331 research outputs found
Mariner 6 and 7 ultraviolet spectrometer experiment - Upper atmosphere data
Ultraviolet emissum spectrum of Mars upper atmosphere from Mariner 6 and 7 spaceprobe
Far-ultraviolet Spectroscopy of Venus and Mars at 4 A Resolution with the Hopkins Ultraviolet Telescope on Astro-2
Far-ultraviolet spectra of Venus and Mars in the range 820-1840 A at 4 A
resolution were obtained on 13 and 12 March 1995, respectively, by the Hopkins
Ultraviolet Telescope (HUT), which was part of the Astro-2 observatory on the
Space Shuttle Endeavour. Longward of 1250 A, the spectra of both planets are
dominated by emission of the CO Fourth Positive band system and strong OI and
CI multiplets. In addition, CO Hopfield-Birge bands, B - X (0,0) at 1151 A and
C - X (0,0) at 1088 A, are detected for the first time, and there is a weak
indication of the E - X (0,0) band at 1076 A in the spectrum of Venus. The B -
X band is blended with emission from OI 1152. Modeling the relative intensities
of these bands suggests that resonance fluorescence of CO is the dominant
source of the emission, as it is for the Fourth Positive system. Shortward of
Lyman-alpha, other emission features detected include OII 834, OI lambda 989,
HI Lyman-beta, and NI 1134 and 1200. For Venus, the derived disk brightnesses
of the OI, OII, and HI features are about one-half of those reported by Hord et
al. (1991) from Galileo EUV measurements made in February 1990. This result is
consistent with the expected variation from solar maximum to solar minimum. The
ArI 1048, 1066 doublet is detected only in the spectrum of Mars and the derived
mixing ratio of Ar is of the order of 2%, consistent with previous
determinations.Comment: 8 pages, 5 figures, accepted for publication in ApJ, July 20, 200
FarâUV emissions from the SL9 impacts with Jupiter
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95348/1/grl8617.pd
The First Habitable-Zone Earth-Sized Planet From TESS. I. Validation Of The TOI-700 System
We present the discovery and validation of a three-planet system orbiting the nearby (31.1 pc) M2 dwarf star TOI-700 (TIC 150428135). TOI-700 lies in the TESS continuous viewing zone in the Southern Ecliptic Hemisphere; observations spanning 11 sectors reveal three planets with radii ranging from 1 Râ to 2.6 Râ and orbital periods ranging from 9.98 to 37.43 days. Ground-based follow-up combined with diagnostic vetting and validation tests enables us to rule out common astrophysical false-positive scenarios and validate the system of planets. The outermost planet, TOI-700 d, has a radius of 1.19 ± 0.11 Râ and resides within a conservative estimate of the host star\u27s habitable zone, where it receives a flux from its star that is approximately 86% of Earth\u27s insolation. In contrast to some other low-mass stars that host Earth-sized planets in their habitable zones, TOI-700 exhibits low levels of stellar activity, presenting a valuable opportunity to study potentially rocky planets over a wide range of conditions affecting atmospheric escape. While atmospheric characterization of TOI-700 d with the James Webb Space Telescope (JWST) will be challenging, the larger sub-Neptune, TOI-700 c (R = 2.63 Râ), will be an excellent target for JWST and future space-based observatories. TESS is scheduled to once again observe the Southern Hemisphere, and it will monitor TOI-700 for an additional 11 sectors in its extended mission. These observations should allow further constraints on the known planet parameters and searches for additional planets and transit timing variations in the system
Bioavailability of Orally Administered rhGM-CSF: A Single-Dose, Randomized, Open-Label, Two-Period Crossover Trial
