Luminosity functions of young clusters: Modeling the substellar mass regime

Peter R. Allen, David E Trilling, David W Koerner, I. Neill Reid

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

We predict near-infrared luminosity functions of young (5 Myr to 1 Gyr) star clusters by combining evolutionary models of very low mass (1 M J to 0.15 M) dwarfs with empirical bolometric corrections. We identify several characteristic features in our results. These can be attributed to three causes: (1) deuterium burning in the most massive substellar objects; (2) methane absorption in bodies with Teff less than 1300 K, the temperature of the L/T transition; and (3) the formation of dust clouds and the rainout of dust at roughly the same effective temperature as methane formation. Accurate reconstruction of the substellar mass function from luminosity function observations requires that these phenomena are taken into account. At present, few observational studies extend to sufficient sensitivities to allow detection of these effects. However, the luminosity function of the young open cluster IC 2391 shows a clear peak at MI ∼ 14, which we attribute to the result of deuterium burning in substellar objects. The location of this feature is a strong function of age, and we estimate an age of 35 Myr for IC 2391. This is significantly younger than the 53 Myr derived from the location of the lithium depletion boundary but agrees with the main-sequence turnoff age. We consider the implications of this result and our multiband luminosity functions for future observational studies. All predicted luminosity function features are, or will be, accessible to observations using new wide-field IR imagers and the Space Infrared Telescope Facility.

Original languageEnglish (US)
Pages (from-to)1222-1230
Number of pages9
JournalAstrophysical Journal
Volume595
Issue number2 I
DOIs
StatePublished - Oct 1 2003

Fingerprint

luminosity
modeling
deuterium
methane
dust
lithium
Space Infrared Telescope Facility
near infrared
open clusters
star clusters
temperature
young
depletion
causes
sensitivity
estimates

Keywords

  • Stars: evolution
  • Stars: low-mass, brown dwarfs
  • Stars: luminosity function, mass function

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Luminosity functions of young clusters : Modeling the substellar mass regime. / Allen, Peter R.; Trilling, David E; Koerner, David W; Reid, I. Neill.

In: Astrophysical Journal, Vol. 595, No. 2 I, 01.10.2003, p. 1222-1230.

Research output: Contribution to journalArticle

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AB - We predict near-infrared luminosity functions of young (5 Myr to 1 Gyr) star clusters by combining evolutionary models of very low mass (1 M J to 0.15 M⊙) dwarfs with empirical bolometric corrections. We identify several characteristic features in our results. These can be attributed to three causes: (1) deuterium burning in the most massive substellar objects; (2) methane absorption in bodies with Teff less than 1300 K, the temperature of the L/T transition; and (3) the formation of dust clouds and the rainout of dust at roughly the same effective temperature as methane formation. Accurate reconstruction of the substellar mass function from luminosity function observations requires that these phenomena are taken into account. At present, few observational studies extend to sufficient sensitivities to allow detection of these effects. However, the luminosity function of the young open cluster IC 2391 shows a clear peak at MI ∼ 14, which we attribute to the result of deuterium burning in substellar objects. The location of this feature is a strong function of age, and we estimate an age of 35 Myr for IC 2391. This is significantly younger than the 53 Myr derived from the location of the lithium depletion boundary but agrees with the main-sequence turnoff age. We consider the implications of this result and our multiband luminosity functions for future observational studies. All predicted luminosity function features are, or will be, accessible to observations using new wide-field IR imagers and the Space Infrared Telescope Facility.

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