The Milky Way`s external disc constrained by 2MASS star counts
... Methods. We use the Two Micron All Sky Survey (hereafter 2MASS) along with the Stellar Population Synthesis Model of the Galaxy, developed in Besançon, to constrain the external disc parameters, such as its scale length, its cutoff radius, and the slope of the warp. To properly interpret the observat ...
... Methods. We use the Two Micron All Sky Survey (hereafter 2MASS) along with the Stellar Population Synthesis Model of the Galaxy, developed in Besançon, to constrain the external disc parameters, such as its scale length, its cutoff radius, and the slope of the warp. To properly interpret the observat ...
Testing Models of Coronal Heating, X
... • Cranmer (2009) used two independent sets of M*, L*, R*, ages, & accretion rates, from Hartigan et al. (1995) and Hartmann et al. (1998). ...
... • Cranmer (2009) used two independent sets of M*, L*, R*, ages, & accretion rates, from Hartigan et al. (1995) and Hartmann et al. (1998). ...
Toward Resolving the Outflow Engine: An Observational Perspective
... leading to eruptive ejection. The estimated timescales, however, seem too short as they are around a few stellar rotation periods. It is also possible that such short-term fluctuations in the outflow may come from disk instabilities or cyclic changes in the stellar magnetic field (as in the Sun). Fu ...
... leading to eruptive ejection. The estimated timescales, however, seem too short as they are around a few stellar rotation periods. It is also possible that such short-term fluctuations in the outflow may come from disk instabilities or cyclic changes in the stellar magnetic field (as in the Sun). Fu ...
Systematics-insensitive periodic signal search with K2
... detrended light curve. The top panel of figure 4 shows the raw light curve of the same target in grey, with the conditioned light curve in black. This conditioned light curve was produced by removing the best fitting systematic trends, described by a certain combination of the ELCs, at the best fitt ...
... detrended light curve. The top panel of figure 4 shows the raw light curve of the same target in grey, with the conditioned light curve in black. This conditioned light curve was produced by removing the best fitting systematic trends, described by a certain combination of the ELCs, at the best fitt ...
On the nature of sn stars. I. A detailed abundance study
... radiative diffusion. Observationally, the maximum rotational velocities measured for HgMn and Am stars are 90 and 120 km/s, respectively (Wolff & Preston 1978; Abt & Moyd 1973). More recent works also present similar maximum values for CP stars (see e.g. Abt & Morrel 1995; Abt 2009). Mermilliod (198 ...
... radiative diffusion. Observationally, the maximum rotational velocities measured for HgMn and Am stars are 90 and 120 km/s, respectively (Wolff & Preston 1978; Abt & Moyd 1973). More recent works also present similar maximum values for CP stars (see e.g. Abt & Morrel 1995; Abt 2009). Mermilliod (198 ...
File - Mr. Catt`s Class
... 1. All galaxies emit radio waves; for a normal galaxy, radio waves constitute only about 1% of the galaxy’s total luminosity. 2. A radio galaxy is a galaxy having greatest luminosity at radio wavelengths. – A typical radio galaxy emits millions of times more energy in radio waves than does a normal ...
... 1. All galaxies emit radio waves; for a normal galaxy, radio waves constitute only about 1% of the galaxy’s total luminosity. 2. A radio galaxy is a galaxy having greatest luminosity at radio wavelengths. – A typical radio galaxy emits millions of times more energy in radio waves than does a normal ...
Eight billion asteroids in the Oort cloud
... (turquoise), impacted Saturn (grey), impacted Uranus (purple), impacted Neptune (blue), Oort cloud comet (pink), ejected (black), and otherwise still active (white). ...
... (turquoise), impacted Saturn (grey), impacted Uranus (purple), impacted Neptune (blue), Oort cloud comet (pink), ejected (black), and otherwise still active (white). ...
Gas Mass Fractions and the Evolution of Spiral Galaxies
... small in late types, and a five fold increase in a small number still results in a very small correction to the final fg . Rather than convolve together all these uncertainties, we simply use equation (5), realizing that this is probably the greatest uncertainty in the process. The uncertainty in th ...
... small in late types, and a five fold increase in a small number still results in a very small correction to the final fg . Rather than convolve together all these uncertainties, we simply use equation (5), realizing that this is probably the greatest uncertainty in the process. The uncertainty in th ...
Stars as cosmological tools: giving light to Dark Matter
... Figure 1.1: The Coma cluster observed by the X-ray telescope ROSAT [6]. The temperature of the intracluster gas is used to infer the total mass of the cluster, revealing the existence of large amounts of invisible mass. virial theorem (relating the kinetic and potential energy of the system), he est ...
... Figure 1.1: The Coma cluster observed by the X-ray telescope ROSAT [6]. The temperature of the intracluster gas is used to infer the total mass of the cluster, revealing the existence of large amounts of invisible mass. virial theorem (relating the kinetic and potential energy of the system), he est ...
