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J/A+A/460/695    Search for Associations Containing Young stars  (Torres+, 2006)

Search for Associations Containing Young stars (SACY). I. Sample & Searching Method. Torres C.A.O., Quast G.R., da Silva L., de la Reza R., Melo C.H.F., Sterzik M. <Astron. Astrophys. 460, 695 (2006)> =2006A&A...460..695T
ADC_Keywords: Stars, nearby ; Stars, late-type ; Photometry, UBVRI ; Radial velocities ; Rotational velocities ; Equivalent widths Spectral types ; X-ray sources Keywords: stars: pre-main sequence - stars: formation - stars: kinematics - stars: rotation - stars: abundances - open clusters and associations: individual: β Pic Association Abstract: We report results from a high-resolution optical spectroscopic survey aimed to search for nearby young associations and young stars among optical counterparts of ROSAT All-Sky Survey (IX/10 and IX/29, X-ray sources in the Southern Hemisphere. We selected 1953 late-type (B-V≥0.6), potentially young, optical counterparts out of a total of 9574 1RXS sources for follow-up observations. At least one high-resolution spectrum was obtained for each of 1511 targets. This paper is the first in a series presenting the results of the SACY survey. Here we describe our sample and our observations. We describe a convergence method in the (UVW) velocity space to find associations. As an example, we discuss the validity of this method in the framework of the Beta Pic Association. Description: The SACY sample is defined by Hipparcos (I/239) and Tycho-2 (I/259) stars within an error radius of 2.6 times the positional error of the ROSAT All-Sky Bright Source Catalogue (1RXS, IX/10). The used cut-off (B-V=0.6), corresponding approximately to a G0 dwarf, is near the hottest stars where the strength of the LiI line can be used as an youth indicator. We excluded all Hipparcos stars having Mv<2.0. In Table 1 of the paper we give the northern boundary limits of the survey. In addition to the 1511 stars observed at least once we add 115 with data taken from the literature to complement the sample. Most of the spectroscopic observations (∼70%) were performed with the FEROS spectrograph at the 1.5m/ESO telescope at La Silla between January 1999 and September 2002 (ON-ESO agreement and ESO program identification 67.C-0123). Two more runs (ESO program identifications 072.C-0393 and 077.C-0138) were carried out at the 2.2m/ESO telescope. Another set of data (∼30%) was collected at the coude spectrograph attached to 1.60m telescope at the Observatorio rio do Pico dos Dias (OPD), LNA, Brazil. Some spectra are a re-analysis of the ones taken for the PDS program. A few observations were collected using the CORALIE attached to the Swiss Euler Telescope at La Silla. UBV(RI)c photometry for part of the sample was obtained using FOTRAP at the 0.60m Zeiss telescope of the OPD. When a star was not observed photometrically by us we tried to obtain some useful photometric data in the Hipparcos and Tycho Catalogues or in the available literature in the SIMBAD. For multiple stars, magnitudes and colors were corrected in order to take into account the presence of the companion. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 228 1626 Astrometric, spectroscopic and photometric data of the SACY sample table4.dat 228 165 Astrometric, spectroscopic and photometric data of other observed stars refs.dat 96 107 References (table5 of the paper)
See also: IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999) IX/29 : ROSAT All-Sky Survey Faint Source Catalog (Voges+ 2000) Byte-by-byte Description of file: table[34].dat
Bytes Format Units Label Explanations
1- 4 I4 --- Seq Running number 7- 22 A16 --- 1RXS 1RXS (<IX/10>,<IX/29>) designation (1) 25- 40 A16 --- Name Hipparcos (<I/239>), Tycho-2 (<II/259>) or UCAC2 (I/289) identification (2) 42- 54 A13 --- OName Other identification (HD, DM, other) (3) 56- 57 I2 h RAh Right ascension (J2000.0) 59- 60 I2 min RAm Right ascension (J2000.0) 62- 65 F4.1 s RAs Right ascension (J2000.0) 68 A1 --- DE- Declination sign (J2000.0) 69- 70 I2 deg DEd Declination (J2000.0) 72- 73 I2 arcmin DEm Declination (J2000.0) 75- 76 I2 arcsec DEs Declination (J2000.0) 79- 85 F7.1 mas/yr pmRA Proper motion in RA (pmRA*cosDE) 87- 93 F7.1 mas/yr pmDE Proper motion in DE (pmDE) 96- 98 A3 ---- r_pmRA Source of proper motions (4) 100-105 F6.1 km/s HRV Heliocentric radial velocity (5) 106 A1 --- f_HRV [:] Quality flag for RV 108-111 F4.1 km/s e_HRV ? rms of the observed RV 113-115 I3 --- Nobs ? Number of observations (6) 116 A1 --- f_Nobs [*] *: RV value comes from the literature (7) 118-120 A3 --- r_HRV ? Source of radial velocity (8) 123-127 A5 ---- n_HRV [D,SB1234 ?] Multiplicity flag (9) 129-132 F4.1 arcsec Sep ? Angular separation of visual binaries (10) 135-138 F4.1 