J/ApJ/871/151 METAL Hubble program. I. Initial results (Roman-Duval+, 2019)
METAL: the Metal Evolution, Transport, and Abundance in the Large Magellanic
Cloud Hubble program.
I. Overview and initial results.
Roman-Duval J., Jenkins E.B., Williams B., Tchernyshyov K., Gordon K.,
Meixner M., Hagen L., Peek J., Sandstrom K., Werk J., Merica-Jones P.Y.
<Astrophys. J., 871, 151 (2019)>
=2019ApJ...871..151R 2019ApJ...871..151R
ADC_Keywords: Abundances; Infrared sources; Interstellar medium;
Magellanic Clouds; Reddening; Stars, OB; Spectra, ultraviolet;
Spectral types
Keywords: dust, extinction ; ISM: abundances ; ISM: atoms
Abstract:
Metal Evolution, Transport, and Abundance in the Large Magellanic
Cloud (METAL) is a large cycle 24 program on the Hubble Space
Telescope aimed at measuring dust extinction properties and
interstellar depletions in the Large Magellanic Cloud (LMC) at
half-solar metallicity. The 101-orbit program is composed of Cosmic
Origins Spectrograph (COS) and Space Telescope Imaging Spectrograph
(STIS) spectroscopy toward 33 LMC massive stars between 1150 and
3180Å and parallel Wide Field Camera 3 (WFC3) imaging in seven
near-UV to near-IR filters. The fraction of silicon in the gas phase
(depletion) obtained from the spectroscopy decreases with increasing
hydrogen column density. Depletion patterns for silicon differ between
the Milky Way, LMC, and Small Magellanic Cloud (SMC), with the silicon
depletion level offsetting almost exactly the metallicity differences,
leading to constant gas-phase abundances in those galaxies for a given
hydrogen column density. The silicon depletion correlates linearly
with the absolute-to-selective extinction, RV, indicating a link
between gas depletion and dust grain size. Extinction maps are derived
from the resolved stellar photometry in the parallel imaging, which
can be compared to far-IR images from Herschel and Spitzer to estimate
the emissivity of dust at LMC metallicity. The full METAL sample of
depletions, UV extinction curves, and extinction maps will inform the
abundance, size, composition, and optical properties of dust grains in
the LMC, comprehensively improve our understanding of dust properties,
and improve the accuracy with which dust-based gas masses, star
formation rates, and star formation histories in nearby and
high-redshift galaxies are estimated. This overview paper describes
the goals, design, data reduction, and initial results of the METAL
survey.
Description:
We selected our targets from the Welty+ (2012, J/ApJ/745/173) catalog
of massive stars in the LMC that have Far Ultraviolet Spectroscopic
Explorer (FUSE) archival data and spectroscopically determined HI and
H2 column densities.
The METAL (Metal Evolution and TrAnsport in the Large Magellanic
Cloud) large Hubble Space Telscope (HST) program (101 orbits,
GO-14675) obtained high signal-to-noise ratio (S/N) UV spectra toward
33 massive stars with STIS and COS between 2016 September and 2017 July.
In addition to UV spectroscopy, METAL obtained parallel Wide Field
Camera 3 (WFC3) NUV-near-IR (NIR) imaging in seven filters to map
the dust column density and extinction properties of the 2175Å
bump-in the vicinity of the LMC massive stars to derive extinction
maps and characterize the FIR emissivity of dust at half-solar
metallicity.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 60 33 Spectroscopic targets and their stellar parameters
table2.dat 70 33 Spectroscopic targets and their interstellar parameters
table4.dat 74 36 *Silicon gas-phase column densities and depletions from
Metal Evolution, Transport, and Abundance (METAL)
table5.dat 48 32 Local standard of rest (LSR) velocities of the
intermediate-velocity cloud (IVC) and high velocity
cloud (HVC)
table9.dat 88 224 Parameters of the parallel wild field camera 3 (WFC3)
imaging
table10.dat 81 207 Photometric depth for the WFC3 observations
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Note on table4.dat: All measurements are from medium resolution
data except for SK-67 5 and SK-70 115, Si II column densities were
also derived from archival E230H/1913 spectra (program GO-9757).
