84 research outputs found
The GAPS Programme with HARPS-N at TNG. X. Differential abundances in the XO-2 planet hosting binary
Binary stars hosting exoplanets are a unique laboratory where chemical
tagging can be performed to measure with high accuracy the elemental abundances
of both stellar components, with the aim to investigate the formation of
planets and their subsequent evolution. Here, we present a high-precision
differential abundance analysis of the XO-2 wide stellar binary based on high
resolution HARPS-N@TNG spectra. Both components are very similar K-dwarfs and
host planets. Since they formed presumably within the same molecular cloud, we
expect they should possess the same initial elemental abundances. We
investigate if the presence of planets can cause some chemical imprints in the
stellar atmospheric abundances. We measure abundances of 25 elements for both
stars with a range of condensation temperature K, achieving
typical precisions of dex. The North component shows abundances in
all elements higher by dex on average, with a mean
difference of +0.078 dex for elements with K. The
significance of the XO-2N abundance difference relative to XO-2S is at the
level for almost all elements. We discuss the possibility that this
result could be interpreted as the signature of the ingestion of material by
XO-2N or depletion in XO-2S due to locking of heavy elements by the planetary
companions. We estimate a mass of several tens of in heavy
elements. The difference in abundances between XO-2N and XO-2S shows a positive
correlation with the condensation temperatures of the elements, with a slope of
dex K, which could mean that both
components have not formed terrestrial planets, but that first experienced the
accretion of rocky core interior to the subsequent giant planets.Comment: 10 pages, 5 figures, accepted by Astronomy & Astrophysics. Numbering
of the series change
The GAPS Programme with HARPS-N@TNG VI: The Curious Case of TrES-4b
We revisit the TrES-4 system parameters based on high-precision HARPS-N
radial-velocity measurements and new photometric light curves. A combined
spectroscopic and photometric analysis allows us to determine a spectroscopic
orbit with an amplitude m s. The derived mass of TrES-4b is
found to be , significantly lower than
previously reported. Combined with the large radius () inferred from our analysis, TrES-4b becomes
the second-lowest density transiting hot Jupiter known. We discuss several
scenarios to explain the puzzling discrepancy in the mass of TrES-4b in the
context of the exotic class of highly inflated transiting giant planets.Comment: 5 pages, 4 figures, Letter accepted for publication in Astronomy and
Astrophysic
The Additional Representative Images for Legacy (ARI-L) project for the ALMA Science Archive
The Additional Representative Images for Legacy (ARI-L) project is a European
Development project for ALMA Upgrade approved by the Joint ALMA Observatory
(JAO) and the European Southern Observatory (ESO), started in June 2019. It
aims to increase the legacy value of the ALMA Science Archive (ASA) by bringing
the reduction level of ALMA data from Cycles 2-4 close to that of data from
more recent Cycles processed for imaging with the ALMA Pipeline. As of mid-2021
more than 150000 images have been returned to the ASA for public use. At its
completion in 2022, the project will have provided enhanced products for at
least 70% of the observational data from Cycles 2-4 processable with the ALMA
Pipeline. In this paper we present the project rationale, its implementation,
and the new opportunities offered to ASA users by the ARI-L products. The ARI-L
cubes and images complement the much limited number of archival image products
generated during the data quality assurance stages (QA2), which cover only a
small fraction of the available data for those Cycles. ARI-L imaging products
are highly relevant for many science cases and significantly enhance the
possibilities for exploiting archival data. Indeed, ARI-L products facilitate
archive access and data usage for science purposes even for non-expert data
miners, provide a homogeneous view of all data for better dataset comparisons
and download selections, make the archive more accessible to visualization and
analysis tools, and enable the generation of preview images and plots similar
to those possible for subsequent Cycles.Comment: 15 pages. Accepted for publication in PAS
SN 2012ec: mass of the progenitor from PESSTO follow-up of the photospheric phase
