Phi Andromedae — Double Star in Andromeda

Magnitude 4.2^m DoubleStar Andromeda (And) Visible

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1Physical Properties

Magnitude 4.25

Spectral Type B7Ve

Star Color Blue-white (B-V -0.07)

Distance 1,087 ly

2Position & Identifiers

RA 01h 09m 30.2s

Dec +47° 14' 31.0"

Constellation Andromeda (And)

HR 335

HIP 5434

HD 6811

SAO 36972

Bayer Phi

Flamsteed 42 And

Variable ID Var?

Double Cat 940

3How easy to split?

Primary 4.3 mag Companion 5.6 mag Separation 0.5″

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Telescope	Bortle 3	Bortle 4	Bortle 5
80 mm refractor 80mm refr.	V. hard	V. hard	V. hard
150 mm Newton 150mm Newt.	V. hard+	V. hard+	V. hard+
Celestron C8 (203 mm SCT) C8 203mm	V. hard+	V. hard+	V. hard+

Easy Medium Hard Very hard Impossible

Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs

To reach "Medium" at Bortle 3, you'd need at least a 420 mm reflector.

4Visibility

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Best season Sep – Nov (peak: Oct)

5Multiple Star System

Separation 0.5″

Companion Mag 5.6

Position Angle 114°

Star Colors A: Blue-white B: White

Discoverer STT 515

Notes

4.6 B6IV, 5.5 B9V, 371.6y, a = 0.447". Combined mag., colors. Masses 16 and 10 solar. Resolved by speckle | interferometry 1983.93, sep. 0.64".

Separation over time

Period: 554.0 y Eccentricity: 0.385 Now: 0.53", PA 110° + 0.00" in 5 years

Apparent separation over time, computed from ORB6 orbital elements. Steep curves indicate fast-changing pairs — catch them while they're splittable.

Eyepiece View

Telescope Eyepiece

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80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

A: 4.2 · B: 5.6 · Sep: 0.5″ · PA: 114° · N up, E right

Unresolved · Rayleigh: 2.3″ · Dawes: 1.9″ · Eff: 2.3″

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7

Size Comparison

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8

Compare Stars

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9

Spectral Classification

10

Hertzsprung-Russell Diagram

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Read: The Hertzsprung-Russell Diagram — Reading Stars Like a Map

11

Stellar Lifecycle

12

Blackbody Spectrum

13

Stellar Absorption Spectrum

Simulated absorption spectrum based on spectral type. Hover over lines to identify elements.

14

Stellar Fusion

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15Stellar Notes

Spectral

Also classified B7III, B9IIIe.

Dynamical

0.003".

16

Light Travel Time Machine

17

Relativistic Travel

Nearby in the Sky

Other targets within a few degrees — pan your scope a little and keep exploring.

Visibility scores assume a 150 mm Newton at Bortle 4.

Bright spiral galaxy

Galaxy mag 10.9 3.0° Cassiopeia

Little Dumbbell Nebula

Planetary nebula — try an OIII filter

Planetary Nebula mag 10.1 6.9° Perseus

Emission nebula — try an OIII filter

Emission Nebula mag 7.0 9.7° Cassiopeia

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