J/AJ/146/85 Spectral types of 1576 optical stars in ONC (Hillenbrand+, 2013)
An enhanced spectroscopic census of the Orion Nebula Cluster.
Hillenbrand L.A., Hoffer A.S., Herczeg G.J.
<Astron. J., 146, 85 (2013)>
=2013AJ....146...85H 2013AJ....146...85H
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; Spectral types
Keywords: stars: pre-main sequence
Abstract:
We report new spectral types or spectral classification constraints
for over 600 stars in the Orion Nebula Cluster (ONC) based on medium
resolution (R~1500-2000) red optical spectra acquired using the
Palomar 200" and Kitt Peak 3.5m telescopes. Spectral types were
initially estimated for F, G, and early K stars from atomic line
indices while for late K and M stars, which constitute the majority of
our sample, indices involving TiO and VO bands were used. To ensure
proper classification, particularly for reddened, veiled, or
nebula-contaminated stars, all spectra were then visually examined for
type verification or refinement. We provide an updated spectral type
table that supersedes previous work, increasing the percentage of
optically visible ONC stars with spectral type information from 68% to
90%. However, for many objects, repeated observations have failed to
yield spectral types primarily due to the challenges of adequate sky
subtraction against a bright and spatially variable nebular
background. The scatter between our new and our previously determined
spectral types is approximately two spectral sub-classes. We also
compare our grating spectroscopy results with classification based on
narrow-band TiO filter photometry, finding similar scatter. While the
challenges of working in the ONC may explain much of the spread, we
highlight several stars showing significant and unexplained bona fide
spectral variations in observations taken several years apart; these
and similar cases could be due to a combination of accretion and
extinction changes. Finally, nearly 20% of ONC stars exhibit obvious
CaII triplet emission indicative of strong accretion.
Description:
We obtained low-resolution optical spectra in 15 configurations with
the HYDRA multi-object spectrograph on the 3.5m WIYN telescope at Kitt
Peak during two runs in 2006-2007 (2006 Jan 13, 2006 Jan 15, and 2007
Jan 5-7). We obtained spectra from 5000-10000Å at R∼1500. We also
used the Norris multi-object spectrograph on the 5m Hale Telescope at
Palomar in 1999. The spectral range is 6100-8750Å at R∼2000.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 120 1576 ONC spectral types
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See also:
II/171 : Parenago Catalog of Stars in Orion Nebula (Parenago 1954)
J/ApJ/722/1092 : Optical photometry of the ONC. II. (Da Rio+, 2010)
J/ApJ/677/401 : Xray properties of protostars in ONC (Prisinzano+, 2008)
J/ApJ/671/605 : NGC 2264 and ONC PMS stars in the infrared (Cieza+, 2007)
J/AJ/134/2272 : Visual binaries in the Orion Nebula Cluster (Reipurth+, 2007)
J/ApJ/646/297 : Spitzer observations of pms stars (Rebull+, 2006)
J/A+A/458/461 : Binary stars in the Orion Nebula Cluster (Koehler+, 2006)
J/AJ/129/363 : Spectroscopy in Orion Nebula Cluster (Sicilia-Aguilar+, 2005)
J/ApJ/574/258 : X-ray-emitting young stars in Orion (Feigelson+, 2002)
J/AJ/113/1733 : Orion Nebula Cluster population (Hillenbrand 1997)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Star [1/9326] Star identifier (1)
5 A1 --- m_Star [ab] Component (a or b)
7 A1 --- f_Star [e] Plate defects or nebular knots (2)
9 I1 h RAh Hour of Right Ascension (J2000)
11- 12 I2 min RAm Minute of Right Ascension (J2000)
14- 18 F5.2 s RAs Second of Right Ascension (J2000)
20 A1 --- DE- Sign of the Declination (J2000)
21 I1 deg DEd Degree of Declination (J2000)
23- 24 I2 arcmin DEm Arcminute of Declination (J2000)
26- 29 F4.1 arcsec DEs Arcsecond of Declination (J2000)
31- 96 A66 --- SpT1 Previously reported spectral type (3)
98-118 A21 --- SpT2 Newly reported spectral type (4)
120 A1 --- f_SpT2 [f] Nebular contamination (5)
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Note (1): Star numbers adopted:
* #1-1053 from Jones and Walker (1988AJ.....95.1755J 1988AJ.....95.1755J)
* #1054-2999 from Parenago (1954, cat. II/171)
* #9000-9999 from Prosser et al., 1994ApJ...421..517P 1994ApJ...421..517P
(number is 9000 plus the Prosser number)
* #3000-3999 from Hillenbrand (1997, cat. J/AJ/113/1733; 1993 January CCD data)
* #5000-5999 from Hillenbrand (1997, cat. J/AJ/113/1733; 1995 January CCD data)
* #6000-6999 from Hillenbrand (1997, cat. J/AJ/113/1733; 1996 January CCD data)
Note (2): e = Several optically identified objects from previous studies
apparently are plate defects (JW 459, JW 699) or nebular knots (PSH 9081,
PSH 9326, H97 3071, H97 3089) rather than true stellar point sources. We
list them here for completeness but these sources should be removed from
future lists of ONC stellar objects.
