scholarly journals Searching for gas giant planets on Solar system scales – a NACO/APPL′-band survey of A- and F-type main-sequence stars

2015 ◽  
Vol 453 (3) ◽  
pp. 2534-2540 ◽  
Author(s):  
T. Meshkat ◽  
M. A. Kenworthy ◽  
M. Reggiani ◽  
S. P. Quanz ◽  
E. E. Mamajek ◽  
...  
Keyword(s):  
Solar System ◽  
Main Sequence ◽  
Giant Planets ◽  
Main Sequence Stars ◽  
Gas Giant ◽  
Band Survey

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.

scholarly journals SEARCHING FOR GAS GIANT PLANETS ON SOLAR SYSTEM SCALES: VLT NACO/APP OBSERVATIONS OF THE DEBRIS DISK HOST STARS HD172555 AND HD115892

2011 ◽  
Vol 736 (2) ◽  
pp. L32 ◽  
Author(s):  
Sascha P. Quanz ◽  
Matthew A. Kenworthy ◽  
Michael R. Meyer ◽  
Julien H. V. Girard ◽  
Markus Kasper
Keyword(s):  
Solar System ◽  
Giant Planets ◽  
Debris Disk ◽  
Gas Giant ◽  
Host Stars

scholarly journals Properties which cannot be explained by Planetary Nebulae's progenitors

1997 ◽  
Vol 180 ◽  
pp. 367-367
Author(s):  
Noam Soker
Keyword(s):  
Main Sequence ◽  
Brown Dwarfs ◽  
Giant Planets ◽  
Main Sequence Stars ◽  
Substellar Objects ◽  
Earth Like Planets ◽  
Low Mass ◽  
Inner Region ◽  
Central Stars

Stellar binary companions account for bipolar PNe (∼ 11% of all PNe1), and some ellipticalls (22%2). The rest of axisymmetrical PNe (40% to 60% of all PNe) are due to substellar objects (planets and brown dwarfs)3. This classification of axi symmetrical PNe suggests that substellar objects are commonly present within several × AU around main sequence stars, and that several substellar objects must be present around most main sequence stars3. Some substellar and low mass stellar companions will enter the primary envelope only as the primary reaches the upper AGB. Thus, the early mass loss episode will be spherical, leading to the formation of a spherical halo around an elliptical inner region. Gas giant planets and brown dwarfs close to the primary, will not allow Earth-like planets to have stable orbits. Systems with no Jupiter-like planets will allow Earth-like planets to be present. These stars will form spherical PNe (10%-20% of all PNe, including spherically ejected PNe that have been deformed by the ISM through which they move4). Systems with substellar objects at large separation, as Jupiter in the solar system, will also allow Earth-like planets to be present. These systems will form PNe with spherical halo. Therefore, life may have been present in planets around the central stars of round PNe and elliptical PNe with round halos.

scholarly journals Characterizing planetesimal belts through the study of debris dust

2010 ◽  
Vol 6 (S276) ◽  
pp. 54-59
Author(s):  
Amaya Moro-Martín
Keyword(s):  
Solar System ◽  
Main Sequence ◽  
Planetary Systems ◽  
Dust Particles ◽  
Debris Disks ◽  
Main Sequence Stars ◽  
Wide Range ◽  
Robust Process

AbstractMain sequence stars are commonly surrounded by disks of dust. From lifetime arguments, it is inferred that the dust particles are not primordial but originate from the collision of planetesimals, similar to the asteroids, comets and KBOs in our Solar system. The presence of these debris disks around stars with a wide range of masses, luminosities, and metallicities, with and without binary companions, is evidence that planetesimal formation is a robust process that can take place under a wide range of conditions. Debris disks can help us learn about the formation, evolution and diversity of planetary systems.

