J/PASP/118/1238 Radial velocity curve of RBS 490 (Thorstensen+, 2006)
The unusual cataclysmic binary star RBS 0490 and the space density of
cataclysmic variables.
Thorstensen J.R., Lepine S., Shara M.
<Publ. Astron. Soc. Pac., 118, 1238-1244 (2006)>
=2006PASP..118.1238T 2006PASP..118.1238T
ADC_Keywords: Stars, variable ; Radial velocities ; Photometry, UBVRI ;
Proper motions
Abstract:
RBS (ROSAT Bright Source) 0490 is a cataclysmic variable star (CV)
with unusually strong emission lines. The strength of the emission
lines has led to a suggestion that the object is intrinsically faint
and correspondingly nearby (33pc), which, if true, would strongly
affect estimates of the CV space density. Here we report astrometry,
filter photometry, and time-series spectroscopy of this object. The
astrometry gives an absolute parallax of 4.5±1.5mas and a relative
proper motion of 102mas/yr. A Bayesian procedure gives a very
uncertain distance estimate of d∼300pc, and the small parallax alone
implies d>133pc (at 2 standard deviations). The mean V magnitude is
17.4, which implies MV=10.9-5log[d/(200pc)], neglecting extinction.
At 200pc, the space velocity would be over 90km/s with respect to the
local standard of rest. The time-series spectroscopy shows a possible
emission-line radial velocity period near 46 minutes. This would be
unusually short for an orbital period, and it may represent some other
clock in the system.
Description:
All our data are from the 2.4m Hiltner reflector at MDM Observatory
on Kitt Peak, Arizona.
Objects:
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RA (2000) DE Designation(s)
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03 54 10.33 -16 52 49.2 RBS 490 = 1RXS J035410.4-165244
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 67 21 *Filter photometry (for 20 stars)
table4.dat 16 105 Radial Velocities for RBS 490
([TLS2006] J035410.31-165250.3)
table6.dat 69 44 *Astrometric parameters for all the stars
measured in the field
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Note on table2.dat and table6.dat:
Stars identified as [TLS2006] JHHMMSS.ss+DDMMSS.s in Simbad
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1 A1 --- Sample [FV] Field stars (averages of two observations)
or Variable star (two observations separately)
3 I1 h RAh Right ascension (ICRS) (1)
5- 6 I2 min RAm Right ascension (ICRS) (1)
8- 12 F5.2 s RAs Right ascension (ICRS) (1)
14 A1 --- DE- Declination sign (IRCS) (1)
15- 16 I2 deg DEd Declination (IRCS) (1)
18- 19 I2 arcmin DEm Declination (IRCS) (1)
21- 24 F4.1 arcsec DEs Declination (IRCS) (1)
26- 30 F5.2 mag U-B ?=- U-B colour index
32- 35 F4.2 mag e_U-B ? rms uncertainty on U-B (2)
37- 41 F5.2 mag B-V B-V colour index
43- 46 F4.2 mag e_B-V rms uncertainty on B-V (2)
48- 52 F5.2 mag Vmag V magnitude
54- 57 F4.2 mag e_Vmag rms uncertainty on Vmag (2)
59- 62 F4.2 mag V-I V-I colour index
64- 67 F4.2 mag e_V-I rms uncertainty on V-I (2)
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Note (1): Coordinates referred to the ICRS and are from a fit to 24
USNOA2.0 stars, with a scatter of 0.6".
Note (2): Uncertainties greater than 0.01mag are derived from counting
statistics. Counting statistics errors less than 0.005mag have been
rounded up to 0.01mag; systematic errors are expected to be several
times larger than this in any case
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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- 12 F12.4 d HJD Heliocentric Julian Date of mid-exposure
14- 16 I3 km/s RVemm Average velocity of Hβ, HeI 5876, and
HeI 6678
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1 A1 --- Star [*] * for program star (RBS 490)
2 I1 h RAh Right ascension (ICRS, J2000)
4- 5 I2 min RAm Right ascension (ICRS, J2000)
7- 11 F5.2 s RAs Right ascension (ICRS, J2000)
13 A1 --- DE- Declination sign (IRCS, J2000)
14- 15 I2 deg DEd Declination (IRCS, J2000)
17- 18 I2 arcmin DEm Declination (IRCS, J2000)
20- 23 F4.1 arcsec DEs Declination (IRCS, J2000)
25 I1 --- Weight [0/1] Weight, 1 or 0, depending on whether the
star is used as reference
27- 29 I3 mag sigma rms deviation from the relative positions
predicted by the best-fit parallax and
proper motion
31- 35 F5.2 mag Vmag V magnitude
37- 40 F4.2 mag V-I V-I colour index
42- 46 F5.1 mag plx Relative parallax
48- 51 F4.1 mag e_plx rms uncertainty on plx
53- 57 F5.1 mas/yr pmX Proper motion along X (1)
59- 64 F6.1 mas/yr pmY Proper motion along Y (1)
66- 69 F4.1 mas/yr e_pmX rms uncertainty on pmX and pmY
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Note (1): Proper motions are relative to the set of reference stars used
and are not on an inertial system.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 11-Jan-2008