A linfo-histiocitose hemofagocítica (HLH) é caracterizada por hiperativação imunológica e destruição de tecidos, causada pela ausência de regulação negativa dos macrófagos e linfócitos ativados, mais ...comum em crianças do nascimento aos 18 meses. Um gatilho comum desta condição é processo infeccioso, especialmente vírus Epstein-Barr, tanto em pacientes com predisposição genética como em casos esporádicos. Os genes associados ao HLH codificam componentes para citotoxicidade dependente de perforina, em geral relacionados à consanguinidade. A síndrome de Chediak-Higashi (SCH) é uma doença autossômica recessiva rara, causada pela mutação no gene CHS1/LYST (1q42.1-2), cuja proteína expressa é fundamental para regular o início da produção dos grânulos contendo perforina e granzimas em células da imunidade celular mediada por grânulos (linfócitos T citotóxicos e células NK). O quadro clínico é sugerido pela presença de albinismo óculo-cutâneo, cabelos cinza-prateados, anormalidades neurológicas progressivas, defeitos leves de coagulação, infecções recorrentes e um alto risco de desenvolver HLH.
Sexo feminino, 11 anos, filha única de pais consanguíneos (primos de 3°grau), procedente da zona rural na Bahia, antecedente de síndrome de Chediak-Higashi (diagnosticada em exames de sangue periférico e medula óssea de 2013). Seguia ambulatório de hematologia cada 6 meses, com avaliações clínico-laboratoriais. Em 2020, procurou PS com queixa de dores em membros inferiores há 15 dias, acompanhada de dor abdominal, associada a vômitos, constipação, inapetência, perda de peso não mensurado e febre não aferida, em uso de analgésico. Refere infecção urinária há 30 dias. Nega quadros infecciosos e uso de antibióticos prévios. Ao exame físico: palidez cutânea e febril (38,4°C). Cabelos acinzentados, olhos claros e pele rendilhada. Abdome globoso, distendido, hepatoesplenomegalia (baço 6 cm e fígado 3 cm, do rebordo costal).
Mielograma: presença de grânulações citoplasmáticas nos leucócitos, sugestivo de síndrome de Chediak-Higashi. Pancitopenia (Hb 5,0 Leuco 1.800 Plaq 24.000), ferritina 1307, triglicerídeos 443, fibrinogênio 40, preenchendo mais de 5 critérios de HLH. Iniciado protocolo com dexametasona e etoposídeo. Recidivou duas vezes, reiniciando o protocolo HLH 2004. Atualmente na fase de manutenção, aguardando doador idêntico de medula óssea, para TMO.
A SCH caracterizada por infecções bacterianas recorrentes, devido seu defeito nos grânulos dos neutrófilos e linfócitos T citotóxicos, prejudicando a função bactericida e citotóxica. Os locais mais frequentes de infecção são pele, trato respiratório e membranas mucosas. Nesta condição acabam entrando na fase acelerada da doença, caracterizada por doença HLH com infiltração linfo-histiocítica maciça em fígado, baço e medula óssea com grande produção de citoquinas inflamatórias que causam disfunção de múltiplos órgãos. O diagnóstico de SCH é sugerido por grânulos citoplasmáticos gigantes patognomônicos em leucócitos no sangue periférico e medula óssea e confirmado pela identificação da mutação gênica. O tratamento consiste na supressão da hiperinflamação (com imunossupressores), eliminação de células imunes ativadas (corticosteróides e etoposide), eliminação do “gatilho”e terapia de suporte para neutropenia, coagulopatia, infecções. Com a remissão do quadro acelerado, necessita de transplante de células tronco hematopoéticas, para correção do defeito imunológico herdado.
A HLH ocorre em 80% dos pacientes com SCH, com altas taxas de mortalidade. Assim, a investigação dos critérios clínicos na suspeita de HLH são de suma importância para o diagnóstico e tratamento precoce e, consequentemente, melhor a sobrevida.
ABSTRACT
CHEOPS (CHaracterising ExOPlanet Satellite) is an ESA S-class mission that observes bright stars at high cadence from low-Earth orbit. The main aim of the mission is to characterize ...exoplanets that transit nearby stars using ultrahigh precision photometry. Here, we report the analysis of transits observed by CHEOPS during its Early Science observing programme for four well-known exoplanets: GJ 436 b, HD 106315 b, HD 97658 b, and GJ 1132 b. The analysis is done using pycheops, an open-source software package we have developed to easily and efficiently analyse CHEOPS light-curve data using state-of-the-art techniques that are fully described herein. We show that the precision of the transit parameters measured using CHEOPS is comparable to that from larger space telescopes such as Spitzer Space Telescope and Kepler. We use the updated planet parameters from our analysis to derive new constraints on the internal structure of these four exoplanets.
