1. |
- Anderson, Beverley H., et al.
(författare)
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Mutations in CTC1, encoding conserved telomere maintenance component 1, cause Coats plus
- 2012
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 44:3, s. 338-342
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Tidskriftsartikel (refereegranskat)abstract
- Coats plus is a highly pleiotropic disorder particularly affecting the eye, brain, bone and gastrointestinal tract. Here, we show that Coats plus results from mutations in CTC1, encoding conserved telomere maintenance component 1, a member of the mammalian homolog of the yeast heterotrimeric CST telomeric capping complex. Consistent with the observation of shortened telomeres in an Arabidopsis CTC1 mutant and the phenotypic overlap of Coats plus with the telomeric maintenance disorders comprising dyskeratosis congenita, we observed shortened telomeres in three individuals with Coats plus and an increase in spontaneous gamma H2AX-positive cells in cell lines derived from two affected individuals. CTC1 is also a subunit of the alpha-accessory factor (AAF) complex, stimulating the activity of DNA polymerase-alpha primase, the only enzyme known to initiate DNA replication in eukaryotic cells. Thus, CTC1 may have a function in DNA metabolism that is necessary for but not specific to telomeric integrity.
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2. |
- Tran, Quang H., et al.
(författare)
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TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration
- 2022
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 163:5
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of two transiting planets around the bright (V = 9.9 mag) main-sequence F7 star TOI-1670 by the Transiting Exoplanet Survey Satellite. TOI-1670 b is a sub-Neptune (R-b = 2.06(-0.15)(+0.19) R-circle plus) on a 10.9 day orbit, and TOI-1670 c is a warm Jupiter (R-c= 0.987(-0.025)(+0.025) R-Jup) on a 40.7 day orbit. Using radial velocity observations gathered with the Tull Coude Spectrograph on the Harlan J. Smith telescope and HARPS-N on the Telescopio Nazionale Galileo, we find a planet mass of M-c = 0.63(-0.08)(+0.09) M(Jup )for the outer warm Jupiter, implying a mean density of rho(c) = 0.81(-0.11)(+0.13) g cm(-3). The inner sub-Neptune is undetected in our radial velocity data (M-b < 0.13 M-Jup at the 99% confidence level). Multiplanet systems like TOI-1670 hosting an outer warm Jupiter on a nearly circular orbit (l(e) = 0.09(-0.04)(+0.05)) and one or more inner coplanar planets are more consistent with "gentle" formation mechanisms such as disk migration or in situ formation rather than high-eccentricity migration. Of the 11 known systems with a warm Jupiter and a smaller inner companion, eight (73%) are near a low-order mean-motion resonance, which can be a signature of migration. TOI-1670 joins two other systems (27% of this subsample) with period commensurabilities greater than 3, a common feature of in situ formation or halted inward migration. TOI-1670 and the handful of similar systems support a diversity of formation pathways for warm Jupiters.
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3. |
- Goffo, Elisa, et al.
(författare)
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Company for the Ultra-high Density, Ultra-short Period Sub-Earth GJ 367 b: Discovery of Two Additional Low-mass Planets at 11.5 and 34 Days
- 2023
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Ingår i: Astrophysical Journal Letters. - : Institute of Physics (IOP). - 2041-8213 .- 2041-8205. ; 955:1
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Tidskriftsartikel (refereegranskat)abstract
- GJ 367 is a bright (V ≈ 10.2) M1 V star that has been recently found to host a transiting ultra-short period sub-Earth on a 7.7 hr orbit. With the aim of improving the planetary mass and radius and unveiling the inner architecture of the system, we performed an intensive radial velocity follow-up campaign with the HARPS spectrograph—collecting 371 high-precision measurements over a baseline of nearly 3 yr—and combined our Doppler measurements with new TESS observations from sectors 35 and 36. We found that GJ 367 b has a mass of M b = 0.633 ± 0.050 M ⊕ and a radius of R b = 0.699 ± 0.024 R ⊕, corresponding to precisions of 8% and 3.4%, respectively. This implies a planetary bulk density of ρ b = 10.2 ± 1.3 g cm−3, i.e., 85% higher than Earth’s density. We revealed the presence of two additional non-transiting low-mass companions with orbital periods of ∼11.5 and 34 days and minimum masses of M c sin i c = 4.13 ± 0.36 M ⊕ and M d sin i d = 6.03 ± 0.49 M ⊕, respectively, which lie close to the 3:1 mean motion commensurability. GJ 367 b joins the small class of high-density planets, namely the class of super-Mercuries, being the densest ultra-short period small planet known to date. Thanks to our precise mass and radius estimates, we explored the potential internal composition and structure of GJ 367 b, and found that it is expected to have an iron core with a mass fraction of 0.91 − 0.23 + 0.07 . How this iron core is formed and how such a high density is reached is still not clear, and we discuss the possible pathways of formation of such a small ultra-dense planet.
