The Initial Mass Function of Be Stars

Allowing for systematic differences in the counting of Be Stars due to their overluminosity, changes produced by their fast rotation on spectral types and time spent in the main sequence, a difference between the IMF (Be) and IMF(B) appears, which indicates that the appearance of the Be phenomenon may relay on differences in the initial star formation conditions.

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Star Formation in Cooling Flows

Symposium - International Astronomical Union ◽

10.1017/s0074180900185158 ◽

1987 ◽

Vol 127 ◽

pp. 167-177

Author(s):

R. W. O'Connell

Keyword(s):

Star Formation ◽

Stellar Populations ◽

Mass Function ◽

Initial Mass Function ◽

Initial Mass ◽

Flow Forming ◽

Cooling Flows ◽

Cd Galaxies ◽

Ngc 1275 ◽

The Imf

Star formation, probably with an abnormal initial mass function, represents the most plausible sink for the large amounts of material being accreted by cD galaxies from cooling flows. There are three prominent cases (NGC 1275, PKS 0745-191, and Abell 1795) where cooling flows have apparently induced unusual stellar populations. Recent studies show that about 50% of other accreting cD's have significant ultraviolet excesses. It therefore appears that detectable accretion populations are frequently associated with cooling flows. The questions of the form of the IMF, the fraction of the flow forming stars, and the lifetime of the flow remain open.

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On the Bulk Yields of Nucleosynthesis from Massive Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100067476 ◽

1977 ◽

Vol 45 ◽

pp. 161-164

Author(s):

W. David Arnett

Keyword(s):

Solar System ◽

Main Sequence ◽

Massive Stars ◽

Mass Function ◽

Initial Mass Function ◽

Initial Mass ◽

Iron Group ◽

Helium Stars ◽

The Absolute ◽

The Imf

Preliminary estimates are made of the absolute yields of abundant nuclei synthesized in observed stars. The compositions of helium stars of mass 3 ≤ Mα / Mʘ≤ 64 are presented, taken at the instant of instability. These stars of mass Mα are identified with stars of main sequence mass M. The amount of synthesized matter for each mass M ≥ MʘHe is estimated (Table 1). Using a variety of choices for the initial mass function (IMF) the yield per stellar generation is calculated. For standard choices of the IMF the absolute and relative yields of12C,16O,20Ne,24Mg, the Si to Ca group and the iron group agree with solar system values, to the accuracy of the calculations.

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The Initial Mass Function in Young Star Clusters

Highlights of Astronomy ◽

10.1017/s1539299600006821 ◽

1986 ◽

Vol 7 ◽

pp. 489-499

Author(s):

Hans Zinnecker

Keyword(s):

Star Formation ◽

Recent Work ◽

Star Clusters ◽

Mass Function ◽

Young Star ◽

Initial Mass Function ◽

Initial Mass ◽

Stellar Content ◽

Young Star Clusters ◽

The Imf

AbstractThis review discusses both the earlier and the most recent work on the IMF in young star clusters. It is argued that the study of the stellar content of young star clusters offers the best chance of developing a theory of star formation and of the IMF.

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On the Initial Mass Function of Be Stars and the Missing Be Stars of Late Spectral Types

International Astronomical Union Colloquium ◽

10.1017/s0252921100055573 ◽

2000 ◽

Vol 175 ◽

pp. 51-54

Author(s):

J. Zorec

Keyword(s):

Power Function ◽

Mass Function ◽

Stellar Mass ◽

Initial Mass Function ◽

Initial Mass ◽

Apparent Magnitude ◽

The Sun ◽

Be Stars ◽

B Stars ◽

The Imf

AbstractThis is an attempt at determining the IMF (Initial Mass Function) of Be stars relative to that of B stars in the vicinity of the Sun. We have represented the IMF as a power function of the stellar mass Mβ, so that the relative IMF is then proportional to Mβ(Be)–β(B). Allowing for systematic differences in the counting of Be stars due to their apparent overluminosity, a difference β(Be) – β(B) ~ 0 is found, which may indicate that there are no huge intrinsic differences between the two types of objects. In these calculations changes of spectral types due to high rotation were not taken into account. This effect may still strongly affect the results obtained. By extrapolating the MβBe) – β(B) curve to spectral types later than B7, we reckon that in a volume limited to the apparent magnitude V = 7 there may be about 150 still undetected Be stars of late spectral types.

