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P. Molaro

Publications and source records attributed to P. Molaro.

At least 37 records · Page 2Linked to original sources
arXiv2024

TESS and ESPRESSO discover a super-Earth and a mini-Neptune orbiting the K-dwarf TOI-238

The number of super-Earth and mini-Neptune planet discoveries has increased significantly in the last two decades thanks to transit and radial velocity surveys. When it is possible to apply both techniques, we can characterise the internal composition of exoplanets, which in turn provides unique insights on their architecture, formation and evolution. We performed a combined photometric and radial velocity analysis of TOI-238 (TYC 6398-132-1), which has one short-orbit super-Earth planet candidate announced by NASA's TESS team. We aim to confirm its planetary nature using radial velocities taken with the ESPRESSO and HARPS spectrographs, to measure its mass and to detect the presence of other possible planetary companions. We carried out a joint analysis by including Gaussian processes and Keplerian orbits to account for the stellar activity and planetary signals simultaneously. We detected the signal induced by TOI-238 b in the radial velocity time-series, and the presence of a second transiting planet, TOI-238 c, whose signal appears in RV and TESS data. TOI-238 b is a planet with a radius of 1.402$^{+0.084}_{-0.086}$ R$_{\oplus}$ and a mass of 3.40$^{+0.46}_{-0.45}$ M$_{\oplus}$. It orbits at a separation of 0.02118 $\pm$ 0.00038 AU of its host star, with an orbital period of 1.2730988 $\pm$ 0.0000029 days, and has an equilibrium temperature of 1311 $\pm$ 28 K. TOI-238 c has a radius of 2.18$\pm$ 0.18 R$_{\oplus}$ and a mass of 6.7 $\pm$ 1.1 M$_{\oplus}$. It orbits at a separation of 0.0749 $\pm$ 0.0013 AU of its host star, with an orbital period of 8.465652 $\pm$ 0.000031 days, and has an equilibrium temperature of 696 $\pm$ 15 K. The mass and radius of planet b are fully consistent with an Earth-like composition, making it likely a rocky super-Earth. Planet c could be a water-rich planet or a rocky planet with a small H-He atmosphere.

astro-ph.EP↗
arXiv2024

The compact multi-planet system GJ 9827 revisited with ESPRESSO

GJ 9827 is a bright, nearby K7V star orbited by two super-Earths and one mini-Neptune on close-in orbits. The system was first discovered using K2 data and then further characterized by other spectroscopic and photometric instruments. Previous literature studies provide several mass measurements for the three planets, however, with large variations and uncertainties. To better constrain the planetary masses, we added high-precision radial velocity measurements from ESPRESSO to published datasets from HARPS, HARPS-N, and HIRES and we performed a Gaussian process analysis combining radial velocity and photometric datasets from K2 and TESS. This method allowed us to model the stellar activity signal and derive precise planetary parameters. We determined planetary masses of $M_b = 4.28_{-0.33}^{+0.35}$ M${_\oplus}$, $M_c = 1.86_{-0.39}^{+0.37}$ M${_\oplus}$, and $M_d = 3.02_{-0.57}^{+0.58}$ M${_\oplus}$, and orbital periods of $1.208974 \pm 0.000001$ days for planet b, $3.648103_{-0.000010}^{+0.000013}$ days for planet c, and $6.201812 \pm 0.000009$ days for planet d. We compared our results to literature values and found that our derived uncertainties for the planetary mass, period, and radial velocity amplitude are smaller than the previously determined uncertainties. We modeled the interior composition of the three planets using the machine-learning-based tool ExoMDN and conclude that GJ 9827 b and c have an Earth-like composition, whereas GJ 9827 d has an hydrogen envelope, which, together with its density, places it in the mini-Neptune regime.

astro-ph.EP↗
arXiv2023

The physical properties of T Pyx as measured by MUSE I. The geometrical distribution of the ejecta and the distance to the remnant