We present the results of a photometric and spectroscopic monitoring campaign of SN 2012ec, which exploded in the spiral galaxy NGC 1084, during the photospheric phase. The photometric light curve exhibits a plateau with luminosity L = 0.9 × 1042 erg s−1 and duration ∼90 d, which is somewhat shorter than standard Type II-P supernovae (SNe). We estimate the nickel mass M(56Ni) = 0.040 ± 0.015 M⊙ from the luminosity at the beginning of the radioactive tail of the light curve. The explosion parameters of SN 2012ec were estimated from the comparison of the bolometric light curve and the observed temperature and velocity evolution of the ejecta with predictions from hydrodynamical models. We derived an envelope mass of 12.6 M⊙, an initial progenitor radius of 1.6 × 1013 cm and an explosion energy of 1.2 foe. These estimates agree with an independent study of the progenitor star identified in pre-explosion images, for which an initial mass of M = 14-22 M⊙ was determined. We have applied the same analysis to two other Type II-P SNe (SNe 2012aw and 2012A), and carried out a comparison with the properties of SN 2012ec derived in this paper. We find a reasonable agreement between the masses of the progenitors obtained from pre-explosion images and masses derived from hydrodynamical models. We estimate the distance to SN 2012ec with the standardized candle method (SCM) and compare it with other estimates based on other primary and secondary indicators. SNe 2012A, 2012aw and 2012ec all follow the standard relations for the SCM for the use of Type II-P SNe as distance indicators
The GAPS programme at TNG. XLV. HI Balmer lines transmission spectroscopy and NLTE atmospheric modelling of the ultra-hot Jupiter KELT-20b/MASCARA-2b
We aim at extracting the transmission spectrum of the HI Balmer lines of the
ultra-hot Jupiter (UHJ) KELT-20b/MASCARA-2b from observations and to further
compare the results with what obtained through forward modelling accounting for
non-local thermodynamic equilibrium (NLTE) effects. We extract the line
profiles from six transits obtained with the HARPS-N high-resolution
spectrograph attached to the Telescopio Nazionale Galileo telescope. We compute
the temperature-pressure (TP) profile employing the helios code in the lower
atmosphere and the Cloudy NLTE code in the middle and upper atmosphere. We
further use Cloudy to compute the theoretical planetary transmission spectrum
in LTE and NLTE for comparison with observations. We detected the Halpha
(0.79+/-0.03%; 1.25 Rp), Hbeta (0.52+/-0.03%; 1.17 Rp), and Hgamma
(0.39+/-0.06%; 1.13 Rp) lines, while we detected the Hdelta line at almost 4
sigma (0.27+/-0.07%; 1.09 Rp). The models predict an isothermal temperature of
about2200 K at pressures >10^-2 bar and of about 7700 K at pressures <10^-8
bar, with a roughly linear temperature rise in between. In the middle and upper
atmosphere, the NLTE TP profile is up to about 3000 K hotter than in LTE. The
synthetic transmission spectrum derived from the NLTE TP profile is in good
agreement with the observed HI Balmer line profiles, validating our obtained
atmospheric structure. Instead, the synthetic transmission spectrum derived
from the LTE TP profile leads to significantly weaker absorption compared to
the observations. Metals appear to be the primary agents leading to the
temperature inversion in UHJs and the impact of NLTE effects on them increases
the magnitude of the inversion. We find that the impact of NLTE effects on the
TP profile of KELT-20b/MASCARA-2b is larger than for the hotter UHJ KELT-9b,
and thus NLTE effects might be relevant also for planets cooler than
KELT-20b/MASCARA-2b.Comment: Accepted for publication in Astronomy and Astrophysic
SN 2012ec: Mass of the progenitor from PESSTO follow-up of the photospheric phase
We present the results of a photometric and spectroscopic monitoring campaign of SN 2012ec, which exploded in the spiral galaxy NGC 1084, during the photospheric phase. The photometric light curve exhibits a plateau with luminosity L = 0.9 × 1042 erg s−1 and duration ∼90 d, which is somewhat shorter than standard Type II-P supernovae (SNe). We estimate the nickel mass M(56Ni) = 0.040 ± 0.015 M from the luminosity at the beginning of the radioactive tail of the light curve. The explosion parameters of SN 2012ec were estimated from the comparison of the bolometric light curve and the observed temperature and velocity evolution of the ejecta with predictions from hydrodynamical models. We derived an envelope mass of 12.6 M, an initial progenitor radius of 1.6 × 1013 cm and an explosion energy of 1.2 foe. These estimates agree with an independent study of the progenitor star identified in
pre-explosion images, for which an initial mass of M = 14−22 M was determined. We have applied the same analysis to two other Type II-P SNe (SNe 2012aw and 2012A), and carried out a comparison with the properties of SN 2012ec derived in this paper. We find a reasonable agreement between the masses of the progenitors obtained from pre-explosion images and masses derived from hydrodynamical models. We estimate the distance to SN 2012ec with
the standardized candle method (SCM) and compare it with other estimates based on other primary and secondary indicators. SNe 2012A, 2012aw and 2012ec all follow the standard relations for the SCM for the use of Type II-P SNe as distance indicators
The GAPS programme at TNG. XLVI. Deep search for low-mass planets in late-dwarf systems hosting cold Jupiters
Context. With the growth of comparative exoplanetology, it is increasingly clear that the relationship between inner and outer planets plays a key role in unveiling the mechanisms governing formation and evolution models. For this reason, it is important to probe the inner region of systems hosting long-period giants in search of undetected lower mass planetary companions.
