# What is the distance modulus formula?

## What is the distance modulus formula?

Apparent magnitude, absolute magnitude and distance are related by an equation: m – M = 5 log d – 5. m is the apparent magnitude of the object. M is the absolute magnitude of the object. d is the distance to the object in parsecs.

**Why is the quantity M − M called the distance modulus?**

The only reason those two numbers are different for various stars is because every star is not the same distance from us. This difference is called the distance modulus, m – M. Recall that apparent magnitude is a measure of how bright a star appears from Earth, at its “true distance,” which we call D.

### What would be the distance from Earth to a star if its apparent magnitude m is 16 and its absolute magnitude M is 15?

List of apparent magnitudes

Apparent magnitude (V) | Object | Seen from… |
---|---|---|

−20.20 | star Sun | seen from Uranus at aphelion |

−19.30 | star Sun | seen from Neptune |

−18.20 | star Sun | seen from Pluto at aphelion |

−16.70 | star Sun | seen from Eris at aphelion |

**What is a distance modulus used for?**

The ‘distance modulus’ is the difference between the apparent magnitude and absolute magnitude of a celestial object (m – M), and provides a measure of the distance to the object, r.

#### What is the distance modulus of the supernova 1998aq?

The Distance Modulus on an average for six galaxies is 31.13, which yields a distance of ~16.8 Mpc (The major diameter of the Cloud is 11.1 degrees or 3.3 Mpc).

**How do you find the magnitude and distance?**

If you know a star’s absolute magnitude, then when you compare it to calibration stars, you can determine its distance. Its distance = 10(apparent magnitude – absolute magnitude + 5)/5.

## What is the distance in parsec of Proxima Centauri knowing its observed parallax angle is 0.77 Arcsecs?

The first person to succeed at measuring the distance to a star using parallax was F.W. Bessel, who in 1838 measured the parallax angle of 61 Cygni as 0.28 arcseconds, which gives a distance of 3.57 pc. The nearest star, Proxima Centauri, has a parallax of 0.77 arcseconds, giving a distance of 1.30 pc.

**What is the orbital period of Caprica?**

Caprica is in the third orbit around the Helios Alpha star and shares its orbit with the planet Gemenon. They revolve around their common barycenter, or center-of-gravity, with an orbital period of 28.2 days.

### How does lumosity calculate distance?

Using brightness and luminosity to get distance

- The luminosity of the lightbulb is L = 100 W.
- The brightness is b = 0.1 W/m2.
- So the distance is given by d2 = (100 W)/(4 Pi x 0.1 W/m2).
- Since 4 Pi is approximately 10, this is d2 = (100 / 1) m2.
- Thus d2 = 100 m2.
- We now know what d2 is.
- So d = 10 m.

**What is the apparent magnitude of Sirius?**

-1.46

Sirius/Magnitude

#### What is the ‘distance modulus’?

The ‘ distance modulus ’ is the difference between the apparent magnitude and absolute magnitude of a celestial object ( m – M ), and provides a measure of the distance to the object, r. This table shows the apparent and absolute visual magnitudes of some stars and their distances:

**What is the distance modulus of the Large Magellanic Cloud?**

For example, the Large Magellanic Cloud is at a distance modulus of 18.5, the Andromeda Galaxy ‘s distance modulus is 24.4, and the galaxy NGC 4548 in the Virgo Cluster has a DM of 31.0. In the case of the LMC, this means that the supernova SN1987A, with a peak apparent magnitude of 2.8, had an absolute magnitude of -15.7,…

## How do we calculate the distance of a star?

We can take advantage of this by using the difference between a star’s apparent magnitude and absolute magnitude to actually calculate the distance of the star. This difference is called the distance modulus, m – M.

**What is the role of absorption and distance moduli?**

Absorption is another important factor and it may even be a dominant one in particular cases (e. g. in the direction of the galactic center). Thus a distinction is made between distance moduli uncorrected for interstellar absorption (whose values would overestimate the distance if used naively) and absorption-corrected moduli.