EXPANDING THE CHARA/FLUOR HOT DISKS SURVEY

2013 ◽  
Vol 02 (02) ◽  
pp. 1340010 ◽  
Author(s):  
B. MENNESSON ◽  
N. SCOTT ◽  
T. TEN BRUMMELAAR ◽  
G. BRYDEN ◽  
N. TURNER ◽  
...  
Keyword(s):  
Solar System ◽  
Main Sequence ◽  
Near Infrared ◽  
Dust Cloud ◽  
Main Sequence Stars ◽  
Second Development ◽  
Zodiacal Dust ◽  
Dust Component ◽  
Initial Survey ◽  
Better Than

Little is presently known about the hot (>300 K) dust component of debris disks surrounding main sequence stars, similar to the zodiacal dust cloud found in the inner solar system. While extensive surveys have been carried out from space, the majority of detections have surprisingly come from the ground, where near infrared interferometric observations have recently revealed small (~1%) resolved excesses around a dozen nearby main sequence stars. Most of these results have come from the CHARA array "FLUOR" instrument (Mt. Wilson, CA), which has demonstrated the best sensitivity worldwide so far for this type of studies, and has carried out an initial survey of ~40 stars. In order to further understand the origin of this "hot dust phenomenon", we will extend this initial survey to a larger number of stars and lower excess detection limits, i.e. higher visibility accuracy providing higher contrast measurements. To this end, two major instrumental developments are underway at CHARA. The first one aims at improving FLUOR's sensitivity to a median K-band magnitude limit of 5 (making 200 targets available). The second development is based on a method that we recently developed for accurate (better than 0.1%) null depth measurements of stars, and that can be extended to regular interferometric visibility measurements.

The evolution of habitable zones during stellar lifetimes and its implications on the search for extraterrestrial life

2003 ◽  
Vol 2 (4) ◽  
pp. 289-299 ◽  
Author(s):  
D.R. Underwood ◽  
B.W. Jones ◽  
P.N. Sleep
Keyword(s):  
Main Sequence ◽  
Giant Planet ◽  
Giant Planets ◽  
Main Sequence Stars ◽  
Extraterrestrial Life ◽  
The Past ◽  
Habitable Zones ◽  
Gravitational Influence ◽  
Stellar Masses ◽  
Do So

A stellar evolution computer model has been used to determine changes in the luminosity L and effective temperature Te of single stars during their time on the main sequence. The range of stellar masses investigated was from 0.5 to 1.5 times that of the Sun, each with a mass fraction of metals (metallicity, Z) from 0.008 to 0.05. The extent of each star's habitable zone (HZ) has been determined from its values of L and Te. These stars form a reference framework for other main sequence stars. All of the 104 main sequence stars known to have one or more giant planets have been matched to their nearest stellar counterpart in the framework, in terms of mass and metallicity, hence closely approximating their HZ limits. The limits of HZ, for each of these stars, have been compared to their giant planet(s)'s range of strong gravitational influence. This allows a quick assessment as to whether Earth-mass planets could exist in stable orbits within the HZ of such systems, both presently and at any time during the star's main sequence lifetime. A determination can also be made as to the possible existence of life-bearing satellites of giant planets, which orbit within HZs. Results show that about half of the 104 known extrasolar planetary systems could possibly have been housing an Earth-mass planet in HZs during at least the past billion years, and about three-quarters of the 104 could do so for at least a billion years at some time during their main sequence lives. Whether such Earth-mass planets could have formed is an urgent question now being investigated by others, with encouraging results.

scholarly journals Testing planet formation theories with giant stars

2007 ◽  
Vol 3 (S249) ◽  
pp. 209-222
Author(s):  
Luca Pasquini ◽  
M.P. Döllinger ◽  
A. Hatzes ◽  
J. Setiawan ◽  
L. Girardi ◽  
...  
Keyword(s):  
Main Sequence ◽  
Planet Formation ◽  
Mass Range ◽  
Stellar Mass ◽  
Giant Planets ◽  
Main Sequence Stars ◽  
Giant Stars ◽  
Solar Type ◽  
The Subject ◽  
Host Stars

AbstractPlanet searches around evolved giant stars are bringing new insights to planet formation theories by virtue of the broader stellar mass range of the host stars compared to the solar-type stars that have been the subject of most current planet searches programs. These searches among giant stars are producing extremely interesting results. Contrary to main sequence stars planet-hosting giants do not show a tendency of being more metal rich. Even if limited, the statistics also suggest a higher frequency of giant planets (at least 10%) that are more massive compared to solar-type main sequence stars.The interpretation of these results is not straightforward. We propose that the lack of a metallicity-planet connection among giant stars is due to pollution of the star while on the main sequence, followed by dillution during the giant phase. We also suggest that the higher mass and frequency of the planets are due to the higher stellar mass. Even if these results do not favor a specific formation scenario, they suggest that planetary formation might be more complex than what has been proposed so far, perhaps with two mechanisms at work and one or the other dominating according to the stellar mass. We finally stress as the detailed study of the host stars and of the parent sample is essential to derive firm conclusions.

