scholarly journals Survey of planetesimal belts with ALMA: gas detected around the Sun-like star HD 129590

2020 ◽  
Vol 497 (3) ◽  
pp. 2811-2830 ◽  
Author(s):  
Quentin Kral ◽  
Luca Matrà ◽  
Grant M Kennedy ◽  
Sebastian Marino ◽  
Mark C Wyatt
Keyword(s):  
Solar System ◽  
Main Sequence ◽  
Signal To Noise Ratio ◽  
Gas Detection ◽  
Continuum Emission ◽  
Geometrical Properties ◽  
Upper Limits ◽  
Co Detection ◽  
Outgassing Rate ◽  
First Time

ABSTRACT Gas detection around main-sequence stars is becoming more common with around 20 systems showing the presence of CO. However, more detections are needed, especially around later spectral type stars to better understand the origin of this gas and refine our models. To do so, we carried out a survey of 10 stars with predicted high likelihoods of secondary CO detection using ALMA in band 6. We looked for continuum emission of mm-dust as well as gas emission (CO and CN transitions). The continuum emission was detected in 9/10 systems for which we derived the discs’ dust masses and geometrical properties, providing the first mm-wave detection of the disc around HD 106906, the first mm-wave radius for HD 114082, 117214, HD 15745, HD 191089, and the first radius at all for HD 121191. A crucial finding of our paper is that we detect CO for the first time around the young 10–16 Myr old G1V star HD 129590, similar to our early Sun. The gas seems colocated with its planetesimal belt and its total mass is likely in the range of (2–10) × 10−5 M⊕. This first gas detection around a G-type main-sequence star raises questions as to whether gas may have been released in the Solar system as well in its youth, which could potentially have affected planet formation. We also detected CO gas around HD 121191 at a higher signal-to-noise ratio than previously and find that the CO lies much closer-in than the planetesimals in the system, which could be evidence for the previously suspected CO viscous spreading owing to shielding preventing its photodissociation. Finally, we make estimates for the CO content in planetesimals and the HCN/CO outgassing rate (from CN upper limits), which we find are below the level seen in Solar system comets in some systems.

scholarly journals Detection of polarized continuum emission of the Dusty S-cluster Object (DSO/G2)

2016 ◽  
Vol 11 (S322) ◽  
pp. 233-234
Author(s):  
B. Shahzamanian ◽  
M. Zajaček ◽  
M. Valencia-S. ◽  
F. Peissker ◽  
A. Eckart ◽  
...  
Keyword(s):  
Near Infrared ◽  
Galactic Center ◽  
Continuum Emission ◽  
Polarization Angle ◽  
Imaging Data ◽  
Intrinsic Geometry ◽  
Infrared Excess ◽  
Geometrical Properties ◽  
Sgr A ◽  
First Time

AbstractA peculiar source in the Galactic center known as the Dusty S-cluster Object (DSO/G2) moves on a highly eccentric orbit around the supermassive black hole with the pericenter passage in the spring of 2014. Its nature has been uncertain mainly because of the lack of any information about its intrinsic geometry. For the first time, we use near-infrared polarimetric imaging data to obtain constraints about the geometrical properties of the DSO. We find out that DSO is an intrinsically polarized source, based on the significance analysis of polarization parameters, with the degree of the polarization of ~30% and an alternating polarization angle as it approaches the position of Sgr A*. Since the DSO exhibits a near-infrared excess of Ks-L′ > 3 and remains rather compact in emission-line maps, its main characteristics may be explained with the model of a pre-main-sequence star embedded in a non-spherical dusty envelope.

scholarly journals Upper limits on protolunar disc masses using ALMA observations of directly imaged exoplanets

