J/A+AS/123/329 New weak-line T Tauri stars in Lupus (Krautter+ 1997)
New "weak-line" T Tauri stars in Lupus
Krautter J., Wichmann R., Schmitt J.H.M.M., Alcala J.M., Neuhaeuser R.,
Terranegra L.
<Astron. Astrophys. Suppl. Ser. 123, 329 (1997)>
=1997A&AS..123..329K 1997A&AS..123..329K
ADC_Keywords: Stars, pre-main sequence ; X-ray sources
Mission_Name: ROSAT
Keywords: stars: formation - stars: pre-main sequence - X-rays: stars -
surveys - ISM: Lupus clouds
Abstract:
We present first results obtained by a survey of the Lupus star
forming region in search of new T Tauri stars. This study has been
performed on the basis of deep pointed ROSAT observations in the Lupus
dark clouds as well as data from the ROSAT All-Sky-Survey in the
surrounding, less obscured regions. Our survey covers an area of about
230 square degrees, located between 15h6m and 16h24m in right
ascension and between -47° and -32° in declination.
Identification of ROSAT All-Sky-Survey sources in this area by means
of optical spectroscopy revealed 89 T Tauri stars, 86 of them
"weak-line" T Tauri stars (WTTS not known from previous studies of
this region. Our pointed ROSAT observations led to the identification
of 47 more T Tauri stars, giving a total of 136 new T Tauri stars. The
large area of our study, as compared with previous works, allows us to
study the spatial distribution of WTTS in this star forming region on
alarge scale. We find the new WTTS to be distributed over the whole
area of our survey, indicating that their spatial distribution might
extend well beyond our study area. Contrary to the Lupus T Tauri stars
known prior to this study, the WTTS discovered by the ROSAT
All-Sky-Survey are not clustered in the regions of highest extinction,
i.e. the dark clouds.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 71 136 New T Tauri stars in Lupus
table6.dat 84 44 New Non-TTS emission-line objects in Lupus
table7.dat 106 70 Sources in pointed observations (Lupus 1)
table8.dat 106 52 Sources in pointed observations (Lupus 2)
table9.dat 106 96 Sources in pointed observations (Lupus 3)
table10.dat 103 129 X-ray data for new T Tauri stars in Lupus
table11.dat 98 136 Spectral fit results for new T Tauri stars in Lupus
table12.dat 107 51 X-ray data from pointed observations and
spectral fit results for T Tauri stars in
Lupus known prior to our study
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See also:
IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1996)
IX/11 : ROSAT Source Catalog (Voges+ 1994)
J/A+A/320/185 : T Tauri UBVRIcJHKL photometry (Wichmann+ 1997)
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 4 I3 --- TTauNo Sequential number
6- 20 A15 --- Star Identifier of star
23 I1 --- NA [1/3]? Note on X-ray discovery (1)
25- 26 I2 h RAh Right Ascension for equinox J2000.0 (2)
28- 29 I2 min RAm Right Ascension for equinox J2000.0 (2)
31- 35 F5.2 s RAs Right Ascension for equinox J2000.0 (2)
37 A1 --- DE- Declination sign
38- 39 I2 deg DEd Declination for equinox J2000.0 (2)
41- 42 I2 arcmin DEm Declination for equinox J2000.0 (2)
44- 48 F5.2 arcsec DEs Declination for equinox J2000.0 (2)
51- 56 F6.2 0.1nm EWHa Equivalent width for Hα
60- 64 A5 --- SpT Spectral type
67- 71 F5.2 mag Vmag ?=0.00 V magnitude (3)
--------------------------------------------------------------------------------
Note (1): Stars marked with '1', '2', or '3' have been discovered by pointed
observations in the Lupus 1, Lupus 2 or Lupus 3 clouds, respectively.
Left blank for stars discovered by the ROSAT All-Sky Survey.
Note (2): If declination is given with one decimal only, the coordinates refer
to the position of the X-ray source, otherwise the coordinates are
taken from the Guide Star Catalogue.
Note (3): Magnitudes given with two decimals are from our own measurements
(Wichmann et al. 1997A&A...320..185W 1997A&A...320..185W), those given with one decimal
only are taken from the GSC. A value of zero means that no magnitude
is available.
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- No Sequential number
5- 19 A15 --- Star Identifier of star
21 I1 --- NA [1/3]? Note on X-ray discovery (1)
23- 24 I2 h RAh Right Ascension for equinox J2000.0 (2)
26- 27 I2 min RAm Right Ascension for equinox J2000.0 (2)
29- 33 F5.2 s RAs Right Ascension for equinox J2000.0 (2)
36 A1 --- DE- Declination sign
37- 38 I2 deg DEd Declination for equinox J2000.0 (2)
40- 41 I2 arcmin DEm Declination for equinox J2000.0 (2)
43- 47 F5.2 arcsec DEs Declination for equinox J2000.0 (2)
51- 55 F5.3 ct/s CTS ? ROSAT X-Ray count rate (3)
58- 62 F5.3 ct/s e_CTS ? Error of ROSAT X-Ray count rate
66- 70 A5 --- SpT Spectral type
74- 78 F5.1 0.1nm EWHa Equivalent width for Hα
81- 84 F4.1 mag Vmag ?=0.00 V magnitude (4)
--------------------------------------------------------------------------------
Note (1): Stars marked with '1', '2', or '3' have been discovered by pointed
observations in the Lupus 1, Lupus 2 or Lupus 3 clouds, respectively.
