17 research outputs found
Planet Hunters X: Searching for Nearby Neighbors of 75 Planet and Eclipsing Binary Candidates from the K2 Kepler Extended Mission
We present high-resolution observations of a sample of 75 K2 targets from
Campaigns 1-3 using speckle interferometry on the Southern Astrophysical
Research (SOAR) telescope and adaptive optics (AO) imaging at the Keck II
telescope. The median SOAR -band and Keck -band detection limits at 1"
were ~mag and ~mag, respectively. This
sample includes 37 stars likely to host planets, 32 targets likely to be
eclipsing binaries (EBs), and 6 other targets previously labeled as likely
planetary false positives. We find nine likely physically bound companion stars
within 3" of three candidate transiting exoplanet host stars and six likely
EBs. Six of the nine detected companions are new discoveries; one of the six,
EPIC 206061524, is associated with a planet candidate. Among the EB candidates,
companions were only found near the shortest period ones ( days), which is
in line with previous results showing high multiplicity near short-period
binary stars. This high-resolution data, including both the detected companions
and the limits on potential unseen companions, will be useful in future planet
vetting and stellar multiplicity rate studies for planets and binaries.Comment: Accepted in A
Two mini-Neptunes Transiting the Adolescent K-star HIP 113103 Confirmed with TESS and CHEOPS
We report the discovery of two mini-Neptunes in near 2:1 resonance orbits
( d for HIP 113103 b and d for HIP 113103 c) around
the adolescent K-star HIP 113103 (TIC 121490076). The planet system was first
identified from the TESS mission, and was confirmed via additional photometric
and spectroscopic observations, including a 17.5 hour observation for the
transits of both planets using ESA CHEOPS. We place min and
min limits on the absence of transit timing variations over the three year
photometric baseline, allowing further constraints on the orbital
eccentricities of the system beyond that available from the photometric transit
duration alone. With a planetary radius of
, HIP 113103 b resides within the
radius gap, and this might provide invaluable information on the formation
disparities between super-Earths and mini-Neptunes. Given the larger radius
for HIP 113103 c, and close proximity
of both planets to HIP 113103, it is likely that HIP 113103 b might have lost
(or is still losing) its primordial atmosphere. We therefore present simulated
atmospheric transmission spectra of both planets using JWST, HST, and Twinkle.
It demonstrates a potential metallicity difference (due to differences in their
evolution) would be a challenge to detect if the atmospheres are in chemical
equilibrium. As one of the brightest multi sub-Neptune planet systems suitable
for atmosphere follow up, HIP 113103 b and HIP 113103 c could provide insight
on planetary evolution for the sub-Neptune K-star population.Comment: 18 pages, 12 figures, accepted for publication in the Monthly Notices
of the Royal Astronomical Societ
Planet Hunters X: Searching for nearby neighbors of 75 planet and eclipsing binary candidates from the K2 Kepler extended mission
We present high resolution observations of a sample of 75 K2 targets from Campaigns 1-3 using speckle interferometry on the Southern Astrophysical Research (SOAR) telescope and adaptive optics (AO) imaging at the Keck II telescope. The median SOAR -band and Keck -band detection limits at 1'' were mag and mag, respectively. This sample includes 37 stars likely to host planets, 32 targets likely to be EBs, and 6 other targets previously labeled as likely planetary false positives. We find nine likely physically bound companion stars within 3'' of three candidate transiting exoplanet host stars and six likely eclipsing binaries (EB). Six of the nine detected companions are new discoveries, one of them associated with a planet candidate (EPIC 206061524). Among the EB candidates, companions were only found near the shortest period ones (P<3 days), which is in line with previous results showing high multiplicity near short-period binary stars. This high resolution data, including both the detected companions and the limits on potential unseen companions, will be useful in future planet vetting and stellar multiplicity rate studies for planets and binaries
Two mini-Neptunes Transiting the Adolescent K-star HIP 113103 Confirmed with TESS and CHEOPS
Tracing HIV-1 strains that imprint broadly neutralizing antibody responses.
Understanding the determinants of broadly neutralizing antibody (bNAb) evolution is crucial for the development of bNAb-based HIV vaccines. Despite emerging information on cofactors that promote bNAb evolution in natural HIV-1 infections, in which the induction of bNAbs is genuinely rare, information on the impact of the infecting virus strain on determining the breadth and specificity of the antibody responses to HIV-1 is lacking. Here we analyse the influence of viral antigens in shaping antibody responses in humans. We call the ability of a virus strain to induce similar antibody responses across different hosts its antibody-imprinting capacity, which from an evolutionary biology perspective corresponds to the viral heritability of the antibody responses. Analysis of 53 measured parameters of HIV-1-binding and neutralizing antibody responses in a cohort of 303 HIV-1 transmission pairs (individuals who harboured highly related HIV-1 strains and were putative direct transmission partners or members of an HIV-1 transmission chain) revealed that the effect of the infecting virus on the outcome of the bNAb response is moderate in magnitude but highly significant. We introduce the concept of bNAb-imprinting viruses and provide evidence for the existence of such viruses in a systematic screening of our cohort. The bNAb-imprinting capacity can be substantial, as indicated by a transmission pair with highly similar HIV-1 antibody responses and strong bNAb activity. Identification of viruses that have bNAb-imprinting capacities and their characterization may thus provide the potential to develop lead immunogens