T Pyx is one of the most enigmatic recurrent novae, and it has been proposed as a potential Galactic type-Ia supernova progenitor. Using spatially-resolved data obtained with MUSE, we characterized the geometrical distribution of the material expelled in previous outbursts surrounding the white dwarf progenitor. We used a 3D model for the ejecta to determine the geometric distribution of the extended remnant. We have also calculated the nebular parallax distance ($d = 3.55 \pm 0.77$ kpc) based on the measured velocity and spatial shift of the 2011 bipolar ejecta. These findings confirm previous results, including data from the GAIA mission. The remnant of T Pyx can be described by a two-component model, consisting of a tilted ring at $i = 63.7$ deg, relative to its normal vector and by fast bipolar ejecta perpendicular to the plane of the equatorial ring. We find an upper limit for the bipolar outflow ejected mass in 2011 of the bipolar outflow of $M_{ej,b} < (3.0 \pm 1.0) \times 10^{-6}$ M$_{\odot}$, which is lower than previous estimates given in the literature. However, only a detailed physical study of the equatorial component could provide an accurate estimate of the total ejecta of the last outburst, a fundamental step to understand if T Pyx will end its life as a type-Ia supernova.

astro-ph.SR↗
arXiv2023

Revisiting the classics: On the evolutionary origin of the "Fe II" and "He/N" spectral classes of novae

The optical spectra of novae are characterized by emission lines from the hydrogen Balmer series and either Fe II or He/N, leading to their traditional classification into two spectral classes: "Fe II" and "He/N". For decades, the origins of these spectral features were discussed in the literature in the contexts of different bodies of gas or changes in the opacity of the ejecta, particularly associated with studies by R. E. Williams and S. N. Shore. Here, we revisit these major studies with dedicated, modern data sets, covering the evolution of several novae from early rise to peak all the way to the nebular phase. Our data confirm previous suggestions in the literature that the "Fe II" and "He/N" spectral classes are phases in the spectroscopic evolution of novae driven primarily by changes in the opacity, ionization, and density of the ejecta, and most if not all novae go through at least three spectroscopic phases as their eruptions evolve: an early He/N (phase 1; observed during the early rise to visible peak and characterized by P Cygni lines of He I, N II, and N III), then an Fe II (phase 2; observed near visible peak and characterized by P Cygni lines of Fe II and O I), and then a later He/N (phase 3; observed during the decline and characterized by emission lines of He I. He II, N II, and N III), before entering the nebular phase. This spectral evolution seems to be ubiquitous across novae, regardless of their speed class; however the duration of each of these phase differs based on the speed class of the nova.

astro-ph.SR↗
arXiv2023

On the 12C/13C isotopic ratio at the dawn of chemical evolution

The known Mega and Hyper Metal-Poor (MMP-HMP) stars with [Fe/H]<-6.0 and <-5.0, respectively, likely belong to the CEMP-no class, i.e. carbon-enhanced stars with low or absent second peak neutron capture elements. They are likely second generation stars and the few elements measurable in their atmospheres are used to infer the properties of single or very few progenitors. The high carbon abundance in the CEMP-no stars offers a unique opportunity to measure the carbon isotopic ratio, which directly monitors the presence of mixing between the He and H-burning layers either within the star or in the progenitor(s). By means of high-resolution spectra acquired with the ESPRESSO spectrograph at the VLT we aim to derive values for the 12C/13C ratio at the lowest metallicities. A spectral synthesis technique based on the SYNTHE code and on ATLAS models is used within a Markov-chain Monte Carlo methodology to derive 12C/13C in the stellar atmospheres of five of the most metal poor stars. These are the Mega Metal-Poor giant SMS J0313-6708 ([Fe/H]<-7.1), the Hyper Metal-Poor dwarf HE1327-2326 ([Fe/H]=-5.8),the Hyper Metal-Poor giant SDSS J1313-0019 ([Fe/H] = -5.0) and the Ultra Metal-Poor subgiant HE0233-0343 ([Fe/H]=-4.7). We also revise a previous value for the Mega Metal-Poor giant SMSS J1605-1443 with ([Fe/H] = -6.2). In four stars we derive an isotopic value while for HE1327-2326 we provide a lower limit. All Measurements are in the range 39<12C/13C<100 showing that the He- and H-burning layers underwent partial mixing either in the stars or, more likely, in their progenitors. This provides evidence of a primary production of 13C at the dawn of chemical evolution. [abridged]

astro-ph.SR↗
arXiv2023

A compact multi-planet system transiting HIP 29442 (TOI-469) discovered by TESS and ESPRESSO. Radial velocities lead to the detection of transits with low signal-to-noise ratio

