J/ApJ/703/2177 Metal-poor MS turnoff stars summary (Schlaufman+, 2009)
Insight into the formation of the Milky Way through cold halo substructure.
I. The ECHOS of Milky Way formation.
Schlaufman K.C., Rockosi C.M., Prieto C.A., Beers T.C., Bizyaev D.,
Brewington H., Lee Y.S., Malanushenko V., Malanushenko E., Oravetz D.,
Pan K., Simmons A., Snedden S., Yanny B.
<Astrophys. J., 703, 2177-2204 (2009)>
=2009ApJ...703.2177S 2009ApJ...703.2177S
ADC_Keywords: Milky Way ; Stars, metal-deficient
Keywords: Galaxy: formation - Galaxy: halo - Galaxy: kinematics and dynamics
Abstract:
We identify 10 -- seven for the first time -- elements of cold halo
substructure (ECHOS) in the volume within 17.5kpc of the Sun in the
inner halo of the Milky Way. Our result is based on the observed
spatial and radial velocity distribution of metal-poor main-sequence
turnoff (MPMSTO) stars in 137 Sloan Extension for Galactic
Understanding and Exploration lines of sight. We show that all of our
detections are statistically significant and that we expect no false
positives. These ECHOS represent the observable stellar debris of
ancient merger events in the stellar accretion history of the Milky
Way, and we use our detections and completeness estimates to infer a
formal upper limit of 0.34+0.02-0.02 on the fraction of the MPMSTO
population in the inner halo that belong to ECHOS.
Description:
The SEGUE survey obtained 240000 moderate-resolution (R∼1800)
fiber-fed spectra of Milky Way stars in the magnitude interval
14.0<g<20.3. The spectroscopic targets were selected using SDSS
photometry and additional SEGUE ugriz imaging data at low Galactic
latitude and in the South Galactic Cap. In this analysis, we use the
subset of SEGUE targets selected as metal-poor main-sequence turnoff
(MPMSTO) stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 69 137 Summary of completeness calculation
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See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/AJ/136/2070 : SEGUE stellar parameter pipeline. III. (Allende Prieto+, 2008)
J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 F5.1 deg RAdeg Right Ascension in decimal degrees (J2000)
7- 11 F5.1 deg DEdeg Declination in decimal degrees (J2000)
13- 17 F5.1 deg GLON Galactic longitude
19- 23 F5.1 deg GLAT Galactic latitude
25- 27 I3 --- Ns [10/173] Number of spectra obtained along that
line of sight that lie in the inner halo as
defined in Section 2
29- 32 I4 --- Np Number of photometrically classified MPMSTO stars
in the volume scanned by SEGUE along that line
of sight that lie in the inner halo as defined
in Section 2 (1)
34- 38 F5.3 kpc3 Vol Volume
40 A1 --- l_Ob Limit flag on Ob
41- 45 F5.2 --- Ob [0/1] Fraction of total MPMSTO spectra sample
that must belong to a single cold element of
substructure for it to be classified as a bin
detection 95% of the time (1)
47 A1 --- l_OI Limit flag on OI
48- 52 F5.2 --- OI [0/1] Fraction of total MPMSTO spectra sample
that must belong to a single cold element of
substructure for it to be classified as a
class I detection 95% of the time (1)
54 A1 --- l_OII Limit flag on OII
55- 59 F5.2 --- OII [0/1] Fraction of total MPMSTO spectra sample
that must belong to a single cold element of
substructure for it to be classified as a
class II detection 95% of the time (1)
61- 69 A9 --- Com Comment (Strm = stream)
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Note (1): MPMSTO = metal-poor main-sequence turnoff stars.
See Section 3.3 for the classes of peak detections.
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History:
From electronic version of the journal
References:
Schlaufman et al. Paper II. 2011ApJ...734...49S 2011ApJ...734...49S
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 03-Nov-2011