Earth and Planetary Astrophysics
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- [1] arXiv:2406.12996 [pdf, html, other]
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Title: TOI-2374 b and TOI-3071 b: two metal-rich sub-Saturns well within the Neptunian desertAlejandro Hacker, Rodrigo F. Díaz, David J. Armstrong, Jorge Fernández Fernández, Simon Müller, Elisa Delgado-Mena, Sérgio G. Sousa, Vardan Adibekyan, Keivan G. Stassun, Karen A. Collins, Samuel W. Yee, Daniel Bayliss, Allyson Bieryla, François Bouchy, R. Paul Butler, Jeffrey D. Crane, Xavier Dumusque, Joel D. Hartman, Ravit Helled, Jon Jenkins, Marcelo Aron F. Keniger, Hannah Lewis, Jorge Lillo-Box, Michael B. Lund, Louise D. Nielsen, Ares Osborn, David Osip, Martin Paegert, Don J. Radford, Nuno C. Santos, Sara Seager, Stephen A. Shectman, Gregor Srdoc, Paul A. Strøm, Thiam-Guan Tan, Johanna K. Teske, Michael Vezie, David Watanabe, Cristilyn N. Watkins, Peter J. Wheatley, Joshua N. Winn, Bill Wohler, Carl ZieglerComments: 24 pages, 22 figures, 10 tables, accepted for publication in MNRASSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
We report the discovery of two transiting planets detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-2374 b and TOI-3071 b, orbiting a K5V and an F8V star, respectively, with periods of 4.31 and 1.27 days, respectively. We confirm and characterize these two planets with a variety of ground-based and follow-up observations, including photometry, precise radial velocity monitoring and high-resolution imaging. The planetary and orbital parameters were derived from a joint analysis of the radial velocities and photometric data. We found that the two planets have masses of $(57 \pm 4)$ $M_\oplus$ or $(0.18 \pm 0.01)$ $M_J$, and $(68 \pm 4)$ $M_\oplus$ or $(0.21 \pm 0.01)$ $M_J$, respectively, and they have radii of $(6.8 \pm 0.3)$ $R_\oplus$ or $(0.61 \pm 0.03)$ $R_J$ and $(7.2 \pm 0.5)$ $R_\oplus$ or $(0.64 \pm 0.05)$ $R_J$, respectively. These parameters correspond to sub-Saturns within the Neptunian desert, both planets being hot and highly irradiated, with $T_{\rm eq} \approx 745$ $K$ and $T_{\rm eq} \approx 1812$ $K$, respectively, assuming a Bond albedo of 0.5. TOI-3071 b has the hottest equilibrium temperature of all known planets with masses between $10$ and $300$ $M_\oplus$ and radii less than $1.5$ $R_J$. By applying gas giant evolution models we found that both planets, especially TOI-3071 b, are very metal-rich. This challenges standard formation models which generally predict lower heavy-element masses for planets with similar characteristics. We studied the evolution of the planets' atmospheres under photoevaporation and concluded that both are stable against evaporation due to their large masses and likely high metallicities in their gaseous envelopes.
- [2] arXiv:2406.13037 [pdf, html, other]
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Title: Large Interferometer For Exoplanets (LIFE): XIII. The Value of Combining Thermal Emission and Reflected Light for the Characterization of Earth TwinsE. Alei, S. P. Quanz, B. S. Konrad, E. O. Garvin, V. Kofman, A. Mandell, D. Angerhausen, P. Mollière, M. R. Meyer, T. Robinson, S. Rugheimer, the LIFE CollaborationComments: 16 pages (main text, incl. 12 figures) + appendix; accepted for publication in A&A (current version: post 1st revision). Thirteenth paper of LIFE telescope seriesSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Following the recommendations to NASA and ESA, the search for life on exoplanets will be a priority in the next decades. Two direct imaging space mission concepts are being developed: the Habitable Worlds Observatory (HWO) and the Large Interferometer for Exoplanets (LIFE). HWO focuses on reflected light spectra in the ultraviolet/visible/near-infrared (UV/VIS/NIR), while LIFE captures the mid-infrared (MIR) emission of temperate exoplanets. We assess the potential of HWO and LIFE in characterizing a cloud-free Earth twin orbiting a Sun-like star at 10 pc, both separately and synergistically, aiming to quantify the increase in information from joint atmospheric retrievals on a habitable planet. We perform Bayesian retrievals on simulated data from an HWO-like and a LIFE-like mission separately, then jointly, considering the baseline spectral resolutions currently assumed for these concepts and using two increasingly complex noise simulations. HWO would constrain H$_2$O, O$_2$, and O$_3$, in the atmosphere, with ~ 100 K uncertainty on the temperature profile. LIFE would constrain CO$_2$, H$_2$O, O$_3$ and provide constraints on the thermal atmospheric structure and surface temperature (~ 10 K uncertainty). Both missions would provide an upper limit on CH$_4$. Joint retrievals on HWO and LIFE data would accurately define the atmospheric thermal profile and planetary parameters, decisively constrain CO$_2$, H$_2$O, O$_2$, and O$_3$, and weakly constrain CO and CH$_4$. The detection significance is greater or equal to single-instrument retrievals. Both missions provide specific information to characterize a terrestrial habitable exoplanet, but the scientific yield is maximized with synergistic UV/VIS/NIR+MIR observations. Using HWO and LIFE together will provide stronger constraints on biosignatures and life indicators, potentially transforming the search for life in the universe.
