91 research outputs found
Alignment and preliminary outcomes of an ELT-size instrument to a very large telescope: LINC-NIRVANA at LBT
LINC-NIRVANA (LN) is a high resolution, near infrared imager that uses a
multiple field-of-view, layer-oriented, multi-conjugate AO system, consisting
of four multi-pyramid wavefront sensors (two for each arm of the Large
Binocular Telescope, each conjugated to a different altitude). The system
employs up to 40 star probes, looking at up to 20 natural guide stars
simultaneously. Its final goal is to perform Fizeau interferometric imaging,
thereby achieving ELT-like spatial resolution (22.8 m baseline resolution). For
this reason, LN is also equipped with a fringe tracker, a beam combiner and a
NIR science camera, for a total of more than 250 optical components and an
overall size of approximately 6x4x4.5 meters. This paper describes the
tradeoffs evaluated in order to achieve the alignment of the system to the
telescope. We note that LN is comparable in size to planned ELT
instrumentation. The impact of such alignment strategies will be compared and
the selected procedure, where the LBT telescope is, in fact, aligned to the
instrument, will be described. Furthermore, results coming from early
night-time commissioning of the system will be presented.Comment: 8 pages, 6 pages, AO4ELT5 Proceedings, 201
Data processing on simulated data for SHARK-NIR
A robust post processing technique is mandatory to analyse the coronagraphic
high contrast imaging data. Angular Differential Imaging (ADI) and Principal
Component Analysis (PCA) are the most used approaches to suppress the
quasi-static structure in the Point Spread Function (PSF) in order to revealing
planets at different separations from the host star. The focus of this work is
to apply these two data reduction techniques to obtain the best limit detection
for each coronagraphic setting that has been simulated for the SHARK-NIR, a
coronagraphic camera that will be implemented at the Large Binocular Telescope
(LBT). We investigated different seeing conditions () for stellar
magnitude ranging from R=6 to R=14, with particular care in finding the best
compromise between quasi-static speckle subtraction and planet detection.Comment: 9 pages, 8 figures, proceeding for the fifth Adaptive Optics for
Extremely Large Telescopes (AO4ELT5) meeting in 201
CDKN1B mutation and copy number variation are associated with tumor aggressiveness in luminal breast cancer
The CDKN1B gene, encoding for the CDK inhibitor p27kip1, is mutated in defined human cancer subtypes, including breast, prostate carcinomas and small intestine neuroendocrine tumors. Lessons learned from small intestine neuroendocrine tumors suggest that CDKN1B mutations could be subclonal, raising the question of whether a deeper sequencing approach could lead to the identification of higher numbers of patients with mutations. Here, we addressed this question and analyzed human cancer biopsies from breast (n = 396), ovarian (n = 110) and head and neck squamous carcinoma (n = 202) patients, using an ultra-deep sequencing approach. Notwithstanding this effort, the mutation rate of CDKN1B remained substantially aligned with values from the literature, showing that essentially only hormone receptor-positive breast cancer displayed CDKN1B mutations in a relevant number of cases (3%). However, the analysis of copy number variation showed that another fraction of luminal breast cancer displayed loss (8%) or gain (6%) of the CDKN1B gene, further reinforcing the idea that the function of p27kip1 is important in this type of tumor. Intriguingly, an enrichment for CDKN1B alterations was found in samples from premenopausal luminal breast cancer patients (n = 227, 4%) and in circulating cell-free DNA from metastatic luminal breast cancer patients (n = 59, 8.5%), suggesting that CDKN1B alterations could correlate with tumor aggressiveness and/or occur later during disease progression. Notably, many of the identified somatic mutations resulted in p27kip1 protein truncation, leading to loss of most of the protein or of its C-terminal domain. Using a gene-editing approach in a luminal breast cancer cell line, MCF-7, we observed that the expression of p27kip1 truncating mutants that lose the C-terminal domains failed to rescue most of the phenotypes induced by CDKN1B gene knockout, indicating that the functions retained by the C-terminal portion are critical for its role as an oncosuppressor, at least in luminal breast cancer. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland
A CHEOPS-enhanced view of the HD 3167 system
A. C. C. and T. G. W. acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant number ST/R003203/1.Much remains to be understood about the nature of exoplanets smaller than Neptune, most of which have been discovered in compact multi-planet systems. With its inner ultra-short period planet b aligned with the star and two larger outer planets d-c on polar orbits, the multi-planet system HD 3167 features a peculiar architecture and offers the possibility to investigate both dynamical and atmospheric evolution processes. To this purpose we combined multiple datasets of transit photometry and radial velocimetry (RV) to revise the properties of the system and inform models of its planets. This effort was spearheaded by CHEOPS observations of HD 3167b, which appear inconsistent with a purely rocky composition despite its extreme irradiation. Overall the precision on the planetary orbital periods are improved by an order of magnitude, and the uncertainties on the densities of the transiting planets b and c are decreased by a factor of 3. Internal structure and atmospheric simulations draw a contrasting picture between HD 3167d, likely a rocky super-Earth that lost its atmosphere through photo-evaporation, and HD 3167c, a mini-Neptune that kept a substantial primordial gaseous envelope. We detect a fourth, more massive planet on a larger orbit, likely coplanar with HD 3167d-c. Dynamical simulations indeed show that the outer planetary system d-c-e was tilted, as a whole, early in the system history, when HD 3167b was still dominated by the star influence and maintained its aligned orbit. RV data and direct imaging rule out that the companion that could be responsible for the present-day architecture is still bound to the HD 3167 system. Similar global studies of multi-planet systems will tell how many share the peculiar properties of the HD 3167 system, which remains a target of choice for follow-up observations and simulations. © 2022 EDP Sciences. All rights reserved.Publisher PDFPeer reviewe
