J/AJ/168/103 Hydra spectroscopy of stars in NGC 2204 (Anthony-Twarog+, 2024)
Li evolution among stars of low/intermediate mass: the metal-deficient open
cluster NGC 2204.
Anthony-Twarog B.J., Deliyannis C.P., Steinhauer A., Sun Q., Twarog B.A.
<Astron. J., 168, 103 (2024)>
=2024AJ....168..103A 2024AJ....168..103A
ADC_Keywords: Clusters, open; Radial velocities; Spectra, optical; Abundances;
Rotational velocities; Stars, giant
Keywords: Open star clusters ; Stellar abundances
Abstract:
We have analyzed high-dispersion spectra in the Li 6708Å region
for 167 stars within the anticenter cluster NGC 2204. From
105 probable members, abundance analysis of 45 evolved stars produces
[Fe/H]=-0.40±0.12, [Si/Fe]=0.14±0.12, [Ca/Fe]=0.29±0.07, and
[Ni/Fe]=-0.12±0.10, where quoted errors are standard deviations.
With E(B-V)=0.07 and (m-M)0=13.12, appropriate isochrones provide an
excellent match from the main sequence through the tip of the giant
branch for an age of 1.85±0.05Gyr. Li spectrum synthesis produces
A(Li) below 1.4 at the base of the red giant branch to a detectable
value of -0.4 at the tip. Six probable asymptotic giant branch stars
and all but one red clump star have only Li upper limits. A rapidly
rotating red giant is identified as a possible Li-rich giant, assuming
it is a red clump star. Main-sequence turnoff stars have a
well-defined A(Li)=2.83±0.03 (sem) down to the Li-dip wall at the
predicted mass of 1.29M☉. Despite having the same isochronal age
as the more metal-rich NGC 2506, the luminosity distribution of red
giants reflects a younger morphology similar to NGC 7789, possibly
indicating a deeper impact of metallicity on stellar structure and
A(Li) than previously assumed. As in NGC 2506 and NGC 7789, the NGC
2204 turnoff exhibits a broad range of rotation speeds, making
abundance estimation impossible for some stars. The place of the
cluster within Galactic A(Li) evolution is discussed.
Description:
Spectra for 167 stars in the field of NGC 2204 were obtained in 2014
and 2015 using the Hydra multiobject spectrograph on the WIYN 3.5m
telescope. The adopted spectrograph setup produces spectra centered on
6650Å with an effective spectral resolution of 13300.
Additional spectra for four giant members of NGC 2204, accessed from
the ESO Science Archive Facility were also obtained for program
ID 167.D-0173, PI R. Gratton in 2001 October. The spectra, with S/N
ranging from 116 to 179, were obtained with the Fibre Large Array
Multi Element Spectrograph fiber-feed assembly to the high-resolution
UVES spectrograph.
Objects:
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RA (ICRS) DE Designation(s)
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06 15 31.68 -18 40 12.0 NGC 2204 = Cl Melotte 44
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 87 167 Hydra sample
table4.dat 33 45 [Fe/H] for giants, in order of increasing V magnitude
table5.dat 23 72 Synthesis results for Lithium
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/MNRAS/174/471 : Melotte 66 (Hawarden+, 1976)
J/AJ/113/1723 : UBVI photometry in 4 open clusters (Kassis+, 1997)
J/ApJ/732/39 : Rotational velocities of K giant stars (Carlberg+, 2011)
J/AJ/141/58 : NGC 2204 and NGC 2243 red giant abundances (Jacobson+, 2011)
J/MNRAS/423/122 : Abundances of 93 solar-type Kepler targets (Bruntt+, 2012)
J/A+A/564/A79 : Proper motions of open clusters from UCAC4 (Dias+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/MNRAS/454/2863 : Teff against colours calibrations (Huang+, 2015)
J/AJ/149/121 : WOCS. LXV. Abundances in NGC 6819 (Lee-Brown+, 2015)
J/ApJ/807/82 : Rotational velocities of APOKASC red giants (Tayar+, 2015)
J/AJ/152/192 : WOCS. LXXII. Study of NGC 2506 (Anthony-Twarog+, 2016)
J/AJ/156/37 : Phot. & Li of cool dwarfs in M35 (Anthony-Twarog+, 2018)
J/AJ/155/138 : WOCS. LXXVI. Vel & abund. in NGC2506 (Anthony-Twarog+, 2018)
J/AJ/158/163 : Li abund. values for stars in NGC 6819 (Deliyannis+, 2019)
J/A+A/674/A33 : Gaia synthetic phot. cat. of white dwarfs (Gaia Coll., 2023)
J/AJ/165/105 : Stromgren photometry in M67 (Twarog+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.5 deg RAdeg [93.6/94.2] Right Ascension (ICRS) at Epoch=2016.0
10- 18 F9.5 deg DEdeg [-19/-18.4] Declination (ICRS) at Epoch=2016.0
20- 24 A5 --- WOCS WIYN Open Cluster Survey identifier (G1)
26- 29 I4 --- WEBDA [1115/6330]? WEBDA identifier (Hawarden T.G.
