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RASSASASEB - RASS/All-Sky Automated Survey Eclipsing Binaries Catalog

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Overview

The authors have combined their catalog of eclipsing binaries from the All-Sky Automated Survey (ASAS) with the ROSAT All-Sky Survey (RASS) Bright and Faint Source Catalogs (RASSBSC and RASSFSC). The combination using a matching radius of 50 arcseconds results in 836 eclipsing binaries that display coronal activity and is the largest sample of active binary stars assembled to the date of publication. By using the (V-I) colors of the ASAS eclipsing binary catalog, the authors are able to determine the distances and thus bolometric luminosities for the majority of eclipsing binaries that display significant stellar activity. A typical value for the ratio of soft X-ray to bolometric luminosity is L_X/L_bol ~ a few x 10-4, similar to the ratio of soft X-ray to bolometric flux F_X/F_bol in the most active regions of the Sun. Unlike rapidly rotating isolated late-type dwarfs - stars with significant outer convection zones - a tight correlation between Rossby number and activity of eclipsing binaries is absent. The authors find evidence for the saturation effect and marginal evidence for the so-called "super-saturation" phenomena. Their work shows that wide-field stellar variability searches can produce a high yield of binary stars with strong coronal activity.

The authors expect that only 1.4% (i.e., 12 out of 836) of the matches between the ASAS eclipsing binary and RASS sources will be false given their maximum angular separation criterion of 50 arcseconds. This Browse table excludes 29 contact binaries for which the separate distance estimates made by the authors using the source V-band and I-band magnitudes differed by more than 20%, and hence contains 807 (836 - 29) eclipsing and X-ray emitting binary systems.

Complete information on ASAS and its freely accessible data are available at the ASAS web site: http://www.astrouw.edu.pl/asas/.


Catalog Bibcode

2008AcA....58..405S

References

Coronal activity from the ASAS eclipsing binaries.
    Szczygiel D.M., Socrates A., Paczynski B., Pojmanski G., Pilecki B.
   <Acta Astron., 58, 405-418 (2008)>
   =2008AcA....58..405S    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in July 2010 based on CDS catalog J/AcA/58/405 file catalog.dat.

Parameters

Asas_Name
The ASAS source identification in the recommended format using the truncated J2000.0 equatorial coordinates , e.g., 'ASAS JHHMMSS+DDMM.m'.

Name
THe RASS source identification in the recommended format using the truncated J2000.0 equatorial coordinates , e.g., '1RXS JHHMMSS.s+DDMMSS'.

RA
The Right Ascension of the RASS Source in the selected equinox. This was created by the HEASARC from the RASS name and hence has a precision of 0.1 seconds of time.

Dec
The Declination of the RASS Source in the selected equinox. This was created by the HEASARC from the RASS name and hence has a precision of 1 arcsecond.

LII
The Galactic Longitude of the RASS Source.

BII
The Galactic Latitude of the RASS Source.

Offset
The angular separation between the ASAS and RASS source positions, in arcseconds.

Period
The orbital period P of the binary, in days.

Minimum_Epoch
The heliocentric date/time of the epoch of minimum light of the eclipsing binary. This was given as a 'modified' Julian Date (HJD - 2450000), where HJD is the heliocentric Julian Date, to a precision of 0.001 days, i.e., of about 1.4 minutes. Given this level of precision, and remembering that HJD and the Barycentric Julian Date (BJD) differ by no more than +/- 4 seconds, this date/time is thus essentially barycentric also.

Max_Vmag
The V-Band brightness at maximum light, expressed as an apparent magnitude.

Max_Imag
The I-Band brightness at maximum light, expressed as an apparent magnitude.

Distance
The distance D to the eclipsing binary, in parsecs. This was calculated as discussed in Section 4 of the reference paper using a main-sequence fit for the detached and semi-detached systems (treating them as single stars) from Hawley et al. (1999, AJ, 117, 1341) assuming solar metallicity, and a fit from Rucinski and Duerbeck (1997, PASP, 109, 1340) for the contact binaries.

Log_Lbol
The logarithm of the bolometric luminosity of the binary system, in erg/s, based on the observed magnitude, the calculated distance and an adopted bolometric correction, as discussed in Section 4.1 of the reference paper.

Hardness_Ratio
The hardness ratio HR = (H-S)/(H+S) of the RASS X-ray source, where H is the counts in the 0.5-2.0 keV energy range and S is the counts in the 0.1-0.4 keV energy range.

Hardness_Ratio_Error
The uncertainty in the hardness ratio.

RASS_Count_Rate
The ROSAT All-Sky Survey X-ray source count rate, CR, in counts per second (ct/s).

RASS_Count_Rate_Error
The uncertainty in the RASS X-ray source count rate, in counts per second (ct/s).

Log_Lx
The logarithm of the X-ray luminosity of the RASS source. in erg/s, based on the observed count rate, CR, and hardness ratio HR of the X-ray source, and the estimated distance D in the usual manner for RASS sources:

      f_X = CR * (5.30*HR + 8.7) * 1.0E-12

      L_X = 1.20E38 * D2 * f_X
  

Log_Rossby_Number
The logarithm of the Rossby Number for the eclipsing binary log R_0 = log (P_rot/tau_C), where the rotational period P_rot is assumed to be equal to the orbital period P, i.e., the system is assumed to be tidally locked, for those binaries with orbital periods less than 10 days, and tau_C is the convective turnover time of the primary star and is calculated as discussed in Section 6 of the reference paper.

Alt_Name
Another identification for the binary from the literature, mainly from the GCVS.

Binary_Type
The ASAS classification of the variability type of the binary, where EC = contact (W UMa type), ESD = semi-detached (Algol), and ED = detached binary.

Class
The HEASARC Browse object classification, based on the binary_type, where we have called detached (ED) systems "RS CVn systems". While it is true that most RS CVn binaries are detached, a few are semi-detached, so that there is not a precise one-to-one match between these classes.


Contact Person

Questions regarding the RASSASASEB database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 19-Jul-2010