J/A+A/572/A42 SagDIG carbon and oxygen stars (Momany+, 2014)
On the HI-hole and AGB stellar population of the Sagittarius dwarf irregular
galaxy. HST proper-motion decontamination.
Momany Y., Clemens M., Bedin L.R., Gullieuszik M., Held E.V., Saviane I.,
Zaggia S., Monaco L., Montalto M., Rich R.M., Rizzi L.
<Astron. Astrophys. 572, A42 (2014)>
=2014A&A...572A..42M 2014A&A...572A..42M
ADC_Keywords: Galaxies, nearby ; Galaxies, photometry ; Photometry, HST
Keywords: galaxy: dwarf - galaxies: ISM - stars: AGB and post-AGB -
stars: carbon - Hertzprung-Russell (HR) and C-M diagrams - astrometry
Description:
The Sagittarius dwarf irregular (also known as SagDIG or UKS 1927-177)
is a gas-rich, low-metallicity and star-forming galaxy, at the
outskirts (D∼1.1Mpc) of the Local Group. Projected relatively close
to the Galactic center [(l,b)=(21.06,-16.29)] the resolved stellar
populations of this galaxy reflects a strong Galactic foreground
contamination, attributed to the thin and thick disk and the halo.
This has so far hampered the reconstruction of its star formation and
chemical enrichment history, and studies of individual stars.
We have analyzed two ACS@HST data-sets (GO-9820 and GO-10472) that
were collected in August 2003 and June 2005, having a ∼1.85 years
epoch separation. The data has allowed the derivation of the relative
proper-motion for the SagDIG stellar population and reduction of the
heavy foreground contamination. This provides a much clearer view of
the red stellar populations (young RSG and intermediate-age AGB as
well as the old RGB and AGB).
The ACS/WFC data was collected in the F475W, F606W and F814W HST
filters, and the published table provides a photometric calibration of
the ACS/WFC filters that follows Bedin et al. (2003AJ....126..247B 2003AJ....126..247B).
This is based on the Vega spectrum and follows the recipes given by
Holtzmann et al. (1995PASP..107..156H 1995PASP..107..156H) for WFPC2, using the most
updated in-flight characterization of the camera (Sirianni et al.
2005PASP..117.1049S 2005PASP..117.1049S). Besides the reported magnitudes and their
relative errors, we also provide the pixel-based offset between the
two F814W epochs, which is used to separate the SagDIG stellar
population from the Galactic foreground (see Sec.3 of the paper for
details).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 86 15681 The SagDIG photometric and astrometric properties
of the known carbon and oxygen stars in our
ACS@HST central pointing
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See also:
J/AJ/119/777 : Sagittarius dwarf irregular galaxy BVRI photometry (Lee+, 2000)
J/A+A/513/A62 : Sgr dSph VIMOS photometry & radial velocities (Giuffrida+ 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- Seq [1/5002639] Sequential star identification number
9- 20 F12.8 deg RAdeg Right ascension (J2000)
22- 33 F12.8 deg DEdeg Declination (J2000)
35- 40 F6.3 mag F475W ?=99.999 HST/ACS F475W visual magnitude (1)
42- 46 F5.3 mag e_F475W ?=9.999 F475W visual magnitude rms (1)
48- 53 F6.3 mag F606W ?=99.999 HST/ACS F606W visual magnitude (1)
55- 59 F5.3 mag e_F606W ?=9.999 F606W visual magnitude rms (1)
61- 66 F6.3 mag F814W ?=99.999 HST/ACS F814W visual magnitude (1)
68- 72 F5.3 mag e_F814W ?=9.999 F814W visual magnitude rms (1)
74- 79 F6.3 pix Xoff [-1/1]?=9.999 Relative proper motion along X-axis
(ACS 0.05"/pixel)
81- 86 F6.3 pix Yoff [-1/1]?=9.999 Relative proper motion along Y-axis
(ACS 0.05"/pixel)
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Note (1): If an object has not been measured in a filter, a flag equal to
99.999 is set for magnitude value and 9.999 for magnitude rms.
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Acknowledgements:
Yazan Momany, yazan.almomany(at)oapd.inaf.it
(End) Patricia Vannier [CDS] 26-Aug-2014