317 research outputs found
An Atmospheric Retrieval of the Brown Dwarf Gliese 229B
© 2022. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/We present results from an atmospheric retrieval analysis of Gl 229B using the Brewster retrieval code. We find the best fit model to be cloud-free, consistent with the T dwarf retrieval work of Line et al.; Zalesky et al. and Gonzales et al. Fundamental parameters (mass, radius, log(L Bol /L Sun), log(g)) determined from our model agree within 1Ï to SED-derived values, except for T eff where our retrieved T eff is approximately 100 K cooler than the evolutionary model-based SED value. We find a retrieved mass of 50â9+12 M Jup, however, we also find that the observables of Gl 229B can be explained by a cloud-free model with a prior on mass at the dynamical value, 70 M Jup . We are able to constrain abundances for H2O, CO, CH4, NH3, Na and K and find a supersolar C/O ratio as compared to its primary, Gl 229A. We report an overall subsolar metallicity due to atmospheric oxygen depletion, but find a solar [C/H], which matches that of the primary. We find that this work contributes to a growing trend in retrieval-based studies, particularly for brown dwarfs, toward supersolar C/O ratios and discuss the implications of this result on formation mechanisms and internal physical processes, as well as model biases.Peer reviewe
A Search for Variability in Exoplanet Analogues and Low-Gravity Brown Dwarfs
We report the results of a -band survey for photometric variability in a
sample of young, low-gravity objects using the New Technology Telescope (NTT)
and the United Kingdom InfraRed Telescope (UKIRT). Surface gravity is a key
parameter in the atmospheric properties of brown dwarfs and this is the first
large survey that aims to test the gravity dependence of variability
properties. We do a full analysis of the spectral signatures of youth and
assess the group membership probability of each target using membership tools
from the literature. This results in a 30 object sample of young low-gravity
brown dwarfs. Since we are lacking in objects with spectral types later than
L9, we focus our statistical analysis on the L0-L8.5 objects. We find that the
variability occurrence rate of L0-L8.5 low-gravity brown dwarfs in this survey
is . We reanalyse the results of Radigan 2014 and find that
the field dwarfs with spectral types L0-L8.5 have a variability occurrence rate
of . We determine a probability of that the samples are
drawn from different distributions. This is the first quantitative indication
that the low-gravity objects are more likely to be variable than the field
dwarf population. Furthermore, we present follow-up and
observations of the young, planetary-mass variable object PSO 318.5-22 over
three consecutive nights. We find no evidence of phase shifts between the
and bands and find higher amplitudes. We use the lightcurves
to measure a rotational period of hr for PSO 318.5-22.Comment: accepted for publication in MNRA
The Perkins INfrared Exosatellite Survey (PINES) II. Transit Candidates and Implications for Planet Occurrence around L and T Dwarfs
We describe a new transit detection algorithm designed to detect single
transit events in discontinuous Perkins INfrared Exosatellite Survey (PINES)
observations of L and T dwarfs. We use this algorithm to search for transits in
131 PINES light curves and identify two transit candidates: 2MASS
J18212815+1414010 (2MASS J1821+1414) and 2MASS J08350622+1953050 (2MASS
J0835+1953). We disfavor 2MASS J1821+1414 as a genuine transit candidate due to
the known variability properties of the source. We cannot rule out the
planetary nature of 2MASS J0835+1953's candidate event and perform follow-up
observations in an attempt to recover a second transit. A repeat event has yet
to be observed, but these observations suggest that target variability is an
unlikely cause of the candidate transit. We perform a Markov chain Monte Carlo
simulation of the light curve and estimate a planet radius ranging from
to , depending on the
host's age. Finally, we perform an injection and recovery simulation on our
light curve sample. We inject planets into our data using measured M dwarf
planet occurrence rates and attempt to recover them using our transit search
algorithm. Our detection rates suggest that, assuming M dwarf planet occurrence
rates, we should have roughly a 1 chance of detecting a candidate that
could cause the transit depth we observe for 2MASS J0835+1953. If 2MASS
J0835+1953 b is confirmed, it would suggest an enhancement in the occurrence of
short-period planets around L and T dwarfs in comparison to M dwarfs, which
would challenge predictions from planet formation models.Comment: 23 pages, 15 figures, accepted to A
