Usage & Decription of tables

Installation (note that this doesn’t work yet)

To use local_volume_database, first install it using pip:

(.venv) $ pip install local_volume_database

Database content

The database is structured as individual yaml files for each system and combined tables as csv and fits files (descriptions of both below). The yaml files are located in data_input/ and the combined csv/fits tables are located in data/.

The tables can be directly loaded into jupyter notebooks without having to download the repository:

import astropy.table as table
dsph_mw = table.Table.read('https://raw.githubusercontent.com/apace7/local_volume_database/main/data/dwarf_mw.csv')

There is also a pdf document summarizing the contents and properties of each combined table.

Decription of tables

The following are the available tables (in csv and fits file formats).

  • dwarf_mw : Milky Way dwarf galaxies (the most distant dwarf galaxy is Eridanus II at ~ 350 kpc)

  • dwarf_m31: M31 dwarf galaxies

  • dwarf_local_field: dwarf galaxies outside of MW/M31 within the Local group to a distance of ~ 3 Mpc. This is an extension of galaxies from McConnachie 2012

  • dwarf_all : combination of dwarf_mw, dwarf_m31, dwarf_local_field

  • dwarf_local_field_distant: dwarf galaxies with distance > 3 Mpc. The limiting distance is set to ~10-40 Mpc (the approximate limits of HST/JWST). This table is not complete.

  • gc_ufsc: faint star-cluster like systems (generally rhalf < 20 pc and M_V > -3 and at high Galactic latitudes abs(b) > ~5-10). A number of these systems are likely tidally stripped star clusters, tidally stripped dwarf galaxies, or the faintest dwarf galaxies. Many have are ambiguous classifications and are difficult to classify. Ultra-faint compact stellar systems.

  • gc_disk: post-Harris catalog globular clusters at low Galactic latitude (abs(b) <10), some of these objects might be open clusters, and some objects have not been confirmed

  • gc_harris: globular clusters in Harris catalog (this excludes Koposov 1 and 2 which are in the gc_ufsc table)

  • gc_dwarf_hosted: Globular clusters hosted by dwarf galaxies. This does not include the Sagittarius GCs which are in gc_harris. Incomplete table.

There are two extra tables (data/pm_overview.csv and data/j_factor.csv). Both are collections of measurements (the other tables have one measurement per object).

pm_overview.csv: key, reference, proper motion measurement, method (this includes most proper motion measurements of dwarf galaxies)

j_factor.csv: key, reference, angle, j-factor measurement [units are log10 GeV^2 cm^-5], notes (this includes some literature j-factor measurements, mostly from A. B. Pace)

columns:

  • key: unique identifier for each system. The yaml input files have the same name.

  • host: host of system [MW, LMC, M31, etc]

  • confirmed_real: system has been confirmed with either deeper photometry, follow-up spectroscopy, proper motion, or other methods

  • confirmed_dwarf: (or confirmed_star_cluster) system has been confirmed to be dwarf galaxy (or star cluster) based on spectroscopy, and/or deeper photometry.

  • ra: right ascension ICRS [degree]

  • dec: declination ICRS [degree]

  • rhalf: major half-light radius (or plummer radius) in [arcmin]

  • ellipticity: 1 - minor/major axis (or 1 - axis ratio)

  • position_angle: N->E [degree]

  • distance_modulus [mag]

  • distance: computed from distance_modulus [kpc]

  • rhalf_physical: half-light radius in physical units – rhalf * distance [parsec] (computed from other columns)

  • rhalf_sph_physical: spherically averaged half-light radius; rhalf * distance * sqrt(1-ellipticity) in [parsec] (computed from other columns)

  • apparent_magnitude_v: apparent magnitude in V-band. Corrected for extinction.

  • M_V: absolute V-band magnitude, computed from distance_modulus and apparent_magnitude_V

  • mass_stellar: log10 stellar mass assuming M/L=2 and computed from M_V [Msun]

  • surface_brightness_rhalf: average surface brightness within spherically averaged half-light radius [mag arcsec^-2]

  • vlos_systemic: heliocentric velocity of system [km/s]

  • vlos_sigma: velocity dispersion in line-of-sight [km/s]

  • metallicity: metallicity, spectroscopic preferred [dex]

  • metallicity_type: lists whether metallicity column is photometric or spectroscopic

  • metallicity_spectroscopic: spectroscopic metallicity [dex]

  • metallicity_spectroscopic_sigma: spectroscopic metallicity dispersion [dex]

  • pmra: proper motion in right ascension, includes cos(dec) term following Gaia [mas/yr]

  • pmdec: proper motion in declination direction [mas/yr]

  • rcore, rking: profile fits with king profile in arcmin

  • rad_sersic, n_sersic: sersic profile parameters. rad_sersic in arcmin

  • age: age of system [Gyr]

  • metallicity_photometric: metallicity from isochrone fitting (or non-spectroscopic metallicity such as metallicity sensitive narrowband imaging)

  • flux_HI: flux in HI [Jy km s^−1]

  • mass_HI: log10 HI mass computed from flux_HI and distance [Msun]

  • ref_ + x : reference columns such as ref_structure, ref_distance, ref_m_v, ref_vlos, ref_proper_motion. All reference columns have the same format: author last name + ADS bibcode.

