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HPERSEICXO - h Persei Chandra X-Ray Point Source Catalog

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Overview

This table contains some of the results from a Chandra/ACIS-I observations of the massive ~ 13-14 Myr-old cluster, h Persei, part of the famous Double Cluster (h and Chi Persei) in Perseus. Combining the list of 330 Chandra-detected sources with new optical/IR photometry and optical spectroscopy reveals ~ 165 X-ray bright stars with V <~ 23. Roughly 142 have optical magnitudes and colors consistent with cluster membership. The observed distribution of X-ray luminosity L_x peaks at L_x ~ 1030.3 erg s-1 and likely traces the bright edge of a far larger population of ~ 0.4-2 M_sun X-ray active stars. From a short list of X-ray active stars with IRAC 8-micron excess from warm, terrestrial zone dust, the authors derive a maximum X-ray flux incident on forming terrestrial planets. Although there is no correlation between X-ray activity and IRAC excess, the fractional X-ray luminosity correlates with optical colors and spectral type. By comparing the distribution of L_x/L_star versus spectral type and (V-I) in h Per with results for other 1-100 Myr-old clusters, the authors show that stars slightly more massive than the Sun (>~ 1.5 M_sun) fall out of X-ray saturation by ~ 10-15 Myr. Changes in stellar structure for >~ 1.5 M_sun stars likely play an important role in this decline of X-ray emission.

Chandra observations of h Persei were taken with a 41.1 ks exposure on 2004 December 2, (Obs. ID 5407; Sequence Number 200341) with the ACIS detector (chips 0, 1, 2, 3, 6, and 7). The data were obtained in dithered, timed mode, with a frametime of 3.2 s. On-board event rejection and event telemetry was in the VFAINT mode. The field was centered on RA(2000) = 2h19m00s, Dec(2000) = 57d07'12", close to the center of h Persei from Bragg & Kenyon (2005, AJ, 130, 134) (RA(2000) = 2h18m56.4s, Dec(2000) = 57d08'25") and observed at a roll angle of 229 degrees. The data were not registered to an astrometric reference frame (e.g., Two Micron All Sky Survey, 2MASS). The ACIS-I field covers a 17' x 17' area.


Catalog Bibcode

2009AJ....137.3210C

References

The X-Ray Environment During the Epoch of Terrestrial Planet Formation:
Chandra Observations of h Persei
    Currie T., Remage Evans N., Spitzbart B.D., Irwin J., Wolk S.J.,
    Hernandez J., Kenyon S.J., Pasachoff J.M.
   <Astron. J., 137, 3210-3221 (2009)>
   =2009AJ....137.3210C

Provenance

This table was created by the HEASARC in March 2009 based on the electronic versions of Tables 1 and 2 from the paper which were obtained from the Astronomical Journal web site.

Parameters

Source_Number
A source number which uniquely identifies the X-ray source.

Name
The X-ray source identifier using the '[CES2009]' prefix (for Currie, Evans, Spitzbart 2009) and the source number. This name style (created by the HEASARC) has not yet been, but is expected to be, registered with the CDS Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-4 degrees (0.36 arcseconds) in the original table.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-4 degrees (0.36 arcseconds) in the original table.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Raw_Counts
The raw X-ray counts in the 95%-encircled energy radius centered on the X-ray source position.

Counts
The net background-subtracted X-ray counts in the 95%-encircled energy radius centered on the X-ray source position.

Counts_Error
The uncertainty in the net X-ray source counts.

HR1
The hardness ratio HR1 = (H-S)/(H+S), where H is the 2-8 keV counts and S is the 0.5-2.0 keV counts. This parameter therefore compares the full range of CXO's sensitivity. Entries with insufficient data to construct this hardness ratio have been left blank (they were denoted with values of -999. in the original machine-readable table).

HR2
The hardness ratio HR2 = (H-S)/(H+S), where H is the 1.7-2.8 keV counts and S is the 0.5-1.7 keV counts. This parameter therefore highlights differences in the softer energy region. Entries with insufficient data to construct this hardness ratio have been left blank (they were denoted with values of -999. in the original machine-readable table).

HR3
The hardness ratio HR3 = (H-S)/(H+S), where H is the 2.8-8.0 keV counts and S is the 1.7-2.8 keV counts. This parameter therefore highlights differences in the harder energy region. Entries with insufficient data to construct thischardness ratio have been left blank (they were denoted with values of -999. in the original machine-readable table).

Apec_kT
The best-fit X-ray temperature kT in keV, using a one-temperature APEC model (with an assumed fixed abundance of 0.3 solar and an absorption column density of 0.3 x 1022 H atoms cm-2 based on the well-constrained reddening E(B-V) ~ 0.56 to h Persei) for the X-ray source spectrum, and using the CIAO fitting and modeling package Sherpa, version 3.4. The median X-ray temperature for the entire sample is ~ 1.6 keV, which is reasonable for stars with ages intermediate between ~ 1 Myr and 100 Myr as described in Section 2.2 of the reference paper.

