J/ApJ/867/62 White dwarf population of Messier 67 (Williams+, 2018)
Ensemble properties of the white dwarf population of the old, solar metallicity
open star cluster Messier 67.
Williams K.A., Canton P.A., Bellini A., Bolte M., Rubin K.H.R.,
Gianninas A., Kilic M.
<Astrophys. J., 867, 62 (2018)>
=2018ApJ...867...62W 2018ApJ...867...62W
ADC_Keywords: Clusters, open; Stars, white dwarf; Photometry, SDSS;
Spectra, optical; Spectral types; Redshifts; Stars, masses
Keywords: open clusters and associations: individual (M67) ; stars: evolution ;
white dwarfs
Abstract:
White dwarfs (WDs) are excellent forensic tools for studying
end-of-life issues surrounding low- and intermediate-mass stars, and
the old, solar metallicity open star cluster Messier 67 is a proven
laboratory for the study of stellar evolution for solar-type stars. In
this paper, we present a detailed spectroscopic study of brighter
(Mg≤12.4) WDs in Messier 67, and in combination with previously
published proper motion membership determinations, we identify a
clean, representative sample of cluster WDs, including 13 members with
hydrogen-dominated atmospheres, at least one of which is a candidate
double degenerate, and 5 members with helium-dominated atmospheres.
Using this sample we test multiple predictions surrounding the final
stages of stellar evolution in solar-type stars. In particular, the
stochasticity of the integrated mass lost by ∼1.5 solar mass stars is
less than 7% of the WD remnant mass. We identify WDs likely resulting
from binary evolution, including at least one blue straggler remnant
and two helium-core WDs. We observe no evidence of a significant
population of helium-core WDs formed by enhanced mass loss on the red
giant branch of the cluster. The distribution of WD atmospheric
compositions is fully consistent with that in the field, limiting
proposed mechanisms for the suppression of helium atmosphere WD
formation in star clusters. In short, the WD population of Messier 67
is fully consistent with basic predictions of single- and
multiple-star stellar evolution theories for solar metallicity stars.
Description:
We obtained imaging data with the Megacam wide-field CCD imager on the
MMT 6.5m telescope over three nights in 2004 Mar 22 and 2005 Jan 11-13.
Total exposure times were 21000s in u, 2400s in g, and 1800s in r.
We obtained spectroscopic data with the Low-Resolution Imaging
Spectrograph (LRIS) on the Keck I telescope over four nights in 2007
Jan 19-20 and 2010 Feb 8-9.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 102 52 White dwarf candidate photometry
table5.dat 38 33 Spectroscopically confirmed white dwarfs
table6.dat 36 16 Spectroscopic identifications of non-white dwarfs
table7.dat 50 25 Derived quantities and cluster membership for DA WDs
sp/* . 46 Individual reduced spectra in FITS format;
shown in Figures 4-6
--------------------------------------------------------------------------------
See also:
III/211 : Keck/HIRES Sky Line Atlas (Osterbrock+ 1997)
III/210 : Spectroscopically Identified White Dwarfs (McCook+, 1999)
VII/270 : SDSS quasar catalog: tenth data release (Paris+, 2014)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
J/AJ/106/181 : CCD photometry of open cluster M67 (Montgomery+ 1993)
J/AJ/112/628 : BATC Color Survey of M67 (Fan+ 1996)
J/ApJ/576/880 : CCD UBV photometry of h and χ Per (Slesnick+, 2002)
J/A+A/418/509 : Chandra observation of M67 (Van Den Berg+, 2004)
J/ApJS/156/47 : DA white dwarfs from the Palomar Green Survey (Liebert+, 2005)
J/AJ/132/1221 : VJHK and SDSS photometry of DA white dwarfs (Holberg+, 2006)
J/ApJ/723/1072 : The ELM survey. I. Low-mass white dwarfs (Brown+, 2010)
J/ApJ/743/138 : Spectroscopic survey of bright white dwarfs (Gianninas+, 2011)
J/ApJ/730/128 : Spectroscopy of DA WD from the SDSS-DR4 (Tremblay+, 2011)
J/ApJ/812/167 : The ELM survey. VI. 11 new ELM WD binaries (Gianninas+, 2015)
J/MNRAS/446/4078 : New white dwarf stars in SDSS DR10 (Kepler+, 2015)
J/A+A/583/A86 : DB white dwarfs in SDSS DR10 and DR12 (Koester+, 2015)
J/ApJ/848/11 : Spectroscopic and photometric analysis of WDs (Bedard+, 2017)
J/A+A/616/A10 : 46 open clusters Gaia DR2 diag. HR (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 1 I1 --- Set [1/2] Spectra subset (1)
3- 8 I6 --- Seq [2231/292440] Running index (2)
10- 10 I1 h RAh [8] Hour of Right Ascension (J2000)
12- 13 I2 min RAm [50/52] Minute of Right Ascension (J2000)
15- 19 F5.2 s RAs Second of Right Ascension (J2000)
21 A1 --- DE- [+] Sign of Declination (J2000)
22- 23 I2 deg DEd [11] Degree of Declination (J2000)
25- 26 I2 arcmin DEm [37/58] Arcminute of Declination (J2000)
28- 31 F4.1 arcsec DEs Arcsecond of Declination (J2000)
33- 38 F6.3 mag gmag [18.6/24.2] Megacam/MMT g band magnitude
40- 44 F5.3 mag e_gmag [0.02/0.05] Uncertainty in gmag
46- 51 F6.3 mag (u-g) [-0.5/1.2] Megacam/MMT u-g color index
53- 57 F5.3 mag e_(u-g) [0.02/0.2] Uncertainty in (u-g)
59- 64 F6.3 mag (g-r) [-0.6/0.8] Megacam/MMT g-r color index
66- 70 F5.3 mag e_(g-r) [0.02/0.08] Uncertainty in (g-r)
72- 72 A1 --- f_gmag c=Star off plate in our r image;
data from SDSS DR14
74- 97 A24 --- OID Cross-identification(s) (3)
99-102 A4 --- Ref Reference(s) (4)
--------------------------------------------------------------------------------
Note (1): Spectra selection criteria subset as follows:
1 = WD candidates (35 occurrences)
2 = Entries do not meet the post facto photometric criteria but were
targeted spectroscopically either due to results of first-iteration
photometric reduction or the desire to fill slit masks with targets
to explore parameter space outside the formal selection criteria.
