The DUNES archive
This document contains information on the DUNES
archive in addition, and complementary to what is provided in the paper entitled "DUst around NEarby Stars.
The survey observational results" (Eiroa et al. (2013)).
In what follows, the contents of the several parts of the archive are described.
Any question on further details can be addressed to:
The prime identifier used by DUNES is the Hipparcos (HIP) number. When available,the HD (Henry Draper), HR (Harvard Revised)/BS (Bright Star) and other denomination of the type, e.g. 24 Cas, η Cas, EP Eri, are given.
The equatorial (IRCS, right ascension and declination), galactic (longitude and latitude), and ecliptic (longitude and latitude) coordinates are provided. All data are referred to the J2000.0 equinox and epoch (proper motions have been taken into account).
Stellar parallaxes and proper motions and errors are from the revision of the Hipparcos catalogue by van Leeuwen (2007), Vizier catalogue I/311. References for the remaining stellar parameters, namely, spectral type, effective temperature, gravity, metallicity, projected rotational velocity, bolometric luminosity and age can be found in Eiroa et al. (2013).
Several magnitudes and colour indices have been used to build the spectral energy distribution (SED) for each star. Each item below describes the source of the data and gives the corresponding reference for the zero points (fluxes at zero magnitude) that have been used to compute the fluxes included in the files hipxxxxxx_sed.dat that can be found by clicking the option Full SED.
Quick summary sheets
A summary sheet called hipxxxxxx_summary_sheet.pdf contains in a single page all the relevant information for each star. Hereafter, the string xxxxxx in the file names contains the Hipparcos identification of the star padded with zeros to the left when necessary (e.g. hip000910 or hip049908). Identifications, equatorial coordinates, the parallax, proper motions, stellar parameters, plots of the PACS and SPIRE mosaics and the SED, and the PACS and SPIRE fluxes are provided.
Spectral Energy Distributions (SED)
By clicking this option, two files are provided for each star:
The first one contains the whole SED including the PACS and SPIRE fluxes; the second one is contains a plot of the full SED.
|Wv (mu)||F_nu(mJy)||Delta F_nu(mJy)||Band/comments|
|1.235||1.214E+04||3.003E+03||2MASS J [quality flag: D]|
|1.662||1.220E+04||4.945E+02||2MASS H [quality flag: A]|
|2.159||9.665E+03||1.424E+02||2MASS K_s [quality flag: A]|
|9.000||7.125E+02||4.246E+00||Akari 9 [colour corrected]|
|12.000||3.527E+02||2.822E+01||IRAS 12 [colour corrected]|
|160.000||<4.20||PACS 160 [3-sigma upper limit]|
|250.000||<19.5||SPIRE 250 [3-sigma upper limit]|
|350.000||<21.0||SPIRE 350 [3-sigma upper limit]|
|500.000||<24.6||SPIRE 500 [3-sigma upper limit]|
The data are organized in four columns: (1) wavelengths in µm, (2) fluxes
and (3) uncertainties in mJy, and (4) descriptions of the bands (and any
Details on the calibration from magnitudes to fluxes are given above in the
paragrpah devoted to the photometry.
The Akari fluxes have been colour corrected using the data provided in Section
4.8 of the "Akari IRC Data User Manual. Version 1.4"
(look for the document in section "Instrument Data Users Manuals"). The observed fluxes were divided by the corresponding constants, K(9 µm), K(18 µm). Values in Table 4.8.11 were taken and the effective temperature was used as independent variable. Typical values for the corrections at the temperatures of the DUNES stars are 1.18, 0.99 at 9 and 18 µm, respectively. The IRAS fluxes have been colour corrected dividing the observed fluxes by the corresponding corrections K(12 µm), K(25 µm) and K(60 µm). Their values are estimated by interpolation of the numbers given in the IRAS Explanatory Supplement. VI. Flux Reconstruction and Calibration. Table Suppl. VI.C.6 - Color Correction Factors, K. (see the last table of that web page) using the effective temperature as the independent variable. Typical values of the corrections are 1.43, 1.40 and 1.32 for 12, 25 and 60 µm, respectively. The PACS -and SPIRE, when available- fluxes (or 3-σ upper limits) are given in the last lines of the table. The uncertainties in those fluxes contain only the statistical errors.