ABSTRACT
We present a precise characterization of the TOI-561 planetary system obtained by combining previously published data with TESS and CHEOPS photometry, and a new set of 62 HARPS-N radial ...velocities (RVs). Our joint analysis confirms the presence of four transiting planets, namely TOI-561 b (P = 0.45 d, R = 1.42 R⊕, M = 2.0 M⊕), c (P = 10.78 d, R = 2.91 R⊕, M = 5.4 M⊕), d (P = 25.7 d, R = 2.82 R⊕, M = 13.2 M⊕), and e (P = 77 d, R = 2.55 R⊕, M = 12.6 R⊕). Moreover, we identify an additional, long-period signal (>450 d) in the RVs, which could be due to either an external planetary companion or to stellar magnetic activity. The precise masses and radii obtained for the four planets allowed us to conduct interior structure and atmospheric escape modelling. TOI-561 b is confirmed to be the lowest density (ρb = 3.8 ± 0.5 g cm−3) ultra-short period (USP) planet known to date, and the low metallicity of the host star makes it consistent with the general bulk density-stellar metallicity trend. According to our interior structure modelling, planet b has basically no gas envelope, and it could host a certain amount of water. In contrast, TOI-561 c, d, and e likely retained an H/He envelope, in addition to a possibly large water layer. The inferred planetary compositions suggest different atmospheric evolutionary paths, with planets b and c having experienced significant gas loss, and planets d and e showing an atmospheric content consistent with the original one. The uniqueness of the USP planet, the presence of the long-period planet TOI-561 e, and the complex architecture make this system an appealing target for follow-up studies.
The GAPS Programme with HARPS-N at TNG Esposito, M.; Covino, E.; Desidera, S. ...
Astronomy and astrophysics (Berlin),
5/2017, Letnik:
601
Journal Article
The GAPS Programme at TNG Damasso, M.; Locci, D.; Benatti, S. ...
Astronomy and astrophysics (Berlin),
04/2023, Letnik:
672
Journal Article
Recenzirano
Odprti dostop
Context.
The GAPS collaboration is carrying out a spectroscopic and photometric follow-up of a sample of young stars with planets (age ≲600 Myr) to characterise planetary systems at the early stages ...of their evolution.
Aims.
For more than 2 yr, we monitored with the HARPS-N spectrograph the 400 Myr-old star HD 63433, which hosts two close-in (orbital periods
P
b
~ 7.1 and
P
c
~ 20.5 days) sub-Neptunes detected by the TESS space telescope, and it was announced in 2020. Using radial velocities and additional TESS photometry, we aim to provide the first measurement of their masses, improve the measure of their size and orbital parameters, and study the evolution of the atmospheric mass-loss rate due to photoevaporation.
Methods.
We tested state-of-the-art analysis techniques and different models to mitigate the dominant signals due to stellar activity that are detected in the radial velocity time series. We used a hydro-based analytical description of the atmospheric mass-loss rate, coupled with a core-envelope model and stellar evolutionary tracks, to study the past and future evolution of the planetary masses and radii.
Results.
We derived new measurements of the planetary orbital periods and radii (
P
b
= 7.10794 ± 0.000009 days, r
b
= 2.02
+0.06
-0.05
R
⊕
;
P
c
= 20.54379 ± 0.00002 days,
r
c
= 2.44 ± 0.07
R
⊕
), and determined mass upper limits (
m
b
≲11
M
⊕
;
m
c
≲31
M
⊕
; 95% confidence level), with evidence at a 2.1–2.7
σ
significance level that HD 63433 c might be a dense mini-Neptune with a Neptune-like mass. For a grid of test masses below our derived dynamical upper limits, we found that HD 63433 b has very likely lost any gaseous H-He envelope, supporting HST-based observations that are indicative of there being no ongoing atmospheric will keep evaporating over the next ~5 Gyr if its current mass is
m
c
≲15
M
⊕
, while it should be hydrodynamically stable for higher masses.
Context.
A large sample of long-period giant planets has been discovered thanks to long-term radial velocity surveys, but only a few dozen of these planets have a precise radius measurement. ...Transiting gas giants are crucial targets for the study of atmospheric composition across a wide range of equilibrium temperatures and, more importantly, for shedding light on the formation and evolution of planetary systems. Indeed, compared to hot Jupiters, the atmospheric properties and orbital parameters of cooler gas giants are unaltered by intense stellar irradiation and tidal effects.
Aims.
We aim to identify long-period planets in the Transiting Exoplanet Survey Satellite (TESS) data as single or duo-transit events. Our goal is to solve the orbital periods of TESS duo-transit candidates with the use of additional space-based photometric observations and to collect follow-up spectroscopic observations in order to confirm the planetary nature and measure the mass of the candidates.
Methods.
We use the CHaracterising ExOPlanet Satellite (CHEOPS) to observe the highest-probability period aliases in order to discard or confirm a transit event at a given period. Once a period is confirmed, we jointly model the TESS and CHEOPS light curves along with the radial velocity datasets to measure the orbital parameters of the system and obtain precise mass and radius measurements.
Results.
