scholarly journals Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?

2020 ◽  
Vol 639 ◽  
pp. A132 ◽  
Author(s):  
P. Bluhm ◽  
R. Luque ◽  
N. Espinoza ◽  
E. Pallé ◽  
J. A. Caballero ◽  
...  
Keyword(s):  
Theoretical Models ◽  
Space Mission ◽  
High Resolution Imaging ◽  
M Dwarfs ◽  
Earth Planet ◽  
Exoplanetary Systems ◽  
Interesting Object ◽  
Resolution Imaging ◽  
Rocky Planets ◽  
M Dwarf

We report the confirmation of a transiting planet around the bright weakly active M0.5 V star TOI-1235 (TYC 4384–1735–1, V ≈ 11.5 mag), whose transit signal was detected in the photometric time series of sectors 14, 20, and 21 of the TESS space mission. We confirm the planetary nature of the transit signal, which has a period of 3.44 d, by using precise RV measurements with the CARMENES, HARPS-N, and iSHELL spectrographs, supplemented by high-resolution imaging and ground-based photometry. A comparison of the properties derived for TOI-1235 b with theoretical models reveals that the planet has a rocky composition, with a bulk density slightly higher than that of Earth. In particular, we measure a mass of Mp = 5.9 ± 0.6 M⊕ and a radius of Rp = 1.69 ± 0.08 R⊕, which together result in a density of ρp = 6.7− 1.1+ 1.3 g cm−3. When compared with other well-characterized exoplanetary systems, the particular combination of planetary radius and mass places our discovery in the radius gap, which is a transition region between rocky planets and planets with significant atmospheric envelopes. A few examples of planets occupying the radius gap are known to date. While the exact location of the radius gap for M dwarfs is still a matter of debate, our results constrain it to be located at around 1.7 R⊕ or larger at the insolation levels received by TOI-1235 b (~60 S⊕). This makes it an extremely interesting object for further studies of planet formation and atmospheric evolution.

scholarly journals The CARMENES search for exoplanets around M dwarfs

2018 ◽  
Vol 609 ◽  
pp. A117 ◽  
Author(s):  
T. Trifonov ◽  
M. Kürster ◽  
M. Zechmeister ◽  
L. Tal-Or ◽  
J. A. Caballero ◽  
...  
Keyword(s):  
M Dwarfs ◽  
Earth Planet ◽  
Low Mass Stars ◽  
Dwarf Stars ◽  
Orbital Parameters ◽  
Short Period ◽  
Show Evidence ◽  
Bona Fide ◽  
M Dwarf Stars ◽  
Rocky Planets

Context. The main goal of the CARMENES survey is to find Earth-mass planets around nearby M-dwarf stars. Seven M dwarfs included in the CARMENES sample had been observed before with HIRES and HARPS and either were reported to have one short period planetary companion (GJ 15 A, GJ 176, GJ 436, GJ 536 and GJ 1148) or are multiple planetary systems (GJ 581 and GJ 876). Aims. We aim to report new precise optical radial velocity measurements for these planet hosts and test the overall capabilities of CARMENES. Methods. We combined our CARMENES precise Doppler measurements with those available from HIRES and HARPS and derived new orbital parameters for the systems. Bona-fide single planet systems were fitted with a Keplerian model. The multiple planet systems were analyzed using a self-consistent dynamical model and their best fit orbits were tested for long-term stability. Results. We confirm or provide supportive arguments for planets around all the investigated stars except for GJ 15 A, for which we find that the post-discovery HIRES data and our CARMENES data do not show a signal at 11.4 days. Although we cannot confirm the super-Earth planet GJ 15 Ab, we show evidence for a possible long-period (Pc = 7030-630+970 d) Saturn-mass (mcsini = 51.8-5.8+5.5M⊕) planet around GJ 15 A. In addition, based on our CARMENES and HIRES data we discover a second planet around GJ 1148, for which we estimate a period Pc = 532.6-2.5+4.1 days, eccentricity ec = 0.342-0.062+0.050 and minimum mass mcsini = 68.1-2.2+4.9M⊕. Conclusions. The CARMENES optical radial velocities have similar precision and overall scatter when compared to the Doppler measurements conducted with HARPS and HIRES. We conclude that CARMENES is an instrument that is up to the challenge of discovering rocky planets around low-mass stars.

