Protoplanetary Discs
... There is no unique answer to the question which process dominates. A high or low accretion rate is a good indicator, especially in low-mass stars. In high-mass stars, such as Herbig Be stars, the stellar luminosity may always win. ...
... There is no unique answer to the question which process dominates. A high or low accretion rate is a good indicator, especially in low-mass stars. In high-mass stars, such as Herbig Be stars, the stellar luminosity may always win. ...
Extrasolar Planet Studies:The Italian Contribution
... Contrast of 16 mag at 0.5 arcsec from a J=5 star Improvement of 2 orders of magnitude with respect to current instrumentation AO mag limit R=9 Congresso SAIt, Teramo, 8-52008 ...
... Contrast of 16 mag at 0.5 arcsec from a J=5 star Improvement of 2 orders of magnitude with respect to current instrumentation AO mag limit R=9 Congresso SAIt, Teramo, 8-52008 ...
Lokal fulltext - Chalmers Publication Library
... The first detections of circumstellar dust emission were announced in the mid 1980s. Direct observations of the edge-on disc of β Pictoris provided evidence that the dust was part of possible planetary systems. About a decade later, in 1995, the first confirmed extrasolar planet around a main sequen ...
... The first detections of circumstellar dust emission were announced in the mid 1980s. Direct observations of the edge-on disc of β Pictoris provided evidence that the dust was part of possible planetary systems. About a decade later, in 1995, the first confirmed extrasolar planet around a main sequen ...
Powerpoint slides - Earth & Planetary Sciences
... • Which elements actually condense will depend on the local nebular conditions (temperature) • E.g. volatile species will only be stable beyond a “snow line”. This is why the inner planets are rock-rich and the outer planets gas- and ice-rich • The compounds formed from the elements will be determin ...
... • Which elements actually condense will depend on the local nebular conditions (temperature) • E.g. volatile species will only be stable beyond a “snow line”. This is why the inner planets are rock-rich and the outer planets gas- and ice-rich • The compounds formed from the elements will be determin ...
m V
... • Colour is blue, as blue light is the most readily scattered • Scattering of light from blue stars, usually type B; spectrum is also of this type, i.e. absorption lines • Light is often highly polarized (20 – 30 per cent) • Amongst best known examples are the reflection nebulae from circumstellar d ...
... • Colour is blue, as blue light is the most readily scattered • Scattering of light from blue stars, usually type B; spectrum is also of this type, i.e. absorption lines • Light is often highly polarized (20 – 30 per cent) • Amongst best known examples are the reflection nebulae from circumstellar d ...
Angular momentum transport in accretion discs
... now take r ∼ 1 AU, we obtain tvisc /tdyn = Re ∼ 1014 . Since the dynamical time scale for protoplanetary discs is of the order of a few years, the tvis turns out to be of the order of age of Universe. Evidently, molecular viscosity is so small that can not provide an adequate evolutionary timescale ...
... now take r ∼ 1 AU, we obtain tvisc /tdyn = Re ∼ 1014 . Since the dynamical time scale for protoplanetary discs is of the order of a few years, the tvis turns out to be of the order of age of Universe. Evidently, molecular viscosity is so small that can not provide an adequate evolutionary timescale ...
SciPoster_Jan2009
... Another isolated dark nebula is LDN 425. While it is not directly associated with any molecular cloud complex, there is mention of an extended distribution of dust between the main clouds in Chamaeleon, Lupus and Ophiuchus (Sartori 2000). Ophiuchus is another region of active star formation, much of ...
... Another isolated dark nebula is LDN 425. While it is not directly associated with any molecular cloud complex, there is mention of an extended distribution of dust between the main clouds in Chamaeleon, Lupus and Ophiuchus (Sartori 2000). Ophiuchus is another region of active star formation, much of ...
The Occurrence and Architecture of Exoplanetary Systems
... The occurrence rate is the mean number of planets per star having properties (such as mass and orbital distance) within a specified range. The basic idea is to count the number of detected planets with the stipulated properties and divide by the effective number of stars in the survey for which such ...
... The occurrence rate is the mean number of planets per star having properties (such as mass and orbital distance) within a specified range. The basic idea is to count the number of detected planets with the stipulated properties and divide by the effective number of stars in the survey for which such ...
Presolar Cloud Collapse and the Formation and Early Evolution of
... This central core is supported primarily by the thermal pressure of the molecular hydrogen gas, while the remainder of the cloud continues to fall onto the core. For a 1 M cloud, this core has a mass of about 0.0 M (Larson, 1969). Once the central temperature reaches about 2000 K, thermal energy goe ...
