J/ApJ/811/78 Elemental depletions in the Magellanic Clouds (Tchernyshyov+, 2015)
Elemental depletions in the Magellanic Clouds and the evolution of depletions
with metallicity.
Tchernyshyov K., Meixner M., Seale J., Fox A., Friedman S.D., Dwek E.,
Galliano F.
<Astrophys. J., 811, 78 (2015)>
=2015ApJ...811...78T 2015ApJ...811...78T (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds ; Spectra, ultraviolet ; Stars, giant
Keywords: dust, extinction; galaxies: abundances; ISM: abundances;
Magellanic Clouds
Abstract:
We present a study of the composition of gas and dust in the Large and
Small Magellanic Clouds (LMC and SMC) using UV absorption
spectroscopy. We measure PII and FeII along 84 spatially distributed
sightlines toward the MCs using archival Far Ultraviolet Spectroscopic
Explorer observations. For 16 of those sightlines, we also measure
SiII, CrII, and ZnII from new Hubble Space Telescope Cosmic Origins
Spectrograph observations. We analyze these spectra using a new
spectral line analysis technique based on a semi-parametric Voigt
profile model. We have combined these measurements with HI and H2
column densities and reference stellar abundances from the literature
to derive gas-phase abundances, depletions, and gas-to-dust ratios
(GDRs). Of our 84 P and 16 Zn measurements, 80 and 13, respectively,
are depleted by more than 0.1dex, suggesting that P and Zn abundances
are not accurate metallicity indicators at and above the metallicity
of the SMC. Si, Cr, and Fe are systematically less depleted in the SMC
than in the Milky Way (MW) or LMC. The minimum Si depletion in the SMC
is consistent with zero. We find GDR ranges of 190-565 in the LMC and
480-2100 in the SMC, which is broadly consistent with GDRs from the
literature. These ranges represent actual location to location
variation and are evidence of dust destruction and/or growth in the
diffuse neutral phase of the interstellar medium. Where they overlap
in metallicity, the gas-phase abundances of the MW, LMC, and SMC and
damped Lyα systems evolve similarly with metallicity.
Description:
The spectra presented in this study are a combination of new
observations from the Cosmic Origins Spectrograph (COS) on the Hubble
Space Telescope (HST) along 16 sightlines and supplementary archival
spectra for these 16 and 69 additional sightlines from the Far
Ultraviolet Spectroscopic Explorer (FUSE).
The COS spectra of the Magellanic Cloud sightlines presented here were
obtained between 2012 October 12 and 2013 August 19 as part of HST
program number 13004. Observations were conducted with the near-UV
(NUV) G185M grating at central wavelengths of 1921 and 1953Å and a
spectral resolution of 17km/s.
Data for the 69 supplementary sightlines, of which 32 are toward the
LMC and 37 are toward the SMC, have been downloaded from the FUSE MC
Legacy Project archive (Blair et al. 2009, J/PASP/121/634) and
analyzed with no further processing.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 16 Locations, stellar parameters, and ISM parameters
of the COS sample
table2.dat 74 16 Logarithmic ion column densities toward LMC and
SMC targets in the COS sample
table3.dat 51 70 Logarithmic ion column densities towards LMC and
SMC targets in the FUSE sample
table5.dat 78 86 Phosphorus, zinc, silicon, chromium, and
iron depletions in the LMC and SMC
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See also:
J/AJ/146/62 : HERschel HERITAGE in Magellanic Clouds (Meixner+, 2013)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJ/745/173 : UV absorption sight lines of LMC and SMC (Welty+, 2012)
J/A+A/530/A33 : DLA depletion estimations (Vladilo+, 2011)
