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Package {astronomR}

Type: Package
Title: Cosmic Insights: Statistical Frameworks for Astronomers
Version: 0.1.0
Description: A comprehensive toolkit for astronomical and cosmological computations. Provides functions for angular coordinate conversions (degrees, hours-minutes-seconds, degrees-minutes-seconds, and radians), access to fundamental physical constants, queries to the Gaia Archive TAP (Table Access Protocol) service, cosmological distance calculations, and early-universe thermal physics including photon density and 'Saha' equation solutions.
License: MIT + file LICENSE
Encoding: UTF-8
Language: en-US
URL: https://github.com/samrit2442/astronomR
BugReports: https://github.com/samrit2442/astronomR/issues
Imports: dplyr, httr, jsonlite, pracma, readr, stringr, tibble, tidyr
Depends: R (≥ 4.1.0)
Suggests: testthat (≥ 3.0.0)
Config/testthat/edition: 3
Config/roxygen2/version: 8.0.0
NeedsCompilation: no
Packaged: 2026-05-19 12:08:19 UTC; samri
Author: Samrit Pramanik ORCID iD [aut, cre], Kazi Abu Rousan ORCID iD [aut]
Maintainer: Samrit Pramanik <samrit.2442@gmail.com>
Repository: CRAN
Date/Publication: 2026-05-27 09:20:02 UTC

Convert Megaparsecs to Kilometers

Description

This function converts a distance value from megaparsecs (Mpc) to kilometers (km). The conversion factor is based on 1 parsec being equivalent to 3.262 light-years, and 1 light-year being approximately 9.461 \times 10^{12} kilometers.

Usage

Mpc_to_km(mpc)

Arguments

mpc

A numeric value representing the distance in megaparsecs.

Value

A numeric value representing the equivalent distance in kilometers (km).

Examples

Mpc_to_km(1) # Converts 1 Mpc to kilometers

Ionization Fraction Using the Saha Equation

Description

Calculates the ionization fraction X_e as a function of redshift z using the Saha equation for hydrogen recombination.

Usage

Saha_Xe(z)

Arguments

z

Numeric. The redshift value.

Value

Numeric. The ionization fraction X_e (between 0 and 1).

Examples

Saha_Xe(1300)
Saha_Xe(1100)

Retrieve the Value of a Physical Constant

Description

Retrieves the value and unit of a specified physical constant from the constants_df dataset. You can search by the constant's name and choose whether to retrieve the value in SI units or natural units.

Usage

constant_value(constant_name, unit = "SI")

Arguments

constant_name

Character. The name (or part of the name) of the constant to search for. Case-insensitive and partial matches are allowed.

unit

Character. The unit system to retrieve the constant in. Options are:

  • "SI": Retrieves the value in SI units (default).

  • "Natural": Retrieves the value in natural units.

Value

A list containing:

Examples

constant_value("speed of light", unit = "SI")
constant_value("planck", unit = "SI")
constant_value("electron mass", unit = "Natural")

Fundamental Physical Constants in SI and Natural Units

Description

A dataset containing commonly used physical constants in both SI units and natural units. The dataset includes the constant's name, symbol, value in SI units, SI unit, value in natural units, and natural unit representation.

Usage

constants_df

Format

A tibble with 19 rows and 6 columns:

name

Character. Name of the physical constant.

symbol

Character. Symbol representing the constant.

value_SI

Numeric. The value of the constant in SI units.

unit_SI

Character. The SI unit for the constant.

value_Natural

Numeric. The value of the constant in natural units.

unit_Natural

Character. The unit of the constant in natural units.

Value

A tibble (data frame) with 19 rows and 6 columns:

name

Character. Full name of the physical constant.

symbol

Character. Symbol representing the constant.

value_SI

Numeric. Value of the constant in SI units.

unit_SI

Character. The SI unit string for the constant.

value_Natural

Numeric. Value of the constant in natural units.

unit_Natural

Character. The natural unit string for the constant.

Examples

constants_df

Convert Degrees to Radians

Description

Converts angles from degrees to radians. Supports vectorized input.