- [3] arXiv:2406.13222 [pdf, other]
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Title: The Origin of Jupiter's Great Red SpotAgustín Sánchez-Lavega, Enrique García-Melendo, Jon Legarreta, Arnau Miró, Manel Soria, Kevin Ahrens-VelásquezJournal-ref: Geophysical Research Letters, Volume 51, Issue 12, 28 June 2024, e2024GL108993Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Jupiter's Grat Red Spot (GRS) is the largest and longest-lived vortex of all solar system planets but its lifetime is debated and its formation mechanism remains hidden. G. D. Cassini discovered in 1665 the presence of a dark oval at the GRS latitude, known as the "Permanent Spot" (PS) that was observed until 1713. We show from historical observations of its size evolution and motions that PS is unlikely to correspond to the current GRS, that was first observed in 1831. New numerical simulations rule out that the GRS formed by the merging of vortices or by a superstorm, but most likely formed from a flow disturbance between the two opposed Jovian zonal jets north and south of it. If so, the aearly GRS should have had a low tangential velocity so that its rotation velocity has increased over time as it shrunk.
- [4] arXiv:2406.13637 [pdf, other]
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Title: The Source of Hydrogen in Earth's Building BlocksThomas J Barrett (1), James F. J. Bryson (1), Kalotina Geraki (2) ((1) University of Oxford, Department of Earth Sciences, (2) Diamond Light Source)Comments: 19 pages, 12 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Despite being pivotal to the habitability of our planet, the process by which Earth gained its present-day hydrogen budget is unclear. Due to their isotopic similarity to terrestrial rocks across a range of elements, enstatite chondrites (ECs) are thought to be the meteorites that best represent Earth's building blocks. Because of ECs' nominally anhydrous mineralogy, these building blocks have long been presumed to have supplied negligible hydrogen to the proto-Earth. Instead, hydrogen has been proposed to have been delivered to our planet after its main stage of formation by impacts from hydrated asteroids. In this case, our planet's habitability would have its origins in a stochastic process. However, ECs have recently been found to unexpectedly contain enough hydrogen to readily explain Earth's present-day water budget. Although this result would transform the processes we believe are required for rocky planets to be suitable to life, the mineralogical source of ~80% of hydrogen in these meteorites was previously unknown. As such, the reason ECs are seemingly rich in hydrogen was unclear. Here, we apply sulfur X-ray absorption near edge structure (S-XANES) spectroscopy to ECs, finding that most (~70%) of their hydrogen is bonded to sulfur. Moreover, the concentration of the S-H bond is intimately linked to the abundance of micrometre-scale pyrrhotite (Fe1-xS, 0<x<0.125), suggesting most hydrogen in these meteorites is carried in this phase. These findings elucidate the presence of hydrogen in Earth's building blocks, providing the key evidence that unlocks a systematic, rather than stochastic, origin of Earth's hydrogen.
- [5] arXiv:2406.13697 [pdf, html, other]
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Title: Detection of Moving Objects in Earth Observation Satellite Images: VerificationComments: Submitted to the Journal of Astronomical InstrumentationSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
In multi-spectral images made by Earth observation satellites that use push-broom scanning, such as those operated by Planet Labs Corp., moving objects can be identified by the appearance of the object at a different locations in each spectral band. The apparent velocity can be measured if the relative acquisition time between images in different spectral bands is known to millisecond accuracy. The images in the Planet Labs archive are mosaics of individual exposures acquired at different times. Thus there is not a unique acquisition time for each spectral band. In an earlier paper, we proposed a method to determine the relative acquisition times from the information in the images themselves. High altitude balloons provide excellent targets to test our proposed method because of their high apparent velocity due to the orbital velocity of the satellite and geometric parallax in images aligned to the level of the ground. We use images of the Chinese balloon that crossed the US in February, 2024 as well as images of an identical balloon over Colombia to test our method. Our proposed method appears to be successful and allows the measurement of the apparent velocity of moving objects from the information available in the archive.
- [6] arXiv:2406.13710 [pdf, html, other]
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Title: Velocity Analysis of Moving Objects in Earth Observation Satellite Images Using Multi-Spectral Push Broom ScanningComments: Submitted to Remote SensingSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
In this study, we present a method for detecting and analyzing the velocities of moving objects in Earth observation satellite images, specifically using data from Planet Labs' push broom scanning satellites. By exploiting the sequential acquisition of multi-spectral images, we estimate the relative differences in acquisition times between spectral bands. This allows us to determine the velocities of moving objects, such as aircraft, even without precise timestamp information from the image archive. We validate our method by comparing the velocities of aircraft observed in satellite images with those reported by onboard ADS-B transponders. The results demonstrate the potential, despite challenges posed by proprietary data limitations, of a new, useful application of commercial satellite data originally intended as an ongoing, once-daily survey of single images covering the entire land-area of the Earth. Our approach extends the applicability of satellite survey imagery for dynamic object tracking and contributes to the broader use of commercial satellite data in scientific research.
