help

star database + sed models

General

The purpose of this database is to provide stellar photometry and fitted models in an accessible way. Most parts are automated, which is good for including many stars, but potentially bad when the photometry isn't simple. Take the results with a grain of salt.

While it is possible to view individual SED pages without being logged in, you must be logged in to search or view samples. If you want access, please ask.

Search

Search will try to find whatever is entered in the box, and uses the sesame service. Thus, if sesame is down then the search will hang. If the target exists in sdb then a link to the SED page will be returned. If not, import will be attempted. This is commonly successful, but can fail for various reasons. Import is not instantaneous, so wait a minute before clicking on the target name. If this just returns the same page, trying again will not help. Better to drop me a line.

SED pages

Results for individual stars are on SED pages. These attempt to summarise the results of model fitting to the photometry. Normally several models are fitted, and the results from the "best" one used in the summary ("best" means highest evidence, but a more complex model will nearly always fit IRS spectra better). Tabs give access to the different models fitted. The plots are zoomable with a mouse, and some photometry information is available with a mouseover.

Residual plots show the significance of the difference between the photometry and the best fit model (i.e. the values used to compute the model likelihood). They therefore do not include any uncertainty in the model, so should not be interpreted as the significance of any excess over the stellar photosphere.

Links along the top of the page point to various resources. These show the SED or fractional luminosity limits, the photometry input file and a json file with model results (see here for example usage), corner plots with fitted and derived parameters, and external links to various databases. The ellipsis has extra links, to the files produced in the fitting, Herschel PSF fitting results, and ALMA archive (where available).

A general issue is that systems with excesses and IRS spectra commonly prefer fits that include more than one disk component. This is simply because it is fairly easy to improve the fit sufficiently that the penalty for added model complication is outweighed. The current solution is that by default two-component fits are carried out when an excess is present, but only considered to be the best fit when they are explicitly configured as such (via a table that I control). The two-component fits can be viewed in the tabs, and I will over time (with your help) set the configurations such that each system has the "best" fit prioritised.

Samples

Stars are grouped into samples, found at the link from the home page. These are simply directories with files that display various sample properties, and links to individual stars. An HR diagram and some flux vs. radius plots are available. Some sample properties can be downloaded in votable form.

Filters

The filters used can be visualised.

Calibration

Plots used to aid and verify absolute and relative calibration between photometric systems are available. These can take some time to load.