Distance errors and the stellar luminosity function

Stobie, R. S.; Ishida, Keiichi; Peacock, J. A.

doi:10.1093/mnras/238.3.709

Cited by 78 publications

(122 citation statements)

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“…We compute the maximum volume probed by our magnitude-limited survey at a given colour (that is at a given absolute magnitude). This geometric volume is corrected to take into account the decrease of the stellar density with increasing distance above the Galactic plane (Felten 1976;Stobie et al 1989;Tinney et al 1993):…”

Section: The Brown Dwarf Space-densitymentioning

confidence: 99%

“…Malmquist (1920) gave the first correction method for this bias, assuming a Gaussian distribution of the luminosity at a given colour, and later Stobie et al (1989) proposed the following analytic correction: ΔΦ Φ (0.6 ln 10) 2 σ 2 − 0.6 ln 10σ 2 Φ Φ , where σ is the luminosity dispersion, Φ the luminosity function, and Φ = dΦ dM . The first term is the volume element correction, the second term corrects for the magnitude translation from M to M 0 .…”

Section: Malmquist Biasmentioning

confidence: 99%

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The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

Reylé

Delorme

Willott

et al. 2010

A&A

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Context. Thanks to recent and ongoing large scale surveys, hundreds of brown dwarfs have been discovered in the last decade. The Canada-France Brown Dwarf Survey is a wide-field survey for cool brown dwarfs conducted with the MegaCam camera on the Canada-France-Hawaii Telescope. Aims. Our objectives are to find ultracool brown dwarfs and to constrain the field brown-dwarf luminosity function and the mass function from a large and homogeneous sample of L and T dwarfs. Methods. We identify candidates in CFHT/MegaCam i and z images and follow them up with pointed near infrared (NIR) imaging on several telescopes. Halfway through our survey we found ∼50 T dwarfs and ∼170 L or ultra cool M dwarfs drawn from a larger sample of 1400 candidates with typical ultracool dwarfs i − z colours, found in 780 square degrees. Results. We have currently completed the NIR follow-up on a large part of the survey for all candidates from mid-L dwarfs down to the latest T dwarfs known with utracool dwarfs' colours. This allows us to draw on a complete and well defined sample of 102 ultracool dwarfs to investigate the luminosity function and space density of field dwarfs. Conclusions. We found the density of late L5 to T0 dwarfs to be 2.0 +0.8 −0.7 × 10 −3 objects pc −3 , the density of T0.5 to T5.5 dwarfs to be 1.4 +0.3 −0.2 × 10 −3 objects pc −3 , and the density of T6 to T8 dwarfs to be 5.3 +3.1 −2.2 × 10 −3 objects pc −3 . We found that these results agree better with a flat substellar mass function. Three latest dwarfs at the boundary between T and Y dwarfs give the high density 8.3 +9.0 −5.1 × 10 −3 objects pc −3 . Although the uncertainties are very large this suggests that many brown dwarfs should be found in this late spectral type range, as expected from the cooling of brown dwarfs, whatever their mass, down to very low temperature.

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Section: The Brown Dwarf Space-densitymentioning

confidence: 99%

Section: Malmquist Biasmentioning

confidence: 99%

The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

Reylé

Delorme

Willott

et al. 2010

A&A

View full text Add to dashboard Cite

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“…It is worthwhile to compare our LF with the one of low-mass field stars in the solar neighborhood, as it is constructed with data taken from Stobie et al (1989) (for M V > 7 mag) and Scalo (1986) (7 ! M V /mag !…”

Section: Luminosity Functionmentioning

confidence: 99%

The Low‐Mass Initial Mass Function of the Field Population in the Large Magellanic Cloud withHubble Space TelescopeWFPC2 Observations

Gouliermis¹,

Brandner²,

Henning³

2006

ApJ

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We present V-and I-equivalent HST WFPC2 stellar photometry of an area in the Large Magellanic Cloud (LMC), located to the west of the bar of the galaxy, which accounts for the general background field of its inner disk. The WFPC2 observations reach magnitudes as faint as V ¼ 25 mag, and the large sample of more than 80,000 stars allows us to determine in detail the present-day mass function ( PDMF) of the detected main-sequence stars, which is identical to the initial mass function ( IMF) for masses M P 1 M . The low-mass main-sequence mass function of the LMC field is found not to have a uniform slope throughout the observed mass range; i.e., the slope does not follow a single power law. This slope changes at about 1 M to become more shallow for stars with smaller masses down to the lowest observed mass of $0.7 M , giving clear indications of flattening for even smaller masses. We verified statistically that for stars with M P 1 M the IMF has a slope À around À2, with an indicative slope À ' À1:4 for 0:7 P M /M P 0:9, while for more massive stars the main-sequence mass function becomes much steeper with À ' À5. The main-sequence luminosity function ( LF) of the observed field is in very good agreement with the Galactic LF as it was previously found. Taking into account several assumptions concerning evolutionary effects, which should have changed through time the stellar content of the observed field, we reconstruct qualitatively its IMF for the whole observed mass range (0:7 P M/M P 2:3), and we find that the number of observed evolved stars is not large enough to have affected significantly the form of the IMF, which thus is found almost identical to the observed PDMF.

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“…Evans 1991) continue to increase our understanding of the complexities and processes involved in star formation, any understanding of how the IMF does, or does not, depend on environment and metallicity is still elusive. For low mass stars, which are the subject of this paper, large surveys (see Reid & Gilmore 1982;Hawkins & Bessell 1988;Stobie, Ishida & Peacock 1989;Bessell & Stringfellow 1993) have provided a fairly well determined measure of the field star luminosity function near the Sun. Extensive modelling is required to derive the corresponding stellar initial mass function.…”

Section: Introductionmentioning

confidence: 99%

The Metallicity Dependence of the Stellar Luminosity and Initial Mass Function: HST Observations of Open and Globular Clusters

Hippel¹,

Gilmore²,

Tanvir³

et al. 1996

The Astronomical Journal

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Using HST and the WFPC2 we have acquired very deep V-and I-band photometry of stars in NGC 2420 and NGC 2477 to study cluster luminosity functions at approximately solar metallicity. We have determined these cluster luminosity functions down to M I = 10.5 (0.2 M ⊙ ) and find that the luminosity function of NGC 2420 turns over at M I ≈ 9.0, and possibly stops altogether by M I ≈ 9.5. The luminosity function of NGC 2477 may flatten at M I ≥ 9.5. We compare our open cluster luminosity functions to the solar neighborhood field star luminosity function of Kroupa, Tout & Gilmore (1993) Saumon 1995;Alexander et al. 1996). We interpret this smooth and systematic behavior in the cluster luminosity functions as strong evidence in favor of an invariant initial mass function and a metallicity-dependent mass-luminosity relation.

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Distance errors and the stellar luminosity function

Cited by 78 publications

References 0 publications

The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

The Low‐Mass Initial Mass Function of the Field Population in the Large Magellanic Cloud withHubble Space TelescopeWFPC2 Observations

The Metallicity Dependence of the Stellar Luminosity and Initial Mass Function: HST Observations of Open and Globular Clusters

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