Aims: We aim to present the results of a high-cadence and high-precision radial velocity (RV) monitoring of three late-type dwarf stars hosting long-period giants with well-measured orbits in order to search for short-period sub-Neptunes (SN, M sin i < 30 M⊕).
Methods: Building on the results and expertise of our previous studies, we carried out combined fits of our HARPS-N data with literature RVs. We used Markov chain Monte Carlo (MCMC) analyses to refine the literature orbital solutions and search for additional inner planets, applying Gaussian process regression techniques to deal with the stellar activity signals where required. We then used the results of our survey to estimate the frequency of sub-Neptunes in systems hosting cold Jupiters, f(SN|CJ), and compared it with the frequency around field M dwarfs, f(SN).
Results: We identify a new short-period, low-mass planet orbiting GJ 328, GJ 328 c, with Pc = 241.8-1.7+1.3 days and Mc sin i = 21.4-3.2+3.4M⊕. We moreover identify and model the chromospheric activity signals and rotation periods of GJ 649 and GJ 849, around which no additional planet is found. Then, taking into account also planetary system around the previously analysed low-mass star BD-11 4672, we derive an estimate of the frequencies of inner planets in such systems. In particular, f(SN|CJ) = 0.25-0.07+0.58 for mini-Neptunes (10 M⊕ < M sin i < 30 M⊕, P < 150 d), marginally larger than f(SN). For lower mass planets (M sin i < 10 M⊕) instead f(SN|CJ) < 0.69, which is compatible with f(SN).
Conclusions: In light of the newly detected mini-Neptune, we find tentative evidence of a positive correlation between the presence of long-period giant planets and that of inner low-mass planets, f(SN|CJ) > f(SN). This might indicate that cold Jupiters have an opposite influence in the formation of inner sub-Neptunes around late-type dwarfs as opposed to their solar-type counterparts, boosting the formation of mini-Neptunes instead of impeding it
The GAPS Programme at TNG XXXVIII. Five molecules in the atmosphere of the warm giant planet WASP-69b detected at high spectral resolution
The field of exo-atmospheric characterisation is progressing at an
extraordinary pace. Atmospheric observations are now available for tens of
exoplanets, mainly hot and warm inflated gas giants, and new molecular species
continue to be detected revealing a richer atmospheric composition than
previously expected. Thanks to its warm equilibrium temperature (96318~K)
and low-density (0.2190.031~g cm), the close-in gas giant WASP-69b
represents a golden target for atmospheric characterization. With the aim of
searching for molecules in the atmosphere of WASP-69b and investigating its
properties, we performed high-resolution transmission spectroscopy with the
GIANO-B near-infrared spectrograph at the Telescopio Nazionale Galileo. We
observed three transit events of WASP-69b. During a transit, the planetary
lines are Doppler-shifted due to the large change in the planet's radial
velocity, allowing us to separate the planetary signal from the
quasi-stationary telluric and stellar spectrum. Considering the three nights
together, we report the detection of CH, NH, CO, CH, and
HO, at more than level. We did not identify the presence of HCN
and CO with confidence level higher than 3. This is the first time
that five molecules are simultaneously detected in the atmosphere of a warm
giant planet. These results suggest that the atmosphere of WASP-69b is possibly
carbon-rich and characterised by the presence of disequilibrium chemistry.Comment: 10 pages, 5 figures. Accepted for publication in Astronomy &
Astrophysic
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