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4. |
- Knudstrup, Emil, et al.
(författare)
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A puffy polar planet The low density, hot Jupiter TOI-640 b is on a polar orbit
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 671
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Tidskriftsartikel (refereegranskat)abstract
- TOI-640 b is a hot, puffy Jupiter with a mass of 0.57 +/- 0.02 M-J and radius of 1.72 +/- 0.05 R-J, orbiting a slightly evolved F-type star with a separation of 6.33(-0.06)(+0.07) R-star. Through spectroscopic in-transit observations made with the HARPS spectrograph, we measured the Rossiter-McLaughlin effect, analysing both in-transit radial velocities and the distortion of the stellar spectral lines. From these observations, we find the host star to have a projected obliquity of lambda = 184 +/- 3 degrees. From the TESS light curve, we measured the stellar rotation period, allowing us to determine the stellar inclination, i(star) = 23(-2)(+3 degrees), meaning we are viewing the star pole-on. Combining this with the orbital inclination allowed us to calculate the host star obliquity, psi = 104 +/- 2(degrees). TOI-640 b joins a group of planets orbiting over stellar poles within the range 80(degrees)-125 degrees. The origin of this orbital configuration is not well understood.
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5. |
- Carleo, Ilaria, et al.
(författare)
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The Multiplanet System TOI-421*
- 2020
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 160:3
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P-b = 5.19672 +/- 0.00049 days, a mass of M-b = 7.17 +/- 0.66 M-circle plus, and a radius of R-b = R-circle plus, whereas the outer warm Neptune, TOI-421 c, has a period of P-c = 16.06819 +/- 0.00035 days, a mass of M-c = 16.42(-1.04)(+1.06)M(circle plus), a radius of R-c = 5.09(-0.15)(+0.16)R(circle plus), and a density of rho(c) = 0.685(-0.072)(+0.080) cm(-3). With its characteristics, the outer planet (rho(c) = 0.685(-0.0072)(+0.080) cm(-3)) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly alpha transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.
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6. |
- Diaz, Matias R., et al.
(författare)
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TOI-132 b: A short-period planet in the Neptune desert transiting a V=11.3 G-type star
- 2020
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 493:1, s. 973-985
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Tidskriftsartikel (refereegranskat)abstract
- The Neptune desert is a feature seen in the radius-period plane, whereby a notable dearth of short period, Neptune-like planets is found. Here, we report the Transiting Exoplanet Survey Satellite (TESS) discovery of a new short-period planet in the Neptune desert, orbiting the G-type dwarf TYC 8003-1117-1 (TOI-132). TESS photometry shows transit-like dips at the level of similar to 1400 ppm occurring every similar to 2.11 d. High-precision radial velocity follow-up with High Accuracy Radial Velocity Planet Searcher confirmed the planetary nature of the transit signal and provided a semi-amplitude radial velocity variation of 11.38(-0.85)(+0.84) m s(-1), which, when combined with the stellar mass of 0.97 +/- 0.06 M-circle dot, provides a planetary mass of 22.40(-1.92)(+1.90) M-circle plus. Modelling the TESS light curve returns a planet radius of 3.42(-0.14)(+0.13) R-circle plus , and therefore the planet bulk density is found to be 3.08(-0.46)(+0.44) g cm(-3). Planet structure models suggest that the bulk of the planet mass is in the form of a rocky core, with an atmospheric mass fraction of 4.3(-2.3)(+1.2) percent. TOI-132 b is a TESS Level 1 Science Requirement candidate, and therefore priority follow-up will allow the search for additional planets in the system, whilst helping to constrain low-mass planet formation and evolution models, particularly valuable for better understanding of the Neptune desert.
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7. |
- Hirano, Teruyuki, et al.
(författare)
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Exoplanets around Low-mass Stars Unveiled by K2
- 2018
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 155:3, s. 127-
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Tidskriftsartikel (refereegranskat)abstract
- We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5–10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96 to 33 days. For one of the planets (K2-151b), we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius R p on stellar insolation and metallicity [Fe/H]. We confirm that for periods P ≲ 2 days, planets with a radius Rp≳ 2 R⊕ are less common than planets with a radius between 1–2 R⊕. We also see a hint of the “radius valley” between 1.5 and 2 R⊕, which has been seen for close-in planets around FGK stars. These features in the radius/period distribution could be attributed to photoevaporation of planetary envelopes by high-energy photons from the host star, as they have for FGK stars. For the M dwarfs, though, the features are not as well defined, and we cannot rule out other explanations such as atmospheric loss from internal planetary heat sources or truncation of the protoplanetary disk. There also appears to be a relation between planet size and metallicity: the few planets larger than about 3 R⊕ are found around the most metal-rich M dwarfs.
