155 research outputs found
Sistemas exoplanetarios múltiples
Se conocen 473 sistemas exoplanetarios múltiples, de los cuales 51 poseen 4 o más planetas. Presentamos análisis estadísticos de las propiedades de las estrellas que los albergan y los planetas que los componen, y de las configuraciones orbitales de estos sistemas. Separando los sistemas en chicos (2 o 3 planetas) y grandes (4 o más planetas), analizamos la metalicidad estelar. Estudiamos si los planetas están ordenados preferentemente por tamaño en sus sistemas. Para los 51 sistemas grandes, medimos la razón de tamaños de los planetas y la compactez de los sistemas, y analizamos la posibilidad de una relación entre éstos. Estudiamos la diversidad de los sistemas planetarios múltiples en relación al Sistema Solar. Investigamos las distribuciones espectrales de energía de las estrellas con sistemas planetarios múltiples en busca de posibles discos debris. Realizamos análisis comparativos de propiedades estelares y planetarias para sistemas con y sin excesos en IR, y estimamos temperaturas y radios de los discos
Feasibility and cost analysis of implementing high intensity aphasia clinics within a sub-acute setting
The current study explored the clinical feasibility and costs of embedding three different intensive service delivery models for aphasia treatment (computer, group therapy, and therapy with a speech pathology therapy assistant) within three sub-acute facilities. The study employed a two cohort comparison design, with the first cohort (n = 22) receiving the standard service of treatment currently offered. This treatment was delivered by a speech-language pathologist and involved on average 3 hours of treatment/week over 8 weeks. Participants in the second cohort (n = 31) received one of the three intensive treatment models providing up to 9 hours of therapy/week for 11 weeks. Organizational data was collected throughout treatment, with participant, caregiver, and clinician satisfaction with the intensive models also being measured. Participants completed the spoken language production sub-tests and the Disability Questionnaire of the Comprehensive Aphasia Test (CAT) pre- and post-treatment. All intensive models yielded high participant attendance, satisfaction, and significant improvements to the CAT sub-tests. The pro-rata cost of providing treatment per hour per client for the computer and group therapy models was found to be ̃ 30% cheaper compared to the standard service. The outcomes support the potential feasibility of embedding the different models into sub-acute facilities to enhance client access to intensive treatment for aphasia
Orbital alignment of the eccentric warm Jupiter TOI-677 b
Warm Jupiters lay out an excellent laboratory for testing models of planet
formation and migration. Their separation from the host star makes tidal
reprocessing of their orbits ineffective, which preserves the orbital
architectures that result from the planet-forming process. Among the measurable
properties, the orbital inclination with respect to the stellar rotational
axis, stands out as a crucial diagnostic for understanding the migration
mechanisms behind the origin of close-in planets. Observational limitations
have made the procurement of spin-orbit measurements heavily biased toward hot
Jupiter systems. In recent years, however, high-precision spectroscopy has
begun to provide obliquity measurements for planets well into the warm Jupiter
regime. In this study, we present Rossiter-McLaughlin (RM) measurements of the
projected obliquity angle for the warm Jupiter TOI-677 b using ESPRESSO at the
VLT. TOI-677 b exhibits an extreme degree of alignment (
deg), which is particularly puzzling given its significant eccentricity (). TOI-677 b thus joins a growing class of close-in giants that
exhibit large eccentricities and low spin-orbit angles, which is a
configuration not predicted by existing models. We also present the detection
of a candidate outer brown dwarf companion on an eccentric, wide orbit ( and yr). Using simple estimates, we show that this
companion is unlikely to be the cause of the unusual orbit of TOI-677 b.
Therefore, it is essential that future efforts prioritize the acquisition of RM
measurements for warm Jupiters.Comment: 15 pages, 6 figures, 5 tables. Accepted for publication in the
Astronomical Journa
APERO: A PipelinE to Reduce Observations -- Demonstration with SPIRou
With the maturation of near-infrared high-resolution spectroscopy, especially
when used for precision radial velocity, data reduction has faced unprecedented
challenges in terms of how one goes from raw data to calibrated, extracted, and
corrected data with required precisions of thousandths of a pixel. Here we
present APERO (A PipelinE to Reduce Observations), specifically focused on
SPIRou, the near-infrared spectropolarimeter on the Canada--France--Hawaii
Telescope (SPectropolarim\`etre InfraROUge, CFHT). In this paper, we give an
overview of APERO and detail the reduction procedure for SPIRou. APERO delivers
telluric-corrected 2D and 1D spectra as well as polarimetry products. APERO
enables precise stable radial velocity measurements on sky (via the LBL
algorithm), good to at least ~2 m/s over the current 5-year lifetime of SPIRou.Comment: Accepted for publication in PASP. 55 pages, 29 figures, 10 pages of
Appendice
A red giant orbiting a black hole
We report spectroscopic and photometric follow-up of a dormant black hole
(BH) candidate from Gaia DR3. We show that the system, which we call Gaia BH2,
contains a red giant and a dark companion with mass that is very likely a BH. The orbital period, days, is much longer than that of any previously studied BH