We followed-up with ESPRESSO the K0V star HIP 29442 (TOI-469), already known to host a validated sub-Neptune companion TOI-469.01. We aim to verify the planetary nature of TOI-469.01. We modelled radial velocity and photometric time series to measure the dynamical mass, radius, and ephemeris, and to characterise the internal structure and composition of TOI-469.01. We confirmed the planetary nature of TOI-469.01. Thanks to ESPRESSO we discovered two additional close-in companions. We also detected their low signal-to-noise transit signals in the TESS light curve. HIP 29442 is a compact multi-planet system, and the three planets have orbital periods $P_{\rm orb, b}=13.63083\pm0.00003$, $P_{\rm orb, c}=3.53796\pm0.00003$, and $P_{\rm orb, d}=6.42975^{+0.00009}_{-0.00010}$ days, and we measured their masses with high precision: $m_{\rm p, b}=9.6\pm0.8~M_{\oplus}$, $m_{\rm p, c}=4.5\pm0.3~M_{\oplus}$, and $m_{\rm p, d}=5.1\pm0.4~M_{\oplus}$. We measured radii and bulk densities of all the planets (the 3$σ$ confidence intervals are shown in parenthesis): $R_{\rm p, b}=3.48^{+0.07 (+0.19)}_{-0.08 (-0.28)} ~R_{\oplus}$ and $ρ_{\rm p, b}=1.3\pm0.2 (0.3) g~cm^{-3}$; $R_{\rm p, c}=1.58^{+0.10 (+0.30)}_{-0.11 (-0.34)}~R_{\oplus}$ and $ρ_{\rm p, c}=6.3^{+1.7 (+6.0)}_{-1.3 (-2.7)} g~cm^{-3}$; $R_{\rm p, d}=1.37\pm0.11^{(+0.32)}_{(-0.43)}~R_{\oplus}$ and $ρ_{\rm p, d}=11.0^{+3.4 (+21.0)}_{-2.4 (-6.3)} g~cm^{-3}$. We used the more conservative 3$σ$ confidence intervals for the radii as input to the interior structure modelling. We find that HIP 29442 $b$ appears as a typical sub-Neptune, likely surrounded by a gas layer of pure H-He with a mass of $0.27^{+0.24}_{-0.17} M_{\oplus}$ and a thickness of $1.4\pm0.5 R_{\oplus}$. For the innermost companions HIP 29442 $c$ HIP 29442 $d$, the model supports an Earth-like composition.

astro-ph.EP↗
arXiv2023

Catching a nova X-ray/UV flash in the visible? Early spectroscopy of the extremely slow Nova Velorum 2022 (Gaia22alz)

We present early spectral observations of the very slow Galactic nova Gaia22alz, over its gradual rise to peak brightness that lasted 180 days. During the first 50 days, when the nova was only 3--4 magnitudes above its normal brightness, the spectra showed narrow (FWHM $\approx$ 400 km s$^{-1}$) emission lines of H Balmer, He I, He II, and C IV, but no P Cygni absorption. A few weeks later, the high-excitation He II and C IV lines disappeared, and P Cygni profiles of Balmer, He I, and eventually Fe II lines emerged, yielding a spectrum typical of classical novae before peak. We propose that the early spectra of Gaia22alz are produced in the white dwarf's envelope or accretion disk, reprocessing X-ray and ultraviolet emission from the white dwarf after a dramatic increase in the rate of thermonuclear reactions, during a phase known as the ``early X-ray/UV flash''. If true, this would be one of the rare times that the optical signature of the early X-ray/UV flash has been detected. While this phase might last only a few hours in other novae and thus be easily missed, it was possible to detect in Gaia22alz due to its very slow and gradual rise and thanks to the efficiency of new all-sky surveys in detecting transients on their rise. We also consider alternative scenarios that could explain the early spectral features of Gaia22alz and its unusually slow rise.