2019 ◽  
Vol 488 (1) ◽  
pp. 1005-1011 ◽  
Author(s):  
Sebastián Pérez ◽  
Sebastián Marino ◽  
Simon Casassus ◽  
Clément Baruteau ◽  
Alice Zurlo ◽  
...  
Keyword(s):  
Solar System ◽  
Radiative Transfer ◽  
Time Scales ◽  
Semimajor Axis ◽  
Continuum Emission ◽  
The Sun ◽  
Hydrodynamic Simulations ◽  
Satellite Systems ◽  
Upper Limits ◽  
Compact Case

ABSTRACT The Solar system gas giants are each surrounded by many moons, with at least 50 prograde satellites thought to have formed from circumplanetary material. Just like the Sun is not the only star surrounded by planets, extrasolar gas giants are likely surrounded by satellite systems. Here, we report on Atacama Large Millimeter/Submillimeter Array (ALMA) observations of four <40 Myr old stars with directly imaged companions: PZ Tel, AB Pic, 51 Eri, and κ And. Continuum emission at 1.3 mm is undetected for any of the systems. Since these are directly imaged companions, there is knowledge of their temperatures, masses, and locations. These allow for upper limits on the amount of circumplanetary dust to be derived from detailed radiative transfer models. These protolunar disc models consider two disc sizes: 0.4 and 0.04 times the exoplanet’s Hill radius. The former is representative of hydrodynamic simulations of circumplanetary discs, while the latter a case with significant radial drift of solids. The more compact case is also motivated by the semimajor axis of Callisto, enclosing Jupiter’s Galilean satellites. All upper limits fall below the expected amount of dust required to explain regular satellite systems (∼10−4 times the mass of their central planet). Upper limits are compared with viscous evolution and debris disc models. Our analysis suggests that the non-detections can be interpreted as evidence of dust growth beyond metre sizes to form moonetesimals in time-scales ≲10 Myr. This sample increases by 50 per cent the number of ALMA non-detections of young companions available in the literature.

New upper limits of a braneworld model with recent Solar System tests

2016 ◽  
Vol 31 (05) ◽  
pp. 1650021 ◽  
Author(s):  
Xue-Mei Deng ◽  
Yi Xie
Keyword(s):  
Time Delay ◽  
Solar System ◽  
Upper Bounds ◽  
Physical Experiments ◽  
Dimensional Spacetime ◽  
Upper Limits ◽  
Perihelion Shift ◽  
Braneworld Model ◽  
Charge Parameter ◽  
First Time

As an extension of previous works on classical tests of a braneworld model which is called as the Dadhich, Maartens, Papadopoulos and Rezania (DMPR) solution, and as an attempt to find more stringent constraints on this model, we investigate its effects on physical experiments and astronomical observations conducted in the Solar System by modeling new observable effects and adopting new datasets. First, we investigate gravitational time delay at inferior conjunction (IC) caused by the braneworld model, which was not considered in previous works, because these measurements are not affected by the solar corona noise. Second, the Cassini superior conjunction (SC) experiment is, for the first time, used to test the DMPR model. Third, compared to previous works, we refine the model, which confronts the perihelion shift induced by the braneworld model with modern Solar System ephemerides INPOP10a (IMCCE, France) and EPM2011 (IAA RAS, Russia). The correction of DMPR solution to Einstein’s general relativity (GR) in the four-dimensional spacetime can be characterized by a constant bulk “tidal charge” parameter [Formula: see text], which is confined in the present work. We find that time delay experiment at IC is independent of [Formula: see text] and not suitable for testing the braneworld model. However, the Cassini SC experiment and modern Solar System ephemerides can give better upper bounds on [Formula: see text]: (1) [Formula: see text] by Cassini, and (2) [Formula: see text] based on the supplementary advances of the perihelia provided by INPOP10a and [Formula: see text] based on the ones of EPM2011. The latter upper bounds are improved to be tighter than the ones of previous works by at least two orders of magnitude. Besides, the stronger constraints on the brane tension are given by the modern ephemerides, which are [Formula: see text] for INPOP10a and [Formula: see text] for EPM2011. These improved upper bounds mean that the Solar System tests can serve as a good testbed for high dimensional theories.