- [7] arXiv:2406.14006 [pdf, html, other]
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Title: Revealing asymmetry on midplane of proto-planetary disc through modelling of axisymmetric emission: methodologyComments: 31 pages, 23 figures, accepted for publication in MNRASSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
This study proposes an analytical framework for deriving the surface brightness profile and geometry of a geometrically-thin axisymmetric disc from interferometric observation of continuum emission. Such precise modelling facilitates the exploration of faint non-axisymmetric structures, such as spirals and circumplanetary discs. As a demonstration, we simulate interferometric observations of geometrically-thin axisymmetric discs. The proposed method can reasonably recover the injected axisymmetric structures, whereas Gaussian fitting of the same data yielded larger errors in disc orientation estimation. To further test the applicability of the method, it was applied to the mock data for $m=1,2$ spirals and a point source, which are embedded in a bright axisymmetric structure. The injected non-axisymmetric structures were reasonably recovered except for the innermost parts, and the disc geometric parameter estimations were better than Gasussian fitting. The method was then applied to the real data of Elias 20 and AS 209, and it adequately subtracted the axisymmetric component, notably in Elias 20, where substantial residuals remained without our method. We also applied our method to continuum data of PDS 70 to demonstrate the effectiveness of the method. We successfully recovered emission from PDS 70 c consistently with previous studies, and also tentatively discovered new substructures. The current formulation can be applied to any data for disc continuum emission, and aids in the search of spirals and circumplanetary discs, whose detection is still limited.
- [8] arXiv:2406.14072 [pdf, html, other]
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Title: IGRINS observations of WASP-127 b: H$_2$O, CO, and super-Solar atmospheric metallicity in the inflated sub-SaturnKrishna Kanumalla, Michael R. Line, Megan Weiner Mansfield, Luis Welbanks, Peter C. B. Smith, Jacob L. Bean, Lorenzo Pino, Matteo Brogi, Vatsal PanwarComments: 18 pages, 15 figures, submitted to AJ, poster at Exo5 conference area-ASubjects: Earth and Planetary Astrophysics (astro-ph.EP)
High resolution spectroscopy of exoplanet atmospheres provides insights into their composition and dynamics from the resolved line shape and depth of thousands of spectral lines. WASP-127 b is an extremely inflated sub-Saturn (R$_\mathrm{p}$= 1.311 R$_\mathrm{Jup}$, M$_\mathrm{p}$= 0.16 M$_\mathrm{Jup}$) with previously reported detections of H$_2$O, CO$_2$, and Na. However, the seeming absence of the primary carbon reservoir expected at WASP-127 b temperatures (T$_{eq}$ $\sim$ 1400 K) from chemical equilibrium, CO, posed a mystery. In this manuscript, we present the analysis of high resolution observations of WASP-127 b with the Immersion GRating INfrared Spectrometer (IGRINS) on Gemini South. We confirm the presence of H$_2$O (8.67 $\sigma$) and report the detection of CO (4.34 $\sigma$). Additionally, we conduct a suite of Bayesian retrieval analyses covering a hierarchy of model complexity and self-consistency. When freely fitting for the molecular gas volume mixing ratios, we obtain super-solar metal enrichment for H$_2$O abundance of log$_{10}$X$_\mathrm{H_2O}$ = --1.23$^{+0.29}_{-0.49}$ and a lower limit on the CO abundance of log$_{10}$X$_\mathrm{CO}$ $\ge$ --2.20 at 2$\sigma$ confidence. We also report a tentative evidence of photochemistry in WASP-127 b based upon the indicative depletion of H$_2$S. This is also supported by the data preferring models with photochemistry over free-chemistry and thermochemistry. The overall analysis implies a super-solar ($\sim$ 39$\times$ Solar; [M/H] = $1.59^{+0.30}_{-0.30}$) metallicity for the atmosphere of WASP-127 b and an upper limit on its atmospheric C/O ratio as $<$ 0.68.
- [9] arXiv:2406.14181 [pdf, html, other]
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Title: Secular dynamics and the lifetimes of lunar artificial satellites under natural force-driven orbital evolutionSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
In this paper, we study the long-term (time scale of several years) orbital evolution of lunar satellites under the sole action of natural forces. In particular, we focus on secular resonances, caused either by the influence of the multipole moments of the lunar potential and/or by the Earth's and Sun's third-body effect on the satellite's long-term orbital evolution. Our study is based on a simplified secular model obtained in `closed form' using the same methodology proposed in the recently published report on the semi-analytical propagator of lunar satellite orbits, SELENA. Contrary to the case of artificial Earth satellites, in which many secular resonances compete in dynamical impact, we give numerical evidence that for lunar satellites only the 2 g resonance affects significantly the orbits at secular timescales. We interpret this as a consequence of the strong effect of lunar mascons. We show that the lifetime of lunar satellites is, in particular, nearly exclusively dictated by the 2 g resonance. By deriving a simple analytic model, we propose a theoretical framework which allows for both qualitative and quantitative interpretation of the structures seen in numerically obtained lifetime maps. This involves explaining the main mechanisms driving eccentricity growth in the orbits of lunar satellites. In fact, we argue that the re-entry process for lunar satellites is not necessarily a chaotic process (as is the case for Earth satellites), but rather due to a sequence of bifurcations leading to a dramatic variation in the structure of the separatrices in the 2 g resonance's phase portrait, as we move from the lowest to the highest limit in inclination (at each altitude) where the 2 g resonance is manifested.