The effect of late gas disks on the late stages of planet formation

2020 ◽  
Author(s):  
Quentin Kral
Keyword(s):  
Main Sequence ◽  
Detection Method ◽  
Giant Planets ◽  
Terrestrial Planets ◽  
Main Sequence Stars ◽  
Planet Detection ◽  
New Birth ◽  
Giant Impacts ◽  
Late Stages ◽  
Gas Component

<p>The external supply of gas to planetary atmospheres may be important to set their final compositions. In this talk, I will summarize recent works that quantified in an exoplanetary context, how much gas can be delivered to planets from late gas disks, which appear to be rather ubiquitous around main-sequence stars with bright planetesimal belts. This new gas component is indeed found to be present for tens and sometimes hundreds of millions of years around main-sequence stars. The gas is thought to be released from planetesimals when they collide together in their parent belt, which creates a gas disk (made of volatiles) that can viscously spread further in the system and encounter the already formed planets that can capture this gas, which will affect the primordial atmospheres of these planets. Kral et al. (2020) show that this very late accretion onto planets is very efficient and may allow capturing large quantities of carbon and oxygen (and potentially some nitrogen and hydrogen) leading to new atmospheric masses onto capturing terrestrial planets between that of the Earth's atmosphere to planets with massive atmospheres with sub-Neptune-like pressures. New secondary atmospheres with high metallicities will be created on terrestrial planets bathing in these late gas disks, resetting their primordial compositions inherited from the protoplanetary disk phase, and providing a new birth to planets that lost their atmospheres to photoevaporation or giant impacts. This volatile delivery for tens of Myr may also be favourable to the development of the first bricks of life. It will also affect the metallicity and C/O ratio of giant planets accreting late gas, which is an effect that may be observable in the close future. This very efficient accretion opens the way to a new planet detection method (for planets down to Earth masses at a few au from their stars) that I will present in this talk.</p>

scholarly journals Spectral Analysis of Stars on Planet-Search Surveys

2004 ◽  
Vol 219 ◽  
pp. 29-40 ◽  
Author(s):  
Debra Fischer ◽  
Jeff A. Valenti ◽  
Geoff Marcy
Keyword(s):  
Main Sequence ◽  
Spectroscopic Analysis ◽  
Underlying Mechanism ◽  
Convective Zone ◽  
Giant Planets ◽  
Occurrence Rate ◽  
Initial Condition ◽  
Solar Metallicity ◽  
Gas Giant ◽  
Orbital Periods

We present spectroscopic analysis of ∼1000 stars on the Lick, Keck and AAT planet search projects. This analysis provides a quantitative, and unbiased correlation between metallicity and the rate of occurrence of detected gas giant planets with orbital periods shorter than three years. As stellar metallicity increases, the occurrence of planets increases. Stars with [Fe/H] that is one third of solar only have gas giants detected ∼ 3% of the time. Stars with solar metallicity have a planet occurrence rate of 5 − 10%. The occurrence of gas giant planets rises to 20% in stars with a metallicity that is three times solar.At issue is whether the quantitative dependence of planet occurrence on metallicity is primarily an initial condition, or a by-product of accretion of gas-depleted material onto the convective zone of the star. Accretion could be distinguished as the underlying mechanism for enhanced metallicity if: 1) planet-bearing F-type stars with thinner convective envelopes show a higher mean metallicity than planet-bearing G- or K-type stars, or 2) planet-bearing sub-giants with diluted convective zones showed statistically lower metallicity than their main sequence counterparts.

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