BACKGROUND: Recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) is usually administered by injection, and its oral administration in a clinical setting has been not yet reported. Here we demonstrate the bioavailability of orally administered rhGM-CSF in healthy volunteers. The rhGM-CSF was expressed in Bombyx mori expression system (BmrhGM-CSF). METHODS AND FINDINGS: Using a single-dose, randomized, open-label, two-period crossover clinical trial design, 19 healthy volunteers were orally administered with BmrhGM-CSF (8 microg/kg) and subcutaneously injected with rhGM-CSF (3.75 microg/kg) respectively. Serum samples were drawn at 0.0h, 0.5h ,0.75h,1.0h,1.5h,2.0h ,3.0h,4.0h,5.0h,6.0h,8.0h,10.0h and 12.0h after administrations. The hGM-CSF serum concentrations were determined by ELISA. The AUC was calculated using the trapezoid method. The relative bioavailability of BmrhGM-CSF was determined according to the AUC ratio of both orally administered and subcutaneously injected rhGM-CSF. Three volunteers were randomly selected from 15 orally administrated subjects with ELISA detectable values. Their serum samples at the 0.0h, 1.0h, 2.0h, 3.0h and 4.0h after the administrations were analyzed by Q-Trap MS/MS TOF. The different peaks were revealed by the spectrogram profile comparison of the 1.0h, 2.0h, 3.0h and 4.0h samples with that of the 0.0h sample, and further analyzed using both Enhanced Product Ion (EPI) scanning and Peptide Mass Fingerprinting Analysis. The rhGM-CSF was detected in the serum samples from 15 of 19 volunteers administrated with BmrhGM-CSF. Its bioavailability was observed at an average of 1.0%, with the highest of 3.1%. The rhGM-CSF peptide sequences in the serum samples were detected by MS analysis, and their sizes ranging from 2,039 to 7,336 Da. CONCLUSIONS: The results demonstrated that the oral administered BmrhGM-CSF was absorbed into the blood. This study provides an approach for an oral administration of rhGM-CSF protein in clinical settings. TRIAL REGISTRATION: www.chictr.orgChiCTR-TRC-00000107
TESS discovery of a super-Earth and two sub-Neptunes orbiting the bright, nearby, Sun-like star HD 22946
We report the Transiting Exoplanet Survey Satellite (TESS) discovery of a
three-planet system around the bright Sun-like star HD~22946(V=8.3 mag),also
known as TIC~100990000, located 63 parsecs away.The system was observed by TESS
in Sectors 3, 4, 30 and 31 and two planet candidates, labelled TESS Objects of
Interest (TOIs) 411.01 (planet ) and 411.02 (planet ), were identified on
orbits of 9.57 and 4.04 days, respectively. In this work, we validate the two
planets and recover an additional single transit-like signal in the light
curve, which suggests the presence of a third transiting planet with a longer
period of about 46 days.We assess the veracity of the TESS transit signals and
use follow-up imaging and time series photometry to rule out false positive
scenarios, including unresolved binary systems, nearby eclipsing binaries or
background/foreground stars contaminating the light curves. Parallax
measurements from Gaia EDR3, together with broad-band photometry and
spectroscopic follow-up by TFOP allowed us to constrain the stellar parameters
of TOI-411, including its radius of. Adopting this value,
we determined the radii for the three exoplanet candidates and found that
planet is a super-Earth, with a radius of , while
planet and are sub-Neptunian planets, with radii
of and respectively. By using
dynamical simulations, we assessed the stability of the system and evaluated
the possibility of the presence of other undetected, non-transiting planets by
investigating its dynamical packing. We find that the system is dynamically
stable and potentially unpacked, with enough space to host at least one more
planet between and .(Abridged)Comment: 21 pages, 12 figures. Accepted for publication on A&
The LHS 1678 system : two earth-sized transiting planets and an astrometric companion orbiting an M dwarf near the convective boundary at 20 pc