scholarly journals Super-Earths, M Dwarfs, and Photosynthetic Organisms: Habitability in the Lab

Life ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 10
Author(s):  
Riccardo Claudi ◽  
Eleonora Alei ◽  
Mariano Battistuzzi ◽  
Lorenzo Cocola ◽  
Marco Sergio Erculiani ◽  
...  
Keyword(s):  
Light Condition ◽  
Oxygenic Photosynthesis ◽  
Space Telescopes ◽  
M Dwarfs ◽  
Orbital Periods ◽  
Light Components ◽  
Photosynthetic Performances ◽  
Rocky Planets ◽  
M Dwarf

In a few years, space telescopes will investigate our Galaxy to detect evidence of life, mainly by observing rocky planets. In the last decade, the observation of exoplanet atmospheres and the theoretical works on biosignature gasses have experienced a considerable acceleration. The most attractive feature of the realm of exoplanets is that 40% of M dwarfs host super-Earths with a minimum mass between 1 and 30 Earth masses, orbital periods shorter than 50 days, and radii between those of the Earth and Neptune (1–3.8 R⊕). Moreover, the recent finding of cyanobacteria able to use far-red (FR) light for oxygenic photosynthesis due to the synthesis of chlorophylls d and f, extending in vivo light absorption up to 750 nm, suggests the possibility of exotic photosynthesis in planets around M dwarfs. Using innovative laboratory instrumentation, we exposed different cyanobacteria to an M dwarf star simulated irradiation, comparing their responses to those under solar and FR simulated lights. As expected, in FR light, only the cyanobacteria able to synthesize chlorophyll d and f could grow. Surprisingly, all strains, both able or unable to use FR light, grew and photosynthesized under the M dwarf generated spectrum in a similar way to the solar light and much more efficiently than under the FR one. Our findings highlight the importance of simulating both the visible and FR light components of an M dwarf spectrum to correctly evaluate the photosynthetic performances of oxygenic organisms exposed under such an exotic light condition.

Optical design of a high-resolution imaging channel for the Bepi Colombo space mission

2005 ◽  
Author(s):  
G. Marra ◽  
L. Colangeli ◽  
E. Mazzotta Epifani ◽  
P. Palumbo ◽  
E. Flamini ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical Design ◽  
Space Mission ◽  
High Resolution Imaging ◽  
Resolution Imaging

scholarly journals A hot terrestrial planet orbiting the bright M dwarf L 168-9 unveiled by TESS

2020 ◽  
Vol 636 ◽  
pp. A58 ◽  
Author(s):  
N. Astudillo-Defru ◽  
R. Cloutier ◽  
S. X. Wang ◽  
J. Teske ◽  
R. Brahm ◽  
...  
Keyword(s):  
High Resolution ◽  
Mass Measurement ◽  
Terrestrial Planet ◽  
High Resolution Imaging ◽  
Orbital Eccentricity ◽  
Scientific Objective ◽  
The Earth ◽  
Resolution Imaging ◽  
The Masses ◽  
M Dwarf

We report the detection of a transiting super-Earth-sized planet (R = 1.39 ± 0.09 R⊕) in a 1.4-day orbit around L 168-9 (TOI-134), a bright M1V dwarf (V = 11, K = 7.1) located at 25.15 ± 0.02 pc. The host star was observed in the first sector of the Transiting Exoplanet Survey Satellite (TESS) mission. For confirmation and planet mass measurement purposes, this was followed up with ground-based photometry, seeing-limited and high-resolution imaging, and precise radial velocity (PRV) observations using the HARPS and Magellan/PFS spectrographs. By combining the TESS data and PRV observations, we find the mass of L 168-9 b to be 4.60 ± 0.56 M⊕ and thus the bulk density to be 1.74−0.33+0.44 times higher than that of the Earth. The orbital eccentricity is smaller than 0.21 (95% confidence). This planet is a level one candidate for the TESS mission’s scientific objective of measuring the masses of 50 small planets, and it is one of the most observationally accessible terrestrial planets for future atmospheric characterization.