... This central core is supported primarily by the thermal pressure of the molecular hydrogen gas, while the remainder of the cloud continues to fall onto the core. For a 1 M cloud, this core has a mass of about 0.0 M (Larson, 1969). Once the central temperature reaches about 2000 K, thermal energy goe ...
A STEP - Observatoire de la Côte d`Azur
... Hot Jupiter planets at given transit depth and target star magnitude. These effects, combined with the unfavorable window function, severely lower the detectability of hot Jupiter transits from the ground at normal latitudes. The detection rates are down to values of about 1 per 10'000 targets even ...
... Hot Jupiter planets at given transit depth and target star magnitude. These effects, combined with the unfavorable window function, severely lower the detectability of hot Jupiter transits from the ground at normal latitudes. The detection rates are down to values of about 1 per 10'000 targets even ...
Unravelling the Origin and Evolution of Our Galaxy
... than our Sun. These are all within a distance of about 100 light-years. The planets detectable by this method are rather massive, comparable to Jupiter (which has about 300 times the mass of Earth). The systems have some surprising properties: two thirds of these giant planets are orbiting their hos ...
... than our Sun. These are all within a distance of about 100 light-years. The planets detectable by this method are rather massive, comparable to Jupiter (which has about 300 times the mass of Earth). The systems have some surprising properties: two thirds of these giant planets are orbiting their hos ...
Formation, Habitability, and Detection of Extrasolar Moons
... around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasola ...
... around extrasolar planets. Of peculiar interest from an astrobiological perspective, the number of sizable moons in the stellar habitable zones may outnumber planets in these circumstellar regions. With technological and theoretical methods now allowing for the detection of sub-Earth-sized extrasola ...
Document
... Two isolated BHs in a globular cluster? eVLA observations showed two flat-spectrum sources without X-ray or/and optical identfications. Most probably, they are accreting BHs. Probably, isolated. Numerical model for the cluster evolution and the number of BHs was calculated in the paper 1211.6608. ...
... Two isolated BHs in a globular cluster? eVLA observations showed two flat-spectrum sources without X-ray or/and optical identfications. Most probably, they are accreting BHs. Probably, isolated. Numerical model for the cluster evolution and the number of BHs was calculated in the paper 1211.6608. ...
Document
... Two isolated BHs in a globular cluster? eVLA observations showed two flat-spectrum sources without X-ray or/and optical identfications. Most probably, they are accreting BHs. Probably, isolated. Numerical model for the cluster evolution and the number of BHs was calculated in the paper 1211.6608. ...
... Two isolated BHs in a globular cluster? eVLA observations showed two flat-spectrum sources without X-ray or/and optical identfications. Most probably, they are accreting BHs. Probably, isolated. Numerical model for the cluster evolution and the number of BHs was calculated in the paper 1211.6608. ...
Hipparcos distance estimates of the Ophiuchus and the Lupus cloud
... dark molecular clouds and their dense cores. One of the main motivations for these investigations is the study of the process of star and planet formation in its entirety, and a deeper understanding of the effects of the local environment. A key aspect of the scientific analysis of a dark molecular c ...
... dark molecular clouds and their dense cores. One of the main motivations for these investigations is the study of the process of star and planet formation in its entirety, and a deeper understanding of the effects of the local environment. A key aspect of the scientific analysis of a dark molecular c ...
The Habitability of Planets Orbiting M
... The spectral slope and the strengths of molecular and atomic features differentiate M dwarf spectral types from one another, though metallicity variation makes this a subtle endeavor (Gizis, 1997). A full suite of spectral “standard" stars from 6300 to 9000 Å enabled the technique of least-squares c ...
... The spectral slope and the strengths of molecular and atomic features differentiate M dwarf spectral types from one another, though metallicity variation makes this a subtle endeavor (Gizis, 1997). A full suite of spectral “standard" stars from 6300 to 9000 Å enabled the technique of least-squares c ...
Advances in exoplanet science from Kepler (Lissauer et al. 2014)
... Earth, the smallest of which is Mars-sized41. Kepler-37b, only slightly larger than Earth’s Moon, is the first planet smaller than Mercury to be found orbiting a main-sequence star; its period is 13 days, and the stellar host is 80% as massive as the Sun42. KIC 12557548b exhibits transits of varying ...
... Earth, the smallest of which is Mars-sized41. Kepler-37b, only slightly larger than Earth’s Moon, is the first planet smaller than Mercury to be found orbiting a main-sequence star; its period is 13 days, and the stellar host is 80% as massive as the Sun42. KIC 12557548b exhibits transits of varying ...