Funding: The MEarth Team gratefully acknowledges funding from the David and Lucile Packard Fellowship for Science and Engineering (awarded to D.C.). This material is based upon work supported by the National Science Foundation under grants AST-0807690, AST-1109468, AST-1004488 (Alan T. Waterman Award), and AST-1616624, and upon work supported by the National Aeronautics and Space Administration under Grant No. 80NSSC18K0476 issued through the XRP Program. This work is made possible by a grant from the John Templeton Foundation. N. A.-D. acknowledges the support of FONDECYT project 3180063. TD acknowledges support from MITâs Kavli Institute as a Kavli postdoctoral fellow. KH acknowledges support from STFC grant ST/R000824/1. E.A.G. thanks the LSSTC Data Science Fellowship Program, which is funded by LSSTC, NSF Cybertraining Grant #1829740, the Brinson Foundation, and the Moore Foundation; The material is based upon work supported by NASA under award number 80GSFC21M0002. This work was supported by the lead authorâs appointment to the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Universities Space Research Association under contract with NASAWe present the Transiting Exoplanet Survey Satellite (TESS) discovery of the LHS 1678 (TOI-696) exoplanet system, comprised of two approximately Earth-sized transiting planets and a likely astrometric brown dwarf orbiting a bright (VJ = 12.5, Ks = 8.3) M2 dwarf at 19.9 pc. The two TESS-detected planets are of radius 0.70 ± 0.04 Râ and 0.98 ± 0.06 Râ in 0.86 day and 3.69 day orbits, respectively. Both planets are validated and characterized via ground-based follow-up observations. High Accuracy Radial Velocity Planet Searcher RV monitoring yields 97.7 percentile mass upper limits of 0.35 Mâ and 1.4 Mâ for planets b and c, respectively. The astrometric companion detected by the Cerro Tololo Inter-American Observatory/Small and Moderate Aperture Telescope System 0.9 m has an orbital period on the order of decades and is undetected by other means. Additional ground-based observations constrain the companion to being a high-mass brown dwarf or smaller. Each planet is of unique interest; the inner planet has an ultra-short period, and the outer planet is in the Venus zone. Both are promising targets for atmospheric characterization with the James Webb Space Telescope and mass measurements via extreme-precision radial velocity. A third planet candidate of radius 0.9 ± 0.1 Râ in a 4.97 day orbit is also identified in multicycle TESS data for validation in future work. The host star is associated with an observed gap in the lower main sequence of the HertzsprungâRussell diagram. This gap is tied to the transition from partially to fully convective interiors in M dwarfs, and the effect of the associated stellar astrophysics on exoplanet evolution is currently unknown. The culmination of these system properties makes LHS 1678 a unique, compelling playground for comparative exoplanet science and understanding the formation and evolution of small, short-period exoplanets orbiting low-mass stars.Publisher PDFPeer reviewe
Two Warm Super-Earths Transiting the Nearby M Dwarf TOI-2095
We report the detection and validation of two planets orbiting TOI-2095 (TIC
235678745). The host star is a 3700K M1V dwarf with a high proper motion. The
star lies at a distance of 42 pc in a sparsely populated portion of the sky and
is bright in the infrared (K=9). With data from 24 Sectors of observation
during TESS's Cycles 2 and 4, TOI-2095 exhibits two sets of transits associated
with super-Earth-sized planets. The planets have orbital periods of 17.7 days
and 28.2 days and radii of 1.30 and 1.39 Earth radii, respectively. Archival
data, preliminary follow-up observations, and vetting analyses support the
planetary interpretation of the detected transit signals. The pair of planets
have estimated equilibrium temperatures of approximately 400 K, with stellar
insolations of 3.23 and 1.73 times that of Earth, placing them in the Venus
zone. The planets also lie in a radius regime signaling the transition between
rock-dominated and volatile-rich compositions. They are thus prime targets for
follow-up mass measurements to better understand the properties of warm,
transition radius planets. The relatively long orbital periods of these two
planets provide crucial data that can help shed light on the processes that
shape the composition of small planets orbiting M dwarfs.Comment: Submitted to AAS Journal
- âŠ