Application of Novel Low Current OBIRCH Amplifier and Nanoprobing to Identify Subtle Leakages in Advanced Node Technologies

2018 ◽  
Author(s):  
Satish Kodali ◽  
Liangshan Chen ◽  
Yuting Wei ◽  
Tanya Schaeffer ◽  
Chong Khiam Oh
Keyword(s):  
Signal To Noise Ratio ◽  
Semiconductor Industry ◽  
Fault Isolation ◽  
Ring Oscillator ◽  
High Signal ◽  
The Novel ◽  
Resistance Change ◽  
Three Samples ◽  
Relative Threshold ◽  
First Time

Abstract Optical beam induced resistance change (OBIRCH) is a very well-adapted technique for static fault isolation in the semiconductor industry. Novel low current OBIRCH amplifier is used to facilitate safe test condition requirements for advanced nodes. This paper shows the differences between the earlier and novel generation OBIRCH amplifiers. Ring oscillator high standby leakage samples are analyzed using the novel generation amplifier. High signal to noise ratio at applied low bias and current levels on device under test are shown on various samples. Further, a metric to demonstrate the SNR to device performance is also discussed. OBIRCH analysis is performed on all the three samples for nanoprobing of, and physical characterization on, the leakage. The resulting spots were calibrated and classified. It is noted that the calibration metric can be successfully used for the first time to estimate the relative threshold voltage of individual transistors in advanced process nodes.

scholarly journals Frequency-diverse multimode millimetre-wave constant-ϵr lens-loaded cavity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
M. A. B. Abbasi ◽  
V. F. Fusco ◽  
O. Yurduseven ◽  
T. Fromenteze
Keyword(s):  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Doa Estimation ◽  
Frequency Diversity ◽  
Millimetre Wave ◽  
Single Lens ◽  
Dielectric Lens ◽  
Diversity Principle ◽  
First Time ◽  
Multi Mode

AbstractThis paper presents a physical frequency-diverse multimode lens-loaded cavity, designed and used for the purpose of the direction of arrival (DoA) estimation in millimetre-wave frequency bands for 5G and beyond. The multi-mode mechanism is realized using an electrically-large cavity, generating spatio-temporally incoherent radiation masks leveraging the frequency-diversity principle. It has been shown for the first time that by placing a spherical constant dielectric lens (constant-ϵr) in front of the radiating aperture of the cavity, the spatial incoherence of the radiation modes can be enhanced. The lens-loaded cavity requires only a single lens and output port, making the hardware development much simpler and cost-effective compared to conventional DoA estimators where multiple antennas and receivers are classically required. Using the lens-loaded architecture, an increase of up to 6 dB is achieved in the peak gain of the synthesized quasi-random sampling bases from the frequency-diverse cavity. Despite the fact that the practical frequency-diverse cavity uses a limited subset of quasi-orthogonal modes below the upper bound limit of the number of theoretical modes, it is shown that the proposed lens-loaded cavity is capable of accurate DoA estimation. This is achieved thanks to the sufficient orthogonality of the leveraged modes and to the presence of the spherical constant-ϵr lens which increases the signal-to-noise ratio (SNR) of the received signal. Experimental results are shown to verify the proposed approach.

scholarly journals Determining habitability: which exoEarths should we search for life?

2010 ◽  
Vol 9 (4) ◽  
pp. 273-291 ◽  
Author(s):  
J. Horner ◽  
B.W. Jones
Keyword(s):  
Solar System ◽  
Positive Result ◽  
Habitable Zone ◽  
Detailed Search ◽  
First Time