binary. Our radial velocity (RV) follow-up over a 6-month period spans most of
the orbit's dynamic range in RV and is in excellent agreement with predictions
of the Gaia solution. UV imaging and high-resolution optical spectra rule out
all plausible luminous companions that could explain the orbit. The star is a
bright (), slightly metal-poor () low-luminosity
giant (; ; ). The binary's orbit is moderately eccentric
(). The giant is strongly enhanced in elements, with , but the system's Galactocentric orbit is typical of the
thin disk. We obtained X-ray and radio nondetections of the source near
periastron, which support BH accretion models in which the net accretion rate
at the horizon is much lower than the Bondi-Hoyle-Lyttleton rate. At a distance
of 1.16 kpc, Gaia BH2 is the second-nearest known BH, after Gaia BH1. Its orbit
-- like that of Gaia BH1 -- seems too wide to have formed through common
envelope evolution. Gaia BH1 and BH2 have orbital periods at opposite edges of
the Gaia DR3 sensitivity curve, perhaps hinting at a bimodal intrinsic period
distribution for wide BH binaries. Dormant BH binaries like Gaia BH1 and Gaia
BH2 likely significantly outnumber their close, X-ray bright cousins, but their
formation pathways remain uncertain.Comment: 22 pages, 15 figures. Submitted to MNRA
The SOPHIE search for northern extrasolar planets XIV. A temperate (Teq ~ 300 K) super-earth around the nearby star Gliese 411
Periodic radial velocity variations in the nearby M-dwarf star Gl 411 are reported, based on measurements with the SOPHIE spectrograph. Current data do not allow us to distinguish between a 12.95-day period and its one-day alias at 1.08 days, but favour the former slightly. The velocity variation has an amplitude of 1.6 m s−1, making this the lowest-amplitude signal detected with SOPHIE up to now. We have performed a detailed analysis of the significance of the signal and its origin, including extensive simulations with both uncorrelated and correlated noise, representing the signal induced by stellar activity. The signal is significantly detected, and the results from all tests point to its planetary origin. Additionally, the presence of an additional acceleration in the velocity time series is suggested by the current data. On the other hand, a previously reported signal with a period of 9.9 days, detected in HIRES velocities of this star, is not recovered in the SOPHIE data. An independent analysis of the HIRES dataset also fails to unveil the 9.9-day signal. If the 12.95-day period is the real one, the amplitude of the signal detected with SOPHIE implies the presence of a planet, called Gl 411 b, with a minimum mass of around three Earth masses, orbiting its star at a distance of 0.079 AU. The planet receives about 3.5 times the insolation received by Earth, which implies an equilibrium temperature between 256 and 350 K, and makes it too hot to be in the habitable zone. At a distance of only 2.5 pc, Gl 411 b, is the third closest low-mass planet detected to date. Its proximity to Earth will permit probing its atmosphere with a combination of high-contrast imaging and high-dispersion spectroscopy in the next decade
Three Warm Jupiters around Solar-analog Stars Detected with TESS*
We report the discovery and characterization of three giant exoplanets orbiting solar-analog stars, detected by the TESS space mission and confirmed through ground-based photometry and radial velocity measurements taken at La Silla observatory with FEROS. TOI-2373 b is a warm Jupiter orbiting its host star every ∼13.3 days, and is one of the most massive known exoplanet with a precisely determined mass and radius around a star similar to the Sun, with an estimated mass of m _p = and a radius of r _p = . With a mean density of , TOI-2373 b is among the densest planets discovered so far. TOI-2416 b orbits its host star on a moderately eccentric orbit with a period of ∼8.3 days and an eccentricity of e = . TOI-2416 b is more massive than Jupiter with m _p = , however is significantly smaller with a radius of r _p = , leading to a high mean density of . TOI-2524 b is a warm Jupiter near the hot Jupiter transition region, orbiting its star every ∼7.2 days on a circular orbit. It is less massive than Jupiter with a mass of m _p = , and is consistent with an inflated radius of r _p = , leading to a low mean density of . The newly discovered exoplanets TOI-2373 b, TOI-2416 b, and TOI-2524 b have estimated equilibrium temperatures of K, K, and K, respectively, placing them in the sparsely populated transition zone between hot and warm Jupiters
TOI-3235 b: a transiting giant planet around an M4 dwarf star
We present the discovery of TOI-3235 b, a short-period Jupiter orbiting an
M-dwarf with a stellar mass close to the critical mass at which stars
transition from partially to fully convective. TOI-3235 b was first identified
as a candidate from TESS photometry, and confirmed with radial velocities from
ESPRESSO, and ground-based photometry from HATSouth, MEarth-South,
TRAPPIST-South, LCOGT, and ExTrA. We find that the planet has a mass of
and a radius of . It
orbits close to its host star, with an orbital period of ,
but has an equilibrium temperature of , well below
the expected threshold for radius inflation of hot Jupiters. The host star has
a mass of , a radius of
, an effective temperature of , and a J-band magnitude of . Current planet
formation models do not predict the existence of gas giants such as TOI-3235 b
around such low-mass stars. With a high transmission spectroscopy metric,
TOI-3235 b is one of the best-suited giants orbiting M-dwarfs for atmospheric
characterization.Comment: 15 pages, 4 figures. Accepted for publication in APJ
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