Do O-stars form in isolation?
نویسندگان
چکیده
Around 4% of O-stars are observed in apparent isolation, with no associated cluster, and no indication of having been ejected from a nearby cluster. We define an isolated O-star as a star > 17.5M⊙ in a cluster with total mass < 100M⊙ which contains no other massive (> 10M⊙) stars. We show that the fraction of apparently isolated O-stars is reproduced when stars are sampled (randomly) from a standard initial mass function and a standard cluster mass function of the form N(M) ∝ M. This result is difficult to reconcile with the idea that there is a fundamental relationship between the mass of a cluster and the mass of the most massive star in that cluster. We suggest that such a relationship is a typical result of star formation in clusters, and that ‘isolated O-stars’ are low-mass clusters in which massive stars have been able to form.
منابع مشابه
A Fast Algorithm for Covering Rectangular Orthogonal Polygons with a Minimum Number of r-Stars
Introduction This paper presents an algorithm for covering orthogonal polygons with minimal number of guards. This idea examines the minimum number of guards for orthogonal simple polygons (without holes) for all scenarios and can also find a rectangular area for each guards. We consider the problem of covering orthogonal polygons with a minimum number of r-stars. In each orthogonal polygon P,...
متن کاملPulsating red giant and supergiant stars in the Local Group dwarf galaxy Andromeda I
We have conducted an optical long-term monitoring survey of the majority of dwarf galaxies in the Local Group, with the Isaac Newton Telescope (INT), to identify the long period variable (LPV) stars. LPV stars vary on timescales of months to years, and reach the largest amplitudes of their brightness variations at optical wavelengths, due to the changing temperature. They trace stellar populati...
متن کاملStar Formation in the Milky Way
How and where do stars form? One of the challenges in star formation theory today is describing the different processes by which stars form. They form not only in isolation, but also in groups of 10-100 stars and in clusters of more than 100 stars. The particular mode of star formation may depend on the initial conditions. Stars form in molecular clouds, regions of dense gas and dust, that can ...
متن کاملDouble-Star Detection Using Convolutional Neural Network in Atmospheric Turbulence
In this paper, we investigate the usage of machine learning in the detection and recognition of double stars. To do this, numerous images including one star and double stars are simulated. Then, 100 terms of Zernike expansion with random coefficients are considered as aberrations to impose on the aforementioned images. Also, a telescope with a specific aperture is simulated. In this work, two k...
متن کاملForbidden Lines in Herbig Ae/be Stars. the [o I] (1f) 6300.31å and 6363.79å Lines Ii. Longslit Observations of Selected Objects
This paper presents first long-slit spectroscopic observations of the forbidden [O I](1F) emission line regions around selected pre-main sequence Herbig Ae/Be stars. Contrary to the lower-mass T Tauri stars, the observations show that the selected Herbig stars do not reveal neither signs of extended or positionally decentered [O I](1F) emission regions, nor signs of outflows or jets in the prox...
متن کامل