J/ApJ/767/51 Clusters of starburst galaxy NGC4214 (Andrews+, 2013)
An initial mass function study of the dwarf starburst galaxy NGC 4214.
Andrews J.E., Calzetti D., Chandar R., Lee J.C., Elmegreen B.G.,
Kennicutt R.C., Whitmore B., Kissel J.S., da Silva R.L., Krumholz M.R.,
O'Connell R.W., Dopita M.A., Frogel J.A., Kim H.
<Astrophys. J., 767, 51 (2013)>
=2013ApJ...767...51A 2013ApJ...767...51A
ADC_Keywords: Galaxies, nearby ; Photometry, H-alpha ; Extinction
Keywords: galaxies: individual: NGC 4214;
galaxies: star clusters: general; galaxies: star formation
stars: luminosity function, mass function; stars: massive
Abstract:
The production rate of ionizing photons in young (≤8Myr), unresolved
stellar clusters in the nearby irregular galaxy NGC 4214 is probed
using multi-wavelength Hubble Space Telescope WFC3 data. We normalize
the ionizing photon rate by the cluster mass to investigate the upper
end of the stellar initial mass function (IMF). We have found that
within the uncertainties the upper end of the stellar IMF appears to
be universal in this galaxy, and that deviations from a universal IMF
can be attributed to stochastic sampling of stars in clusters with
masses ≲103M☉. Furthermore, we have found that there does
not seem to be a dependence of the maximum stellar mass on the cluster
mass. We have also found that for massive clusters, feedback may cause
an underrepresentation in Hα luminosities, which needs to be
taken into account when conducting this type of analysis.
Description:
Observations were taken with HST WFC3/UVIS and WFC3/IR as part of
GO 11360 (PI: O'Connell). The observations on which we concentrate
here include F225W (1665s), F336W (1683s), F438W (1530s), F547M
(1820s), F657N (1592s), F814W (1339s), F110W (1198s), and F128N
(1198s), as shown in Figure 1. For ease of discussion, we will refer
to these as NUV, U, B, V, Hα, I, J, and Pβ, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 52 Ages, masses, and extinctions of clusters
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See also:
J/A+A/549/A70 : NGC 4214 multiband images (Hermelo+, 2013)
J/ApJ/755/40 : HII regions in the Magellanic clouds (Pellegrini+, 2012)
J/ApJ/744/44 : Hα and UV fluxes in nearby galaxies (Weisz+, 2012)
J/ApJS/192/6 : A GALEX UV imaging survey of nearby galaxies (Lee+, 2011)
J/ApJ/706/599 : Hα and UV SFR in the local volume (Lee+, 2009)
J/ApJS/178/247 : Hα and [NII] survey in local 11 Mpc (Kennicutt+, 2008)
J/AJ/133/917 : HST photometry of two NGC 4214 clusters (Ubeda+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/434] Identification number
5 A1 --- f_ID [c] PSF consistent with a high-mass star (1)
7- 8 I2 h RAh [12] Hour of right ascension (J2000)
10- 11 I2 min RAm [15] Minute of right ascension (J2000)
13- 18 F6.3 s RAs [34.5/45.7] Second of right ascension (J2000)
20 A1 --- DE- [+] Sign of declination (J2000)
21- 22 I2 deg DEd [36] Degree of declination (J2000)
24- 25 I2 arcmin DEm [18/21] Arcminute of declination (J2000)
27- 31 F5.2 arcsec DEs Arcsecond of declination (J2000)
33- 35 F3.1 Myr Age1 [2.1/7.5] SLUG age (2)
37- 39 F3.1 Myr e_Age1 [0.4/3] Age1 uncertainty
41- 45 F5.2 10+3Msun Mass1 [0.49/94] SLUG mass (2)
47- 50 F4.1 10+3Msun E_Mass1 [0.1/40] Positive uncertainty on Mass1
52- 55 F4.1 10+3Msun e_Mass1 [0.4/40] Negative uncertainty on Mass1
57- 60 F4.2 mag E(B-V)1 [0/0.4] SLUG extinction (2)
62- 64 F3.1 Myr Age2 [3.2/7.6] SB99 age (2)
66- 70 F5.2 10+3Msun Mass2 [0.1/97.81] SB99 mass (2)
72- 75 F4.2 mag E(B-V)2 [0/0.4] SB99 extinction (2)
77 A1 --- l_LHa [l] Limit flag on LHa (3)
79- 85 E7.2 10-7W LHa Hα luminosity
86 A1 --- f_LHa [d] Luminosity derived from literature (4)
88- 93 A6 --- OName Other designation (5)
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Note (1): c = PSF consistent with a single star at the distance of NGC 4214
(FWHM∼1.3pc), and SED colors consistent with either a single O star with
several low-mass (B5 or later) stars or a few early-B type stars.
See section 3.2.
Note (2): In order to accurately determine ages and masses of the clusters,
the spectral energy distributions (SEDs) created from the photometry
of the NUV, U, B, V, I observations were compared to stellar synthesis
models. While the norm has been to use deterministic models such as
STARBURST99 (SB99; Leitherer et al. 1999ApJS..123....3L 1999ApJS..123....3L), we mainly
focused on the stochastic models of SLUG (da Silva et al.
2012ApJ...745..145D 2012ApJ...745..145D, Stochastically Lighting Up Galaxies).
See section 3.1.
Note (3): l = clusters with only 3σ detections of Hα.
Clusters 1-4 likely contain Hα emission, but due to size and
nearness of other clusters have blown cavities surrounding them.
Note (4): d = Luminosity derived from Table 3 in MacKenty et al.
(2000AJ....120.3007M 2000AJ....120.3007M).
Note (5): Other names come from MacKenty et al. (2000AJ....120.3007M 2000AJ....120.3007M;
<[MMP2000] R-ANa> in Simbad).
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 11-May-2015