astro-ph.HE↗
arXiv2023

Detection of a high-velocity sodium feature on the ultra-hot Jupiter WASP-121 b

Ultra-hot Jupiters, with their high equilibrium temperatures and resolved spectral lines, have emerged as a perfect testbed for new analysis techniques in the study of exoplanet atmospheres. In particular, the resolved sodium doublet as a resonant line has proven a powerful indicator to probe the atmospheric structure over a wide pressure range. We explore an atmospheric origin of the observed blueshifted feature next to the sodium doublet of the ultra-hot Jupiter WASP-121~b, using a partial transit obtained with the 4-UT mode of ESPRESSO. We study its atmospheric dynamics visible across the terminator by splitting the data into mid-transit and egress. We determine that the blueshifted high-velocity absorption component is generated only during the egress part of the transit when a larger fraction of the day side of the planet is visible. For the egress data, MERC retrieves the blueshifted high-velocity absorption component as an equatorial day-to-night side wind across the evening limb, with no zonal winds visible on the morning terminator with weak evidence compared to a model with only vertical winds. For the mid-transit data, the observed line broadening is attributed to a vertical, radial wind. We attribute the equatorial day-to-night side wind over the evening terminator to a localised jet and restrain its existence between the substellar point and up to $10^\circ$ to the terminator in longitude, an opening angle of the jet of at most $60^\circ$ in latitude, and a lower boundary in altitude between [1.08, 1.15] $R_p$. Due to the partial nature of the transit, we cannot make any statements on whether the jet is truly super-rotational and one-sided or part of a symmetric day-to-night side atmospheric wind from the hotspot.

astro-ph.EP↗
arXiv2023

Shock shaping? Nebular Spectroscopy of Nova V906 Carinae

V906 Carinae was one of the best observed novae of recent times. It was a prolific dust producer and harboured shocks in the early evolving ejecta outflow. Here, we take a close look at the consequences of these early interactions through study of high-resolution UVES spectroscopy of the nebular stage and extrapolate backwards to investigate how the final structure may have formed. A study of ejecta geometry and shaping history of the structure of the shell is undertaken following a spectral line SHAPE model fit. A search for spectral tracers of shocks in the nova ejecta is undertaken and an analysis of the ionised environment. Temperature, density and abundance analyses of the evolving nova shell are presented.

astro-ph.SR↗
arXiv2023

The pristine nature of SMSS 1605$-$1443 revealed by ESPRESSO

SMSS J160540.18$-$144323.1 is the carbon-enhanced metal-poor (CEMP) star with the lowest iron abundance ever measured, [Fe/H]=-6.2, which was first reported with the SkyMapper telescope. The carbon abundance is A(C)~6.1 in the low-C band, as the majority of the stars in this metallicity range. Yet, constraining the isotopic ratio of key species, such as carbon, sheds light on the properties and origin of these elusive stars. We performed high-resolution observations of SMSS1605$-$1443 with the ESPRESSO spectrograph to look for variations in the radial velocity ($v_{rad}$) with time. These data have been combined with older MIKE and UVES archival observations to enlarge the temporal baseline. The $^{12}$C/$^{13}$C isotopic ratio is also studied to explore the possibility of mass transfer from a binary companion. A cross-correlation function against a natural template was applied to detect $v_{rad}$ variability and a spectral synthesis technique was used to derive $^{12}$C/$^{13}$C in the stellar atmosphere. We confirm previous indications of binarity in SMSS1605$-$1443 and measured a lower limit $^{12}$C/$^{13}$C$>60$ at more than a 3$σ$ confidence level, proving that this system is chemically unmixed and that no mass transfer from the unseen companion has happened so far. Thus, we confirm the CEMP-no nature of SMSS1605$-$1443 and show that the pristine chemical composition of the cloud from which it formed is currently imprinted in its stellar atmosphere free of contamination.