Many columns also have associated error columns. These follow the format of name + _em, + _ep + _ul (e.g., rhalf_em).

error columns:

  • _em = error minus = minus 1 sigma (or 16% confidence interval)

  • _ep = error plus = plus 1 sigma (84% confidence interval)

  • _ul = upper limit at 95% confidence interval (some are at 5sigma, 90% or 84%, but the goal is to make it consistent)

The reference format is author last name + ADS bibcode. The author’s last name has special characters removed but the capitalization is unchanged. There is an associated bibtex file (latex/lvdb.bib) that includes all references in the database.

Decription of yaml files

There is an example yaml file in the /code/ folder. It includes all collections and keys in the database with a short descrition and units. Not all keys are entered into the csv tables. The yaml keys are Bolded below and the bullet points follow the yaml collection structure. Errors columns are not included. The collections are split such that a single reference can describe the contents.

  • key —- unique internal identifier. This should be the same as the name of the file (without .yaml) (required yaml key)

  • table – table to place system into (required yaml key)

  • location – center of the system (yaml collection)

    • ra – right ascension ICRS [degree] (required yaml key)

    • dec – declination ICRS [degree] (required yaml key)

  • name_discovery

    • name – name of system

    • other_name – list of additional names of the system

    • ref_discovery — List of discovery references. There can be multiple discovery references due to independent discoveries made on similar timescales. Follow-up confirmation studies (i.e. HST imaging for distant candidate dwarfs around local volume hosts). Re-discoveries of systems (i.e. globular clusters hosted by dwarf galaxies).

    • discovery_year – year of discovery. This may follow the arxiv year instead of the journal publication year.

    • host – host of system.

    • confirmed_dwarf – 0/1 1 = confirmed dwarf galaxy.

    • confirmed_star_cluster – 0 or 1. 1 = confirmed star cluster.

    • confirmed_real – 1 = Object is confirmed to be physical system. Generally from spectroscopic radial velocity measurements.

    • false_positive – 1 = Object is confirmed to be a false positive.

  • structure – yaml collection

    • rhalf – elliptical half-light radius (or plummer radius) [arcmin]. This corresponds to the major axis. Note that for the distant objects (currently dwarf_local_field_distant) the units are arcsec.

    • ellipticity – Ellipticity of the system, defined as 1 - b/a = 1- minor axis/major axis.

    • position_angle – position angle defined north to east [degree]

    • ref_structure – reference

  • distance – yaml collection

    • distance_modulus – distance modulus of the system. [mag] This quantity is used to compute the distance in kpc for each system.

    • ref_distance

  • m_v – yaml collection

    • apparent_magnitude_v – Apparent V-band magnitude of the system. This quantity is corrected for extinction. This quantity is combined with distance_modulus to compute the absolute V-band magnitude in the combined tables.

    • ref_m_v – reference

  • velocity – stellar velocity/kinematics

    • vlos_systemic – systemic heliocentric velocity of the system. Stellar velocities are preferred but some distant objects are from HI observations. [km/s]

    • vlos_sigma – stellar velocity dispersion. [km/s]

    • ref_vlos – reference

  • proper_motion

    • pmra – systemic proper motion in the direction of right ascension (includes cosdec term) [mas/yr]

    • pmdec – systemic proper motion in the direction of declination [mas/yr]

    • ref_proper_motion – reference

  • spectroscopic_metallicity

    • metallicity_spectroscopic – mean metallicity

    • metallicity_spectroscopic_sigma – metallicity dispersion

    • ref_metallicity_spectroscopic – reference

  • metallicity_photometric

    • metallicity_photometric – photometric metallicity. This can include isochrone fitting or narrow band photometry.

    • metallicity_photometric_sigma – metallicity dispersion from photometric measurements. Many for narrow band photometry.

    • ref_metallicity_photometric – reference

  • structure_king

    • rcore – King core radius [arcmin]

    • rking – King limiting radius, sometimes referred to as the tidal radius [arcmin]

    • ellipticity and position_angle – these are specfic to the King profile fit

    • ref_structure_king – reference

  • structure_sersic

  • structure_eff

  • flux_HI

    • flux_HI

    • ref_flux_HI

  • age

    • age – mean age of the systemic in [Gyr]. Mainly for star clusters.

    • ref_age – reference

Citations to database and citations to the LVDB input

The LVDB is set up to enable citations to the analysis and papers that serves as input to the LVDB. All reference columns (ref_) follow the same format of author last name (removed of special characters) + NASA ADS bibcode. There is a BibTeX file (table/lvdb.bib) with BibTeX entries from ADS with the key matching the LVDB reference column. There is an ADS public library that contains many of the input papers to the LVDB (with the goal to eventually contain all papers in the LVDB). Papers replaced in the future will likely not be removed. The example notebook example_notebooks/example_latex_citations.ipynb/ contains an example of creating a latex table with citations using the LVDB.

As ADS bibcode are a fixed length of 19 characters, the ADS bibcode can be retrieved from the LVDB reference columns. Other public tools such as adstex can be used to create bibtex files.

Users of the LVDB are encouraged to cite the LVDB input of the objects studied in their analysis to give proper acknowledgment to the community.

If you use this in your research please include a link to the github repository (https://github.com/apace7/local_volume_database) and cite the database paper (once it is written). An example in latex is: This work has made use of the Local Volume Databasefootnote{url{https://github.com/apace7/local_volume_database }}.