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What does the IMF really tell us about star formation?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310003261 ◽

2009 ◽

Vol 5 (S262) ◽

pp. 368-369

Author(s):

M. B. N. Kouwenhoven ◽

S. P. Goodwin

Keyword(s):

Star Formation ◽

Formation Process ◽

Stellar Population ◽

Mass Function ◽

Initial Mass Function ◽

Initial Mass ◽

Detailed Knowledge ◽

Mass Ratio ◽

Ratio Distribution ◽

The Imf

AbstractObtaining accurate measurements of the initial mass function (IMF) is often considered to be the key to understanding star formation, and a universal IMF is often assumed to imply a universal star formation process. Here, we illustrate that different modes of star formation can result in the same IMF, and that, in order to truly understand star formation, a deeper understanding of the primordial binary population is necessary. Detailed knowledge on the binary fraction, mass ratio distribution, and other binary parameters, as a function of mass, is a requirement for recovering the star formation process from stellar population measurements.

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The initial mass function in the extended ultraviolet disc of M83

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3151 ◽

2019 ◽

Vol 491 (2) ◽

pp. 2366-2390 ◽

Cited By ~ 1

Author(s):

S M Bruzzese ◽

David A Thilker ◽

G R Meurer ◽

Luciana Bianchi ◽

A B Watts ◽

...

Keyword(s):

Main Sequence ◽

Hubble Space Telescope ◽

Formation Rate ◽

Mass Function ◽

Initial Mass Function ◽

High Mass ◽

Initial Mass ◽

Main Sequence Stars ◽

Red Giant ◽

The Imf

ABSTRACT Using Hubble Space Telescope ACS/WFC data we present the photometry and spatial distribution of resolved stellar populations of four fields within the extended ultraviolet disc (XUV disc) of M83. These observations show a clumpy distribution of main-sequence stars and a mostly smooth distribution of red giant branch stars. We constrain the upper end of the initial mass function (IMF) in the outer disc using the detected population of main-sequence stars and an assumed constant star formation rate (SFR) over the last 300 Myr. By comparing the observed main-sequence luminosity function to simulations, we determine the best-fitting IMF to have a power-law slope α = −2.35 ± 0.3 and an upper mass limit $M_{\rm u}=25_{-3}^{+17} \, \mathrm{M}_\odot$. This IMF is consistent with the observed H $\rm \alpha$ emission, which we use to provide additional constraints on the IMF. We explore the influence of deviations from the constant SFR assumption, finding that our IMF conclusions are robust against all but strong recent variations in SFR, but these are excluded by causality arguments. These results, along with our similar studies of other nearby galaxies, indicate that some XUV discs are deficient in high-mass stars compared to a Kroupa IMF. There are over one hundred galaxies within 5 Mpc, many already observed with HST, thus allowing a more comprehensive investigation of the IMF, and how it varies, using the techniques developed here.

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Fragmentation and the Initial Mass Function

International Astronomical Union Colloquium ◽

10.1017/s0252921100023472 ◽

1989 ◽

Vol 120 ◽

pp. 44-55

Author(s):

Richard B. Larson

Keyword(s):

Star Formation ◽

Power Law ◽

Mass Function ◽

Initial Mass Function ◽

Initial Mass ◽

Solar Mass ◽

Universal Feature ◽

Basic Features ◽

The Imf

A central problem in the theory of star formation is to understand the spectrum of masses, or Initial Mass Function, with which stars are formed. The fundamental role of the IMF in galactic evolution has been described by Tinsley (1980), and an extensive review of evidence concerning the IMF and its possible variability has been presented by Scalo (1986). Although the IMF derived from the observations is subject to many uncertainties, two basic features seem reasonably well established. One is that the typical stellar mass, defined such that equal amounts of matter condense into stars above and below this mass, is within a factor of 3 of one solar mass. A theory of star formation should therefore be able to explain why most stars are formed with masses of order one solar mass. The second apparently universal feature is that the IMF for relatively massive stars can be approximated by a power law with a slope not greatly different from that originally proposed by Salpeter (1955). Thus we also need to understand why the IMF always has a similar power-law tail toward higher masses.

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