J/A+A/488/167 Low-mass stars in σ Ori and λ Ori (Sacco+, 2008)
FLAMES spectroscopy of low-mass stars in the young clusters σ Ori
and λ Ori.
Sacco G.G., Franciosini E., Randich S., Pallavicini R.
<Astron. Astrophys., 488, 167-179 (2008)>
=2008A&A...488..167S 2008A&A...488..167S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, late-type ; Photometry, infrared ;
Spectroscopy
Keywords: stars: formation - stars: pre-main sequence - stars: late-type -
Galaxy: open clusters and associations:
individual: sigma Ori, lambda Ori
Abstract:
We performed a detailed membership selection and studied the accretion
properties of low-mass stars in the two apparently very similar young
(1-10Myr) clusters σ Ori and λ Ori.
We observed 98 and 49 low-mass (0.2-1.0M☉stars in σ Ori
and λ Ori respectively, using the multi-object optical
spectrograph FLAMES at the VLT, with the high-resolution (R∼17000)
HR15N grating (6470-6790Å). We used radial velocities, Li and
Hα to establish cluster membership and Hα and other
optical emission lines to analyze the accretion properties of members.
We identified 65 and 45 members of the σ Ori and λ Ori
clusters, respectively, and discovered 16 new candidate binary
systems.
Description:
Observations were carried out using the fiber-fed multi-object
spectrograph FLAMES (Fiber Large Array Multi Element Spectrograph),
mounted on the UT2 telescope at the VLT and operated in the MEDUSA
mode (132 fibers, each with an aperture of 1.2" on the sky).
Observations were performed in service mode and were divided into
separate runs of 1h duration each, including instrument overheads.
The σ Ori cluster was observed in 6 runs in October and
December 2004, while λ Ori was observed in 8 runs in October
and November 2005.
Objects:
-------------------------------------------------
RA (2000) DE Designation(s)
-------------------------------------------------
05 38 48.9 -02 34 22 sigma Ori = HR 1931
05 35 06.5 +09 56 00 lambda Ori = HIP 26207
-------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 131 98 Photometry and membership for the observed sample
stars in σ Ori cluster
table2.dat 131 49 Photometry and membership for the observed sample
stars in λ Ori cluster
table4.dat 82 65 Accretion properties of σ Ori cluster members
table5.dat 81 45 Accretion properties of λ Ori cluster members
rv.dat 27 144 Radial velocities of the candidate binary systems
identified in σ and λ Ori cluster
samples (table 6 and 7 of the paper)
--------------------------------------------------------------------------------
See also:
J/A+A/419/249 : RJHKs photometry of sigma Ori low-mass stars (Scholz+, 2004)
J/AJ/128/2316 : BVRIJHKs photometry in sigma Ori cluster (Sherry+, 2004)
J/AN/325/705 : RIJHKs of low-mass stars in sigma Ori (Bejar+, 2004)
J/MNRAS/356/89 : sigma Ori low-mass stars (Kenyon+, 2005)
J/MNRAS/356/1583 : RV of Sigma Ori low-mass cand. members (Burningham+, 2005)
J/AJ/118/2409 : VRI photometry of lambda Ori PMS stars (Dolan+, 1999)
J/ApJ/610/1064 : Substellar pop. of lambda Ori (Barrado y Navascues+, 2004)
Byte-by-byte Description of file: table[12].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- [SFR2008] Object identification (G1)
5- 23 A19 --- Name Name (1)