We report the discovery of a long-period transiting Neptune-mass planet orbiting the G7-type star TOI-5678. Our spectroscopic analysis shows that TOI-5678 is a star with a solar metallicity. The TESS light curve of TOI-5678 presents two transit events separated by almost two years. In addition, CHEOPS observed the target as part of its Guaranteed Time Observation program. After four non-detections corresponding to possible periods, CHEOPS detected a transit event matching a unique period alias. Follow-up radial velocity observations were carried out with the ground-based high-resolution spectrographs CORALIE and HARPS. Joint modeling reveals that TOI-5678 hosts a 47.73 day period planet, and we measure an orbital eccentricity consistent with zero at 2
σ
. The planet TOI-5678 b has a mass of 20 ± 4 Earth masses (
M
⊕
) and a radius of 4.91 ± 0.08
R
⊕
Using interior structure modeling, we find that TOI-5678 b is composed of a low-mass core surrounded by a large H/He layer with a mass of 3.2
±1.7
−1.3
M
⊕
.
Conclusions.
TOI-5678 b is part of a growing sample of well-characterized transiting gas giants receiving moderate amounts of stellar insolation (11
S
⊕
). Precise density measurement gives us insight into their interior composition, and the objects orbiting bright stars are suitable targets to study the atmospheric composition of cooler gas giants.
The GAPS programme at TNG Maldonado, J.; Petralia, A.; Mantovan, G. ...
Astronomy and astrophysics (Berlin),
06/2023, Letnik:
674
Journal Article
Recenzirano
Odprti dostop
Context.
Massive substellar companions orbiting active low-mass stars are rare. They, however, offer an excellent opportunity to study the main mechanisms involved in the formation and evolution of ...substellar objects.
Aims.
We aim to unravel the physical nature of the transit signal observed by the TESS space mission on the active M dwarf TOI-5375.
Methods.
We analysed the available TESS photometric data as well as high-resolution (
R
~ 115 000) HARPS-N spectra. We combined these data to characterise the star TOI-5375 and to disentangle signals related to stellar activity from the companion transit signal in the light-curve data. We ran a Markov chain Monte Carlo analysis to derive the orbital solution and applied state-of-the-art Gaussian process regression to deal with the stellar activity signal.
Results.
We reveal the presence of a companion in the boundary between the brown dwarfs and the very-low-mass stars orbiting around the star TOI-5375. The best-fit model corresponds to a companion with an orbital period of 1.721564 ± 10
−6
d, a mass of 77 ± 8
M
J
, and a radius of 0.99 ± 0.16
R
J
.
Conclusions.
We derive a rotation period for the host star of 1.9692 ± 0.0004 d, and we conclude that the star is very close to synchronising its rotation with the orbital period of the companion.
ABSTRACT
HIP 9618 (HD 12572, TOI-1471, TIC 306263608) is a bright (G = 9.0 mag) solar analogue. TESS photometry revealed the star to have two candidate planets with radii of 3.9 ± 0.044 R⊕ (HIP 9618 ...b) and 3.343 ± 0.039 R⊕ (HIP 9618 c). While the 20.77291 d period of HIP 9618 b was measured unambiguously, HIP 9618 c showed only two transits separated by a 680-d gap in the time series, leaving many possibilities for the period. To solve this issue, CHEOPS performed targeted photometry of period aliases to attempt to recover the true period of planet c, and successfully determined the true period to be 52.56349 d. High-resolution spectroscopy with HARPS-N, SOPHIE, and CAFE revealed a mass of 10.0 ± 3.1M⊕ for HIP 9618 b, which, according to our interior structure models, corresponds to a $6.8\pm 1.4~{{\ \rm per\ cent}}$ gas fraction. HIP 9618 c appears to have a lower mass than HIP 9618 b, with a 3-sigma upper limit of <18M⊕. Follow-up and archival RV measurements also reveal a clear long-term trend which, when combined with imaging and astrometric information, reveal a low-mass companion ($0.08^{+0.12}_{-0.05} M_\odot$) orbiting at $26.0^{+19.0}_{-11.0}$ au. This detection makes HIP 9618 one of only five bright (K < 8 mag) transiting multiplanet systems known to host a planet with P > 50 d, opening the door for the atmospheric characterization of warm (Teq < 750 K) sub-Neptunes.
The GAPS programme with HARPS-N at TNG Covino, E; Esposito, M; Barbieri, M ...
Astronomy and astrophysics (Berlin),
06/2013, Letnik:
554
Journal Article
Recenzirano
Odprti dostop
Our understanding of the formation and evolution of planetary systems is still fragmentary because most of the current data provide limited information about the orbital structure and dynamics of ...these systems. The knowledge of the orbital properties for a variety of systems and at different ages yields information on planet migration and on star-planet tidal interaction mechanisms. In this context, a long-term, multi-purpose, observational programme has started with HARPS-N at TNG and aims to characterise the global architectural properties of exoplanetary systems. The goal of this first paper is to fully characterise the orbital properties of the transiting system Qatar-1 as well as the physical properties of the star and the planet. We find that the system is well aligned and fits well within the general lambda versus Tsubeff trend. We can definitely rule out any significant orbital eccentricity. The evolutionary status of the system is inferred based on gyrochronology, and the present orbital configuration and timescale for orbital decay are discussed in terms of star-planet tidal interactions.
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