Apec_kT_Error
The 1-sigma uncertainty in kT, in keV.

Flux
The unabsorbed X-ray flux of the Chandra source, in erg cm-2 s-1, as derived from the Sherpa fit. The median value for the entire sample of the unabsorbed flux is 10-14.6 erg cm-2 s-1.

Absorbed_Flux
The absorbed X-ray flux of the Chandra source, in erg cm-2 s-1, as derived from the Sherpa fit. The median value for the entire sample of the absorbed flux is 10-14.8 erg cm-2 s-1.

Reduced_Chi_Squared
The reduced Chi2 of the Sherpa fit to the X-ray source spectrum.

RA_Optical
The Right Ascension of the optical counterpart to the X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-4 degrees (0.36 arcseconds) in the original table.

Dec_Optical
The Declination of the optical counterpart to the X-ray source in the selected equinox. This was given in J2000.0 decimal degrees to an accuracy of 10-4 degrees (0.36 arcseconds) in the original table.

Log_Lx
The logarithm of the absorption-corrected X-ray luminosity, in erg/s, for those X-ray sources having optical counterparts, and assuming that they are the distance of h Persei (2.3-2.4 kpc).

Num_Spect_Type
A numerical code for the spectral type of the optical counterpart to the Chandra X-ray source, where 10 = B0, 20 = A0, 30 = F0, 40 = G0, 50 = K0, etc. These were obtained using Hectospec/MMT, FAST/1.5m Tillinghast, and Hydra/3.5m WIYN spectra. To derive spectral types from these spectra, the authors employed the semi-automatic quantitative spectral-typing code SPTCLASS from Hernandez et al. (2004, AJ, 127, 1682; see http://www.astro.lsa.umich.edu/~hernandj/SPTclass/sptclass.html for more information), which is useful for classifying stars regardless of luminosity class and surface gravity. SPTCLASS calculates the spectral types of stars using spectral indices which compare the line flux of each spectral feature to continuum levels. The relationships between spectral indices and spectral types are derived from spectroscopic standards observed with Hectospec. Thus, SPTCLASS is particularly well suited to spectral type h Persei stars. The errors in spectral types are typically ~ 2 subclasses. Sources without spectral types have blank entries (denoted with values of >=99 in the original machine-readable table).

Num_Spect_Type_Error
The 1-sigma uncertainty in the numerical spectral type. The errors in spectral types are typically ~ 2 subclasses. Sources without spectral type errors have blank entries (denoted with values of -10.00 in the original machine-readable table).

Jmag
The 2MASS J-band magnitude of the infrared counterpart to the Chandra X-ray source. Sources without photometry in a given filter have blank entries (denoted with values of 0.00 or -10.00 in the original machine-readable table).

Hmag
The 2MASS H-band magnitude of the infrared counterpart to the Chandra X-ray source. Sources without photometry in a given filter have blank entries (denoted with values of 0.00 in the original machine-readable table).

Ks_Mag
The 2MASS K_S-band magnitude of the infrared counterpart to the Chandra X-ray source. Sources without photometry in a given filter have blank entries (denoted with values of 0.00 in the original machine-readable table).

IRAC_3p6_um_Mag
The Spitzer/IRAC 3.6-micron band magnitude of the infrared counterpart to the Chandra X-ray source. Sources without photometry in a given filter have blank entries (denoted with values of 0.000 or 99.000 in the original machine-readable table).

IRAC_4p5_um_Mag
The Spitzer/IRAC 4.5-micron band magnitude of the infrared counterpart to the Chandra X-ray source. Sources without photometry in a given filter have blank entries (denoted with values of 0.000 or 99.000 in the original machine-readable table).

IRAC_5p8_um_Mag
The Spitzer/IRAC 5.8-micron band magnitude of the infrared counterpart to the Chandra X-ray source. Sources without photometry in a given filter have blank entries (denoted with values of 0.000 or 99.000 in the original machine-readable table).

IRAC_8p0_um_Mag
The Spitzer/IRAC 8.0-micron band magnitude of the infrared counterpart to the Chandra X-ray source. Sources without photometry in a given filter have blank entries (denoted with values of 0.000 or 99.000 in the original machine-readable table).

Vmag
The V-mand magnitude of the optical counterpart to the Chandra X-ray source.

Vmag_Error
The 1-sigma uncertainty in the V magnitude of the optical counterpart to the Chandra X-ray source.

Imag
The I-band magnitude of the optical counterpart to the Chandra X-ray source.

Imag_Error
The 1-sigma uncertainty in the I magnitude of the optical counterpart to the Chandra X-ray source.

Class
The HEASARC Browse object classification, based on the value of the num_spect_type parameter (truncated to the nearest integer value) for those objects with num_spect_type values < 69.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 20-Apr-2009