25- 26 I2 h RAh Right ascension (J2000) (2)
28- 29 I2 min RAm Right ascension (J2000) (2)
31- 35 F5.2 s RAs Right ascension (J2000) (2)
37 A1 --- DE- Declination sign (J2000) (2)
38- 39 I2 deg DEd Declination (J2000) (2)
41- 42 I2 arcmin DEm Declination (J2000) (2)
44- 47 F4.1 arcsec DEs Declination (J2000) (2)
49- 53 F5.2 mag Imag ? I magnitude
55- 58 F4.2 mag R-I ? R-I colour index
60 I1 --- r_R-I [1/5]? I,R photometry reference (3)
62- 66 F5.2 mag Jmag ? 2MASS J magnitude
68- 71 F4.2 mag H-Ks ? 2MASS H-Ks colour index
73- 76 A4 --- SpT MK spectral type
77 A1 --- n_SpT [*] * for spectroscopic spectral type (4)
79- 84 F6.2 km/s RV ? Mean radial velocity
86- 89 F4.2 km/s e_RV ? rms uncertainty on RV
91 A1 --- l_vsini Limit flag on vsini
92- 96 F5.1 km/s vsini ? Rotational velocity
98-101 F4.1 km/s E_vsini ? Error on vsini (upper limit)
104-106 F3.1 km/s e_vsini ? Error on vsini (lower limit)
108-110 I3 0.1nm EW(Li) ? Li pseudo-equivalent width (G2)
112-114 I3 0.1nm e_EW(Li) ? rms uncertainty on EW(Li)
115 A1 --- n_EW(Li) [Y/N] For double-lined spectroscopic binary (5)
117 A1 --- MVt [Y?N] Membership from tangential velocity
119 A1 --- MLi [Y?N] Membership from Li measurements
121-122 A2 --- MHa [YN? ] Membership from Hα measurements
124-125 A2 --- Mmb [YN? ] Final membership
127 A1 --- X [YN-] Detection line flag in XMM field
(Yes, No or outside XMM field)
129-131 A3 --- Notes Notes
--------------------------------------------------------------------------------
Note (1): Star names are from the following sources:
NNNN-NNNN = Wolk (1996, Ph.D. Thesis), [W96] NNNN-NNNN in Simbad
rHHMMSS+DDMM = Wolk (1996, Ph.D. Thesis), [W96] rJHHMMSS+DDMM in Simbad
pHHMMSS+DDMM = Wolk (1996, Ph.D. Thesis), [W96] pJHHMMSS+DDMM in Simbad
SE NNN = Scholz & Eisloeffel (2004, Cat. J/A+A/419/249),
[SE2004] NNN in Simbad
SWW NNN = Sherry et al. (2004, Cat. J/AJ/128/2316),
[SWW2004] JHHMMSS.sss+DDMMSS.ss in Simbad
JHHMMSS.s+DDMMSS = Bejar et al. (2004, Cat. J/AN/325/705) and
Zapatero Osorio et al. (2002A&A...384..937Z 2002A&A...384..937Z),
[BMZ2001] S Ori JHHMMSS.s+DDMMSS and
K N.NN-NNNN = Kenyon et al. (2005, Cat. J/MNRAS/356/89),
[KJN2005] F.FF NNNN in Simbad
B N.NN-NNNN = Burningham et al. (2005, Cat. J/MNRAS/356/1583),
[KJN2005] F.FF NNNN in Simbad
2M JHHMMSSss-DDMMSSs = 2MASS catalogue, 2MASS JHHMMSSss-DDMMSSs in Simbad
DM NN = Dolan & Mathieu (1999, Cat. J/AJ/118/2409),
[DM99] NN in Simbad
LORi NNN = Barrado y Navascues et al. (2004, Cat. J/ApJ/610/1064)
LOri-CFHT NNN in Simbad
For object S92, J053826.8-022846 is a misprint for J053826.8-023846
(corrected in the table)
Note (2): Coordinates from 2MASS (II/246) catalog.
Note (3): Optical photometric data are taken from the following sources:
1 = Sherry et al. (2004, Cat. J/AJ/128/2316)
2 = Wolk (1996, Ph.D. Thesis)
3 = Kenyon et al. (2005, Cat. J/MNRAS/356/1583)
4 = Dolan & Mathieu (1999, Cat. J/AJ/118/2409)
5 = Barrado y Navascues et al. (2004)
Note (4): Spectral types marked with asterisk have been derived
spectroscopically by Zapatero Osorio et al. (2002A&A...384..937Z 2002A&A...384..937Z)
for σ Ori and by Barrado y Navascues et al. (2004) for λ
Ori. The other spectral types have been derived from photometry
(see Sect. 2.1 of paper).