1976MNRAS.174..225H 1976MNRAS.174..225H ; in Simbad)
31- 36 F6.3 mag Vmag [11.49/16.91] Apparent V band magnitude
38- 42 F5.3 mag B-V [0.36/1.77] The (B-V) color index
44- 44 A1 --- Mm Membership: (M)ember, (N)on-member
46- 51 F6.2 km/s RV [-81.4/168.5] Radial velocity
53- 56 F4.2 km/s e_RV [0.5/9.6] Uncertainty in RV
58- 87 A30 --- Notes Additional notes (1)
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Note (1): Code for notes:
1 = Star is outside photometric survey area, Vmag and B-V
synthesized from Gaia DR3 GSPC;
2 = Only VLT spectrum;
3 = Also VLT spectrum;
4 = Photometric variability designated by
Gaia (G), Hawarden (H),
Rozyczka+ 2007AcA....57..323R 2007AcA....57..323R (K) or ASAS-SN (A);
5 = DR3 indicates non-single star;
6 = Reported radial velocity is an average from two epochs
and/or configurations - reported error is average of each
epoch's formal error;
7 = Radial velocity variation detected from Hydra spectra or reported
by Mermilliod & Mayor 2007A&A...470..919M 2007A&A...470..919M (MM);
8 = Gaia magnitude g and V appear discrepant;
9 = Gaia ruwe significantly different from 1.0;
10 = no astrometry in DR3.
Individual notes:
a = Hydra radial velocity estimated from Hα only;
b = RV variability suggested by comparison to
DR2 (79.96±1.34km/s), DR3 (87.94±4.29km/s);
c = RV variability for WOCS4009 suggested by VLT offset and DR3 value;
d = RV value for WOCS11733 is from 2014.
The 2015 values are 83.3±0.74km/s;
e = WOCS24009 reports single epoch only.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- WOCS WIYN Open Cluster Survey identifier
(among nos 1002 to 14011) (G1)
7- 11 F5.2 [-] [Fe/H] [-0.7/-0.27] Metallicity
13- 14 I2 --- N [10/14] Number of measurements
16- 19 F4.2 --- MAD [0.02/0.2] Median absolute deviation
21- 24 I4 K Teff [3805/5161] Effective temperature
26- 28 F3.1 [cm/s2] logg [1/3.3] Log of surface gravity
30- 33 F4.2 km/s Vt [1.3/1.8] Microturbulent velocity ξ
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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- 5 A5 --- WOCS WIYN Open Cluster Survey identifier (G1)
7- 10 F4.1 km/s Vrot [4.4/47.6] Rotational velocity
12- 14 F3.1 km/s e_Vrot [0/3]? Vrot uncertainty
16- 17 A2 --- l_A(Li) [≤ ] Limit flag on A(Li)
19- 23 F5.2 --- A(Li) [-1.5/3] Lithium abundance
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Global notes:
Note (G1): The WIYN Open Cluster Survey (WOCS) numbers are assigned in
a forthcoming photometric survey by A. Steinhauer et al. (2024, in
preparation; SD24). A handful of stars are outside the area covered by
SD24 and are noted by letters A through E.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Nov-2024