Bibcode
DOI
Vaduvescu, Ovidiu; Richer, Michael G.; McCall, Marshall L.
Bibliographical reference
The Astronomical Journal, Volume 131, Issue 3, pp. 1318-1335.
Advertised on:
3
2006
Citations
29
Refereed citations
27
Description
A sample of 16 blue compact dwarf galaxies (BCDs) in the Virgo Cluster
has been imaged in the near-infrared (NIR) in J and Ks on the
2.1 m telescope at the Observatorio Astronómico Nacional in the
Sierra San Pedro Mártir in Mexico. Isophotes as faint as
μJ=24 mag arcsec-2 and
μKs=23 mag arcsec-2 have been
reached in most of the targets. Surface brightness profiles can be
fitted across the whole range of radii by the sum of two components: a
hyperbolic secant (sech) function, which is known to fit the light
profiles of dwarf irregular galaxies (dIs), and a Gaussian component,
which quantifies the starburst near the center. Isophotal and total
fitted NIR magnitudes have been calculated, along with semimajor axes at
μJ=23 mag arcsec-2 and
μKs=22 mag arcsec-2. The diffuse
underlying component and the young starburst have been quantified using
the profile fitting. Most color profiles show a constant color, between
J-Ks=0.7 and 0.9 mag. The diffuse component represents the
overwhelming majority of the NIR light for most BCDs, with the starburst
enhancing the flux by less than about 0.3 mag. Linear correlations were
found between the sech scale length and the sech magnitude and between
the sech semimajor axis and the sech magnitude. Overall, galaxies with
more luminous diffuse components are larger and brighter in the center.
The central burst correlates with the diffuse component, with brighter
BCDs having stronger starbursts, suggesting that more massive objects
are forming stars more efficiently. BCDs lie on the ``fundamental
plane'' defined by dIs in Paper I, following the same relation between
sech absolute magnitude, sech central surface brightness, and the
hydrogen line width W20, although the scatter is larger than
for the dIs. On the other hand, correlations between the sech absolute
magnitude and the sech central surface brightness in Ks for
BCDs and dIs are equally good, indicating that BCD line widths may be
enhanced by turbulence or winds.
These data were acquired at the Observatorio Astronómico Nacional
in the Sierra San Pedro Mártir, Mexico.