around low-mass stars.
Methods. We employed the α-test method on confirmed planets searching for shifts between spectral and photometric mid-transit times. This technique is sensitive to mass imbalances within the planetary orbit, allowing us to identify non-negligible co-orbital masses.
Results. Among the 95 transiting planets examined, we find one robust exotrojan candidate with a significant 3-σ detection. Additionally, 25 exoplanets show compatibility with the presence of exotrojan companions at a 1-σ level, requiring further observations to better constrain their presence. For two of those weak candidates, we find dimmings in their light curves within the predicted Lagrangian region. We established upper limits on the co-orbital masses for either the candidates and null detections.
Conclusions. Our analysis reveals that current high-resolution spectrographs effectively rule out co-orbitals more massive than Saturn around low-mass stars. This work points out to dozens of targets that have the potential to better constraint their exotrojan upper mass limit with dedicated radial velocity observations. We also explored the potential of observing the secondary eclipses of the confirmed exoplanets in our sample to enhance the exotrojan search, ultimately leading to a more accurate estimation of the occurrence rate of exotrojans.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa50119-24/aa50119-24.html
Autoren: Y. C. Damasceno, J. V. Seidel, B. Prinoth, A. Psaridi, E. Esparza-Borges, M. Stangret, N. C. Santos, M. R. Zapatero-Osorio, Y. Alibert, R. Allart, T. Azevedo Silva, M. Cointepas, A. R. Costa Silva, E. Cristo, P. Di Marcantonio, D. Ehrenreich, J. I. González Hernández, E. Herrero-Cisneros, M. Lendl, J. Lillo-Box, C. J. A. P. Martins, G. Micela, E. Pallé, S. G. Sousa, M. Steiner, V. Vaulato, Y. Zhao und F. Pepe
Inhalt: 18 Seiten, 22 Abbildungen, 7 Tabellen
Kurztext: Context. Ultra-hot Jupiters (UHJ) have emerged as ideal testbeds for new techniques for studying exoplanet atmospheres. Only a limited number of them are currently well studied, however.
Aims. We search for atmospheric constituents for the UHJ WASP-178 b with two ESPRESSO transits. Additionally, we show parallel photometry that we used to obtain updated and precise stellar, planetary, and orbital parameters.
Methods. The two transits we obtained were analysed with narrow-band transmission spectroscopy and with the cross-correlation technique to provide detections at different altitude levels. We focused on searching for Na I, Hα, Hβ, Hγ, Mg I, and Li I lines in narrow-band data, as well as Fe I and Fe II, and attempted to confirm Mg I with the cross-correlation technique. We corrected for the Rossiter-McLaughlin effect and regions with a low signal-to-noise ratio due to Na I absorption in the interstellar medium. We then verified our results via bootstrapping.
Results. We report the resolved line detections of Na I (5.5σ and 5.4σ), Hα (13σ), Hβ (7.1σ), and tentatively Mg I (4.6σ). With a cross-correlation, we confirm the Mg I detection (7.8 σ and 5.8 σ), and we additionally report the detections of Fe I (12σ and 10σ) and Fe II (11σ and 8.4σ) on both nights separately. The detection of Mg I remains tentative, however, because the results on the two nights differ. The results also differ compared with the properties derived from the narrow-band data.
Conclusions. None of our resolved spectral lines probing the middle to upper atmosphere shows significant shifts relative to the planetary rest frame. Hα and Hβ exhibit a respective line broadening of 39.6 ± 2.1 km s−1 and 27.6 ± 4.6 km s−1, however, indicating the onset of possible escape. WASP-178 b differs from similar UHJ by its lack of strong atmospheric dynamics in the upper atmosphere. The broadening seen for Fe I (15.66 ± 0.58 km s−1) and Fe II (11.32 ± 0.52 km s−1) might indicate the presence of winds in the mid-atmosphere, however. Future studies of the impact of the flux variability caused by the host star activity might shed more light on the subject. Previous work indicated the presence of SiO cloud-precursors in the atmosphere of WASP-178 b and a lack of Mg I and Fe II. However, our results suggest that a scenario in which the planetary atmosphere is dominated by Mg I and Fe II is more likely. In light of our results, we encourage future observations to further elucidate these atmospheric properties.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa50552-24/aa50552-24.html
Autoren: Longkang Dai, Wencheng Shao und Zheng Sheng
Inhalt: 12 Seiten, 12 Abbildungen, 1 Tabelle