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8. |
- Kabath, Petr, et al.
(författare)
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TOI-2046b, TOI-1181b, and TOI-1516b, three new hot Jupiters from TESS: planets orbiting a young star, a subgiant, and a normal star
- 2022
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 513:4, s. 5955-5972
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Tidskriftsartikel (refereegranskat)abstract
- We present the confirmation and characterization of three hot Jupiters, TOI-118 lb, TOI-1516b, and TOI-2046b, discovered by the "NESS space mission. The reported hot Jupiters have orbital periods between 1.4 and 2.05 d. The masses of the three planets are 1.18 +/- 0.14 Mj, 3.16 +/- 0.12 Mj, and 2.30 +/- 0.28 Mj, for TOI-1181b, TOI-1516b, and TOI-2046b, respectively. The stellar host of TOI-1181b is a F9IV star, whereas TOI-1516b and TOI-2046b orbit F main sequence host stars. The ages of the first two systems are in the range of 2-5 Gyrs. However, TOI-2046 is among the few youngest known planetary systems hosting a hot Jupiter, with an age estimate of 100-400 Myrs. The main instruments used for the radial velocity follow-up of these three planets are located at OndIejov, Tautenburg, and McDonald Observatory, and all three are mounted on 2-3 m aperture telescopes, demonstrating that mid-aperture telescope networks can play a substantial role in the follow-up of gas giants discovered by TESS and in the future by PLATO.
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9. |
- Lam, Kristine W. F., et al.
(författare)
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It Takes Two Planets in Resonance to Tango around K2-146
- 2020
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Ingår i: Astronomical Journal. - : American Astronomical Society. - 1538-3881 .- 0004-6256. ; 159:3
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Tidskriftsartikel (refereegranskat)abstract
- K2-146 is a cool, 0.358M dwarf that was found to host a mini-Neptune with a 2.67 day period. The planet exhibited strong transit timing variations (TTVs) of greater than 30 minutes, indicative of the presence of an additional object in the system. Here we report the discovery of the previously undetected outer planet in the system, K2-146 c, using additional photometric data. K2-146 c was found to have a grazing transit geometry and a 3.97 day period. The outer planet was only significantly detected in the latter K2 campaigns presumably because of precession of its orbital plane. The TTVs of K2-146 b and c were measured using observations spanning a baseline of almost 1200 days. We found strong anti -correlation in the TTVs, suggesting the two planets are gravitationally interacting. Our TTV and transit model analyses revealed that K2-146 b has a radius of 2.25 0.10 Re and a mass of 5.6 0.7 Me, whereas K2-146 c has a radius of 2.591 Re and a mass of 7.1 0.9 Me. The inner and outer planets likely have moderate eccentricities of e = 0.14 0.07 and 0.16 0.07, respectively. Long-term numerical integrations of the two -planet orbital solution show that it can be dynamically stable for at least 2 Myr. We show that the resonance angles of the planet pair are librating, which may be an indication that K2-146 b and c are in a 3:2 mean motion resonance. The orbital architecture of the system points to a possible convergent migration origin.
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10. |
- Livingston, John H, et al.
(författare)
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Leukoencephalopathy with Calcifications and Cysts : A Purely Neurological Disorder Distinct from Coats Plus
- 2014
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Ingår i: Neuropediatrics. - : Georg Thieme Verlag KG. - 0174-304X .- 1439-1899. ; 45:3, s. 175-182
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Tidskriftsartikel (refereegranskat)abstract
- Objective With the identification of mutations in the conserved telomere maintenance component 1 (CTC1) gene as the cause of Coats plus (CP) disease, it has become evident that leukoencephalopathy with calcifications and cysts (LCC) is a distinct genetic entity. Patients and Methods A total of 15 patients with LCC were identified from our database of patients with intracranial calcification. The clinical and radiological features are described. Results The median age (range) at presentation was 10 months (range, 2 days-54 years). Of the 15 patients, 9 presented with epileptic seizures, 5 with motor abnormalities, and 1 with developmental delay. Motor abnormalities developed in 14 patients and cognitive problems in 13 patients. Dense calcification occurred in the basal ganglia, thalami, dentate nucleus, brain stem, deep gyri, deep white matter, and in a pericystic distribution. Diffuse leukoencephalopathy was present in all patients, and it was usually symmetrical involving periventricular, deep, and sometimes subcortical, regions. Cysts developed in the basal ganglia, thalamus, deep white matter, cerebellum, or brain stem. In unaffected areas, normal myelination was present. No patient demonstrated cerebral atrophy. Conclusion LCC shares the neuroradiological features of CP. However, LCC is a purely neurological disorder distinguished genetically by the absence of mutations in CTC1. The molecular cause(s) of LCC has (have) not yet been determined.
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