We present the discoveries of a brown dwarf (BD) and a low-mass star from the Kepler and K2 missions. The newly discovered BD is EPIC 212036875b and the low-mass star is KOI-607b. EPIC 212036875b has ...a mass of Mb = 52.3 1.9 MJ, a radius of Rb = 0.874 0.017 RJ, and orbits its host star in P = 5.169885 0.000027 days. Its host star is a late F-type star with M = 1.288 0.065 M , R = 1.498 0.025 R , and Teff = 6238 60 K. KOI-607b has a mass of Mb = 95.1 3.4 MJ, a radius of Rb = 1.089 0.089 RJ, and an orbital period of P = 5.89399148 0.00000060 days. The primary star in the KOI-607 system is a G dwarf with M =0.993 0.052 M , R = 0.915 0.031 R , and Teff = 5418 87 K. We also revisit a BD, CWW 89Ab, that was previously published by Nowak et al. (under the designation EPIC 219388192b). CWW 89Ab is one of two known transiting BDs associated with a star cluster, which illustrates the need for more BDs with accurate masses, radii, and reliable age determinations to test theoretical models. We find that the newly discovered BD, EPIC 212036875b, falls in the middle of the so-called BD desert, indicating that EPIC 212036875b is either a particularly rare object, or the BD desert may not be so dry after all.
Abstract
This article presents the history of the Visual Survey Group (VSG)—a Professional-Amateur (Pro-Am) collaboration within the field of astronomy working on data from several space missions ...(Kepler, K2 and Transiting Exoplanet Survey Satellite). This paper covers the formation of the VSG, its survey-methods including the most common tools used and its discoveries made over the past decade. So far, the group has visually surveyed nearly 10 million light curves and authored 69 peer-reviewed papers which mainly focus on exoplanets and discoveries involving multistellar systems. The preferred manual search-method carried out by the VSG has revealed its strength by detecting numerous objects which were overlooked or discarded by automated search programs, uncovering some of the most rare stars in our galaxy, and leading to several serendipitous discoveries of unprecedented astrophysical phenomena. The main purpose of the VSG is to assist in the exploration of our local universe, and we therefore advocate continued crowd-sourced examination of time-domain data sets, and invite other research teams to reach out in order to establish collaborating projects.
Abstract
HIP 67522 b is a 17 Myr old, close-in (
P
orb
= 6.96 days), Jupiter-sized (
R
= 10
R
⊕
) transiting planet orbiting a Sun-like star in the Sco–Cen OB association. We present our measurement ...of the system’s projected orbital obliquity via two spectroscopic transit observations using the CHIRON spectroscopic facility. We present a global model that accounts for large surface brightness features typical of such young stars during spectroscopic transit observations. With a value of
∣
λ
∣
=
5.8
−
5.7
+
2.8
°
it is unlikely that this well-aligned system is the result of a high-eccentricity-driven migration history. By being the youngest planet with a known obliquity, HIP 67522 b holds a special place in contributing to our understanding of giant planet formation and evolution. Our analysis shows the feasibility of such measurements for young and very active stars.
Abstract
We report the discovery of two transiting brown dwarfs (BDs), TOI-811b and TOI-852b, from NASA’s Transiting Exoplanet Survey Satellite mission. These two transiting BDs have similar masses ...but very different radii and ages. Their host stars have similar masses, effective temperatures, and metallicities. The younger and larger transiting BD is TOI-811b at a mass of
M
b
= 59.9 ± 13.0
M
J
and radius of
R
b
= 1.26 ± 0.06
R
J
, and it orbits its host star in a period of
P
= 25.16551 ± 0.00004 days. We derive the host star’s age of
Myr from an application of gyrochronology. The youth of this system, rather than external heating from its host star, is why this BD’s radius is relatively large. This constraint on the youth of TOI-811b allows us to test substellar mass–radius evolutionary models at young ages where the radius of BDs changes rapidly. TOI-852b has a similar mass at
M
b
= 53.7 ± 1.4
M
J
but is much older (4 or 8 Gyr, based on bimodal isochrone results of the host star) and is also smaller with a radius of
R
b
= 0.83 ± 0.04
R
J
. TOI-852b’s orbital period is
P
= 4.94561 ± 0.00008 days. TOI-852b joins the likes of other old transiting BDs that trace out the oldest substellar mass–radius evolutionary models where contraction of the BD’s radius slows and approaches a constant value. Both host stars have a mass of
M
⋆
= 1.32
M
⊙
± 0.05 and differ in their radii,
T
eff
, and Fe/H, with TOI-811 having
R
⋆
= 1.27 ± 0.09
R
⊙
,
T
eff
= 6107 ± 77 K, and Fe/H = + 0.40 ± 0.09 and TOI-852 having
R
⋆
= 1.71 ± 0.04
R
⊙
,
T
eff
= 5768 ± 84 K, and Fe/H = + 0.33 ± 0.09. We take this opportunity to examine how TOI-811b and TOI-852b serve as test points for young and old substellar isochrones, respectively.