Kurztext: Atmospheric chemistry plays a crucial role in the evolution of climate habitability on Venus. It has been widely explored by chemistry-transport models, but some characteristics are still poorly interpreted. This study is devoted to developing an open-access chemistry-transport model spanning both the middle and lower atmospheres of Venus. It provides a scheme for the structure of the chemistry, especially for the sulfur and oxygen, and investigates the influence of the cloud diffusivity and the SO2 dissolution that are adopted in the clouds. The developed model is based on the VULCAN framework and was updated with the state-of-the-art Venusian atmospheric chemistry. It includes vertical eddy diffusion retrieved recently with the Venus Express observations, and it resolves radiative transfer containing gas absorption and scattering, Mie scattering of the cloud droplets, and absorption of the unknown UV absorber. The obtained abundance profiles of SO, SO2, CO, COS, O, O2, O3, HCl, and NO are in overall agreement with the observations. The results show that the increase in cloud diffusivity has slight effects on the chemical structure. The SO2 mainly dissolves in 50–90 km and evaporates below the clouds. The rapid dissolution-release cycle is responsible for the large upward flux of SO2 at 58 km. At around 70 km, SO has a significant peak that is larger than that of previous studies by an order of magnitude, and S and SO2 also show slight increases. They are attributed to the buffering effects of liquid SO2 in the clouds. O2 is significantly eliminated by SO in this layer. We emphasize the superior regulation of the sulfur cycle on O2 at 70 km and its potential contributions to the long-standing problem of the overestimated O2 abundance.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa49698-24/aa49698-24.html
Autoren: L. Rampinelli, S. Facchini, M. Leemker, J. Bae, M. Benisty, R. Teague, C. J. Law, K. I. Öberg, B. Portilla-Revelo und A. J. Cridland
Inhalt: 24 Seiten, 18 Abbdildungen, 4 Tabellen
Kurztext: With two directly detected protoplanets, the PDS 70 system is a unique source in which to study the complex interplay between forming planets and their natal environment. The large dust cavity carved by the two giant planets can affect the disk chemistry, and therefore the molecular emission morphology. On the other hand, chemical properties of the gas component of the disk are expected to leave an imprint on the planetary atmospheres. In this work, we reconstruct the emission morphology of a rich inventory of molecular tracers in the PDS 70 disk, and we look for possible chemical signatures of the two actively accreting protoplanets, PDS 70b and c. We leverage Atacama Large Millimeter/submillimeter Array (ALMA) band 6 high-angular-resolution and deep-sensitivity line emission observations, together with image and uv-plane techniques, to boost the detection of faint lines. We robustly detect ring-shaped emission from 12CO, 13CO, C18O, H13CN, HC15N, DCN, H2CO, CS, C2H, and H13CO+ lines in unprecedented detail. Most of the molecular tracers show a peak of the emission inside the millimeter dust peak. We interpret this as the direct impact of the effective irradiation of the cavity wall, as a result of the planet formation process. Moreover, we have found evidence of an O-poor gas reservoir in the outer disk, which is supported by the observations of bright C-rich molecules, the non-detection of SO, and a lower limit on the CS/SO ratio of ~1. Eventually, we provide the first detection of the c-C3H2 transitions at 218.73 GHz, and the marginal detection of an azimuthal asymmetry in the higher-energy H2CO (32,1−22,0) line, which could be due to accretion heating near PDS 70b.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa50163-24/aa50163-24.html
Autoren: Dane Spaeth, Sabine Reffert, Emily L. Hunt, Adrian Kaminski und Andreas Quirrenbach
Inhalt: 22 Seiten, 14 Abbildungen, 3 Tabellen
Kurztext: Context. Several evolved stars have been found to exhibit long-period radial velocity variations that cannot be explained by planetary or brown dwarf companions. Non-radial oscillations caused by oscillatory convective modes have been put forth as an alternative explanation, but no modeling attempt has yet been undertaken.
Aims. We provide a model of a non-radial oscillation, aiming to explain the observed variations of the cluster giant NGC 4349 No. 127. The star was previously reported to host a brown dwarf companion, but whose existence was later refuted in the literature.
Methods. We reanalyzed 58 archival HARPS spectra of the intermediate-mass giant NGC 4349 No. 127. We reduced the spectra using the SERVAL and RACCOON pipelines, acquiring additional activity indicators. We searched for periodicity in the indicators and correlations between the indicators and radial velocities. We further present a simulation code able to produce synthetic HARPS spectra, incorporating the effect of non-radial oscillations, and compare the simulated results to the observed variations. We discuss the possibility that non-radial oscillations cause the observed variations.
Results. We find a positive correlation between chromatic index and radial velocity, along with closed-loop Lissajous-like correlations between radial velocity and each of the spectral line shape indicators (full width at half maximum, and contrast of the cross-correlation function and differential line width). Simulations of a low-amplitude, retrograde, dipole (l = 1, m = 1), non-radial oscillation can reproduce the observed behavior and explain the observables. Photometric variations below the detection threshold of the available ASAS-3 photometry are predicted. The oscillation and stellar parameters are largely in agreement with the prediction of oscillatory convective modes.