Note (3): The sources of the literature spectral types are as listed in
Hillenbrand (1997, cat. J/AJ/113/1733) with more recent additions as
detailed in the text. The codes in brackets are:
B = Blanco (1963ApJ...137..513B 1963ApJ...137..513B);
C = Correia et al. (2013A&A...557A..63C 2013A&A...557A..63C);
CK = Cohen & Kuhi (1979ApJS...41..743C 1979ApJS...41..743C);
D = Duncan (1993ApJ...406..172D 1993ApJ...406..172D);
Dae = Daemgen et al. (2012A&A...540A..46D 2012A&A...540A..46D);
E = Edwards et al. (1993AJ....106..372E 1993AJ....106..372E);
GS = Greenstein & Struve (1946PASP...58..366G 1946PASP...58..366G);
H = Hillenbrand (1997, cat. J/AJ/113/1733) and subsequent updates to
electronically available table. An "e" indicates emission in the
CaII triplet lines. A "<" indicates spectral type is earlier than
that listed while ">" indicates spectral type is later than that
listed;
Ham = C. Hamilton 1994 unpublished masters thesis;
Her = Herbig, quoted in Walker (1969ApJ...155..447W 1969ApJ...155..447W);
HP = Herbig 1996, private communication;
HT = Herbig & Terndrup (1986ApJ...307..609H 1986ApJ...307..609H) or reference therein;
J = Johnson (1965ApJ...142..964J 1965ApJ...142..964J);
LA = Levato & Abt (1976PASP...88..712L 1976PASP...88..712L) or Abt & Levato
(1977PASP...89..797A 1977PASP...89..797A);
LDW = Lallemand, Duchesne & Walker (1960PASP...72..268L 1960PASP...72..268L);
LR = Luhman et al. (2000, cat. J/ApJ/540/1016);
Luc01 = Lucas et al. (2001MNRAS.326..695L 2001MNRAS.326..695L), by matching given positions to
known objects of similar magnitude within 2" and translating quoted
log-g=4Teff values into a SpT using the same Teff-SpT calibration
employed in Hillenbrand (1997, cat. J/AJ/113/1733), largely from CK;
Luc06 = Lucas et al. (2006MNRAS.373L..60L 2006MNRAS.373L..60L);
M = McNamara (1976AJ.....81..845M 1976AJ.....81..845M);
P = Prosser & Stauffer 1995, private communication;
Par = Parenago (1954, cat. II/171);
Petal = Penston et al. (1975MNRAS.171..219P 1975MNRAS.171..219P) or Penston
(1973ApJ...183..505P 1973ApJ...183..505P);
R = Rhode et al. (2001AJ....122.3258R 2001AJ....122.3258R) identification of SB2's;
RRL = Riddick et al. (2007MNRAS.381.1077R 2007MNRAS.381.1077R), by matching given positions
to known objects of similar magnitude within 2";
S = Strand (1958ApJ...128...14S 1958ApJ...128...14S) reference (mostly to Sharpless);
Sam = A.E. Samuel 1993 unpublished PhD thesis;
SBB = Smith et al. (1983ApJ...271..237S 1983ApJ...271..237S);
SHC = Slesnick et al. (2004ApJ...610.1045S 2004ApJ...610.1045S). SHC indiates optical
spectral types and SHC-ir infrared spectral types;
Sta = K. Stassun 2005, private communication, low dispersion spectra;
Ste = H C. Stempels 2008, private communication, high dispersion spectra;
T = Trumpler (1931PASP...43..255T 1931PASP...43..255T);
vA = van Altena et al. (1988AJ.....95.1744V 1988AJ.....95.1744V);
W = Walker (1983ApJ...271..642W 1983ApJ...271..642W);
WLR = Weights et al. (2009MNRAS.392..817W 2009MNRAS.392..817W), by matching given positions
to known objects of similar magnitude within 2"; method is similar to
Luc and latest types may be too late);
WSH = Wolff et al. (2004, cat. J/ApJ/601/979);
Note (4): Spectral type derived in the present study, from the Kitt Peak/WIYN
data and/or the Palomar/Norris data. Many stars were classified based on
several different spectra and in the cases of disagreements multiple types
are listed.
Note (5): f = These sources have nebular contamination in our spectra but may in
clude some CaII emission contribution.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 10-Jul-2014