Usage

deg2rad(deg)

Arguments

deg

Numeric. The angle(s) in degrees to convert to radians.

Value

Numeric. The corresponding angle(s) in radians.

Examples

deg2rad(180)
deg2rad(c(0, 90, 180))

Convert Decimal Degrees to Degrees, Minutes, and Seconds (DMS) Format

Description

Converts a decimal degree angle to the Degrees-Minutes-Seconds (DMS) format commonly used in astronomy for expressing declination and other angles.

Usage

deg_to_dms(deg, type = "cat", digit = 5)

Arguments

deg

Numeric vector of angles in decimal degrees. All values must be between -90 and 90.

type

Character string specifying the output format. Options are:

  • "cat" (default): Prints the angle as a formatted string in DMS notation.

  • "mat": Returns a matrix with columns for sign, degrees, minutes, and seconds.

digit

Integer specifying the number of digits to round the seconds to. Default is 5.

Value

When type = "cat", prints the DMS string and returns NULL invisibly. When type = "mat", returns a character matrix with columns SIGN, DEG, MIN, and SEC.

Examples

deg_to_dms(45.5042)
deg_to_dms(-12.5, type = "mat")
deg_to_dms(c(10.25, 45.5), type = "mat")

Convert Decimal Degrees to Hours, Minutes, and Seconds (HMS) Format

Description

Converts a decimal degree angle to Hours-Minutes-Seconds (HMS) format, which is used in astronomy to express Right Ascension (RA).

Usage

deg_to_hms(deg, type = "cat", digit = 5)

Arguments

deg

Numeric vector of angles in decimal degrees. Values can range from 0 to 360.

type

Character string specifying the output format. Options are:

  • "cat" (default): Prints a formatted string (e.g., 3H0M0S).

  • "mat": Returns a matrix with columns for hours, minutes, and seconds.

digit

Integer specifying the number of decimal places to round seconds to. Default is 5.

Value

When type = "cat", prints the HMS string and returns NULL invisibly. When type = "mat", returns a numeric matrix with columns HRS, MIN, and SEC.

Examples

deg_to_hms(deg = 45)
deg_to_hms(deg = 45, type = "mat")
deg_to_hms(deg = 177.74208, digit = 3)

Convert Degrees, Minutes, and Seconds (DMS) to Decimal Degrees

Description

Converts an angle expressed in Degrees-Minutes-Seconds (DMS) format to decimal degrees. Accepts either separate numeric arguments or a single formatted string.

Usage

dms_to_deg(d, m, s, digit = 5)

Arguments

d

Numeric or character. The degrees component. If a single character string is provided (e.g., "12\u00B034'56\""), the degrees, minutes, and seconds are parsed automatically, and m and s should be omitted.

m

Numeric. The minutes component. Must be less than 60. Optional when d is a string.

s

Numeric. The seconds component. Must be less than 60. Optional when d is a string.

digit

Integer. Number of decimal places to round the result to. Default is 5.

Value

Numeric. The angle in decimal degrees.

Examples

dms_to_deg(d = 12, m = 34, s = 56)
dms_to_deg(d = "12\u00B034'56\"", digit = 3)

Query Gaia Archive Data

Description

Queries the Gaia Archive TAP service to retrieve stellar data based on specified variables and filter conditions. Uses the Gaia Early Data Release 3 (EDR3) catalog.

Usage

get_gaia_data(vars, condition)

Arguments

vars

A character string specifying the variables (columns) to retrieve, separated by commas (e.g., "source_id, ra, dec").

condition

A character string specifying the SQL WHERE clause used to filter rows (e.g., "parallax > 10").

Details

This function sends a synchronous ADQL query to the Gaia Archive TAP service at https://gea.esac.esa.int/tap-server/tap/sync. An internet connection is required.

Value

A data frame containing the requested columns for all rows matching condition.