The Kuiper Belt and Other Debris Disks - UCLA
... are compressed, however, into a degenerate (metallic) liquid that supports convection and sustains a magnetic field through dynamo action. The compositional similarity to the Sun suggests to some investigators that the gas giants might form by simple hydrodynamic collapse of the protoplanetary gas n ...
... are compressed, however, into a degenerate (metallic) liquid that supports convection and sustains a magnetic field through dynamo action. The compositional similarity to the Sun suggests to some investigators that the gas giants might form by simple hydrodynamic collapse of the protoplanetary gas n ...
Eight billion asteroids in the Oort cloud
... We plot the fate of particles after 4.5 Gyr of evolution in Fig. 1. Beyond 1.5 au, ejection is the most common outcome for particles which are lost. Interior to 1.5 au, no single outcome dominates, with ejection, and collisions with Earth, Venus, and the Sun all important. The majority of particles ...
... We plot the fate of particles after 4.5 Gyr of evolution in Fig. 1. Beyond 1.5 au, ejection is the most common outcome for particles which are lost. Interior to 1.5 au, no single outcome dominates, with ejection, and collisions with Earth, Venus, and the Sun all important. The majority of particles ...
Advances in exoplanet science from Kepler
... which come from many different surveys and which usually do not include null results); and most of the parameter space that it explores — typical radii of 1 – 3 R⊕ and orbital periods up to ∼ 1 year (Figure 1) — is not easily accessible by other techniques. One of the most fundamental statistics des ...
... which come from many different surveys and which usually do not include null results); and most of the parameter space that it explores — typical radii of 1 – 3 R⊕ and orbital periods up to ∼ 1 year (Figure 1) — is not easily accessible by other techniques. One of the most fundamental statistics des ...
The Evolution of Molecular Clouds
... formation of molecular clouds must itself be a rather rapid process, and cannot take many dynamical timescales. Since the timescales for the formation, internal evolution, and destruction of molecular clouds are all of the same order, these processes probably cannot be clearly separated in time, and ...
... formation of molecular clouds must itself be a rather rapid process, and cannot take many dynamical timescales. Since the timescales for the formation, internal evolution, and destruction of molecular clouds are all of the same order, these processes probably cannot be clearly separated in time, and ...
Comparison of low- and high-mass star formation
... to competitive accretion. One may plausibly identify the dense filament in the early phase and the dense region at the bottom of the global gravitational potential well in the late phase as a McKee–Tan core (McKee & Tan 2003). However, the “cores” so identified are transient objects that are not in ...
... to competitive accretion. One may plausibly identify the dense filament in the early phase and the dense region at the bottom of the global gravitational potential well in the late phase as a McKee–Tan core (McKee & Tan 2003). However, the “cores” so identified are transient objects that are not in ...
Eight billion asteroids in the Oort cloud
... and we find 3 and 2 respectively. Some surviving objects become scattered disk objects/centaurs. A significant number of objects remain in the inner solar system between the terrestrial planets, a result previously found by Evans & Tabachnik (1999, 2002). These are not observed, whatever physics cau ...
... and we find 3 and 2 respectively. Some surviving objects become scattered disk objects/centaurs. A significant number of objects remain in the inner solar system between the terrestrial planets, a result previously found by Evans & Tabachnik (1999, 2002). These are not observed, whatever physics cau ...
Seminar Outburst of Comet 17P/Holmes
... nucleus together with dust and rocky particles. Material ejected from the nucleus forms sparse atmosphere which is called a coma. At some distance from the nucleus the coma becomes so tenuous that particles in it become unbound and they interact only with solar radiation. Neutral (uncharged) particl ...
... nucleus together with dust and rocky particles. Material ejected from the nucleus forms sparse atmosphere which is called a coma. At some distance from the nucleus the coma becomes so tenuous that particles in it become unbound and they interact only with solar radiation. Neutral (uncharged) particl ...
Comets in ancient India
... The above discussion makes it clear that for the seers of antiquity, the night sky and its attendants were sacred. It is highly unlikely that comets of the past would have gone unnoticed. Asko Parpola (2009) has drawn attention to a late Rigvedic verse that speaks of an Indian fig tree whose aerial ...
... The above discussion makes it clear that for the seers of antiquity, the night sky and its attendants were sacred. It is highly unlikely that comets of the past would have gone unnoticed. Asko Parpola (2009) has drawn attention to a late Rigvedic verse that speaks of an Indian fig tree whose aerial ...