Conclusions. The periodic variations of the radial velocities and activity indicators, along with the respective phase shifts, measured for the intermediate-mass cluster giant NGC 4349 No. 127, can be explained by a non-radial oscillation.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa44087-22/aa44087-22.html
Autoren: René Heller
Inhalt: 6 Seiten, 7 Abbildungen
Kurztext: The ~23 Myr young star β Pictoris (β Pic) is a laboratory for planet formation studies because of its observed debris disk, its directly imaged super-Jovian planets β Pic b and c, and the evidence of extrasolar comets that regularly transit in front of the star. The most recent evidence of exocometary transits around β Pic came from stellar photometric time series obtained with the TESS space mission. Previous analyses of these transits constrained the orbital distribution of the underlying exocomet population to a range between about 0.03 and 1.3 AU assuming a fixed transit impact parameter. We examine the distribution of the observed transit durations (Δt) to infer the orbital surface density distribution (δ) of the underlying exocomet sample. The effect of the geometric transit probability for circular orbits was properly taken into account, but we assumed that the radius of the transiting comets and their possible clouds of evaporating material are much smaller than the stellar radius. We show that a narrow belt of exocomets around β Pic, in which the transit impact parameters are randomized but the orbital semimajor axes are equal, results in a pile-up of long transit durations. This is in contrast to observations, which reveal a pile-up of short transit durations (Δt ≈ 0.1 d) and a tail of only a few transits with Δt > 0.4 d. A flat density distribution of exocomets between about 0.03 and 2.5 AU results in a better match between the resulting Δt distribution and the observations, but the slope of the predicted Δt histogram is not sufficiently steep. An even better match to the observations can be produced with a δ ∝ aβ power law. Our modeling reveals a best fit between the observed and predicted Δt distribution for β = −0.15−0.10+0.05. A more reasonable scenario in which the exocometary trajectories are modeled as hyperbolic orbits can also reproduce the observed Δt distribution to some extent. Future studies might reproduce the observed Δt distribution with a full exploration of the four-dimensional parameter space of highly eccentric orbits, and they might need to relax our assumption that the transiting objects are smaller than the stellar disk. The number of observed exocometary transits around β Pic is currently too small to validate the previously reported distinction of two distinct exocomet families, but this might be possible with future TESS observations of this star. Our results nevertheless imply that cometary material exists on highly eccentric orbits with a more extended range of semimajor axes than suggested by previous spectroscopic observations.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa50629-24/aa50629-24.html
Autoren: S. Das, N. T. Kurtovic und M. Flock
Inhalt: 12 Seiten, 6 Abbildungen, 4 Tabellen
Kurztext: Context. Current ALMA surveys often underestimate protoplanetary disk sizes as many disks have extended low surface-brightness regions that fall below ALMA’s detection limits. To effectively capture faint millimeter continuum emission in these outer regions, increased sensitivity is required.
Aims. In order to gain insights on the connection between disk structure and planet formation, we aim to uncover continuum emission in the outer regions of the disk around TW Hya. Additionally, we aim to investigate the evolution of this disk by studying its dust properties.
Methods. We present Atacama Large Millimeter Array (ALMA) observations of TW Hya at 0.65 mm with ~0.5 arcsecond angular resolution, together with high angular resolution archival observations at 0.87,1.3, 2.1 and 3.1 mm. We constrain the outer disk emission with both image-plane retrieval, and visibility-plane modeling with non-parametric and parametric fitting tools.
Results. Our results confirm emission in the outer disk regions of TW Hya (60 au ≤ R ≤ 110 au) at 0.65, 0.87 and 1.3 mm. With image-plane retrieval, we resolve the new continuum gap and ring, namely D79 and B86, at 0.87 and 1.3 mm. With visibility-plane modeling, we also detect this substructure at 0.65 mm in the form of a quasi-constant emission at the 1σ level. Furthermore, it has a high spectral index of 3.7, which may indicate dust grain sizes <<1 mm. It may be a dust trap or a traffic jam, that has a flux density of ~60 mJy and a mass (1.59 M⊕) that accounts for up to 2% of the dust disk at 0.65 mm.
Conclusions. We confirm the existence of a faint ring in the outer regions of TW Hya at multiple millimeter wavelengths. With visibility-plane modeling, we are able to set constrains that are 3 times better than the resolution of our Band 8 observations.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa49150-24/aa49150-24.html
Autoren: R. Nath-Ranga, O. Absil, V. Christiaens und E. O. Garvin
Inhalt: 15 Seiten, 7 Abbildungen
Kurztext: Context. The advent of high-contrast imaging instruments combined with medium-resolution spectrographs allows spectral and temporal dimensions to be combined with spatial dimensions to detect and potentially characterize exoplanets with higher sensitivity.