Eight billion asteroids in the Oort cloud
... than modelling the effects of the Galactic tide and passing stars. Scaling the 3.3-5.2 au result down to 1 au, Weissman & Levison (1997) estimated 2.3% of the Oort cloud to have come from the region interior to Jupiter’s orbit. Followup observations found that although 1996 PW’s appearance was compa ...
... than modelling the effects of the Galactic tide and passing stars. Scaling the 3.3-5.2 au result down to 1 au, Weissman & Levison (1997) estimated 2.3% of the Oort cloud to have come from the region interior to Jupiter’s orbit. Followup observations found that although 1996 PW’s appearance was compa ...
K through 8
... The constellation Cygnus, is beyond Cepheus. Facing Polaris, pass through the righthand pair of stars forming the trapezoid of Cepheus for about the same distance as Cepheus was from Polaris, reaching Deneb, the brightest star which is at the top of the Northern Cross. Thus, the Big Dipper, Polaris, ...
... The constellation Cygnus, is beyond Cepheus. Facing Polaris, pass through the righthand pair of stars forming the trapezoid of Cepheus for about the same distance as Cepheus was from Polaris, reaching Deneb, the brightest star which is at the top of the Northern Cross. Thus, the Big Dipper, Polaris, ...
CHAPTER 4 THE SPATIAL DISTRIBUTION OF GALAXIES 4.13
... current distribution of galaxies up to the largest observable scales. In this chapter we will discuss how astronomers have come to their present understanding of the way in which galaxies, and more generally, matter is distributed throughout space. This has been one of the great scientific endeavour ...
... current distribution of galaxies up to the largest observable scales. In this chapter we will discuss how astronomers have come to their present understanding of the way in which galaxies, and more generally, matter is distributed throughout space. This has been one of the great scientific endeavour ...
The uniqueness of Antarctica for the study of AGB stars
... Antarctica will allow us also to study stars in the final phases of their evolution from all the Dwarf Spheroidal Satellites of the Milky Way, at very different metallicities. (For the dSphs we could observe at least the giants at the tip of the RGB phase). ...
... Antarctica will allow us also to study stars in the final phases of their evolution from all the Dwarf Spheroidal Satellites of the Milky Way, at very different metallicities. (For the dSphs we could observe at least the giants at the tip of the RGB phase). ...
A PCA approach to stellar effective temperatures⋆
... the flux normalized to a pseudo-continuum. We have performed our analysis both at a resolving power of R = 10 000 and 1000, finding slightly better results at lower resolution. Smoothing and resampling the spectra can only destroy information, but it is also possible that it helps reducing the impac ...
... the flux normalized to a pseudo-continuum. We have performed our analysis both at a resolving power of R = 10 000 and 1000, finding slightly better results at lower resolution. Smoothing and resampling the spectra can only destroy information, but it is also possible that it helps reducing the impac ...
Dust input from AGB stars in the Large Magellanic Cloud
... and chemical enrichment history are known. The LMC is close enough to permit global and spatially resolved reconstruction of its star formation history (SFH) with better spatial and temporal resolution than in any other galaxy. Harris & Zaritsky (2009) performed such a reconstruction for the LMC by ...
... and chemical enrichment history are known. The LMC is close enough to permit global and spatially resolved reconstruction of its star formation history (SFH) with better spatial and temporal resolution than in any other galaxy. Harris & Zaritsky (2009) performed such a reconstruction for the LMC by ...
CAN PLANETESIMALS FORM BY COLLISIONAL FUSION?
... statistics we test the recently developed concept of collisional fusion which provides a physical basis for a range of collisional velocities exhibiting perfect sticking. A boulder can then grow sufficiently rapidly to settle into a Keplerian orbit on disk evolution time scales. Subject headings: ac ...
... statistics we test the recently developed concept of collisional fusion which provides a physical basis for a range of collisional velocities exhibiting perfect sticking. A boulder can then grow sufficiently rapidly to settle into a Keplerian orbit on disk evolution time scales. Subject headings: ac ...
Star formation
Star formation is the process by which dense regions within molecular clouds in interstellar space, sometimes referred to as ""stellar nurseries"" or ""star-forming regions"", collapse to form stars. As a branch of astronomy, star formation includes the study of the interstellar medium (ISM) and giant molecular clouds (GMC) as precursors to the star formation process, and the study of protostars and young stellar objects as its immediate products. It is closely related to planet formation, another branch of astronomy. Star formation theory, as well as accounting for the formation of a single star, must also account for the statistics of binary stars and the initial mass function.In June 2015, astronomers reported evidence for Population III stars in the Cosmos Redshift 7 galaxy at z = 6.60. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it.