The photometry from the optical up to Spitzer/MIPS 70 µm is plotted as
light-blue solid circles, the PACS and SPIRE fluxes are plotted as red circles;
3-σ upper limits are clearly indicated. The Spitzer/IRS spectra are
plotted in magenta. The normalized photospheric model is plotted in black.
Each graph shows the fluxes Fν, in mJy, plotted against the wavelength in
µm. These plot can be reproduced for a given star using the following set
of files that can be found in this archive:
Full SED fluxes: hipxxxxxx_sed.dat
Spitzer/IRS spectrum: hipxxxxxx_irs_spectrum.dat
Model photosphere: hipxxxxxx_model_photosphere.dat
Note that SPIRE data and IRS spectra are not available for all the objects.
By clicking this option, files called hipxxxxxx_model_photosphere.dat are provided for the stars selected. They have typically ∼28000 lines, run from ∼0.04 to 4000 µm and are organized in two columns: (1) wavelengths in µm and (2) fluxes in Jy. The files look like this:
They contain photospheric models normalized to the photometry that has been
used to build the SED (see above). Details on the original models and the method
used to normalize them to the photometry are given in Eiroa et al. (2013).
Several combinations of bands (BVI+ 2MASS JHKs + auxiliar JHKLM + WISE)
were used to carry out normalizations of the original model; the one with the least
reduced χ2 was chosen. Only 2MASS photometry with quality A or B was used,
and special care was taken not to include the WISE W4 band when the star showed
an infrared excess starting at wavelengths around ∼20 µm.
The Spitzer/IRS (Houck et al. 2004) spectra provided in the archive are a combination of all low-resolution modules available from the Spitzer archive. For each module, data are taken with the star positioned at two locations along the slit, to allow for background subtraction. The resulting spectra are averages from the two slit positions, while the uncertainty at each wavelength is estimated from their difference. The slit for the long-wavelength mode (LL2: 14-21 µm and LL1: 20-40 µm) is much wider (11 arcsec) than the telescope pointing uncertainty (1 arcsec; Werner et al. 2004), such that flux loss outside of the slit is minimal and no scaling of individual modules is needed. The shorter wavelength modules (SL2: 5-8 µm and SL1: 8-14 µm), however, can suffer from slit loss and need to be normalized to match the longer wavelength spectra; the adjustement in flux is typically between 0 and 10% (see e.g. Lawler et al. 2009, who found a dispersion of 8% when they normalized short-wavelength data to an independent model photosphere).
The files, called hipxxxxxx_irs.dat, look like this:
|Wv (mu)||F_nu (Jy)||Delta F_nu (Jy)|
and the data are organized in three columns: (1) wavelengths in µm, (2) fluxes
and (3) uncertainties in Jy.
Note: All IRS the spectra but two were built by members of the DUNES team. The origin of the spectra for HIP 7978 and HIP 17439 can be found in the corresponding headers of the files; the original format of the data they contain has been kept unchanged in the archive.
PACS mosaics and SPIRE small maps
A complete account of the Herschel PACS and SPIRE observations and data reduction can be found in Sect. 4 of Eiroa et al. (2013). After the reduction process, the two individual PACS scans were combined in a single mosaic to reduce sky noise and suppress 1/f stripping effects from the scanning. Final -standard- image scales were 1 arcsec per pixel at 70 and 100 µm and 2 arcsec per pixel at 160 µm compared to native instrument pixel sizes of 3.2 and 6.4 arcsec respectively. Both the native and standard image scale mosaics are provided by clicking this option in the archive. The files are called:
where lambda is a 2- or 3-character string specifying the corresponding wavelength, and std/ntv stand for "standard" or "native". For the SPIRE observations, the small maps were created using the standard pipeline routine in HIPE, using the naive mapper option. Image scales of 6, 10 and 14 arcsec per pixel were used at 250, 350 and 500 µm, respectively. The files are called:
where again lambda indicates the corresponding wavelength.
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This document was prepared by Benjamín Montesinos on behalf of the DUNES consortium.
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