Extensive epidemiological data have demonstrated an exponential rise in the incidence of non-Hodgkin lymphoma (NHL) that is associated with increasing age. The molecular etiology of this remains ...largely unknown, which impacts the effectiveness of treatment for patients. We proposed that age-dependent circulating microRNA (miRNA) signatures in the host influence diffuse large B cell lymphoma (DLBCL) development. Our objective was to examine tumor development in an age-based DLBCL system using an inventive systems biology approach. We harnessed a novel murine model of spontaneous DLBCL initiation (Smurf2-deficient) at two age groups: 3 and 15 months old. All Smurf2-deficient mice develop visible DLBCL tumor starting at 15 months of age. Total miRNA was isolated from serum, bone marrow and spleen and were collected for all age groups for Smurf2-deficient mice and age-matched wild-type C57BL/6 mice. Using systems biology techniques, we identified a list of 10 circulating miRNAs being regulated in both the spleen and bone marrow that were present in DLBCL forming mice starting at 3 months of age that were not present in the control mice. Furthermore, this miRNA signature was found to occur circulating in the blood and it strongly impacted JUN and MYC oncogenic signaling. In addition, quantification of the miRNA signature was performed via Droplet Digital PCR technology. It was discovered that a key miRNA signature circulates throughout a host prior to the formation of a tumor starting at 3 months old, which becomes further modulated by age and yielded calculation of a 'carcinogenic risk score'. This novel age-based circulating miRNA signature may potentially be leveraged as a DLBCL risk profile at a young age to predict future lymphoma development or disease progression as well as for potential innovative miRNA-based targeted therapeutic strategies in lymphoma.
There remains a need to identify new sensitive diagnostic and predictive blood-based platforms in lymphoma. We previously discovered a novel circulating microRNA (miRNA) signature in a ...Smurf2-deficient mouse model that spontaneously develops diffuse large B-cell lymphoma (DLBCL). Herein, we investigated this 10-miRNA signature (miR-15a, let-7c, let-7b, miR-27a, miR-10b, miR-18a, miR-497, miR-130a, miR24, and miR-155) in human lymphoma cell lines, mice engrafted with patient-derived xenografts (PDXs), and DLBCL patient serum samples leveraging systems biology analyses and droplet digital PCR (ddPCR) technology. Overall, 90% of the miRNAs were enriched in PDX DLBCL models and human lymphoma cell lines. Circulating miRNAs from the serum of 86 DLBCL patients were significantly increased compared with healthy controls and had similar patterns to the murine models. Strikingly, miRNAs were identified up to 27-fold higher levels in the serum of PDX-bearing mice and human patients compared with lymphoma cell lysates, suggesting a concentration of these factors over time within sera. Using cut-points from recursive partitioning analysis, we derived a 5-miRNA signature (let-7b, let-7c, miR-18a, miR-24, and miR-15a) with a classification rate of 91% for serum from patients with DLBCL versus normal controls. In addition, higher levels of circulating let-7b miRNA were associated with more advanced stage disease (i.e., III-IV vs. I-II) in DLBCL patients and higher levels of miR-27a and miR-24 were associated with MYC rearrangement. Taken together, circulating multi-miRNAs were readily detectable in pre-clinical cell line and human lymphoma models as well as in DLBCL patients where they appeared to distinguish clinico-pathologic subtypes and disease features.
Potential molecular alterations based on age and sex are not well defined in diffuse large B-cell lymphoma (DLBCL). We examined global transcriptome DLBCL data from The Cancer Genome Atlas (TCGA) via ...a systems biology approach to determine the molecular differences associated with age and sex. Collectively, sex and age revealed striking transcriptional differences with older age associated with decreased metabolism and telomere functions and female sex was associated with decreased interferon signaling, transcription, cell cycle, and PD-1 signaling. We discovered that the key genes for most groups strongly regulated immune function activity. Furthermore, older females were predicted to have less DLBCL progression versus older males and young females. Finally, analyses in systems biology revealed that JUN and CYCS signaling were the most critical factors associated with tumor progression in older and male patients. We identified important molecular perturbations in DLBCL that were strongly associated with age and sex and were predicted to strongly influence tumor progression.
Abstract
Planets around young stars trace the early evolution of planetary systems. We report the discovery and validation of two planetary systems with ages ≲300 Myr from observations by the ...Transiting Exoplanet Survey Satellite (TESS). The
Myr old G star TOI-251 hosts a
mini-Neptune with a
day period. The
Myr old K star TOI-942 hosts a system of inflated Neptune-sized planets, with TOI-942b orbiting in a period of
days with a radius of
and TOI-942c orbiting in a period of
days with a radius of
. Though we cannot place either host star into a known stellar association or cluster, we can estimate their ages via their photometric and spectroscopic properties. Both stars exhibit significant photometric variability due to spot modulation, with measured rotation periods of ∼3.5 days. These stars also exhibit significant chromospheric activity, with age estimates from the chromospheric calcium emission lines and X-ray fluxes matching that estimated from gyrochronology. Both stars also exhibit significant lithium absorption, similar in equivalent width to well-characterized young cluster members. TESS has the potential to deliver a population of young planet-bearing field stars, contributing significantly to tracing the properties of planets as a function of their age.
This paper describes how small permanent magnets embedded in a launch package can be used to locate armature position during launch with greater accuracy than can be achieved by detecting the dipole ...field of the armature itself. Using this technique, we determined armature position in a medium-caliber launcher to within a millimeter of the value measured with photonic Doppler velocimetry, a precise optical technique. This paper describes the technique and some experimental results.
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