Search Results
The GAPS Programme at TNG: XXXV. Fundamental properties of transiting exoplanet host stars
2022, Biazzo, K., DāOrazi, V., Desidera, S., Turrini, D., Benatti, S., Gratton, R., Magrini, L., Sozzetti, A., Baratella, M., Bonomo, A.S., Borsa, F., Claudi, R., Covino, E., Damasso, M., Di Mauro, M.P., Lanza, A.F., Maggio, A., Malavolta, L., Maldonado, J., Marzari, F., Micela, G., Poretti, E., Vitello, F., Affer, L., Bignamini, A., Carleo, I., Cosentino, R., Fiorenzano, A.F.M., Giacobbe, P., Harutyunyan, A., Leto, G., Mancini, L., Molinari, E., Molinaro, M., Nardiello, D., Nascimbeni, V., Pagano, I., Pedani, M., Piotto, G., Rainer, M., Scandariato, G.
Context. Exoplanetary properties strongly depend on stellar properties: to know the planet with accuracy and precision it is necessary to know the star as accurately and precisely as possible. Aims. Our immediate aim is to characterize in a homogeneous and accurate way a sample of 27 transiting planet-hosting stars observed within the Global Architecture of Planetary System program. For the wide visual binary XO-2, we considered both components (N: hosting a transiting planet; S: without a known transiting planet). Our final goal is to widely analyze the sample by deriving several stellar properties, abundances of many elements, kinematic parameters, and discuss them in the context of planetary formation. Methods. We determined the stellar parameters (effective temperature, surface gravity, rotational velocity) and abundances of 26 elements (Li, C, N, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, Y, Zr, Ba, La, Nd, Eu). Our study is based on high-resolution HARPS-N at TNG and FEROS at ESO spectra and uniform techniques. Depending on stellar parameters and chemical elements, we used line equivalent widths or spectral synthesis methods. We derived kinematic properties taking advantage of Gaia data and for the first time in exoplanet host stars we estimated ages using elemental ratios as chemical clocks. Results. The effective temperature of our stars is ā¼4400-6700 K, while the iron abundance [Fe/H] is within -0.3 and 0.4 dex. Lithium is present in seven stars. The [X/H] and [X/Fe] abundances versus [Fe/H] are consistent with the Galactic chemical evolution. The dependence of [X/Fe] with the condensation temperature is critically analyzed with respect to stellar and kinematic properties. All targets with measured C and O abundances show C/O < 0.8, compatible with Si present in rock-forming minerals. Mean C/O and [C/O] values are slightly lower than for the Sun. Most of targets show 1.0 < Mg/Si < 1.5, compatible with Mg distributed between olivine and pyroxene, and mean Mg/Si lower than for the Sun. HAT-P-26, the target hosting the lowest-mass planet, shows the highest Mg/Si ratio. From our chemodynamical analysis we find agreement between ages and position within the Galactic disk. Finally, we note a tendency for higher-density planets to be around metal-rich stars and hints of higher stellar abundances of some volatiles (e.g., O) for lower-mass planets. We cannot exclude that part of our results could be also related to the location of the stars within the Galactic disk. Conclusions. We try to trace the planetary migration scenario from the composition of the planets related to the chemical composition of the hosting stars. This kind of study will be useful for upcoming space mission data to get more insights into the formation-migration mechanisms.
The GAPS Programme at TNG XXXVII. A precise density measurement of the young ultra-short period planet TOI-1807 b
2022, Nardiello, D., Malavolta, L., Desidera, S., Baratella, M., DāOrazi, V., Messina, S., Biazzo, K., Benatti, S., Damasso, M., Rajpaul, V.M., Bonomo, A.S., Capuzzo Dolcetta, R., Mallonn, M., Cale, B., Plavchan, P., El Mufti, M., Bignamini, A., Borsa, F., Carleo, I., Claudi, R., Covino, E., Lanza, A.F., Maldonado, J., Mancini, L., Micela, G., Molinari, E., Pinamonti, M., Piotto, G., Poretti, E., Scandariato, G., Sozzetti, A., Andreuzzi, G., Boschin, W., Cosentino, R., Fiorenzano, A.F.M., Harutyunyan, A., Knapic, C., Pedani, M., Affer, L., Maggio, A., Rainer, M.
