منابع مشابه
Temperature fluctuations of interstellar dust grains
The temperatures of interstellar dust grains are analyzed using stochastic simulations, taking into account the grain composition and size and the discreteness of the photon flux. Grains of radii smaller than about 0.02 μm are found to exhibit large temperature fluctuations with narrow spikes following the absorption of UV photons. The temperatures of such grains may rise by a few × 10 K for ve...
متن کاملThe temperature of non - spherical interstellar grains
A model of spheroidal particles is used to calculate the steady-state temperature of dust grains immersed in the interstellar radiation field. It is found that the temperature of non-spherical grains with the aspect ratios a/b < ∼ 2 deviates from that of spheres less than 10 %. More elongated or flattened particles are usually cooler than spheres of the same mass and in some cases the temperatu...
متن کاملThe Spin Temperature of Warm Interstellar H
Collisional excitation of the λ21cm hyperfine transition is not strong enough to thermalize it in warm neutral (" intercloud ") interstellar gas, which we show by simultaneously solving the equations of ionization and collisional equilibrium under typical conditions. Coupling of the λ21cm excitation temperature and local gas motions may be established by the Ly-α radiation field, but only if st...
متن کاملLocal Interstellar Matter: The Apex Cloud
Several nearby individual low column density interstellar cloudlets have been identified previously based on kinematical features evident in high-resolution Ca observations near the Sun. One of these cloudlets, the ‘Apex Cloud” (AC), is within 5 pc of the Sun in the solar apex direction. The question of which interstellar cloud will constitute the next galactic environment of the Sun in princip...
متن کاملLocal Interstellar Matter : The Apex Cloud Priscilla
Several nearby individual low column density interstellar cloudlets have been identified based on kinematical features evident in high-resolution Ca observations near the Sun. One of these cloudlets, the ‘Apex Cloud” (AC), is within 5 pc of the Sun in the solar apex direction. The question of which interstellar cloud will constitute the next galactic environment of the Sun in principle can be d...
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ژورنال
عنوان ژورنال: The Astronomical Journal
سال: 1947
ISSN: 0004-6256
DOI: 10.1086/106008