astro-ph.SR↗
arXiv2022

Planetary system around LTT 1445A unveiled by ESPRESSO: Multiple planets in a triple M-dwarf system

We present radial velocity follow-up obtained with ESPRESSO of the M-type star LTT 1445A (TOI-455), for which a transiting planet b with an orbital period of~5.4 days was detected by TESS. We report the discovery of a second transiting planet (LTT 1445A c) and a third non-transiting candidate planet (LTT 1445A d) with orbital periods of 3.12 and 24.30 days, respectively. The host star is the main component of a triple M-dwarf system at a distance of 6.9 pc. We used 84 ESPRESSO high-resolution spectra to determine accurate masses of 2.3$\pm$0.3 $\mathrm{M}_\oplus$ and 1.0$\pm$0.2 $\mathrm{M}_\oplus$ for planets b and c and a minimum mass of 2.7$\pm$0.7 $\mathrm{M}_\oplus$ for planet d. Based on its radius of 1.43$\pm0.09$ $\mathrm{R}_\oplus$ as derived from the TESS observations, LTT 1445A b has a lower density than the Earth and may therefore hold a sizeable atmosphere, which makes it a prime target for the James Webb Space Telescope. We used a Bayesian inference approach with the nested sampling algorithm and a set of models to test the robustness of the retrieved physical values of the system. There is a probability of 85$\%$ that the transit of planet c is grazing, which results in a retrieved radius with large uncertainties at 1.60$^{+0.67}_{-0.34}$ $\mathrm{R}_\oplus$. LTT 1445A d orbits the inner boundary of the habitable zone of its host star and could be a prime target for the James Webb Space Telescope.

astro-ph.EP↗
arXiv2022

Detection of barium in the atmospheres of the ultra-hot gas giants WASP-76b and WASP-121b

High-resolution spectroscopy studies of ultra-hot Jupiters have been key in our understanding of exoplanet atmospheres. Observing into the atmospheres of these giant planets allows for direct constraints on their atmospheric compositions and dynamics while laying the groundwork for new research regarding their formation and evolution environments. Two of the most well-studied ultra-hot Jupiters are WASP-76b and WASP-121b, with multiple detected chemical species and strong signatures of their atmospheric dynamics. We take a new look at these two exceptional ultra-hot Jupiters by reanalyzing the transit observations taken with ESPRESSO at the Very Large Telescope and attempt to detect additional species. To extract the planetary spectra of the two targets, we corrected for the telluric absorption and removed the stellar spectrum contributions. We then exploited new synthetic templates that were specifically designed for ultra-hot Jupiters in combination with the cross-correlation technique to unveil species that remained undetected by previous analyses. We add a novel detection of Ba+ to the known atmospheric compositions of WASP-76b and WASP-121b, the heaviest species detected to date in any exoplanetary atmosphere, with additional new detections of Co and Sr+ and a tentative detection of Ti+ for WASP-121b. We also confirm the presence of Ca+, Cr, Fe, H, Li, Mg, Mn, Na, and V on both WASP-76b and WASP-121b, with the addition of Ca, Fe+, and Ni for the latter. Finally, we also confirm the clear asymmetric absorption feature of Ca+ on WASP-121b, with an excess absorption at the bluer wavelengths and an effective planet radius beyond the Roche lobe. This indicates that the signal may arise from the escape of planetary atmosphere.

astro-ph.EP↗
arXiv2022

Espresso observations of HE 0107$-$5240 and other CEMP-no stars with $\rm [Fe/H]\le -4.5$