Context. Great strides have been made in recent years in the understanding of the mechanisms involved in the formation and evolution of planetary systems. Despite this, many observational findings have not yet been corroborated by astrophysical explanations. A fine contribution to the study of planetary formation processes comes from the study of young, low-mass planets, with short orbital periods (.100 days). In the last three years, the NASA/TESS satellite has identified many planets of this kind and their characterization is clearly necessary in order to understand how they formed and evolved. Aims. Within the framework of the Global Architecture of Planetary System (GAPS) project, we performed a validation and characterization (radius and mass) of the ultra-short period planet TOI-1807 b, which orbits its young host star BD+39 2643 (ā¼300 Myr) in only 13 h. This is the youngest ultra-short period planet discovered so far. Methods. Thanks to a joint modeling of the stellar activity and planetary signals in the TESS light curve and in new HARPS-N radial-velocity measurements, combined with accurate estimation of stellar parameters, we validated the planetary nature of TOI-1807 b and measured its orbital and physical parameters. Results. By using astrometric, photometric, and spectroscopic observations, we found that BD+39 2643 is a young, active K dwarf star and a member of a 300 Ā± 80 Myr old moving group. Furthermore, it rotates in Prot = 8.8 Ā± 0.1 days. This star hosts an ultra-short period planet, exhibiting an orbital period of only Pb = 0.54937 Ā± 0.00001 days. Thanks to the exquisite photometric and spectroscopic series, along with the accurate information on its stellar activity, we measured both the radius and the mass of TOI-1807 b with high precision, obtaining RP,b = 1.37 Ā± 0.09 Rā and MP,b = 2.57 Ā± 0.50 Mā. These planet parameters correspond to a rocky planet with an Earth-like density (Ļb = 1.0 Ā± 0.3 Ļā) and no extended H/He envelope. From the analysis of the age-RP distribution for planets with well measured ages, we inferred that TOI-1807 b may have already lost a large part of its atmosphere over the course of its 300 Myr lifetime.
RefPlanets: Search for reflected light from extra-solar planets with SPHERE/ZIMPOL
2020, Hunziker, S., Schmid, H.M., Mouillet, D., Milli, J., Zurlo, A., Delorme, P., Abe, L., Avenhaus, H., Baruffolo, A., Bazzon, A., Boccaletti, A., Baudoz, P., Beuzit, J.L., Carbillet, M., Chauvin, G., Claudi, R., Costille, A., Daban, J.B., Desidera, S., Dohlen, K., Dominik, C., Downing, M., Engler, N., Feldt, M., Fusco, T., Ginski, C., Gisler, D., Girard, J.H., Gratton, R., Henning, Th., Hubin, N., Kasper, M., Keller, C.U., Langlois, M., Lagadec, E., Martinez, P., Maire, A.L., Menard, F., Meyer, M.R., Pavlov, A., Pragt, J., Puget, P., Quanz, S.P., Rickman, E., Roelfsema, R., Salasnich, B., Sauvage, J.F., Siebenmorgen, R., Sissa, E., Snik, F., Suarez, M., Szulagyi, J., Thalmann, Ch., Turatto, M., Udry, S., van Holstein, R.G., Vigan, A., Wildi, F.
RefPlanets is a guaranteed time observation (GTO) programme that uses the Zurich IMaging POLarimeter (ZIMPOL) of SPHERE/VLT for a blind search for exoplanets in wavelengths from 600-900 nm. The goals of this study are the characterization of the unprecedented high polarimetic contrast and polarimetric precision capabilities of ZIMPOL for bright targets, the search for polarized reflected light around some of the closest bright stars to the Sun and potentially the direct detection of an evolved cold exoplanet for the first time. For our observations of Alpha Cen A and B, Sirius A, Altair, Eps Eri and Tau Ceti we used the polarimetric differential imaging (PDI) mode of ZIMPOL which removes the speckle noise down to the photon noise limit for angular separations >0.6". We describe some of the instrumental effects that dominate the noise for smaller separations and explain how to remove these additional noise effects in post-processing. We then combine PDI with angular differential imaging (ADI) as a final layer of post-processing to further improve the contrast limits of our data at these separations. For good observing conditions we achieve polarimetric contrast limits of 15.0-16.3 mag at the effective inner working angle of about 0.13", 16.3-18.3 mag at 0.5" and 18.8-20.4 mag at 1.5". The contrast limits closer in (<0.6") depend significantly on the observing conditions, while in the photon noise dominated regime (>0.6"), the limits mainly depend on the brightness of the star and the total integration time. We compare our results with contrast limits from other surveys and review the exoplanet detection limits obtained with different detection methods. For all our targets we achieve unprecedented contrast limits. Despite the high polarimetric contrasts we are not able to find any additional companions or extended polarized light sources in the data that has been taken so far.