Left blank for stars discovered by the ROSAT All-Sky Survey.
Note (2): If declination is given wit one decimal only, the coordinates refer
to the position of the X-ray source, otherwise the coordinates are
taken from the Guide Star Catalogue.
Note (3): Background and vignetting corrected broadband X-ray count rate.
Note (4): Magnitudes are taken from the GSC. A value of zero means that no
magnitude is available.
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Byte-by-byte Description of file: table7.dat table8.dat table9.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- No Sequential number
5- 19 A15 --- Star Identifier of X-ray source
21 A1 --- NS Note on X-ray discovery (1)
24- 25 I2 h RAh Right Ascension for equinox J2000.0 (2)
27- 28 I2 min RAm Right Ascension for equinox J2000.0 (2)
30- 34 F5.2 s RAs Right Ascension for equinox J2000.0 (2)
37 A1 --- DE- Declination sign
38- 39 I2 deg DEd Declination for equinox J2000.0 (2)
41- 42 I2 arcmin DEm Declination for equinox J2000.0 (2)
44- 47 F4.1 arcsec DEs Declination for equinox J2000.0 (2)
51- 56 F6.1 --- ML Likelihood of existence
59- 65 F7.1 s t.exp Exposure time
68- 73 F6.4 ct/s CTS ROSAT X-Ray count rate (3)
76- 81 F6.4 ct/s e_CTS Error of ROSAT X-Ray count rate
83- 87 F5.2 --- HR1 ROSAT hardness ratio 1
90- 93 F4.2 --- e_HR1 Error of ROSAT hardness ratio 1
96-100 F5.2 --- HR2 ROSAT hardness ratio 2
103-106 F4.2 --- e_HR2 Error of ROSAT hardness ratio 2
--------------------------------------------------------------------------------
Note (1): Stars marked with 'S' are also detected in the ROSAT All-Sky Survey.
Note (2): Coordinates always refer to the position of the X-ray source.
Note (3): Background and vignetting corrected broadband X-ray count rate.
------------------------------------------------------------------------------
Byte-by-byte Description of file: table10.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- Star Identifier of X-ray source (1)
18 I1 --- NA [1/3]? Note on X-ray discovery (2)
20- 21 I2 h RAh Right Ascension for equinox J2000.0 (3)
23- 24 I2 min RAm Right Ascension for equinox J2000.0 (3)
26- 30 F5.2 s RAs Right Ascension for equinox J2000.0 (3)
33 A1 --- DE- Declination sign
34- 35 I2 deg DEd Declination for equinox J2000.0 (3)
37- 38 I2 arcmin DEm Declination for equinox J2000.0 (3)
40- 43 F4.1 arcsec DEs Declination for equinox J2000.0 (3)
45- 51 F7.1 --- ML Likelihood of existence
53- 61 F9.3 s t.exp Exposure time
63- 68 F6.4 ct/s CTS ROSAT X-Ray count rate (4)
70- 75 F6.4 ct/s e_CTS Error of ROSAT X-Ray count rate
78- 83 F6.3 --- HR1 ROSAT hardness ratio 1
85- 89 F5.3 --- e_HR1 Error of ROSAT hardness ratio 1
92- 97 F6.3 --- HR2 ROSAT hardness ratio 2
99-103 F5.3 --- e_HR2 Error of ROSAT hardness ratio 2
--------------------------------------------------------------------------------
Note (1): RXJ1507.9-4515, RXJ1533.0-3930, RXJ1539.2-4455 were found due to
the SASS reduction of the RASS, but could not be detected as X-ray
sources in the EXSAS reduction of the RASS. Therefore, no X-ray
data are given for these stars.
Note (2): Stars marked with '1', '2', or '3' have been discovered by pointed
observations in the Lupus 1, Lupus 2 or Lupus 3 clouds,
respectively, and X-ray data are from pointed observations.
Otherwise, X-ray data refer to the ROSAT All-Sky Survey.
Note (3): Coordinates refer to the position of the X-ray source.
Note (4): Background and vignetting corrected broadband X-ray count rate.