Examples


vars <- "source_id, ra, dec, phot_bp_mean_mag, phot_rp_mean_mag, parallax"
condition <- "parallax > 40"
result <- get_gaia_data(vars, condition)
head(result)

Convert Hours, Minutes, and Seconds (HMS) to Decimal Degrees

Description

Converts an angle expressed in Hours-Minutes-Seconds (HMS) format to decimal degrees. Accepts either separate numeric arguments or a single formatted string.

Usage

hms_to_deg(h, m, s, digit = 5)

Arguments

h

Numeric or character. The hours component. If a single character string is provided (e.g., "03h15m30s"), the hours, minutes, and seconds are parsed automatically, and m and s should be omitted.

m

Numeric. The minutes component. Optional when h is a string.

s

Numeric. The seconds component. Optional when h is a string.

digit

Integer. Number of decimal places to round the result to. Default is 5.

Value

Numeric. The angle in decimal degrees.

Examples

hms_to_deg(h = 3, m = 15, s = 30)
hms_to_deg(h = 3, m = 15, s = 30.123)
hms_to_deg(h = "03h15m30s")

Convert Kilometers to Megaparsecs

Description

This function converts a distance value from kilometers (km) to megaparsecs (Mpc). The conversion factor is based on 1 parsec being equivalent to 3.262 light-years, and 1 light-year being approximately 9.461 \times 10^{12} kilometers.

Usage

km_to_Mpc(km)

Arguments

km

A numeric value representing the distance in kilometers.

Value

A numeric value representing the equivalent distance in megaparsecs (Mpc).

Examples

km_to_Mpc(3.086e19) # Converts 3.086e19 km (approx. 1 Mpc) to megaparsecs

Photon Energy Density as a Function of Temperature

Description

Calculates the photon energy density for a given temperature T, using \rho_\gamma = \frac{\pi^2}{15} T^4.

Usage

photon_energy_density_fn_T(temp, unit = "eV")

Arguments

temp

Numeric. Temperature in either eV or Kelvin.

unit

Character. The unit of the temperature input. Either "eV" (default) or "K".

Value

Numeric. The photon energy density in natural units.

Examples

photon_energy_density_fn_T(1, "eV")
photon_energy_density_fn_T(300, "K")

Photon Energy Density as a Function of Redshift

Description

Calculates the photon energy density at a given cosmological redshift z by first converting to temperature in eV.

Usage

photon_energy_density_fn_z(z)

Arguments

z

Numeric. The redshift value.

Value

Numeric. The photon energy density in natural units.

Examples

photon_energy_density_fn_z(1300)

Photon Number Density as a Function of Temperature

Description

Calculates the photon number density for a given temperature T, using n_\gamma = \frac{2\zeta(3)}{\pi^2} T^3.

Usage

photon_number_density_fn_T(temp, unit = "eV")

Arguments

temp

Numeric. Temperature in either eV or Kelvin.

unit

Character. The unit of the temperature input. Either "eV" (default) or "K".

Value

Numeric. The photon number density in natural units.

Examples

photon_number_density_fn_T(1, "eV")
photon_number_density_fn_T(300, "K")

Photon Number Density as a Function of Redshift

Description

Calculates the photon number density at a given cosmological redshift z by first converting to temperature in eV.

Usage

photon_number_density_fn_z(z)

Arguments

z

Numeric. The redshift value.

Value

Numeric. The photon number density in natural units.

Examples

photon_number_density_fn_z(1300)

Convert Radians to Degrees

Description

Converts angles from radians to degrees. Supports vectorized input.

Usage

rad2deg(rad)

Arguments

rad

Numeric. The angle(s) in radians to convert to degrees.

Value

Numeric. The corresponding angle(s) in degrees.

Examples

rad2deg(pi)
rad2deg(c(0, pi / 2, pi))

Deviation of Ionization Fraction from 0.5

Description

Returns X_e(z) - 0.5, useful for finding the redshift at which the ionization fraction equals 0.5 (e.g., via root-finding).

Usage

soln_saha(z)

Arguments

z

Numeric. The redshift value.

Value

Numeric. X_e - 0.5.

Examples

soln_saha(1350)

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