- [10] arXiv:2406.14293 [pdf, other]
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Title: Abundant hydrocarbons in the disk around a very-low-mass starA. M. Arabhavi, I. Kamp, Th. Henning, E. F. van Dishoeck, V. Christiaens, D. Gasman, A. Perrin, M. Güdel, B. Tabone, J. Kanwar, L. B. F. M. Waters, I. Pascucci, M. Samland, G. Perotti, G. Bettoni, S. L. Grant, P. O. Lagage, T. P. Ray, B. Vandenbussche, O. Absil, I. Argyriou, D. Barrado, A. Boccaletti, J. Bouwman, A. Caratti o Garatti, A. M. Glauser, F. Lahuis, M. Mueller, G. Olofsson, E. Pantin, S. Scheithauer, M. Morales-Calderón, R. Franceschi, H. Jang, N. Pawellek, D. Rodgers-Lee, J. Schreiber, K. Schwarz, M. Temmink, M. Vlasblom, G. Wright, L. Colina, G. ÖstlinComments: Published, 36 pages, 8 figuresJournal-ref: Science, Vol 384, Issue 6700, 2024, pp. 1086-1090Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Very low-mass stars (those <0.3 solar masses) host orbiting terrestrial planets more frequently than other types of stars, but the compositions of those planets are largely unknown. We use mid-infrared spectroscopy with the James Webb Space Telescope to investigate the chemical composition of the planet-forming disk around ISO-ChaI 147, a 0.11 solar-mass star. The inner disk has a carbon-rich chemistry: we identify emission from 13 carbon-bearing molecules including ethane and benzene. We derive large column densities of hydrocarbons indicating that we probe deep into the disk. The high carbon to oxygen ratio we infer indicates radial transport of material within the disk, which we predict would affect the bulk composition of any planets forming in the disk.
- [11] arXiv:2406.14444 [pdf, html, other]
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Title: Combining reference-star and angular differential imaging for high-contrast imaging of extended sourcesComments: 21 pages, 18 figures, Accepted to A&ASubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
High-contrast imaging (HCI) is a technique designed to observe faint signals near bright sources, such as exoplanets and circumstellar disks. The primary challenge in revealing the faint circumstellar signal near a star is the presence of quasi-static speckles, which can produce patterns on the science images that are as bright, or even brighter, than the signal of interest. Strategies such as angular differential imaging (ADI) or reference-star differential imaging (RDI) aim to provide a means of removing the quasi-static speckles in post-processing. In this paper, we present and discuss the adaptation of state-of-the-art algorithms, initially designed for ADI, to jointly leverage angular and reference-star differential imaging (ARDI) for direct high-contrast imaging of circumstellar disks. Using a collection of high-contrast imaging data sets, we assess the performance of ARDI in comparison to ADI and RDI based on iterative principal component analysis (IPCA). These diverse data sets are acquired under various observing conditions and include the injection of synthetic disk models at various contrast levels. Our results demonstrate that ARDI with IPCA improves the quality of recovered disk images and the sensitivity to planets embedded in disks, compared to ADI or RDI individually. This enhancement is particularly pronounced when dealing with extended sources exhibiting highly ambiguous structures that cannot be accurately retrieved using ADI alone, and when the quality of the reference frames is suboptimal, leading to an underperformance of RDI. We finally apply our method to a sample of real observations of protoplanetary disks taken in star-hopping mode, and propose to revisit the protoplanetary claims associated with these disks.
- [12] arXiv:2406.14531 [pdf, html, other]
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Title: Roman FFP Revolution: Two, Three, Many PlutosComments: 46 pages, 4 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Roman microlensing stands at a crossroads between its originally charted path of cataloging a population of cool planets that has subsequently become well-measured down to super-Earths, and the path of free-floating planets (FFPs), which did not exist when Roman was chosen in 2010, but by now promises revolutionary insights into planet formation and evolution via their possible connection to a spectrum of objects spanning 18 decades in mass. Until now, it was not even realized that the 2 paths are in conflict: Roman strategy was optimized for bound-planet detections, and FFPs were considered only in the context of what could be learned about them given this strategy. We derive a simple equation that mathematically expresses this conflict and explains why the current approach severely depresses detection of 2 of the 5 decades of potential FFP masses, i.e., exactly the two decades, $M_{\rm Pluto}< M <2\,M_{\rm Mars}$, that would tie terrestrial planets to the proto-planetary material out of which they formed. FFPs can be either truly free floating or can be bound in "Wide", "Kuiper", and "Oort" orbits, whose separate identification will allow further insight into planet formation. In the (low-mass) limit that the source radius is much bigger than the Einstein radius, $\theta_*\gg\theta_{\rm E}$, the number of significantly magnified points on the FFP light curve is $N=2\Gamma\theta_*\sqrt{1-z^2}/\mu$ --> 3.0, when normalized to the adopted Roman cadence $\Gamma=4/$hr, and to source radius $\theta_*=0.3\,\mu$as, lens-source proper motion $\mu=6\,$mas/yr, and source impact parameter $z=0.5$, which are all typical values. By contrast $N=6$ are needed for an FFP detection. Thus, unless $\Gamma$ is doubled, FFP detection will be driven into the (large-$\theta_*$, small-$\mu$) corner of parameter space, reducing the detections by a net factor of 2 and cutting off the lowest-mass FFPs.