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/ApJS/93/211 : IUE survey of H I Lyα absorption. I. (Diplas+ 1994)
J/AJ/117/2244 : HST color-magnitude diagrams of the LMC (Olsen, 1999)
J/ApJS/147/61 : Interstellar Ca I absorption (Welty+, 2003)
J/A+A/421/937 : Metal abundances of LMC RR Lyrae (Gratton+, 2004)
J/MNRAS/357/645 : LMC far-UV HST observations (Almoznino+, 2005)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/ApJ/700/1299 : Gas-phase element depletions in the ISM (Jenkins, 2009)
J/ApJ/702/940 : Radio and UV spectra of HVC toward the MC (Lehner+, 2009)
J/ApJS/197/16 : CO obs. of LMC molecular clouds (MAGMA). (Wong+, 2011)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJ/753/71 : Mass-loss return from LMC evolved stars. VI. (Riebel+, 2012)
J/ApJ/745/173 : UV absorption sight lines of LMC and SMC (Welty+, 2012)
J/AJ/146/62 : HERschel HERITAGE in Magellanic Clouds (Meixner+, 2013)
J/ApJS/215/9 : PHAT X. UV-IR photometry of M31 stars (Williams+, 2014)
J/A+A/578/A46 : Evolution of galaxy clusters metal abundance (Ettori+, 2015)
J/ApJ/811/78 : Elemental depletions Magellanic Clouds (Tchernyshyov+, 2015)
J/ApJ/822/105 : Chemical evolution in the SMC (Acharyya+, 2016)
J/MNRAS/458/4074 : UVES Advanced Data Products Quasar Sample.VI. (Quiret+,2016)
J/MNRAS/457/2814 : SAGE SMC evolved stars candidates (Srinivasan+, 2016)
J/A+A/606/A50 : Fe-rich silicate analogues mass absorption coeff. (Demyk+,2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Name Target name
11-12 I2 h RAh [4/5] Hour of right ascension (J2000) (G1)
14-15 I2 min RAm Minute of right ascension (J2000)
17-22 F6.3 s RAs Second of right ascension (J2000)
24-24 A1 --- DE- Sign of the declination (J2000) (G1)
25-26 I2 deg DEd Degree of declination (J2000) (G1)
28-29 I2 arcmin DEm Arcminute of declination (J2000)
31-35 F5.2 arcsec DEs Arcsecond of declination (J2000)
37-48 A12 --- SpType Spectral type of massive star target
50-54 F5.1 km/s vsini [0/296]? Rotational velocity (v*sin(i)) of target
56-60 F5.2 mag Vmag [10/14] V-band magnitude of target
from Welty+ (2012, J/ApJ/745/173)
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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 --- Name Target name
11-12 I2 h RAh [4/5] Hour of Right Ascension (J2000) (G1)
14-15 I2 min RAm Minute of Right Ascension (J2000)
17-22 F6.3 s RAs Second of Right Ascension (J2000)
24-24 A1 --- DE- Sign of the Declination (J2000) (G1)
25-26 I2 deg DEd Degree of Declination (J2000) (G1)
28-29 I2 arcmin DEm Arcminute of Declination (J2000)
31-35 F5.2 arcsec DEs Arcsecond of Declination (J2000)
37-40 F4.2 mag E(B-V) [0.08/0.4]? Reddening
42-46 F5.2 [cm-2] logNHI-LMC [19/22] HI column density, LMC gas, log (1)
48-51 F4.2 [cm-2] e_logNHI-LMC [0.02/0.68]? Uncertainty in logNHI-LMC
53-57 F5.2 [cm-2] logNH2 [13.9/21] H2 column density (2)
59-63 F5.2 [cm-2] logNHI-MW [18/22]? HI column density, MW gas, log (1)
65-68 F4.2 [cm-2] e_logNHI-MW [0.01/1.4]? Uncertainty in logNHI-MW
70-70 A1 --- Shell Nearby HI shell ? y=yes or n=no
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Note (1): HI column densities are from this work (see Section 4.1), except
for SK-69 220, which is from Welty+ (2012, J/ApJ/745/173).