Note (5): For double-lined spectroscopic binary, we only indicate whether
the line is identified (Y) or not (N)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[45].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- [SFR2008] Object identification (G1)
5- 11 F7.2 0.1nm w(Ha) ? Hα pseudo-equivalent width (G2)
13- 17 F5.2 0.1nm e_w(Ha) ? rms uncertainty on w(Ha)
19- 21 I3 km/s W10(Ha) ? Hα width at 10% of the peak
23- 24 I2 km/s e_W10(Ha) ? rms uncertainty on W10(Ha)
26 A1 --- l_logdM/dt Limit flag on logdM/dt
27- 31 F5.1 [solMass/yr] logdM/dt ? Accretion mass loss
33- 35 F3.1 [solMass/yr] e_logdM/dt ? rms uncertainty on dM/dt
37- 38 A2 --- l_w(NII) [≲ ] Limit flag on w(NII)
39- 43 F5.2 0.1nm w(NII) ? NII6583 pseudo-equivalent width (G2)
45- 46 A2 --- l_w(HeI) [≲ ] Limit flag on w(HeI)
47- 50 F4.2 0.1nm w(HeI) ? HeI6678 pseudo-equivalent width (G2)
53- 54 A2 --- l_w(SII1) [≲ ] Limit flag on w(SII1)
55- 58 F4.2 0.1nm w(SII1) ? SII6716 pseudo-equivalent width (G2)
59 A1 --- --- [/]
60- 63 F4.2 0.1nm w(SII1)b ? Second SII6716 pseudo-equivalent
width (G2)
64 A1 --- n_w(SII1)b [b] b: split in two separate lines
66- 67 A2 --- l_w(SII2) [≲ ] Limit flag on w(SII2)
68- 71 F4.2 0.1nm w(SII2) ? SII6731 pseudo-equivalent width (G2)
72 A1 --- --- [/]
73- 76 F4.2 0.1nm w(SII2)b ? Second SII6731 pseudo-equivalent
width (G2)
77 A1 --- n_w(SII2)b [b] b: split in two separate lines
79- 81 A3 --- Disk Disk class (2)
82 A1 --- n_Disk [dc] Note on Disk class (3)
--------------------------------------------------------------------------------
Note (2): Disk classification as follows:
I = class I candidate
II = thick disk
III = diskless
EV = evolved disk
-- = Spitzer non-members
For σ Ori, classification from Hernandez et al. (2007ApJ...662.1067H 2007ApJ...662.1067H)
For λ Ori, classification from Barrado y Navascues et al. 2004,
Cat. J/ApJ/610/1064
Note (3): Note on Disk class as follows:
c = classified as a transition disk candidate using the whole SED
slope (see Sect. 4.3 in Hernandez et al., 2007ApJ...662.1067H 2007ApJ...662.1067H)
d = classified as a class II using the whole SED slope
(see Sect. 4.3 in Hernandez et al., 2007ApJ...662.1067H 2007ApJ...662.1067H)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: rv.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- [SFR2008] Object identification (G1)
4 A1 --- m_[SFR2008] [ab] Multiplicity index on [SFR2008]
6- 15 F10.2 d HJD Heliocentric Julian date
17- 22 F6.2 km/s RV Radial velocity
24- 27 F4.2 km/s e_RV rms uncertainty on RV
--------------------------------------------------------------------------------
Global notes:
Note (G1): [SFR2008] SNN for σ Ori, [SFR2008] LNN for λ Ori
Note (G2): Due to the presence of molecular bands, which strongly affect
the spectrum of late-type stars, the EWs are measured with respect to
a false continuum. We refer to these measurements as pseudo-equivalent
widths (pEWs).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 15-Sep-2008