- [13] arXiv:2406.14560 [pdf, html, other]
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Title: OH mid-infrared emission as a diagnostic of H$_2$O UV photodissociation. III. Application to planet-forming disksComments: Accepted for publication in Astronomy & AstrophysicsSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
JWST gives a unique access to the physical and chemical structure of inner disks ($<10$~au), where the majority of the planets are forming. However, the interpretation of mid-infrared (mid-IR) spectra requires detailed thermo-chemical models able to provide synthetic spectra readily comparable to spectroscopic observations. Our goal is to explore the potential of mid-IR emission of OH to probe H$_2$O photodissociation. We include in the DALI disk model prompt emission of OH following photodissociation of H$_2$O in its $\tilde{B}$ electronic state ($\lambda < 144$~nm). This model allows to compute in a self-consistent manner the thermo-chemical structure of the disk and the resulting mid-IR line intensities of OH and H$_2$O. The OH line intensities in the $9-13~\mu$m range are proportional to the total amount of water photodissociated. As such, these lines are a tracer of the amount of water exposed to the FUV field, which depends on the temperature, density, and strength of the FUV field reaching the upper molecular layers. In particular, the OH line fluxes primarily scale with the FUV field emitted by the star in contrast with H$_2$O lines in the 10-20$~\mu$m range which scale with the bolometric luminosity. OH is therefore a key diagnostic to probe the effect of Ly$\alpha$ and constrain the dust FUV opacity in the upper molecular layers. A strong asymmetry between the A' and A'' components of each rotational quadruplet is also predicted. OH mid-IR emission is a powerful tool to probe H$_2$O photodissociation and infer the physical conditions in disk atmospheres. As such, the inclusion of OH mid-IR lines in the analysis of JWST-MIRI spectra will be key for robustly inferring the composition of planet-forming disks. The interpretation of less excited OH lines requires additional quantum calculations of the formation pumping of OH levels by O+H$_2$ and the collisional rate coefficients.
New submissions for Friday, 21 June 2024 (showing 13 of 13 entries )
- [14] arXiv:2406.13011 (cross-list from astro-ph.SR) [pdf, other]
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Title: Measuring the Spot Variability of T Tauri Stars Using Near-IR Atomic Fe and Molecular OH LinesShih-Yun Tang (1, 2), Christopher M. Johns-Krull (1), L. Prato (2), Asa G. Stahl (1) ((1) Department of Physics and Astronomy, Rice University, (2) Lowell Observatory)Comments: 31 pages, 19 figures, and 5 tables. Accepted to ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
As part of the Young Exoplanets Spectroscopic Survey (YESS), this study explores the spot variability of 13 T Tauri Stars (TTSs) in the near-infrared $H$ band, using spectra from the Immersion GRating INfrared Spectrometer (IGRINS). By analyzing effective temperature ($T_{\rm eff}$) sensitive lines of atomic FeI at ~1.56259 um and ~1.56362 um, and molecular OH at ~1.56310 um and ~1.56317 um, we develop an empirical equivalent width ratio (EWR) relationship for $T_{\rm eff}$ in the range of 3400-5000 K. This relationship allows for precise relative $T_{\rm eff}$ estimates to within tens of Kelvin and demonstrates compatibility with solar metallicity target models. However, discrepancies between observational data and model predictions limit the extension of the $T_{\rm eff}$-EWR relationship to a broader parameter space. Our study reveals that both classical and weak-line TTSs can exhibit $T_{\rm eff}$ variations exceeding 150 K over a span of two years. The detection of a quarter-phase delay between the EWR and radial velocity phase curves in TTSs indicates spot-driven signals. A phase delay of 0.06 $\pm$ 0.13 for CI Tau, however, suggests additional dynamics, potentially caused by planetary interaction, inferred from a posited 1:1 commensurability between the rotation period and orbital period. Moreover, a positive correlation between $T_{\rm eff}$ variation amplitude and stellar inclination angle support the existence of high-latitude spots on TTSs, further enriching our understanding of stellar surface activity in young stars.
