Spectra of late type stars from 4800 to 9000 Å
نویسندگان
چکیده
منابع مشابه
Convective Wavelength Shifts in the Spectra of Late-type Stars
We present ultra-high resolution spectra for a set of nearby F-G-K stars on, or close to, the main sequence. The wavelength shifts of stellar lines relative to their laboratory wavelengths are measured for more than a thousand Fe i lines per star, finding a clear correlation with line depth. The observed patterns are interpreted as convective blue-shifts that become more prominent for weaker li...
متن کاملMid-infrared Spectra of Late-type Stars: Long-term Evolution
Recent ground-based mid-infrared spectra of 29 late-type stars, most with substantial dust shells, are compared to ground-based spectra of these stars from the 1960s and 1970s and to IRAS-LRS spectra obtained in 1983. The spectra of about half the stars show no detectable changes, implying that their distributions of circumstellar material and associated dust grain properties have changed littl...
متن کاملLimits to Mass Outflows from Late-type Dwarf Stars
We show that the mass-loss rates of active late-type dwarf stars must be significantly lower than recent estimates of up to 15 3 10 MJ yr, 4 orders of magnitude higher than that of the Sun. First, we present aperture-synthesis observations at 3.5 mm of the dMe flare stars YZ CMi and AD Leo, during which neither star was detected at an upper limit of 10 mJy. Although compatible with the tentativ...
متن کاملLetter to the Editor Emission lines in the spectra of late-B type stars
We report detections of weak emission lines in the red spectral region of sharp-lined chemically normal and peculiar (HgMn) late-B type stars from high spectral resolution and high signal-to-noise data. Most emission lines originate from high-excitation states of the ions Cr II and Mn II, with others likely to be attributed to Ti II and Fe II. The emission is observed to extend over the entire ...
متن کاملInfrared imaging of late-type stars
Infrared imaging properties of dusty winds around late-type stars are investigated in detail, employing a self-consistent model that couples the equations of motion and radiative transfer. Because of general scaling properties, the angular profiles of surface brightness are self-similar. In any given star, the profile shape is determined essentially by overall optical depth at each wavelength a...
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ژورنال
عنوان ژورنال: Astronomy and Astrophysics Supplement Series
سال: 1996
ISSN: 0365-0138,1286-4846
DOI: 10.1051/aas:1996142