mag dV ? Magnitude difference of components (11) 139 A1 --- u_dV [?] Uncertainty flag on dV 142-146 F5.1 km/s vsini ? Rotational velocity 148-151 F4.1 km/s e_vsini ? rms uncertainty on vsini 154-156 A3 ---- r_vsini ? Source of vsini (8) 159-163 F5.1 mas Plx ? Trigonometric parallax 166-169 F4.1 mas e_Plx ? Standard error in Plx 172-174 A3 --- r_Plx Source of Plx (8) 177-181 F5.2 mag Vmag Johnson V magnitude 182 A1 ---- f_Vmag [V] Quality flag indicating variability (12) 183-187 F5.2 mag B-V ? Johnson B-V colour index 189-193 F5.2 mag V-I ? Cousins V-I colour index 196-198 A3 --- r_Vmag Source of photometry (13) 199 A1 --- n_Vmag [*] *: photometry corrected for companions (14) 203-210 A8 --- SpType MK spectral type 212-214 I3 0.1pm EWLi ? LiI equivalent width in milli-Angstroms (15) 215 A1 ---- f_EWLi [:?] Quality flag for EWLi 217-221 F5.1 0.1nm EWHa ? Hα line emission in Angstroms 224-228 A5 ---- r_EWLi Source of spectral information (16)
Note (1): ROSAT All-Sky Survey Catalogue source name, in general from the Bright Source Catalogue (IX/10) but sometimes refers to the Faint Source Catalogue (IX/29). A repeated entry means more than one observed possible optical counterpart. The same source may have entries in both Tables 3 and 4, but the best optical candidate may be in any of the tables. Note (2): Order of preference of the identification is Hipparcos, TYCHO-2 or UCAC2, independently of the astrometric data used. Note (3): Order of preference is HD, DM, and other. GSC is only used if there is no TYCHO-2 identification for the star. Note (4): Order of preference of the sources of the proper motions is the same as of the Name, adding other sources, but in some cases we used the best value from our judgment. Note (5): Radial velocities from SB2 observed once or SB1 are mean values, and may not represent the systemic velocity. When there is a systemic velocity from the literature, it is the used value. Note (6): Null refers to no published number of observations in the literature cited in r_HRV. Nobs from SACY includes references N=25 and 26. Note (7): The * means that this is the number of spectral observations in the SACY project, but the systemic HRV value was taken from the literature. For V1005 Ori the non variable HRV is from literature as our spectrum was not properly calibrated. Note (8): If there is no number, the radial velocity is from this work. Note (9): D means visual binary; sometimes the components were observed separately and there is another entry, designated by A, B, C..., in Table 3 or Table 4. If the bright component is also a SB the D is given in the entry of the faint one. A ? means possible evidence for radial velocity variations, sometimes by comparing with published data. In some cases it is difficult to decide between high rotation (+ spots?) and SB2. For other SB2? with low rotation and large e_HRV the star should be considered at least a SB1. For close visual doubles observed together, one of the spectroscopic components may be also the visual one, mainly in SB3 cases. For SBn all other data of this line are for the bright component. In the future we will publish the data for spectroscopic binaries found in the SACY project. Note (10): Separation between the visual components, even if in n_HRV there is a SBn. This means there is D for a faint companion in n_HRV in another entry. Note (11): Magnitude difference between faint companions and the bright one. A negative value means that the faint companions together are brighter than the primary, or the so called primary is a fainter companion with sharper lines. For visual binaries the negative value means that primary is also a SBn, and the visual difference is given in this entry or the primary is in the other table. Note (12): V: photometric variability. Note (13): Source of photometry: H = origin of the photometry from Hipparcos (I/239) T = from TYCHO2 (I/259) converted to Johnson blank = estimated magnitude Note (14): for the proposes of the SACY the photometric measures for close visual doubles and SBs are corrected to take into account the secondaries. As these values are model dependent they must be used with caution. Note (15): For SB2 or SB3 the values are tentatively corrected for the continuum flux ratios. Note (16): For observations from this paper: F = observation with ESO/FEROS d = observation with the OPD coude spectrograph
Byte-by-byte Description of file: refs.dat
Bytes Format Units Label Explanations
1- 3 A3 --- Ref Reference number or letter 5- 23 A19 --- BibCode BibCode 25- 48 A24 --- Aut Author's name 49- 96 A48 --- Com Comments
Acknowledgements: Carlos Torres, beto(at) History: 16-Mar-2007: In table3, cross-id of No 305 corrected (from author)
(End) Patricia Vannier [CDS] 30-Nov-2006
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