Cross submissions for Friday, 21 June 2024 (showing 1 of 1 entries )
- [15] arXiv:2306.13321 (replaced) [pdf, other]
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Title: Comparison of optical spectra between asteroids Ryugu and Bennu:I. Cross calibration between Hayabusa2/ONC-T and OSIRIS-REx/MapCamK. Yumoto, E. Tatsumi, T. Kouyama, D. R. Golish, Y. Cho, T. Morota, S. Kameda, H. Sato, B. Rizk, D. N. DellaGiustina, Y. Yokota, H. Suzuki, J. de Leon, H. Campins, J. Licandro, M. Popescu, J. L. Rizos, R. Honda, M. Yamada, N. Sakatani, C. Honda, M. Matsuoka, M. Hayakawa, H. Sawada, K. Ogawa, Y. Yamamoto, D. S. Lauretta, S. SugitaJournal-ref: Icarus, 417, 116122 (2024)Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Asteroids (162173) Ryugu and (101955) Bennu observed by Hayabusa2 and OSIRIS-REx share many properties, but spectral observations by the telescopic Optical Navigation Camera (ONC-T) and MapCam detected subtle but significant differences, which may reflect differences in their origin and evolution. Comparing these differences on the same absolute scale is necessary for understanding their causes. However, ONC-T and MapCam have a large imager-to-imager systematic error of up to 15% caused by the difference in radiometric calibration targets. To resolve this problem, we cross calibrated albedo and color data between the two instruments using the Moon as the common calibration standard. The images of the Moon taken by ONC-T and MapCam were compared with those simulated using photometry models developed from lunar orbiter data. Our results show that the cross-calibrated reflectance of Ryugu and Bennu can be obtained by upscaling the pre-cross-calibrated reflectance of Bennu by 13.3 +/- 1.6% at b band, 13.2 +/- 1.5% at v band, 13.6 +/- 1.7% at w band, and 14.8 +/- 1.8% at x band, while those for Ryugu are kept the same. These factors compensate for the imager-to-imager bias caused by differences in targets used for radiometric calibration and solar irradiance models used for data reduction. Need for such large upscaling underscore the importance of using the cross-calibrated data for accurately comparing the Ryugu and Bennu data. The uncertainty in these factors show that the reflectance of Ryugu and Bennu can be compared with <2% accuracy after applying our results. By applying our cross calibration, the geometric albedo of Bennu became consistent with those observed by ground-based telescopes and OVIRS. Our result can be simply applied by multiplying a constant to the publicly available data and enables accurate comparison of the optical spectra of Ryugu and Bennu in future studies.
- [16] arXiv:2405.06350 (replaced) [pdf, html, other]
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Title: Three short-period Earth-sized planets around M dwarfs discovered by TESS: TOI-5720b, TOI-6008b and TOI-6086bK. Barkaoui, R.P. Schwarz, N. Narita, P. Mistry, C. Magliano, T. Hirano, M. Maity, A.J. Burgasser, B.V. Rackham, F. Murgas, F.J. Pozuelos, K.G. Stassun, M.E. Everett, D.R. Ciardi, C. Lamman, E.K. Pass, A. Bieryla, C. Aganze, E. Esparza-Borges, K.A. Collins, G. Covone, J. de Leon, M. D'evora-Pajares, J. de Wit, Izuru Fukuda, A. Fukui, R. Gerasimov, M. Gillon, Y. Hayashi, S.B. Howell, M. Ikoma, K. Ikuta, J.M. Jenkins, P.R. Karpoor, Y. Kawai, T. Kimura, T. Kotani, D.W. Latham, M. Mori, E. Palle, H. Parviainen, Y.G. Patel, G. Ricker, H.M. Relles, A. Shporer, S. Seager, E. Softich, G. Srdoc, M. Tamura, C.A. Theissen, J.D. Twicken, R. Vanderspek, N. Watanabe, C.N. Watkins, J.N. Winn, B. WohlerComments: Accepted for publication in Astronomy & AstrophysicsSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
One of the main goals of the NASA's TESS (Transiting Exoplanet Survey Satellite) mission is the discovery of Earth-like planets around nearby M-dwarf stars. Here, we present the discovery and validation of three new short-period Earth-sized planets orbiting nearby M-dwarfs: TOI- 5720b, TOI-6008b and TOI-6086b. We combined TESS data, ground-based multi-color light curves, ground-based optical and near-infrared spectroscopy, and Subaru/IRD RVs data to validate the planetary candidates and constrain the physical parameters of the systems. In addition, we used archival images, high-resolution imaging, and statistical validation techniques to support the planetary validation. TOI-5720b is a planet with a radius of Rp=1.09 Re orbiting a nearby (23 pc) M2.5 host, with an orbital period of P=1.43 days. It has an equilibrium temperature of Teq=708 K and an incident flux of Sp=41.7 Se. TOI-6008b has a period of P=0.86 day, a radius of Rp=1.03 Re, an equilibrium temperature of Teq=707 K and an incident flux of Sp=41.5 Se. The host star (TOI-6008) is a nearby (36 pc) M5 with an effective temperature of Teff=3075 K. Based on the RV measurements collected with Subaru/IRD, we set a 3-sigma upper limit of Mp<4 M_Earth, thus ruling out a star or brown dwarf as the transiting companion. TOI-6086b orbits its nearby (31 pc) M3 host star (Teff=3200 K) every 1.39 days, and has a radius of Rp=1.18 Re, an equilibrium temperature of Teq=634 K and an incident flux of Sp=26.8 Se. Additional high precision radial velocity measurements are needed to derive the planetary masses and bulk densities, and to search for additional planets in the systems. Moreover, short-period earth-sized planets orbiting around nearby M-dwarfs are suitable targets for atmospheric characterization with the James Webb Space Telescope (JWST) through transmission and emission spectroscopy, and phase curve photometry.