Note (2): The H2 column densities are from Welty+ (2012, J/ApJ/745/173).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Target name
11- 17 A7 --- Set Source code (E230H, E230M or "adopted") (1)
21- 25 F5.2 [cm-2] logNH [19/22] Total hydrogen column density, log (2)
27- 30 F4.2 [cm-2] e_logNH [0.02/0.68] Uncertainty in logNH
32- 34 I3 km/s Vmin [180/240]? Heliocentric velocity range,
minimum
36- 38 I3 km/s Vmax [270/370]? Heliocentric velocity range,
maximum
40- 44 F5.1 0.1pm EW [63.9/387.1]? Equivalent width, SiII, (mÅ)
46- 49 F4.1 0.1pm e_EW [6.2/58]? Uncertainty in EW
51- 51 A1 --- l_logNSiII Limit flag for logNSiII
52- 56 F5.2 [cm-2] logNSiII [15.07/16.15] SiII column density
58- 62 F5.3 [cm-2] e_logNSiII [0.02/0.21]? Uncertainty in logNSiII
64- 64 A1 --- l_dSi Limit flag for dSi
65- 69 F5.2 --- dSi [-1.31/0.15]? Si depletion (3)
71- 74 F4.2 --- e_dSi [0.06/0.69]? Uncertainty in dSi (3)
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Note (1): The "Adopted" column density is from the high-resolution measurement.
Note (2): Total hydrogen column density=N(HI)+2N(H2), where N(HI) is
derived from the METAL spectra in Section 4.1 and N(H2) is from
Welty+ (2012, J/ApJ/745/173).
Note (3): Depletions are derived assuming a reference abundance of Silicon
of 12+log(Si/H)=7.35. The random error on depletions combines in
quadrature the error on Si and H column densities.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Target name
11-21 F11.8 deg RAdeg [71/88] Right ascension (J2000) (G1)
23-34 F12.8 deg DEdeg [-72/-65] Declination (J2000) (G1)
36-36 I1 km/s VLSR-MW [0/5] Local Standard of rest velocity,
attributed to MW
38-39 I2 km/s VLSR-IVC [50/95] Local standard of rest velocity,
attributed to IVC
41-43 I3 km/s VLSR-HVC [0/184] Local standard of rest velocity,
attributed to HVC
45-48 I4 km/s VLSR-LMC [220/305] Local standard of rest velocity,
attributed to LMC
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Byte-by-byte Description of file: table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Primary Target
11-19 A9 --- Root Root
21-34 F14.11 deg RAdeg [71/88] Field center right ascension (J2000)
36-50 F15.11 deg DEdeg [-72/-65] Field center declination (J2000)
52-61 F10.6 deg PA [9/359] Position angle of observation
63-66 A4 --- Det Detector used ("IR" or "UVIS")
68-72 A5 --- Filt Filter used (F110W, F160W, F225W, F336W, F475W,
F814W)
74-84 F11.6 s Exp [120/2215] Exposure time
86-88 F3.1 s PF [1.6/4.3]? Post-Flash time
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Byte-by-byte Description of file: table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Primary Target
11-27 A17 --- Field Field Name
29-42 F14.11 deg RAdeg [71/88] Field center right ascension (J2000)
44-58 F15.11 deg DEdeg [-72/-65] Field center declination (J2000)
60-64 A5 --- Filt Filter used (F110W, F160W, F225W, F336W, F475W,
F814W)
66-76 F11.6 s Exp [120/2215] Total exposure time
78-81 F4.1 mag Depth [23.4/27.6] Depth, Vega magnitudes (1)
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Note (1): The depth is given as the Vega mag corresponding to the 50%
completeness limit in the artificial star tests.
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Global notes:
Note (G1): Sk-69 279 is more likely at 05 41 44.655 -69 35 14.90 (J2000)
or 85.43606541 -69.58747351 (J2000); coordinates have been updated
for Tables 1, 2 and 5 at CDS.
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History:
From electronic version of the journal
References:
Roman-Duval et al. Paper II. 2021ApJ...910...95R 2021ApJ...910...95R Cat. J/ApJ/910/95
(End) Prepared by [AAS], Coralie Fix [CDS] 24-Feb-2020