HE 0107$-$5240 is a hyper metal-poor star with $\rm [Fe/H]=-5.39$. We performed high-res observations with the ESPRESSO spectrograph at the VLT to constrain the kinematical properties of the binary system HE 0107$-$5240 and to probe the binarity of the sample of 8 most metal-poor stars with $\rm [Fe/H]<-4.5$. Radial velocities are obtained by using cross-correlation in the interval 4200$-$4315A, which contains the strong CH band, against a template in an iterative process. A Bayesian method is applied to calculate the orbit by using the ESPRESSO measurements and others from the literature. A chemical analysis has also been performed in HE0107$-$5240 by means of spectral synthesis. Observations of HE 0107$-$5240 spanning more than 3 years show a monotonic decreasing trend in radial velocity at a rate of approximately by 0.5 ms$^{-1}$d$^{-1}$. The period is constrained at $P_{\rm orb} = 13009_{-1370}^{+1496}$d. New more stringent upper-limits have been found for several elements: a)[Sr/Fe] and [Ba/Fe] are lower than $-0.76$ and $+0.2$ respectively, confirming the star is a CEMP-no; b)$A(Li)< 0.5$ is well below the plateau at $A(Li)=1.1$ found in the Lower Red Giant Branch stars, suggesting Li was originally depleted; and c)the isotopic ratio $^{12}$C/$^{13}$C is 87$\pm6$ showing very low $^{13}$C in contrast to what expected from a spinstar progenitor. We confirm that HE 0107$-$5240 is a binary star with a long period of about 13000d ($\sim36$ years).The carbon isotopic ratio excludes the possibility that the companion has gone through the AGB phase and transferred mass to the currently observed star. The binarity of HE 0107$-$5240 implies some of the first generations of low-mass stars form in multiple systems and indicates that the low metallicity does not preclude the formation of binaries. Finally, a solid indication of $v_{ rad}$ variation has been found also in SMSS 1605$-$1443.

astro-ph.SR↗
arXiv2022

7Be detection in the 2021 outburst of RS Oph

The recurrent nova RS Oph underwent a new outburst on August 8, 2021, reaching a visible brightness of V = 4.8 mag. Observations of the 2021 outburst made with the high resolution UVES spectrograph at the Kueyen-UT2 telescope of ESO-VLT in Paranal enabled detection of the possible presence of 7Be freshly made in the thermonuclear runaway reactions. The 7Be yields can be estimated in N(Be)/N(H) = 5.7 x 10^(-6), which are close to the lowest yields measured in classical novae so far. 7Be is short-lived and decays only into 7Li. By means of a spectrum taken during the nebular phase we estimated an ejected mass of about 1.1 x 10^(-5) Msun, providing an amount of about 4.4x 10^(-10) Msun of 7Li created in the 2021 event. Recurrent novae of the kind of RS Oph may synthesize slightly lower amount of 7Li per event as classical novae, but occur 10^3 times more frequently. The recurrent novae fraction is in the range of 10-30% and they could have contributed to the making of 7Li we observe today. The detection of 7Be in RS Oph provides further support to the recent suggestion that novae are the most effective source of 7Li in the Galaxy.

astro-ph.SR↗
arXiv2022

Fundamental physics with ESPRESSO: Constraints on Bekenstein and dark energy models from astrophysical and local probes

Dynamical scalar fields in an effective four-dimensional field theory are naturally expected to couple to the rest of the theory's degrees of freedom, unless some new symmetry is postulated to suppress these couplings. In particular, a coupling to the electromagnetic sector will lead to spacetime variations of the fine-structure constant, $α$. Astrophysical tests of the space-time stability of $α$ are therefore a powerful probe of new physics. Here we use ESPRESSO and other contemporary measurements of $α$, together with background cosmology data, local laboratory atomic clock and Weak Equivalence Principle measurements, to place stringent constraints on the simplest examples of the two broad classes of varying $α$ models: Bekenstein models and quintessence-type dark energy models, both of which are parametric extensions of the canonical $Λ$CDM model. In both cases, previously reported constraints are improved by more than a factor of ten. This improvement is largely due to the very strong local constraints, but astrophysical measurements can help to break degeneracies between cosmology and fundamental physics parameters.