Aims. We developed a new method to effectively leverage the spectral and spatial dimensions in integral-field spectroscopy (IFS) datasets using a supervised deep-learning algorithm to improve the detection sensitivity to high-contrast exoplanets.
Methods. We began by applying a data transform whereby the four-dimensional (two spatial dimensions, one spectral dimension, and one temporal dimension) IFS datasets are replaced by four-dimensional cross-correlation coefficient tensors obtained by cross-correlating our data with young gas giant spectral template spectra. Thus, the spectral dimension is replaced by a radial velocity dimension and the rest of the dimensions are retained ‘as is’. This transformed data is then used to train machine learning (ML) algorithms. We trained a 2D convolutional neural network with temporally averaged spectral cubes as input, and a convolutional long short-term memory memory network that uses the temporal data as well. We compared these two models with a purely statistical (non-ML) exoplanet detection algorithm, which we developed specifically for four-dimensional datasets, based on the concept of the standardized trajectory intensity mean (STIM) map. We tested our algorithms on simulated young gas giants inserted into a SINFONI dataset that contains no known exoplanet, and explored the sensitivity of algorithms to detect these exoplanets at contrasts ranging from 10−3 to 10−4 for different radial separations.
Results. We quantify the relative sensitivity of the algorithms by using modified receiver operating characteristic curves (mROCs). We discovered that the ML algorithms produce fewer false positives and have a higher true positive rate than the STIM-based algorithm. We also show that the true positive rate of ML algorithms is less impacted by changing radial separation than the STIM-based algorithm. Finally, we show that preserving the velocity dimension of the cross-correlation coefficients in the training and inference plays an important role in ML algorithms being more sensitive to the simulated young gas giants.
Conclusions. In this paper we demonstrate that ML techniques have the potential to improve the detection limits and reduce false positives for directly imaged planets in IFS datasets, after transforming the spectral dimension into a radial velocity dimension through a cross-correlation operation and that the presence of the temporal dimension does not lead to increased sensitivity.
Link: https://www.aanda.org/articles/aa/full_html/2024/09/aa49149-24/aa49149-24.html
Autoren: Emily O. Garvin, Markus J. Bonse, Jean Hayoz, Gabriele Cugno, Jonas Spiller, Polychronis A. Patapis, Dominique Petit dit de la Roche, Rakesh Nath-Ranga, Olivier Absil, Nicolai F. Meinshausen und Sascha P. Quanz
Inhalt: 26 Seiten, 24 Abbildungen, 1 Tabelle
Kurztext: Context. The new generation of observatories and instruments (VLT/ERIS, JWST, ELT) motivate the development of robust methods to detect and characterise faint and close-in exoplanets. Molecular mapping and cross-correlation for spectroscopy use molecular templates to isolate a planet’s spectrum from its host star. However, reliance on signal-to-noise ratio metrics can lead to missed discoveries, due to strong assumptions of Gaussian-independent and identically distributed noise.
Aims. We introduce machine learning for cross-correlation spectroscopy (MLCCS). The aim of this method is to leverage weak assumptions on exoplanet characterisation, such as the presence of specific molecules in atmospheres, to improve detection sensitivity for exoplanets.
Methods. The MLCCS methods, including a perceptron and unidimensional convolutional neural networks, operate in the cross-correlated spectral dimension, in which patterns from molecules can be identified. The methods flexibly detect a diversity of planets by taking an agnostic approach towards unknown atmospheric characteristics. The MLCCS approach is implemented to be adaptable for a variety of instruments and modes. We tested this approach on mock datasets of synthetic planets inserted into real noise from SINFONI at the K-band.
Results. The results from MLCCS show outstanding improvements. The outcome on a grid of faint synthetic gas giants shows that for a false discovery rate up to 5%, a perceptron can detect about 26 times the amount of planets compared to an S/N metric. This factor increases up to 77 times with convolutional neural networks, with a statistical sensitivity (completeness) shift from 0.7 to 55.5%. In addition, MLCCS methods show a drastic improvement in detection confidence and conspicuity on imaging spectroscopy.
Conclusions. Once trained, MLCCS methods offer sensitive and rapid detection of exoplanets and their molecular species in the spectral dimension. They handle systematic noise and challenging seeing conditions, can adapt to many spectroscopic instruments and modes, and are versatile regarding planet characteristics, enabling the identification of various planets in archival and future data.
Ähnliche Beiträge
Entdecke mehr von Exoplaneten-News
Melde dich für ein Abonnement an, um die neuesten Beiträge per E-Mail zu erhalten.
Neueste Kommentare