- [17] arXiv:2405.15611 (replaced) [pdf, html, other]
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Title: Planet-driven spirals in protoplanetary discs: limitations of the semi-analytical theory for observationsD. Fasano, A. J. Winter, M. Benisty, G. Rosotti, A. Ruzza, G. Lodato, C. Toci, T. Hilder, A. Izquierdo, D. PriceComments: 10 pages, 7 figures. Accepted for publication in A&A May 27, 2024Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Detecting protoplanets during their formation stage is an important but elusive goal of modern astronomy. Kinematic detections via the spiral wakes in the gaseous disc are a promising avenue to achieve this goal. We aim to test the applicability to observations in the low and intermediate planet mass regimes of a commonly used semi-analytical model for planet induced spiral waves. In contrast with previous works which proposed to use the semi-analytical model to interpret observations, in this study we analyse for the first time both the structure of the velocity and density perturbations. We run a set of FARGO3D hydrodynamic simulations and compare them with the output of the semi-analytic model in the code wakeflow, which is obtained by solving Burgers' equation using the simulations as an initial condition. We find that the velocity field derived from the analytic theory is discontinuous at the interface between the linear and nonlinear regions. After 0.2 r$_p$ from the planet, the behaviour of the velocity field closely follows that of the density perturbations. In the low mass limit, the analytical model is in qualitative agreement with the simulations, although it underestimates the azimuthal width and the amplitude of the perturbations, predicting a stronger decay but a slower azimuthal advance of the shock fronts. In the intermediate regime, the discrepancy increases, resulting in a different pitch angle between the spirals of the simulations and the analytic model. The implementation of a fitting procedure based on the minimisation of intensity residuals is bound to fail due to the deviation in pitch angle between the analytic model and the simulations. In order to apply this model to observations, it needs to be revisited accounting also for higher planet masses.
- [18] arXiv:2406.09641 (replaced) [pdf, html, other]
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Title: Phase-resolving the absorption signatures of water and carbon monoxide in the atmosphere of the ultra-hot Jupiter WASP-121b with GEMINI-S/IGRINSJoost P. Wardenier, Vivien Parmentier, Michael R. Line, Megan Weiner Mansfield, Xianyu Tan, Shang-Min Tsai, Jacob L. Bean, Jayne L. Birkby, Matteo Brogi, Jean-Michel Désert, Siddharth Gandhi, Elspeth K. H. Lee, Colette I. Levens, Lorenzo Pino, Peter C. B. SmithComments: 24 pages, 16 figures, resubmitted to PASP (made a few minor changes to the text w.r.t. v1)Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Ultra-hot Jupiters are among the best targets for atmospheric characterization at high spectral resolution. Resolving their transmission spectra as a function of orbital phase offers a unique window into the 3D nature of these objects. In this work, we present three transits of the ultra-hot Jupiter WASP-121b observed with Gemini-S/IGRINS. For the first time, we measure the phase-dependent absorption signals of CO and H$_{\text{2}}$O in the atmosphere of an exoplanet, and we find that they are different. While the blueshift of CO increases during the transit, the absorption lines of H$_{\text{2}}$O become less blueshifted with phase, and even show a redshift in the second half of the transit. These measurements reveal the distinct spatial distributions of both molecules across the atmospheres of ultra-hot Jupiters. Also, we find that the H$_{\text{2}}$O signal is absent in the first quarter of the transit, potentially hinting at cloud formation on the evening terminator of WASP-121b. To further interpret the absorption trails of CO and H$_{\text{2}}$O, as well as the Doppler shifts of Fe previously measured with VLT/ESPRESSO, we compare the data to simulated transits of WASP-121b. To this end, we post-processes the outputs of global circulation models with a 3D Monte-Carlo radiative transfer code. Our analysis shows that the atmosphere of WASP-121b is subject to atmospheric drag, as previously suggested by small hotspot offsets inferred from phase-curve observations. Our study highlights the importance of phase-resolved spectroscopy in unravelling the complex atmospheric structure of ultra-hot Jupiters and sets the stage for further investigations into their chemistry and dynamics.
- [19] arXiv:2406.09802 (replaced) [pdf, html, other]
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Title: Simulating the Escaping Atmosphere of GJ 436 b with Two-fluid Magnetohydrodynamic ModelsSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Observations of transmission spectra reveal that hot Jupiters and Neptunes are likely to possess escaping atmospheres driven by stellar radiation. Numerous models predict that magnetic fields may exert significant influences on the atmospheres of hot planets. Generally, the escaping atmospheres are not entirely ionized, and magnetic fields only directly affect the escape of ionized components within them. Considering the chemical reactions between ionized components and neutral atoms, as well as collision processes, magnetic fields indirectly impact the escape of neutral atoms, thereby influencing the detection signals of planetary atmospheres in transmission spectra. In order to simulate this process, we developed a magneto-hydrodynamic multi-fluid model based on MHD code PLUTO. As an initial exploration, we investigated the impact of magnetic fields on the decoupling of H$^+$ and H in the escaping atmosphere of the hot Neptune GJ436 b. Due to the strong resonant interactions between H and H$^+$, the coupling between them is tight even if the magnetic field is strong. Of course, alternatively, our work also suggests that merging H and H$^+$ into a single flow can be a reasonable assumption in MHD simulations of escaping atmospheres. However, our simulation results indicate that under the influence of magnetic fields, there are noticeable regional differences in the decoupling of H$^+$ and H. With the increase of magnetic field strength, the degree of decoupling also increases. For heavier particles such as O, the decoupling between O and H$^+$ is more pronounced. Our findings provide important insights for future studies on the decoupling processes of heavy atoms in the escaping atmospheres of hot Jupiters and hot Neptunes under the influence of magnetic fields.
