J/AJ/165/245 Abundances in 16 red-giant in NGC 7789 (Nagarajan+, 2023)
Chemical Compositions Of Red Giant Stars in the Old Open Cluster NGC7789.
Nagarajan N., Sneden C., Afsar M., Pilachowski C.A.
<Astron. J., 165, 245 (2023)>
=2023AJ....165..245N 2023AJ....165..245N
ADC_Keywords: Clusters, open; Stars, giant; Spectra, optical; Abundances
Keywords: High resolution spectroscopy ; Stellar atmospheres ; Chemically
peculiar giant stars ; Open star clusters
Abstract:
We have gathered optical-region spectra, derived model atmosphere
parameters, and computed elemental abundances for 15 red giant stars
in the open cluster NGC7789. We focus on the light element group CNOLi
that provides clues to evolutionary changes associated with internal
fusion events and chemical mixing. We confirm and extend an early
report that NGC7789 stars 193 and 301 have anomalously large Li
abundances, and that these values are apparently unconnected to any
other elements' abundances in these stars. A companion study of
HeIλ10830 lines in both field stars and cluster members shows
that star 301 has a strong He feature while star 193 does not.
Possible explanations for the large Li abundances of these stars
include helium flash-induced mixing events and binary interactions at
some past or present times. In either case an internal eruption of
energy could cause fresh synthesis of lithium via the Cameron-Fowler
Berillyum transport mechanism. Rapid transport of lithium to the outer
layers may have created significant chromospheric transient
disturbances, producing enough helium ionization to allow for the
strong λ10830 absorption in star 301.
Description:
We gathered high-resolution spectra of the target stars with the
McDonald Observatory 2.7m Harlan J. Smith Telescope and Tull Echelle
Spectrograph. The combination of slit, dispersing elements, and
detector yielded spectral resolution of R∼45000. The observed spectral
range covered 3500-9500Å.
Objects:
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RA (2000) DE Designation(s)
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23 57 20.16 +56 43 33.5 NGC 7789 = C 2354+564
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 49 16 Basic data for target stars adopted from SIMBAD
table3.dat 85 195 Equivalent Widths
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
J/PASP/110/1318 : NGC 7789 CCD VI photometry (Gim+, 1998)
J/AN/321/277 : Effective temperatures of K-M giants (Strassmeier+, 2000)
J/A+A/431/933 : Abundances of NGC 7789 evolved stars (Tautvaisiene+, 2005)
J/AN/328/938 : Teff/line-depth ratio for ELODIE spectra (Biazzo+, 2007)
J/A+A/523/A48 : Gaia photometry (Jordi+, 2010)
J/A+A/511/A56 : Abundances of five open clusters (Pancino+, 2010)
J/AJ/142/59 : Chemical abundance in 10 open clusters (Jacobson+, 2011)
J/MNRAS/446/3562 : Abundances of red giants in NGC752 (Bocek Topcu+, 2015)
J/AJ/149/15 : Spectroscopy of NGC 7789 (Overbeek+, 2015)
J/MNRAS/463/580 : Abundances of red giants in NGC6940 (Bocek+, 2016)
J/A+A/618/A93 : Gaia DR2 open clusters in Milky Way (Cantat-Gaudin+, 2018)
J/MNRAS/484/2000 : Study of Lithium-rich giants with GALAH (Deepak+, 2019)
J/ApJ/879/105 : Effective temp of low-mass stars (Lopez-Valdivia+, 2019)
J/A+A/655/A23 : Open cluster red clump stars Lit abundances (Magrini+, 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Name [72/1101] Star identifier from
Kustner, 1923VeBon..18....1K 1923VeBon..18....1K
( in Simbad)
6 A1 --- f_Name [a] a: note on Star 193 (1)
8- 13 F6.4 mas plx [0.4/0.7] Parallax
15- 20 F6.3 mas pmRA [-1.13/8.5] Proper motion in RA
22- 27 F6.3 mas pmDE [-2.45/-1.7] Proper motion in DEC
29- 33 F5.2 mag Gmag [9.86/12.65] Gaia G band magnitude
35- 38 F4.2 mag BP-RP [1.48/2.22]? Gaia BP-RP color index
40- 44 F5.2 mag Vmag [10.74/13.05] SIMBAD V magnitude
46- 49 F4.2 mag B-V [1.14/1.9]? SIMBAD B-V color index
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Note (1): Note as follows:
a = Inspection of the parallax and proper motion data in this table reveals
that star 193 is discordant and likely not a member of NGC 7789. The
possibility that star 193 is a nonmember arose in
Pilachowski (1986ApJ...300..289P 1986ApJ...300..289P), but the star was not discarded
because its high Li abundance would make the star interesting
regardless of its membership status. See Text.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Species Atomic species identifier
7- 13 F7.2 0.1nm Wave [4545/7836] Wavelength; Angstroms
15- 19 F5.3 eV chi [0.24/6.19] Excitation energy
21- 25 F5.2 [-] loggf [-4.61/0.55] log transition probability
27- 29 I3 10-13m EW-72 [22/299]? Star 72 equivalent width
31- 33 I3 10-13m EW-193 [28/321]? Star 193 equivalent width
35- 37 I3 10-13m EW-301 [24/275]? Star 301 equivalent width
39- 41 I3 10-13m EW-329 [27/266]? Star 329 equivalent width
43- 45 I3 10-13m EW-353 [23/261]? Star 353 equivalent width
47- 49 I3 10-13m EW-461 [22/299]? Star 461 equivalent width
51- 53 I3 10-13m EW-468 [29/290]? Star 468 equivalent width
55- 57 I3 10-13m EW-494 [19/327]? Star 494 equivalent width
59- 61 I3 10-13m EW-501 [15/275]? Star 501 equivalent width
63- 65 I3 10-13m EW-637 [28/236]? Star 637 equivalent width
67- 69 I3 10-13m EW-669 [26/285]? Star 699 equivalent width
71- 73 I3 10-13m EW-765 [26/243]? Star 765 equivalent width
75- 77 I3 10-13m EW-970 [24/272]? Star 970 equivalent width
79- 81 I3 10-13m EW-1066 [25/279]? Star 1066 equivalent width
83- 85 I3 10-13m EW-1101 [16/209]? Star 1101 equivalent width
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 12-Jan-2024