scholarly journals Magnetic fields of M dwarfs

2020 ◽  
Vol 29 (1) ◽  
Author(s):  
Oleg Kochukhov
Keyword(s):  
Magnetic Fields ◽  
Zeeman Effect ◽  
Mean Field ◽  
Field Measurements ◽  
Theoretical Models ◽  
Planetary Science ◽  
M Dwarfs ◽  
Stellar Magnetospheres ◽  
M Dwarf Stars ◽  
M Dwarf

AbstractMagnetic fields play a fundamental role for interior and atmospheric properties of M dwarfs and greatly influence terrestrial planets orbiting in the habitable zones of these low-mass stars. Determination of the strength and topology of magnetic fields, both on stellar surfaces and throughout the extended stellar magnetospheres, is a key ingredient for advancing stellar and planetary science. Here, modern methods of magnetic field measurements applied to M-dwarf stars are reviewed, with an emphasis on direct diagnostics based on interpretation of the Zeeman effect signatures in high-resolution intensity and polarisation spectra. Results of the mean field strength measurements derived from Zeeman broadening analyses as well as information on the global magnetic geometries inferred by applying tomographic mapping methods to spectropolarimetric observations are summarised and critically evaluated. The emerging understanding of the complex, multi-scale nature of M-dwarf magnetic fields is discussed in the context of theoretical models of hydromagnetic dynamos and stellar interior structure altered by magnetic fields.

Detailed Analysis of the HIRISE FPA

2013 ◽  
Vol 552 ◽  
pp. 64-68 ◽  
Author(s):  
Yan Chun Li ◽  
Ji Hong Dong ◽  
Wei Li ◽  
Quan Feng Guo ◽  
Ke Jun Wang ◽  
...  
Keyword(s):  
High Resolution ◽  
Material Selection ◽  
Design Method ◽  
Thermal Control ◽  
Space Mission ◽  
Control Measures ◽  
High Resolution Imaging ◽  
Imaging Science ◽  
Resolution Imaging ◽  
High Degree

The U.S.A has launched the Mars Orbiter. It brought a high resolution imaging science equipment, and that is the High Resolution Imaging Science Experiment camera(HIRISE). HIRISE is 0.5 m reflecting telescope, which is the highest one ever carried on a deep space mission, and it has a resolution of 1 microradian (μrad), or 0.3 m from an altitude of 300 km. HIRISE can investigate deposits and landforms resulting from geologic and climatic processes and assist in the evaluation of candidate. As a high degree of lightweight ultra-high resolution camera, the design of its FPA is unparalleled .Therefore we should study and learn it carefully. In this article, first of all we discuss and analyze the characters of the HIRISE FPA in terms of the structural layout, material selection, splicing of the CCD, the CCD package, electronics, processing and transmission, and thermal control measures implementation. Next we put forward the design method of highly lightweight space optical remote sensor FPA combined with the characters of the HIRISE FPA, which can provide a reference to the design of the FPA for some space remote sensings.

Alternative approaches to ultra-high resolution imaging

1991 ◽  
Vol 49 ◽  
pp. 650-651
Author(s):  
J.M. Cowley
Keyword(s):  
High Resolution ◽  
High Voltage ◽  
High Resolution Electron Microscopy ◽  
Crystal Defects ◽  
High Resolution Imaging ◽  
General Applicability ◽  
Resolution Electron ◽  
Radiation Resistant ◽  
Resolution Imaging ◽  
Alternative Approaches

By extrapolation of past experience, it would seem that the future of ultra-high resolution electron microscopy rests with the advances of electron optical engineering that are improving the instrumental stability of high voltage microscopes to achieve the theoretical resolutions of 1Å or better at 1MeV or higher energies. While these high voltage instruments will undoubtedly produce valuable results on chosen specimens, their general applicability has been questioned on the basis of the excessive radiation damage effects which may significantly modify the detailed structures of crystal defects within even the most radiation resistant materials in a period of a few seconds. Other considerations such as those of cost and convenience of use add to the inducement to consider seriously the possibilities for alternative approaches to the achievement of comparable resolutions.