- [20] arXiv:2406.12798 (replaced) [pdf, html, other]
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Title: The Aligned Orbit of a Hot Jupiter around the M Dwarf TOI-4201Tianjun Gan, Sharon X. Wang, Fei Dai, Joshua N. Winn, Shude Mao, Siyi Xu, Enric Pallé, Jacob L. Bean, Madison Brady, Nina Brown, Cicero Lu, Rafael Luque, Teo Mocnik, Andreas Seifahrt, Guðmundur K. StefánssonComments: 12 pages, 5 figures, 3 tables, accepted to ApJLSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Measuring the obliquities of stars hosting giant planets may shed light on the dynamical history of planetary systems. Significant efforts have been made to measure the obliquities of FGK stars with hot Jupiters, mainly based on observations of the Rossiter-McLaughlin effect. In contrast, M dwarfs with hot Jupiters have hardly been explored, because such systems are rare and often not favorable for such precise observations. Here, we report the first detection of the Rossiter-McLaughlin effect for an M dwarf with a hot Jupiter, TOI-4201, using the Gemini-North/MAROON-X spectrograph. We find TOI-4201 to be well-aligned with its giant planet, with a sky-projected obliquity of $\lambda=-3.0_{-3.2}^{+3.7}\ ^{\circ}$ and a true obliquity of $\psi=21.3_{-12.8}^{+12.5}\ ^{\circ}$ with an upper limit of $40^{\circ}$ at a 95% confidence level. The result agrees with dynamically quiet formation or tidal obliquity damping that realigned the system. As the first hot Jupiter around an M dwarf with its obliquity measured, TOI-4201b joins the group of aligned giant planets around cool stars ($T_{\rm eff}<6250\ K$), as well as the small but growing sample of planets with relatively high planet-to-star mass ratio ($M_p/M_\ast\gtrsim 3\times 10^{-3}$) that also appear to be mostly aligned.
- [21] arXiv:2405.08312 (replaced) [pdf, html, other]
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Title: Rotation and Abundances of the Benchmark Brown Dwarf HD 33632 Ab from Keck/KPIC High-resolution SpectroscopyChih-Chun Hsu, Jason J. Wang, Jerry W. Xuan, Jean-Baptiste Ruffio, Daniel Echeverri, Yinzi Xin, Joshua Liberman, Luke Finnerty, Evan Morris, Katelyn Horstman, Ben Sappey, Gregory W. Doppmann, Dimitri Mawet, Nemanja Jovanovic, Michael P. Fitzgerald, Jacques-Robert Delorme, J. Kent Wallace, Ashley Baker, Randall Bartos, Geoffrey A. Blake, Benjamin Calvin, Sylvain Cetre, Ronald A. López, Jacklyn Pezzato, Tobias Schofield, Andrew Skemer, Ji WangComments: Accepted for publication in the Astrophysical Journal. 36 pages, 15 figures, 5 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
We present the projected rotational velocity and molecular abundances for HD 33632 Ab obtained via Keck Planet Imager and Characterizer high-resolution spectroscopy. HD 33632 Ab is a nearby benchmark brown dwarf companion at a separation of $\sim$20 au that straddles the L/T transition. Using a forward-modeling framework with on-axis host star spectra, self-consistent substellar atmospheric and retrieval models for HD 33632 Ab, we derive a projected rotational velocity of 53 $\pm$ 3 km/s and carbon/water mass fractions of log CO = $-$2.3 $\pm$ 0.3 and log H$_2$O = $-$2.7 $\pm$ 0.2. The inferred carbon-to-oxygen ratio (C/O = 0.58 $\pm$ 0.14), molecular abundances, and metallicity ([C/H] = 0.0 $\pm$ 0.2 dex) of HD 33632 Ab are consistent with its host star. Although detectable methane opacities are expected in L/T transition objects, we did not recover methane in our KPIC spectra, partly due to the high $v\sin{i}$ and to disequilibrium chemistry at the pressures we are sensitive to. We parameterize the spin as the ratio of rotation over break-up velocity, and compare HD 33632 Ab to a compilation of >200 very low-mass objects (M$\lesssim$0.1 M$_{\odot}$) that have spin measurements in the literature. There appears to be no clear trend for the isolated field low-mass objects versus mass, but a tentative trend is identified for low-mass companions and directly imaged exoplanets, similar to previous findings. A larger sample of close-in gas giant exoplanets and brown dwarfs will critically examine our understanding of their formation and evolution through rotation and chemical abundance measurements.