Note (2): Running index from DAOphot photometry files used as identifier in
slit mask design.
Note (3): Cross-identification(s) from Simbad coordinate matches within
3 arcsec radius.
Note (4): References as follows:
1 = Montgomery et al. (1993, J/AJ/106/181);
2 = van den Berg et al. (2004, J/A+A/418/509);
3 = Luyten (1963LB....C32....1L 1963LB....C32....1L);
4 = Pasquini et al. (1994A&A...290L..17P 1994A&A...290L..17P);
5 = Fleming et al. (1997ASSL..214...91F 1997ASSL..214...91F);
6 = Fan et al. (1996, J/AJ/112/628);
7 = Kepler et al. (2015, J/MNRAS/446/4078);
8 = Paris et al. (2014A&A...563A..54P 2014A&A...563A..54P).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- Seq [2231/207569] Running index (1)
8- 11 A4 --- Alias WD alias used in paper; spectra file naming
13- 18 F6.3 mag gmag [18.6/24] Megacam/MMT g band magnitude
20- 24 F5.3 mag e_gmag [0.02/0.04] Uncertainty in gmag
26- 27 A2 --- Mask Mask name (2)
29- 33 A5 --- SpT White dwarf spectral type
35 A1 --- f_SpT c=Spectral type from
Kepler+ 2015, J/MNRAS/446/4078
37 A1 --- Mm Proper Motion cluster member from
Bellini+ (2010A&A...513A..50B 2010A&A...513A..50B);
column added by CDS from Table 8
38 A1 --- f_Mm b=Outside the region studied by
Bellini+ (2010A&A...513A..50B 2010A&A...513A..50B)
--------------------------------------------------------------------------------
Note (1): Running index from DAOphot photometry files used as identifier in
slit mask design
Note (2): Spectroscopic observing log (Table 4):
-----------------------------------------------------------------------------
UT date Mask Nexp Exp Comments
(s)
-----------------------------------------------------------------------------
2007 Jan 19 f2 9 1200 FWHM=0.9"
f3 6 1200
2007 Jan 20 f1 9 1200 FWHM = 1.0"; clear skies
f4 8 1200
LS ^a 2 600 Target: LB 3600
2010 Feb 8 ma 9 1200 FWHM=1"
md 10 1200 Seeing steadily degrading; FWHM=1"-1.5"
2010 Feb 9 mc 6 1200
mb 3 1200 Poor guiding
me 9 1200
-----------------------------------------------------------------------------
Note ^a: 1.0" wide long slit.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- Seq [3477/292440] Running index (1)
8- 13 F6.3 mag gmag [20/24.2] Megacam/MMT g band magnitude
15- 19 F5.3 mag e_gmag [0.03/0.05] Uncertainty in gmag
21- 28 A8 --- Type Spectra based type (2)
30- 34 F5.3 --- zspec [0.08/2.6]? Spectroscopic redshift;
null (blank) for stars
36 A1 --- f_Seq Observation Notes (3)
--------------------------------------------------------------------------------
Note (1): Running index from DAOPHOT photometry files used as identifier in
slit mask design.
Note (2): Type as follows:
ELG = Emission-line galaxy (4 occurrences);
QSO = Quasar (8 occurrences);
E+A = 2 occurrences;
A star = 1 occurrence
F/G star = 1 occurrence
Note (3): Observation notes as follows:
b = Emission-line galaxy;
c = Not observed in this work; data from Paris+ (2014A&A...563A..54P 2014A&A...563A..54P).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 1 I1 --- Set [1/3] WD subset (1)
3- 6 A4 --- Alias WD alias used in paper
8- 8 A1 --- Sol Atmospheric solution; H: Hot; C:Cold
10- 14 F5.3 Msun Mwd [0.2/0.8] Derived WD mass, solar units
16- 20 F5.3 Msun e_Mwd [0.009/0.5] Uncertainty in Mwd
22- 27 F6.3 mag gMag [8.1/13.9] Absolute g magnitude
29- 33 F5.3 mag e_gMag [0.02/0.8] Uncertainty in Mgmag
35- 40 F6.3 mag d(m-M) [-3/1.4] Difference of WD and cluster apparent
distance moduli
42- 46 F5.3 mag e_d(m-M) [0.04/0.8] Uncertainty in d(m-M)
48 A1 --- PMMm Proper Motion member from
Bellini+ 2010A&A...513A..50B 2010A&A...513A..50B
50 A1 --- PhMm Photometric sequence member? (Y:Yes; N:No;
B: candidate binary member)
--------------------------------------------------------------------------------
Note (1): Table subset(s) as follows:
1 = members;
2 = objects considered field (non-member) WDs;
3 = have too large of errors in spectral parameters to constrain
photometric membership meaningfully.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 09-Oct-2019