J/AN/319/215 Alpha Per cluster low-mass members. II. (Prosser+, 1998)
Identification of new low-mass members of the alpha Persei open cluster
by ROSAT. II.
Prosser C.F., Randich S., Simon T.
<Astron. Nachrichten, 319, 215 (1998)>
=1998AN....319..215P 1998AN....319..215P
ADC_Keywords: Clusters, open ; Photometry ; X-ray sources
Keywords: open clusters and associations: individual (alpha Per = Melotte 20) -
stars: late-type - stars: coronae - stars: activity - X-rays: stars
Abstract:
The present investigation examines possible optical counterparts to
130 X-ray sources in the region of the alpha Persei open cluster
(d∼170pc, age∼50Myr) resulting from the analysis of three 22-25ksec
ROSAT PSPC pointings. In the same manner as for 73 X-ray sources from
a raster survey in alpha Per (Prosser & Randich, 1998, Cat.
J/AN/319/201), CCD photometry is employed to obtain magnitudes
and colors for stars/objects close to the X-ray positions, with
additional echelle and low-dispersion Halpha spectra provided for some
stars. For almost 60 X-ray sources, an optical counterpart with
photometry acceptable for cluster membership is identified, some of
which can be excluded from membership on the basis of discrepant
radial velocity or X-ray characteristics. On the order of 30 new
members or likely members associated with X-ray sources have been
identified based on available data. A photometric rotation period has
been obtained for one rapid rotator identified in X-rays.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 27 Recovered APX X-ray sources
table2.dat 64 130 PSPC APX X-ray source list
table4.dat 108 70 Members/Candidate members associated with
X-ray sources
appena.dat 79 79 Individual notes on the finding charts
table7.dat 30 522 Optical counterparts to X-ray sources
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See also:
J/AN/319/201 : Alpha Per cluster low-mass members. I. (Prosser+, 1998)
Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- APX [1/203] APX (Alpha Per, X-ray) number
4 A1 --- f_APX [a] Note on APX 5 (1)
5 A1 --- n_APX [*] Note in appena.dat file
6- 7 I2 h RAh Right ascension (J2000)
9- 10 I2 min RAm Right ascension (J2000)
12- 15 F4.1 s RAs Right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Declination (J2000)
21- 22 I2 arcmin DEm Declination (J2000)
24- 25 I2 arcsec DEs Declination (J2000)
27- 32 F6.1 --- MLh Hardband Maximum Likelihood value
34- 38 I5 s Exp Effective exposure time
40- 45 F6.4 s-1 CountRate ? PSCP count rate
46 A1 --- n_CountRate [)] ): estimated hardband count rate
48- 53 F6.4 s-1 e_CountRate ? rms uncertainty on CountRate
55- 58 F4.1 arcmin Offax Off-axis
60 A1 --- l_HR Limit flag on HR
61- 64 F4.1 --- HR Hardness ratio (2)
66- 70 A5 --- PSPC PSPC field (only in table1.dat)
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Note (1): a: This PSPC x-ray source may be a blend between APX5 and AP106
Note (2): HR=(H-S)/(H+S), where H and S are the count rates from the hard
and soft (0.1-0.4keV) bands respectively
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [APX] (Alpha Per, X-ray)
4- 6 I3 --- APX ? APX number
7 A1 --- m_APX Multiplicity index on APX
8 A1 --- n_APX [*] Membership note (1)
10- 15 A6 --- Name Other name
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 26 F4.1 s RAs Right ascension (J2000)
28 A1 --- DE- Declination sign (J2000)
29- 30 I2 deg DEd Declination (J2000)
32- 33 I2 arcmin DEm Declination (J2000)
35- 36 I2 arcsec DEs Declination (J2000)
38- 42 F5.2 mag Vmag V magnitude
44- 47 F4.2 mag B-V ? B-V colour index
49- 52 F4.2 mag V-IK V-IK colour index
53 A1 --- u_V-IK rms uncertainty on V-IK
55- 56 A2 --- Mem [YN ?] Membership
58- 61 F4.2 mag B-V0 B-V0 colour index
62 A1 --- u_B-V0 rms uncertainty on B-V0
64- 68 F5.2 [solLum] logLX ? X-ray luminosity
70- 74 F5.2 [solLum] logLbol Bolometric luminosity
76- 80 F5.2 --- log(LX/Lbol) ? X-ray to bolometric luminosity ratio
82-111 A30 --- Notes Notes
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Note (1): *: for X-ray sources for which we believe that the star listed
is the source of emission and that the available data strongly implies
cluster membership.
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Byte-by-byte Description of file: appena.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [APX]
4- 6 I3 --- APX APX number
8- 79 A72 --- Note Text of the note
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- APX [75/203]+= APX number
4 A1 --- m_APX Multiplicity index on APX
5 A1 --- u_APX Uncertainty flag on APX
7- 11 F5.2 mag Vmag V magnitude
14- 17 F4.2 mag B-V ? B-V colour index
20- 23 F4.2 mag V-IK ? V-IK colour index
25- 26 A2 --- Mem [YN ?] Membership
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History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 30-Apr-1999