Stellar abundance information provides one of the primary tools for understanding everything from the evolution of the Milky Way galaxy to the structure and mineralogy of exoplanets. The Hypatia Catalog is a composite stellar abundance catalog that is comprised of multiple literature sources of high-resolution, spectroscopic data which was originally introduced in Hinkel et al. (2014) and subsequently updated in Hinkel et al. (2016, 2017). A breakdown of all the included catalogs (with > 20 stars), including information regarding their telescopes, models, and techniques, is given in this table, where a description of the columns can be found at the bottom of the About page. The NASA Exoplanet Archive data data page is here.
The plot and table can be filtered using the 3 filter boxes on the top right that provide minimum and maximum values (either can be left blank in place of infinity). Changes are enacted by pausing for a few seconds (it is no longer necessary to click the “Submit” button at the bottom of the plot). Options for the filter criteria can be accessed by clicking on the dropdown menu that says “none” as default. From the dropdown menu, if an element is chosen from the Periodic Table, the filter changes to become an X/Y ratio where both the numerator and denominator can be specified. In addition to the neutral state of the element, if the singly ionized element has been measured, the “II” next to the element can be selected (see the About page). Stellar properties are listed along the bottom of the drop down menu in addition to planetary properties. If any of planetary properties are chosen, then the graph will show only planet hosting stars. To look at those stars that have planets without a filter, simply click on “planet letter” in one of the filters (without having to add anything into the “min” or “max” regions). The graph will then plot all of the planets, regardless of whether another planet property is has been selected for the x-, y-, or z-axes, such that a star that hosts multiple planets will be plotted multiple times. The table will also update to include NEA names. The X and Y axes can plot any of the element ratios, stellar properties, or planet properties. Additionally, the Z-axis, or color, can be initialized to show another dimension.
To move, adjust, zoom, or generally change the properties of the plot, the tools listed vertically along the right side of the plot can be toggled to make the appropriate adjustments. Additionally, the figure can be saved by clicking the “Save” button near the bottom.
The Scatter plot is the most basic plot on the Hypatia website, allowing the user to plot nearly any parameter with respect to another. The scatter plot has extremely high functionality and flexibility. The X and Y axes can plot any of the element ratios, stellar properties, or planet properties. Additionally, the Z-axis, or color, can be initialized to show another dimension.
The Target Lists plot is similar to the Scatter plot in functionality, but it also includes a number of pre-defined lists. The available target sets currently include:
A user may plot multiple target lists at once, either individually or using "union" logic to show which stars are in multiple target lists. The user may also plot the rest of the Hypatia Catalog stars that are not in any of the target lists selected.
While the plot showing “Elements and Properties” enables a user to look at either planet hosting stars or stars that are not currently known to have planets, we wanted to provide the ability to look at the two populations simultaneously. Therefore, we have provided a 1D histogram that shows both stars with and without planets. Similar to the other plot, the filter bar can be used to make cuts on those stars analyzed. Additionally, the histogram can viewed either in terms of total number of stars in a bin or normalized (by checking the “Normalize the histogram” toggle) according to the bin with most number of stars, which has a height of 1 by definition.
For those users wishing to change some of the more nuanced aspects of the stellar abundances within the Hypatia Catalog, we provide the ability to make adjustments. In order to ensure that all of the stellar abundances within Hypatia are on the same baseline, all individual catalogs have been renormalized to the same solar normalization. The default is Lodders et al. (2009). As part of the database, the user can change the solar normalization to be with respect to Asplund et al. (2009), Grevesse et al. (2007), Asplund et al. (2005), Grevesse & Sauval (1998), and Anders & Grevesse (1989). If the user would like to view the stellar abundances with respect to the solar normalization employed by each of the catalogs individually, the “Original” option can be chosen. We note that abundances originally published in absolute A(X) notation cannot be shown when the "Original" normalization is selected, since no solar normalization was specified by the authors at the time of publication. However, when a solar normalization is chosen by the Hypatia Catalog user, then all abundances -- [X/H], [X/Fe], or A(X) -- are placed on the same solar scale. The absolute abundances, namely without a solar normalization, can be viewed by choosing “Absolute.” If an element is selected (with respect to H or Fe) and the plot returns “No data points to display,” the original data may be only available as absolute. See Hinkel, Young, & Wheeler (2022) for more details.
The Hypatia Catalog is a multidimensional database, which utilizes all stellar abundances measurements made for an element within a star by 360+ catalogs (see details on the Home page). Therefore, to provide a 2-dimensional table, those measurements must be collapsed or reduced. The toggle “If an element ratio is in multiple catalogs” changes the reduction method to either take the median (default) or mean of all measurements of an element in a star. We note that the stellar abundance dex notation is inherently in log-space, which is explained in Hinkel, Young, & Wheeler (2022). Therefore, to accurately determine the mean value, all of the abundances must first be converted to linear-space, the average taken, and then converted back to log-space. As a result, the mean values will appear slightly more positive than the log-space average. In addition, when viewing the references in the table (by selecting the “Reference” button), only those references that went into the final calculation are provided. Namely, all references are shown when taking the mean, while only the middle one or two references are shown when taking the median.
Users may note that some [Fe/H] column values are repeated by the same first author or group across multiple papers, who often draw upon their previous stellar parameters calculations when determining new element abundances for the same set of stars. Any data entered into the Hypatia Catalog is required to have [Fe/H] data, to ensure that any [X/H] to [X/Fe] conversion is accurate. This means that the same [Fe/H] values are inherently repeated in the [Fe/H] column, ultimately impacting the median or mean calculation. Unfortunately, this is not an issue that can be easily corrected within the Hypatia Catalog database, but we hope that the accessibility of all of the references will allow each user to make the best decision for their science.
Finally, while the Hypatia Catalog is unbiased in its inclusion of datasets, we recognize that the user may wish to look exclusively at particular catalogs. We have provided a toggle that allows the user to switch between “Excluding” or “Allowing” individual catalogs as they see fit.
The table is filtered using the filter bars at the top. The columns that are shown in the table can be adjusted using the “Add/remove columns” button, which gives the user the ability to include individual elements (shown as [X/H] unless the Absolute solar normalization is chosen). Additionally, all stellar properties (RA, Dec, XYZ position, distance, disk, spectral type, V mag, B-V, UVW galactic velocity, Teff, and logg) and all planetary properties (planet letter, period, planet mass, eccentricity, and semimajor axis, where applicable) can be shown in the table (see the About page).
The user can also view the spread (or error) in the stellar abundances. Per the original Hypatia Catalog paper (Hinkel et al. 2014), the spread is defined as the range in the stellar abundance measurements when determined by different groups measuring that same element within that same star. The spread is an exceptionally useful tool to truly define how consistently an element is measured within the star between different datasets, which is why we utilize it as the overall abundance precision, see Hinkel et al. (2016) for more details.