The impact of chromospheric activity on observed initial mass functions

Keivan G. Stassun, Aleks Scholz, Trent J. Dupuy, Kaitlin Kratter

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass function (IMF) across the stellar/substellar boundary in the Upper Sco star-forming region (age 5-10 Myr). We adjust the observed effective temperatures to warmer values using the observed strength of the chromospheric Hα emission, and redetermine the estimated masses of objects using pre-main-sequence evolutionary tracks in the H-R diagram. The effect of the activity-adjusted temperatures is to shift the objects to higher masses by 3%-100%. While the slope of the resulting IMF at substellar masses is not strongly changed, the peak of the IMF does shift from 0.06 to 0.11 M . Moreover, for objects with masses ≲ 0.2 M , the ratio of brown dwarfs to stars changes from 80% to 33%. These results suggest that activity corrections are essential for studies of the substellar mass function, if the masses are estimated from spectral types or from effective temperatures.

Original languageEnglish (US)
Article number119
JournalAstrophysical Journal
Volume796
Issue number2
DOIs
StatePublished - Dec 1 2014

Fingerprint

stars
temperature
shift
diagram
diagrams
slopes
calibration
radii
effect

Keywords

  • Brown dwarfs
  • Stars: activity
  • Stars: fundamental parameters
  • Stars: low-mass
  • Stars: luminosity function, mass function

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

The impact of chromospheric activity on observed initial mass functions. / Stassun, Keivan G.; Scholz, Aleks; Dupuy, Trent J.; Kratter, Kaitlin.

In: Astrophysical Journal, Vol. 796, No. 2, 119, 01.12.2014.

Research output: Contribution to journalArticle

Stassun, Keivan G. ; Scholz, Aleks ; Dupuy, Trent J. ; Kratter, Kaitlin. / The impact of chromospheric activity on observed initial mass functions. In: Astrophysical Journal. 2014 ; Vol. 796, No. 2.
@article{aae615a9e16e4737aaf2946ba2d689cb,
title = "The impact of chromospheric activity on observed initial mass functions",
abstract = "Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass function (IMF) across the stellar/substellar boundary in the Upper Sco star-forming region (age 5-10 Myr). We adjust the observed effective temperatures to warmer values using the observed strength of the chromospheric Hα emission, and redetermine the estimated masses of objects using pre-main-sequence evolutionary tracks in the H-R diagram. The effect of the activity-adjusted temperatures is to shift the objects to higher masses by 3{\%}-100{\%}. While the slope of the resulting IMF at substellar masses is not strongly changed, the peak of the IMF does shift from 0.06 to 0.11 M . Moreover, for objects with masses ≲ 0.2 M , the ratio of brown dwarfs to stars changes from 80{\%} to 33{\%}. These results suggest that activity corrections are essential for studies of the substellar mass function, if the masses are estimated from spectral types or from effective temperatures.",
keywords = "Brown dwarfs, Stars: activity, Stars: fundamental parameters, Stars: low-mass, Stars: luminosity function, mass function",
author = "Stassun, {Keivan G.} and Aleks Scholz and Dupuy, {Trent J.} and Kaitlin Kratter",
year = "2014",
month = "12",
day = "1",
doi = "10.1088/0004-637X/796/2/119",
language = "English (US)",
volume = "796",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "2",

}

TY - JOUR

T1 - The impact of chromospheric activity on observed initial mass functions

AU - Stassun, Keivan G.

AU - Scholz, Aleks

AU - Dupuy, Trent J.

AU - Kratter, Kaitlin

PY - 2014/12/1

Y1 - 2014/12/1

N2 - Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass function (IMF) across the stellar/substellar boundary in the Upper Sco star-forming region (age 5-10 Myr). We adjust the observed effective temperatures to warmer values using the observed strength of the chromospheric Hα emission, and redetermine the estimated masses of objects using pre-main-sequence evolutionary tracks in the H-R diagram. The effect of the activity-adjusted temperatures is to shift the objects to higher masses by 3%-100%. While the slope of the resulting IMF at substellar masses is not strongly changed, the peak of the IMF does shift from 0.06 to 0.11 M . Moreover, for objects with masses ≲ 0.2 M , the ratio of brown dwarfs to stars changes from 80% to 33%. These results suggest that activity corrections are essential for studies of the substellar mass function, if the masses are estimated from spectral types or from effective temperatures.

AB - Using recently established empirical calibrations for the impact of chromospheric activity on the radii, effective temperatures, and estimated masses of active low-mass stars and brown dwarfs, we reassess the shape of the initial mass function (IMF) across the stellar/substellar boundary in the Upper Sco star-forming region (age 5-10 Myr). We adjust the observed effective temperatures to warmer values using the observed strength of the chromospheric Hα emission, and redetermine the estimated masses of objects using pre-main-sequence evolutionary tracks in the H-R diagram. The effect of the activity-adjusted temperatures is to shift the objects to higher masses by 3%-100%. While the slope of the resulting IMF at substellar masses is not strongly changed, the peak of the IMF does shift from 0.06 to 0.11 M . Moreover, for objects with masses ≲ 0.2 M , the ratio of brown dwarfs to stars changes from 80% to 33%. These results suggest that activity corrections are essential for studies of the substellar mass function, if the masses are estimated from spectral types or from effective temperatures.

KW - Brown dwarfs

KW - Stars: activity

KW - Stars: fundamental parameters

KW - Stars: low-mass

KW - Stars: luminosity function, mass function

UR - http://www.scopus.com/inward/record.url?scp=84911407387&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84911407387&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/796/2/119

DO - 10.1088/0004-637X/796/2/119

M3 - Article

AN - SCOPUS:84911407387

VL - 796

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 119

ER -