AbstractWithin the next few years, the first Earth-mass planets will be discovered around other stars. Some of those worlds will certainly lie within the classical ‘habitable zone’ of their parent stars, and we will quickly move from knowing of no exoEarths to knowing many. For the first time, we will be in a position to carry out a detailed search for the first evidence of life beyond our Solar System. However, such observations will be hugely taxing and time consuming to perform, and it is almost certain that far more potentially habitable worlds will be known than it is possible to study. It is therefore important to catalogue and consider the various effects that make a promising planet more or less suitable for the development of life. In this work, we review the various planetary, dynamical and stellar influences that could influence the habitability of exoEarths. The various influences must be taken in concert when we attempt to decide where to focus our first detailed search for life. While there is no guarantee that any given planet will be inhabited, it is vitally important to ensure that we focus our time and effort on those planets most likely to yield a positive result.

scholarly journals Resolved Stellar Populations of the interacting galaxies of the M81 group

2016 ◽  
Vol 11 (S321) ◽  
pp. 22-24
Author(s):  
Sakurako Okamoto ◽  
Nobuo Arimoto ◽  
Annette M.N. Ferguson ◽  
Edouard J. Bernard ◽  
Mike J. Irwin ◽  
...  
Keyword(s):  
Main Sequence ◽  
Field Survey ◽  
State Of The Art ◽  
Young Stars ◽  
Interacting Galaxies ◽  
Wide Field ◽  
Red Giant ◽  
Tidal Streams ◽  
Stellar Associations ◽  
First Time

AbstractWe present the results from the state-of-the-art wide-field survey of the M81 galaxy group that we are conducting with Hyper Suprime-Cam on Subaru Telescope. Our photometry reaches about 2 mag below the tip of the red giant branch (RGB) and reveals the spatial distribution of both old and young stars over an area of 5°2around the M81. The young main-sequence (MS) stars closely follow the HI distribution and can be found in a stellar stream between M81 and NGC 3077 and in numerous outlying stellar associations. Our survey also reveals for the first time the very extended (>2 × R25) halos of RGB stars around M81, M82, and NGC 3077, as well as faint tidal streams that link these systems. The gravitational interactions between M81, M82 and NGC 3077 galaxies induced star formation in tidally stripped gas, and also significantly perturbed the older stellar components leading to disturbed halo morphologies.

Radio Continuum Emission from Sculptor Galaxies

1986 ◽  
Vol 6 (3) ◽  
pp. 325-329 ◽  
Author(s):  
J . I. Harnet
Keyword(s):  
Radio Emission ◽  
Blue Light ◽  
Hii Regions ◽  
Radio Continuum ◽  
Radial Dependence ◽  
Continuum Emission ◽  
Upper Limits ◽  
Peak Flux

AbstractThe five major members of the Sculptor Group of galaxies and NGC 45 have been observed with the Molonglo observatory synthesis telescope. NGC 247 and NGC 300 were not detected and upper limits to their 843 MHz flux densities are given. Radio emission from NGC 7793 is discussed with particular attention to its morphology, radial dependence compared with that of the blue light and possible coincidences between HII regions and 843 MHz peak flux densities.

scholarly journals Testing the Vainshtein mechanism using stars and galaxies

2015 ◽  
Vol 24 (12) ◽  
pp. 1544021 ◽  
Author(s):  
Jeremy Sakstein ◽  
Kazuya Koyama
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Main Sequence ◽  
Alternative Theories Of Gravity ◽  
The Novel ◽  
Main Sequence Stars ◽  
Cosmic Expansion ◽  
Astrophysical Objects ◽  
Theories Of Gravity ◽  
Alternative Theories

The Vainshtein mechanism is of paramount importance in many alternative theories of gravity. It hides deviations from general relativity (GR) in the solar system while allowing them to drive the acceleration of the cosmic expansion. Recently, a class of theories have emerged where the mechanism is broken inside astrophysical objects. In this essay, we look for novel probes of these theories by deriving the modified properties of stars and galaxies. We show that main-sequence stars are colder, less luminous and more ephemeral than GR predicts. Furthermore, the circular velocities of objects orbiting inside galaxies are slower and the lensing of light is weaker. We discuss the prospects for testing these theories using the novel phenomena presented here in light of current astrophysical surveys.

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