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Byte-by-byte Description of file: table11.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- TTauNo [1/136] Number, as in table5
5- 19 A15 --- Star Identifier of star (1)
22 I1 --- NA [1/3]? Note on X-ray discovery (2)
24- 27 F4.2 mag AV ? Extinction A(V) from photometry (3)
30- 34 F5.2 [cm-2] log(NH) ? Absorbing HI column density (4)
38- 41 F4.2 keV kTX ? Temperature of X-ray emitting plasma (5)
42 A1 --- --- [0]
45- 48 F4.2 keV E_kTX ? 1 σ upper error bar of kTX
49 A1 --- --- [0]
52- 55 F4.2 keV e_kTX ? 1 σ lower error bar of kTX
56 A1 --- --- [0]
60- 64 F5.2 [cm-2] log(NH)f ? Fitted absorbing HI column density (5)
66- 70 F5.2 [cm-2] E_log(NH)f ? 1 σ upper error bar of log(NH)f
72- 76 F5.2 [cm-2] e_log(NH)f ? 1 σ lower error bar of log(NH)f
80- 84 F5.3 10+23W LX ? X-ray luminosity (LX/1030erg/s)
86- 91 F6.3 10+23W E_LX ? 1 σ upper error bar of LX
93- 98 F6.3 10+23W e_LX ? 1 σ lower error bar of LX
--------------------------------------------------------------------------------
Note (1): RXJ1507.9-4515, RXJ1533.0-3930, RXJ1539.2-4455 were found due to
the SASS reduction of the RASS, but could not be detected as X-ray
sources in the EXSAS reduction of the RASS. Therefore, no X-ray
data are given for these stars.
Note (2): Stars marked with '1', '2', or '3' have been discovered by pointed
observations in the Lupus 1, Lupus 2 or Lupus 3 clouds,
respectively, and X-ray data are from pointed observations.
Otherwise, X-ray data refer to the ROSAT All-Sky Survey.
Note (3): Data from Wichmann et al., 1997A&A...320..185W 1997A&A...320..185W
Note (4): Calculated from AV as given in row 4
Note (5): Spectral fits with hardness ratio performed with either both TX and
NH as free fit parameters if no AV known, or with NH fixed and TX
free if AV known. In a few cases, where AV is known, no good fit with
NH fixed could be performed, hence fit was performed with both TX and
NH free (in such cases both NH and NH_FIT are given). (If for TX,
NH_FIT, and LX, no errors are given, no good fit could be performed,
possibly because a single-temperature Raymond-Smith model is not
adequate to model the star's X-ray spectrum.)
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Byte-by-byte Description of file: table12.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Schwartz Identifier of star from Schwartz (Sz NNN)
(1977ApJS...35..161S 1977ApJS...35..161S)
8- 14 F7.5 ct/s CTS ROSAT X-Ray count rate (1)
16- 22 F7.5 ct/s e_CTS ? Error of ROSAT X-Ray count rate (1)
24- 29 F6.3 --- HR1 ? ROSAT hardness ratio 1
31- 35 F5.3 --- e_HR1 ? Error of ROSAT hardness ratio 1
36- 39 F4.2 --- HR2 ? ROSAT hardness ratio 2
41- 45 F5.3 --- e_HR2 ? Error of ROSAT hardness ratio 2
46- 49 F4.2 mag AV Extinction A(V) (2)
52- 56 F5.2 [cm-2] log(NH) Absorbing HI column density (3)
58- 62 F5.2 [cm-2] E_log(NH) ? 1 σ upper error bar of log(NH)
64- 68 F5.2 [cm-2] e_log(NH) ? 1 σ lower error bar of log(NH)
70- 73 F4.2 keV kTX ? Temperature of X-ray emitting plasma (3)
75- 79 F5.2 keV E_kTX ? 1 σ upper error bar of kTX
82- 86 F5.2 keV e_kTX ? 1 σ lower error bar of kTX
88- 92 F5.3 10-7W LX X-ray luminosity (LX/10^30) (3)
94- 99 F6.3 10-7W E_LX ? 1 σ upper error bar of LX
102-107 F6.3 10-7W e_LX ? 1 σ lower error bar of LX
--------------------------------------------------------------------------------
Note (1): Background and vignetting corrected broadband X-ray count rate.
Absence of error indicates that count rate is upper limit.
Note (2): Data from Hughes et al., 1994AJ....108.1071H 1994AJ....108.1071H
Note (3): Spectral fits with hardness ratio were performed with TX
as free fit parameter and NH calculated from AV (Hughes et al.,
1994AJ....108.1071H 1994AJ....108.1071H). In a few cases, where AV is known, no good
fit with NH fixed could be performed, hence fit was performed with
both TX and NH free (in such cases NH (fitted) is given).
* Sz 124: no good fit could be performed, possibly because a
single-temperature Raymond-Smith model is not adequate to model the
star's X-ray spectrum. Thus the quoted values are quite uncertain.
* For stars where only upper limits are known, luminosities were
calculated for a Raymond-Smith spectrum with the mean temperature
of kTX = 1.014 keV and NH calculated from AV.
-------------------------------------------------------------------------------
Acknowledgements: Rainer Wichmann <R.Wichmann(at)lsw.uni-heidelberg.de>
References:
Wichmann R., Krautter J., Covino E., Alcala J.M., Neuhaeuser R.,
Schmitt J.H.M.M., 1997A&A...320..185W 1997A&A...320..185W
(End) Patricia Bauer [CDS] 09-Oct-1996