J/A+A/341/L79 Proper motions of faint ROSAT WTT stars (Terranegra+ 1999)
Proper motions of faint ROSAT WTT stars in the Chamaeleon region.
Terranegra L., Morale F., Spagna A., Massone G., Lattanzi M.G.
<Astron. Astrophys. 341, L79 (1999)>
=1999A&A...341..L79T (SIMBAD/NED BibCode)
ADC_Keywords: Proper motions ; Stars, late-type ; Radio sources
Mission_Name: ROSAT
Keywords: astrometry - stars: fundamental parameters - stars: kinematics -
stars: late-type - stars: pre-main sequence
Abstract:
We present proper motions of 59 stars of the ROSAT All-Sky Survey
(RASS) located in direction of the Chamaeleon star forming region
(SFR) in the magnitude range B=5.1-17mag. Proper motions of the
fainter stars were newly derived utilizing survey Schmidt plates from
the GSC∼II plate archive and from a set of special plates taken with
the ESO Schmidt telescope. The vector point diagram (VPD) indicates
that the certified weak emission-line T Tauri (WTT) stars cluster away
from the region occupied by the brighter pre-main-sequence stars (PMS)
in Cha I. The distance to this new association is estimated at ∼100pc,
sensibly smaller than the 150pc generally assumed for the SFR. This
yields an upper limit of 2km/s for the velocity dispersion of this new
kinematic group. The de-reddened CM diagram of the group members
suggest the WTT stars are still PMS objects, but older (3-30Myr) and
less massive than previous determinations. These revised age
estimates, the newly derived group peculiar velocity, and current
distance estimates to the Cha∼I/II/III complex would favour in-situ
formation against that predicted by high velocity cloud models.
Finally, based on a redetermination of the peculiar motions of stars
and gas, we speculate that the whole SFR originated from the local
Orion spur as a result of more classical mechanisms like interactions
with the spiral arms.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 104 59 Proper motions for the 59 RASS stars
table1.ps 72 642 PostScript version of table1
table1.tex 144 122 LaTeX version of table1
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See also:
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/246 : The ACT Reference Catalog (Urban+ 1997)
I/146 : Positions and Proper Motions - North (Roeser+, 1988)
I/193 : Positions and Proper Motions - South (Bastian+ 1993)
J/A+AS/114/109 : Cha X-ray sources + optical identifications (Alcala+ 1995)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Name ROSAT all-sky survey source designation
Alcala' et al. (1995, Cat. J/A+AS/114/109)
or catalogue designation
19- 20 A2 --- n_Name [* KG] Note on Name (1)
22- 33 A12 --- CatNo Astrometric catalog designation
35 A1 --- Cat [APHS] Catalogue name (2)
37- 42 F6.1 mas/yr pmRA Proper motion in right ascension (µRA*cosDE)
44- 46 F3.1 mas/yr e_pmRA ? rms uncertainty on pmRA
48- 52 F5.1 mas/yr pmDE Proper motion in declination
54- 56 F3.1 mas/yr e_pmDE ? rms uncertainty on pmDE
58- 62 F5.2 mas plx ? Parallax from Hipparcos catalogue (I/239)
64- 66 F3.1 mas e_plx ? rms uncertainty on plx
68- 69 A2 --- SpType Spectral Type
71- 74 F4.1 mag Vmag ? Stellar V magnitude
76- 80 A5 --- Type Stellar type (3)
82-104 A23 --- Names Other names
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Note (1): *: The proper motion value for CED 110 is from Grasdalen G.
(1977IAUCo..42...25G 1977IAUCo..42...25G), while the values for SAO 256557 and
RXJ1225.3-7857 are from the original catalogue and they are in the
FK5 system. However the deviation from the Hipparcos system can be
considered negligible in this work.
KG: Stars belong to the kinematical group (see text).
Note (2): A = ACT Catalog (Cat. I/246)
P = PPM Catalog (Cat. I/146, I/193)
H = Hipparcos Catalog (Cat. I/239)
S = GSC S039 plate
Note (3): PMS: Pre-Main Sequence stars from the high resolution spectroscopy
by Covino et al. (1997A&A...328..187C 1997A&A...328..187C)
W: WTTS from low resolution spectroscopy by Alcala' et al.
(1995, Cat. J/A+AS/114/109)
UBS: uncorrelated bright stars by Alcala' et al.
(1995, Cat. J/A+AS/114/109)
CTTS: Classical T Tauri stars
Ae/Be: Herbig Ae/Be stars
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Acknowledgements: Luciano Terranegra
(End) Patricia Bauer [CDS] 08-Jan-1999