J/MNRAS/404/1321 : TiII in Milky way and Magellanic clouds (Welty+, 2010)
J/ApJ/702/940 : Radio and UV spectra of HVC toward the MC (Lehner+, 2009)
J/ApJ/700/1299 : Gas-phase element depletions in the ISM (Jenkins, 2009)
J/PASP/121/634 : FUSE observations in Magellanic Clouds (Blair+, 2009)
J/AJ/136/1039 : CaII index of SMC red giant branch stars (Carrera+, 2008)
J/A+A/466/277 : VLT-FLAMES survey of massive stars (Hunter+, 2007)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/A+A/445/93 : Abundances of DLAs (Dessauges-Zavadsky+, 2006)
J/A+A/324/435 : Chemical composition of 6 K supergiants in the SMC (Hill 1997)
J/A+A/293/347 : LMC F supergiants (Hill+, 1995)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Target Target name
11- 13 A3 --- Gal Galaxy identifier ("SMC" or "LMC")
15- 21 F7.4 deg RAdeg Right ascension in decimal degrees (J2000) (1)
23- 30 F8.4 deg DEdeg Declination in decimal degrees (J2000) (1)
32- 42 A11 --- SpT MK spectral type (1)
44- 48 F5.2 mag Vmag [11.3/13.8] V-band magnitude (1)
50- 53 F4.2 --- E(B-V) [0.1/0.4] E(B-V) (total) (1)
55- 59 F5.2 --- logNHI [20.5/22] Log HI column density (1)
61- 65 F5.2 --- logNH2 [14.7/21] Log H2 column density (1)
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Note (1): All values from Welty et al. (2012, J/ApJ/745/173) and
references therein.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Target Target name
11- 13 A3 --- Gal Galaxy identifier ("SMC" or "LMC")
15- 19 F5.2 [cm-2] logNPII [12.3/14.1] Log P II column density
21- 24 F4.2 [cm-2] e_logNPII [0.01/1.4] logNPII uncertainty
26- 30 F5.2 [cm-2] logNZnII [12.5/13.4] Log Zn II column density
32- 35 F4.2 [cm-2] e_logNZnII [0.02/0.4] logNZnII uncertainty
37- 41 F5.2 [cm-2] logNSiII [15.1/16.1] Log Si II column density
43- 46 F4.2 [cm-2] e_logNSiII [0.01/0.2] logNSiII uncertainty
48- 52 F5.2 [cm-2] logNCrII [11.4/13.8] Log Cr II column density
54- 57 F4.2 [cm-2] e_logNCrII [0.02/1.1] logNCrII uncertainty
59- 63 F5.2 [cm-2] logNFeII [13.9/15.5] Log Fe II column density
65- 68 F4.2 [cm-2] e_logNFeII [0.01/2.1] logNFeII uncertainty
70- 74 F5.2 [cm-2] logN(H) [20.5/22] Log hydrogen column density
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Target Target identifier
21- 23 A3 --- Gal Galaxy identifier ("SMC" or "LMC")
25- 29 F5.2 [cm-2] logN(PII) [12.6/14.8] Log P II column density
31- 34 F4.2 [cm-2] e_logN(PII) [0.01/0.5] Uncertainty in logN(PII)
36- 40 F5.2 [cm-2] logN(FeII) [14/15.8] Log Fe II column density
42- 45 F4.2 [cm-2] e_logN(FeII) [0/0.5] Uncertainty in logN(FeII)
47- 51 F5.2 [cm-2] logN(H) [20.4/22] Log hydrogen column density (1)
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Note (1): Hydrogen column densities are from Welty et al. (2012, J/ApJ/745/173)
and references therein. The typical hydrogen column density
uncertainty is approximately 10%.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Target Target identifier
21- 23 A3 --- Gal Galaxy identifier ("SMC" or "LMC")
25- 29 F5.2 --- delP [-2.3/0.6] Phosphorus depletion (1)
31- 34 F4.2 --- e_delP [0.07/1.5] Uncertainty in delP
36- 40 F5.2 --- delZn [-0.9/-0.03]? Zinc depletion (1)
42- 45 F4.2 --- e_delZn [0.1/0.4]? Uncertainty in delZn
47- 51 F5.2 --- delSi [-1.3/0.01]? Silicon depletion (1)
53- 56 F4.2 --- e_delSi [0.06/0.2]? Uncertainty in delSi
58- 62 F5.2 --- delCr [-3/-0.3]? Chromium depletion (1)
64- 67 F4.2 --- e_delCr [0.07/1.1]? Uncertainty in delCr
69- 73 F5.2 --- delFe [-2.8/-0.2] Iron depletion (1)
75- 78 F4.2 --- e_delFe [0.06/2.2] Uncertainty in delFe
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Note (1): Where the depletion is defined by equations 6 and 7 in Section 3.3.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 24-Dec-2015