J/ApJ/793/62 Triangulum-Andromeda stellar properties (Sheffield+, 2014)
Exploring halo substructure with giant stars.
XIV. The nature of the Triangulum-Andromeda stellar features.
Sheffield A.A., Johnston K.V., Majewski S.R., Damke G., Richardson W.,
Beaton R., Rocha-Pinto H.J.
<Astrophys. J., 793, 62 (2014)>
=2014ApJ...793...62S 2014ApJ...793...62S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Stars, M-type ; Stars, giant ;
Photometry, infrared ; Radial velocities ; Equivalent widths
Keywords: Galaxy: formation - Galaxy: halo - Galaxy: structure
Abstract:
As large-scale stellar surveys have become available over the past
decade, the ability to detect and characterize substructures in the
Galaxy has increased dramatically. These surveys have revealed the
Triangulum-Andromeda (TriAnd) region to be rich with substructures in
the distance range 20-30 kpc, and the relation of these features to
each other, if any, remains unclear. An exploration using Two Micron
All Sky Survey (2MASS) photometry reveals not only the faint sequence
in M giants detected by Rocha-Pinto et al. (2004ApJ...615..732R 2004ApJ...615..732R)
spanning the range 100°<l<160° and -50°<b←15°, but,
in addition, a second, brighter and more densely populated sequence.
These sequences are likely associated with the distinct main sequences
(MSs) discovered (and labeled TriAnd1 and TriAnd2) by Martin et al.
(2007ApJ...668L.123M 2007ApJ...668L.123M) in an optical survey in the direction of M31,
where TriAnd2 is the optical counterpart of the fainter red giant
branch (RGB)/asymptotic giant branch sequence of Rocha-Pinto et al.
Here, the age, distance, and metallicity ranges for TriAnd1 and
TriAnd2 are estimated by simultaneously fitting isochrones to the
2MASS RGB tracks and the optical MS/MS turn-off features. The two
populations are clearly distinct in age and distance: the brighter
sequence (TriAnd1) is younger (6-10 Gyr) and closer (distance of
∼15-21 kpc), whereas the fainter sequence (TriAnd2) is older (10-12 Gyr)
and at an estimated distance of ∼24-32 kpc. A comparison with
simulations demonstrates that the differences and similarities between
TriAnd1 and TriAnd2 can simultaneously be explained if they represent
debris originating from the disruption of the same dwarf galaxy, but
torn off during two distinct pericentric passages.
Description:
To examine what substructures are apparent in TriAnd using the 2MASS
catalog, we selected stars in the region 100°<l<160°,
-50°<b←15°. Colors were restricted to
(J-H)0>0.561(J-KS)0+0.22 and (J-H)0<0.561(J-KS)0+0.36, which
should isolate a relatively pure sample of M giants (Majewski et al.
2003ApJ...599.1082M 2003ApJ...599.1082M). We targeted stars with 9.5<KS,0<12.5.
A reddening restriction of E(B-V)<0.555 was applied to minimize the
contribution of highly reddened sources close to the Galactic plane.
We used the same methodology as Majewski et al. (2003ApJ...599.1082M 2003ApJ...599.1082M)
to deredden the stars (i.e., an interpolated value of the Schlegel et
al. (1998ApJ...500..525S 1998ApJ...500..525S) maps applied to each star).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 92 170 Properties of the Program Stars
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/AJ/125/1352 : Ursa Minor dSph M,T2, DDO51 photometry (Palma+, 2003)
J/AJ/130/2677 : Stars in the Carina dSph galaxy field (Majewski+, 2005)
J/ApJ/649/201 : Velocities and Washington photometry in Carina dSph
(Munoz+, 2006)
J/ApJ/663/960 : Radial velocities of Leo I stars (Sohn+, 2007)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 --- ID Star identifier; HHMMSSs+DDMMSS
16- 21 F6.2 deg GLON Galactic longitude
23- 28 F6.2 deg GLAT Galactic latitude
30- 33 F4.1 mag Ksmag Dereddened 2MASS KS band magnitude
35- 38 F4.2 mag J-Ks Dereddened 2MASS (J-KS) color
40- 45 F6.1 km/s HRV Heliocentric radial velocity
47- 50 F4.1 km/s e_HRV Uncertainty in HRV
52- 53 I2 --- S/N Signal-to-noise ratio
55- 57 F3.1 0.1nm EWNaI1 Na I doublet equivalent width (1)
59- 62 F4.1 0.1nm EWNaI2 Na I doublet equivalent width (2)
64- 74 A11 "date" Date Observation date
76- 82 A7 --- Inst Instrument used in the observation
84 A1 --- Class [DG] Stellar classification (3)
86- 92 A7 --- Group Stellar group (4)
--------------------------------------------------------------------------------
Note (1): By fitting a Gaussian to each line of the doublet simultaneously.
Note (2): By numerical integration (G. Damke et al., in preparation).
Note (3): Classification as follows:
D = dwarf;
G = giant.
Note (4): Indicates which stars have been identified as members of either
TriAnd1 or TriAnd2. All others are labeled "field" for field stars.
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History:
From electronic version of the journal
References:
Majewski et al. Paper I 2000AJ....120.2550M 2000AJ....120.2550M
Majewski et al. Paper II 2000AJ....119..760M 2000AJ....119..760M
Kundu et al. Paper III 2002ApJ...576L.125K 2002ApJ...576L.125K
Palma et al. Paper IV 2003AJ....125.1352P 2003AJ....125.1352P, Cat. J/AJ/125/1352
Crane et al. 2003ApJ...594L.119C 2003ApJ...594L.119C
Rocha-Pinto et al. 2004ApJ...615..732R 2004ApJ...615..732R
Majewski et al. Paper VI 2005AJ....130.2677M 2005AJ....130.2677M, Cat. J/AJ/130/2677
Munoz et al. 2005ApJ...631L.137M 2005ApJ...631L.137M
Westfall et al. Paper VIII 2006AJ....131..375W 2006AJ....131..375W
Munoz et al. 2006ApJ...650L..51M 2006ApJ...650L..51M
Sohn et al. Paper X 2007ApJ...663..960S 2007ApJ...663..960S, Cat. J/ApJ/663/960
Munoz et al. Paper XI 2006ApJ...649..201M 2006ApJ...649..201M, Cat. J/ApJ/649/201
Majewski et al. 2012ApJ...747L..37M 2012ApJ...747L..37M
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 18-Apr-2017