Cancer-related psychosocial factors and self-reported changes in lifestyle among gynecological cancer survivors:Cross-sectional analysis of PROFILES registry data
PURPOSE: Obesity is prevalent in gynecological cancer survivors and is associated with impaired health outcomes. Concerns due to cancer and its treatment may impact changes in lifestyle after cancer. This study aimed to assess the association between cancer-related psychosocial factors and changes in physical activity and diet, 18 months after initial treatment among gynecological cancer survivors. METHODS: Cross-sectional data from the ROGY Care study were used, including endometrial and ovarian cancer patients treated with curative intent. The Impact of Cancer Scale (IOCv2) was used to assess cancer-related psychosocial factors. Self-reported changes in nutrients/food groups and in physical activity post-diagnosis were classified into change groups (less/equal/more). Multivariable logistic regression models were used to assess associations. RESULTS: Data from 229 cancer survivors (59% endometrial, 41% ovarian, mean age 66â±â9.5, 70% tumor stage I) were analyzed. In total, 20% reported to eat healthier from diagnosis up to 18 months after initial treatment, 17% reported less physical activity and 20% more physical activity. Health awareness (OR 2.79, 95% CI: 1.38; 5.65), body change concerns (OR 3.04 95% CI: 1.71; 5.39), life interferences (OR 4.88 95% 2.29; 10.38) and worry (OR 2.62, 95% CI: 1.42; 4.85) were significantly associated with less physical activity up to 18 months after initial treatment whereby gastrointestinal symptoms were an important confounder. CONCLUSION(S): This study underlines the need to raise awareness of the benefits of a healthy lifestyle and to provide tailored lifestyle advice, taking into account survivorsâ health awareness, body change concerns, life interferences, worry and gastrointestinal symptoms, in order to improve health behavior among gynecological cancer survivors. TRIAL REGISTRATION: http://clinicaltrials.gov Identifier: NCT01185626, August 20, 2010 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00520-021-06433-0
Examining the Rotation Period Distribution of the 40 Myr Tucana-Horologium Association with TESS
The Tucana-Horologium Association (Tuc-Hor) is a 40 Myr old moving group in
the southern sky. In this work, we measure the rotation periods of 313 Tuc-Hor
objects with TESS light curves derived from TESS full frame images and
membership lists driven by Gaia EDR3 kinematics and known youth indicators. We
recover a period for 81.4% of the sample and report 255 rotaion periods for
Tuc-Hor objects. From these objects we identify 11 candidate binaries based on
multiple periodic signals or outlier Gaia DR2 and EDR3 re-normalised unit
weight error (RUWE) values. We also identify three new complex rotators
(rapidly rotating M dwarf objects with intricate light curve morphology) within
our sample. Along with the six previously known complex rotators that belong to
Tuc-Hor, we compare their light curve morphology between TESS Cycle 1 and Cycle
3 and find they change substantially. Furthermore, we provide context for the
entire Tuc-Hor rotation sample by describing the rotation period distributions
alongside other youth indicators such as H{\alpha} and Li equivalent width, as
well as near ultra-violet and X ray flux. We find that measuring rotation
periods with TESS to be a fast and effective means to confirm members in young
moving groups.Comment: 27 pages, 12 figure
Screening for germline DND1 mutations in testicular cancer patients
Although several observations suggest that a strong genetic predisposition to developing testicular germ cell tumors (TGCT) exists, no associated, highly penetrant germline mutations have been identified so far. In the 129/Sv mouse strain, a germline mutation in the DND1 gene has been shown to strongly increase the TGCT risk. We screened 272 men with TGCT (89% sporadic cases, 11% familial) for germline mutations in the human homologue of DND1. A single nucleotide substitution c.657CÂ >Â G (p.Asp219Glu) was observed in a non-familial case of testicular embryonal carcinoma. The variant was also present in the patientâs asymptomatic father and two brothers, but not observed in 210 control chromosomes. The wild type DND1 allele was not lost in the patientâs tumor. In silico analysis of the variant predicts it to be non-pathogenic. We conclude that germline DND1 mutations are unlikely to contribute significantly to human testicular germ cell tumor susceptibility. The role of human DND1 in normal physiology and disease, however, is still virtually unknown and it therefore warrants further research
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