He described it as probably 25,000 times fainter than the sun and very blue, its color like that of a B-type star
5-meter telescope at the MMT Observatory at Mount Hopkins, Arizona, have revealed that V838 Mon is a binary system, consisting of a hot B-type star
and, now, a very cool red supergiant.
That makes it hard to know if the blame lies with a particular protostar such as IRc2 or the Becklin-Neugebauer object, which is probably an ordinary B-type star
reddened by thick dust.
The 47 papers also investigate dust formation around main sequence B-emission stars with large infrared excess, the centrifugal magneto-spheres of magnetic B-type stars
, the density structure of 48 LibraeAEs circumstellar disk, and the origin of hard X-rays from ?
The meeting focused on active OB-stars as laboratories for the study of physical processes leading to stellar activity and the ejection of circumstellar material, particularly the orbiting disk that is central to rapidly rotating B-type stars
with prominent emission lines of hydrogen in their spectrums (Be stars).
These are hot B-type stars
with at least one emission line (usually one of the hydrogen Balmer lines).
Accordingly, any short-lived, massive O-and B-type stars
that the cluster might once have harbored have already exploded as supernovae or are nearing that stage.
But astronomers increasingly recognize how ionizing radiation from massive and luminous O- and B-type stars
can kick-start the starbirth process in adjacent clouds of gas and dust.
In the center of the image, a somewhat more mature (but still quite young) cluster of bright O- and B-type stars
called NGC 6193 is bathing RCW 108 with ultraviolet light.
In fact, many types of outward pressure, including that from H II (ionized hydrogen) regions around newly formed hot O- and B-type stars
, can squeeze gas with star-forming potential into actual star-forming gas.
In an ongoing study of our galaxy's starburst regions, an international team of astronomers led by Bernhard Brandl (Cornell University) finds that these stellar nurseries spawn not only massive O- and B-type stars
but also large numbers of stars less massive than our Sun.
In an H II region the gas is ionized by ultraviolet radiation from hot, luminous O- and B-type stars
or (occasionally) by shocks from supernovae.