CHEOPS and TESS view of the ultra-short period super-Earth TOI-561 b
Ultra-short period planets (USPs) are a unique class of super-Earths with an
orbital period of less than a day and hence subject to intense radiation from
their host star. While most of them are consistent with bare rocks, some show
evidence of a heavyweight envelope, which could be a water layer or a secondary
metal-rich atmosphere sustained by an outgassing surface. Much remains to be
learned about the nature of USPs. The prime goal of the present work is to
study the bulk planetary properties and atmosphere of TOI-561b, through the
study of its transits and occultations. We obtained ultra-precise transit
photometry of TOI-561b with CHEOPS and performed a joint analysis of this data
with four TESS sectors. Our analysis of TOI-561b transit photometry put strong
constraints on its properties, especially on its radius, Rp=1.42 +/- 0.02
R_Earth (at ~2% error). The internal structure modelling of the planet shows
that the observations are consistent with negligible H/He atmosphere, however
requiring other lighter materials, in addition to pure iron core and silicate
mantle to explain the observed density. We find that this can be explained by
the inclusion of a water layer in our model. We searched for variability in the
measured Rp/R* over time to trace changes in the structure of the planetary
envelope but none found within the data precision. In addition to the transit
event, we tentatively detect occultation signal in the TESS data with an
eclipse depth of ~27 +/- 11 ppm. Using the models of outgassed atmospheres from
the literature we find that the thermal emission from the planet can mostly
explain the observation. Based on this, we predict that NIR/MIR observations
with JWST should be able to detect silicate species in the atmosphere of the
planet. This could also reveal important clues about the planetary interior and
help disentangle planet formation and evolution models.Comment: 17 pages, 10 + 3 figures, 4 tables, accepted for publication in A&A
(abstract abbreviated
A CHEOPS-enhanced view of the HD3167 system
Much remains to be understood about the nature of exoplanets smaller than
Neptune, most of which have been discovered in compact multi-planet systems.
With its inner ultra-short period planet b aligned with the star and two larger
outer planets d-c on polar orbits, the multi-planet system HD 3167 features a
peculiar architecture and offers the possibility to investigate both dynamical
and atmospheric evolution processes. To this purpose we combined multiple
datasets of transit photometry and radial velocimetry (RV) to revise the
properties of the system and inform models of its planets. This effort was
spearheaded by CHEOPS observations of HD 3167b, which appear inconsistent with
a purely rocky composition despite its extreme irradiation. Overall the
precision on the planetary orbital periods are improved by an order of
magnitude, and the uncertainties on the densities of the transiting planets b
and c are decreased by a factor of 3. Internal structure and atmospheric
simulations draw a contrasting picture between HD 3167d, likely a rocky
super-Earth that lost its atmosphere through photo-evaporation, and HD 3167c, a
mini-Neptune that kept a substantial primordial gaseous envelope. We detect a
fourth, more massive planet on a larger orbit, likely coplanar with HD 3167d-c.
Dynamical simulations indeed show that the outer planetary system d-c-e was
tilted, as a whole, early in the system history, when HD 3167b was still
dominated by the star influence and maintained its aligned orbit. RV data and
direct imaging rule out that the companion that could be responsible for the
present-day architecture is still bound to the HD\,3167 system. Similar global
studies of multi-planet systems will tell how many share the peculiar
properties of the HD3167 system, which remains a target of choice for follow-up
observations and simulations.Comment: 22 pages, 23 pages, accepted for publication in A&A (18 August 2022).
Updated author list in new versio
Refining the properties of the TOI-178 system with CHEOPS and TESS
The TOI-178 system consists of a nearby late K-dwarf transited by six planets
in the super-Earth to mini-Neptune regime, with orbital periods between 1.9 and
20.7 days. All planets but the innermost one form a chain of Laplace
resonances. Mass estimates derived from a preliminary radial velocity (RV)
dataset suggest that the planetary densities do not decrease in a monotonic way
with the orbital distance to the star, contrary to what one would expect based
on simple formation and evolution models. To improve the characterisation of
this key system and prepare for future studies (in particular with JWST), we
perform a detailed photometric study based on 40 new CHEOPS visits, one new
TESS sector, as well as previously published CHEOPS, TESS, and NGTS data. First
we perform a global analysis of the 100 transits contained in our data to
refine the transit parameters of the six planets and study their transit timing
variations (TTVs). We then use our extensive dataset to place constraints on
the radii and orbital periods of potential additional transiting planets in the
system. Our analysis significantly refines the transit parameters of the six
planets, most notably their radii, for which we now obtain relative precisions
3%, with the exception of the smallest planet for which the
precision is 5.1%. Combined with the RV mass estimates, the measured TTVs allow
us to constrain the eccentricities of planets to , which are found to be
all below 0.02, as expected from stability requirements. Taken alone, the TTVs
also suggest a higher mass for planet than the one estimated from the RVs,
which had been found to yield a surprisingly low density for this planet.
However, the masses derived from the current TTV dataset are very
prior-dependent and further observations, over a longer temporal baseline, are
needed to deepen our understanding of this iconic planetary system.Comment: 20 pages, 5 figures, 9 tables. Accepted for publication in A&
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