astro-ph.CO↗
arXiv2022

A candidate short-period sub-Earth orbiting Proxima Centauri

Proxima Centauri is the closest star to the Sun. This small, low-mass, mid M dwarf is known to host an Earth-mass exoplanet with an orbital period of 11.2 days within the habitable zone, as well as a long-period planet candidate with an orbital period of close to 5 years. We report on the analysis of a large set of observations taken with the ESPRESSO spectrograph at the VLT aimed at a thorough evaluation of the presence of a third low-mass planetary companion, which started emerging during a previous campaign. Radial velocities (RVs) were calculated using both a cross-correlation function (CCF) and a template matching approach. The RV analysis includes a component to model Proxima's activity using a Gaussian process (GP). We use the CCF's full width at half maximum to help constrain the GP, and we study other simultaneous observables as activity indicators in order to assess the nature of any potential RV signals. We detect a signal at 5.12 $\pm$ 0.04 days with a semi-amplitude of 39 $\pm$ 7 cm/s. The analysis of subsets of the ESPRESSO data, the activity indicators, and chromatic RVs suggest that this signal is not caused by stellar variability but instead by a planetary companion with a minimum mass of 0.26 $\pm$ 0.05 $M_\oplus$ (about twice the mass of Mars) orbiting at 0.029 au from the star. The orbital eccentricity is well constrained and compatible with a circular orbit.

astro-ph.EP↗
arXiv2021

7Be in the outburst of the ONe nova V6595 Sgr

We report the search for 7Be isotope in the outbursts of the classical nova V6595 Sgr by means of high resolution UVES observations taken at the ESO VLT in April 2021, about two weeks after discovery and under difficult circumstances due to the pandemic. Narrow absorption components with velocities at about -2620 and -2820 km/s, superposed on broader and shallow absorption, are observed in the outburst spectra for the 7BeII 313.0583, 313.1228 nm doublet resonance lines, as well as in several other elements such as CaII, FeI, MgI, NaI, HI but LiI. Using CaII K line as a reference element, we infer N(7Be)/N(H) ~ 7.4 x 10^{-6}, or ~ 9.8 x 10^{-6} when the 7Be decay is taken into account. The 7Be abundance is about half of the value most frequently measured in novae. The possible presence of over-ionization in the layers where 7Be is detected is also discussed. Observations taken at the Telescopio Nazionale Galileo (TNG) in La Palma 91 days after discovery showed prominent emission lines of Oxygen and Neon which allow to classify the nova as ONe type. Therefore, although 7Be is expected to be higher in CO novae, it is found at comparable levels in both nova types.

astro-ph.SR↗
arXiv2021

The Rossiter-McLaughlin effect Revolutions: An ultra-short period planet and a warm mini-Neptune on perpendicular orbits

Comparisons of the alignment of exoplanets with a common host star can be used to distinguish among concurrent evolution scenarios. However, multi-planet systems usually host mini-Neptunes and super-Earths, whose size make orbital architecture measurements challenging. We introduce the Rossiter-McLaughlin effect Revolutions technique, which can access spin-orbit angles of small planets by exploiting the full information contained in spectral transit time series. We validated the technique on published HARPS-N data of the mini-Neptune HD3167c, refining its high sky-projected spin-orbit angle (-108.9+5.4-5.5 deg), and we applied it to new ESPRESSO observations of the super-Earth HD3167b, revealing an aligned orbit (-6.6+6.6-7.9 deg). Surprisingly different variations in the contrast of the stellar lines occulted by the planets can be reconciled with a latitudinal dependence of the stellar line shape. In this scenario, a joint fit to both datasets constrains the inclination of the star (111.6+3.1-3.3 deg) and the 3D spin-orbit angles of HD3167b (29.5+7.2-9.4 deg) and HD3167c (107.7+5.1-4.9 deg). The projected spin-orbit angles do not depend on the model for the line contrast variations, and so, with a mutual inclination of 102.3+7.4-8.0 deg, we conclude that the two planets are on perpendicular orbits. This could be explained by HD3167b being strongly coupled to the star and retaining its primordial alignment, whereas HD3167c would have been brought to a nearly polar orbit via secular gravitational interactions with an outer companion. Follow-up observations and dynamical evolution simulations are required to search for this companion and explore this scenario. HD3167b is the smallest exoplanet with a confirmed spectroscopic Rossiter-McLaughlin signal. Our new technique opens the way to determining the orbital architectures of the super-Earth and Earth-sized planet populations.

astro-ph.EP↗