4-dimensional, high-resolution imaging of living cells

1992 ◽  
Vol 50 (1) ◽  
pp. 416-417
Author(s):  
Shinya Inoué
Keyword(s):  
Light Microscope ◽  
Living Cells ◽  
Live Cells ◽  
Video Tape ◽  
Active Living ◽  
High Resolution Imaging ◽  
3 Dimensional ◽  
Dynamic Architecture ◽  
Resolution Imaging ◽  
Disk Memory

This paper reports progress of our effort to rapidly capture, and display in time-lapsed mode, the 3-dimensional dynamic architecture of active living cells and developing embryos at the highest resolution of the light microscope. Our approach entails: (A) real-time video tape recording of through-focal, ultrathin optical sections of live cells at the highest resolution of the light microscope; (B) repeat of A at time-lapsed intervals; (C) once each time-lapsed interval, an image at home focus is recorded onto Optical Disk Memory Recorder (OMDR); (D) periods of interest are selected using the OMDR and video tape records; (E) selected stacks of optical sections are converted into plane projections representing different view angles (±4 degrees for stereo view, additional angles when revolving stereos are desired); (F) analysis using A - D.

Performance and applications of a field-emission gun TEM/STEM

1992 ◽  
Vol 50 (2) ◽  
pp. 942-943
Author(s):  
Judith M. Brock ◽  
Max T. Otten ◽  
Marc. J.C. de Jong
Keyword(s):  
Field Emission ◽  
High Resolution Imaging ◽  
High Quality ◽  
Small Energy ◽  
High Brightness ◽  
Small Probe ◽  
Resolution Imaging ◽  
Convergent Beam ◽  
Beam Patterns ◽  
Beam Diffraction

A Field Emission Gun (FEG) on a TEM/STEM instrument provides a major improvement in performance relative to one equipped with a LaB6 emitter. The improvement is particularly notable for small-probe techniques: EDX and EELS microanalysis, convergent beam diffraction and scanning. The high brightness of the FEG (108 to 109 A/cm2srad), compared with that of LaB6 (∼106), makes it possible to achieve high probe currents (∼1 nA) in probes of about 1 nm, whilst the currents for similar probes with LaB6 are about 100 to 500x lower. Accordingly the small, high-intensity FEG probes make it possible, e.g., to analyse precipitates and monolayer amounts of segregation on grain boundaries in metals or ceramics (Fig. 1); obtain high-quality convergent beam patterns from heavily dislocated materials; reliably detect 1 nm immuno-gold labels in biological specimens; and perform EDX mapping at nm-scale resolution even in difficult specimens like biological tissue.The high brightness and small energy spread of the FEG also bring an advantage in high-resolution imaging by significantly improving both spatial and temporal coherence.

Principle and practice of high-resolution imaging with a field-emission TEM

1992 ◽  
Vol 50 (1) ◽  
pp. 138-139
Author(s):  
Max T. Otten ◽  
Wim M.J. Coene
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Incidence Angle ◽  
Temporal Coherence ◽  
Energy Spread ◽  
High Resolution Imaging ◽  
Major Improvement ◽  
High Resolution Images ◽  
Resolution Imaging

High-resolution imaging with a LaB6 instrument is limited by the spatial and temporal coherence, with little contrast remaining beyond the point resolution. A Field Emission Gun (FEG) reduces the incidence angle by a factor 5 to 10 and the energy spread by 2 to 3. Since the incidence angle is the dominant limitation for LaB6 the FEG provides a major improvement in contrast transfer, reducing the information limit to roughly one half of the point resolution. The strong improvement, predicted from high-resolution theory, can be seen readily in diffractograms (Fig. 1) and high-resolution images (Fig. 2). Even if the information in the image is limited deliberately to the point resolution by using an objective aperture, the improved contrast transfer close to the point resolution (Fig. 1) is already worthwhile.

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