When is the best time to observe HIP 105259?

HIP 105259 is best observed from July through September, with peak visibility during August when it transits around midnight in the Northern Hemisphere.

Where is HIP 105259 located in the sky?

HIP 105259 lies in the constellation Cepheus at right ascension 21h 19m and declination +58° 37′.

What telescope do I need to split HIP 105259?

Splitting HIP 105259 requires an aperture of roughly 100 mm or larger — the components are separated by about 4.6″ at magnitudes near 5.7. The companion is about 3.6 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

HIP 105259 — Double Star in Cepheus

Magnitude 5.5–5.8^m DoubleStar Cepheus (Cep) Visible

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1Physical Properties

Magnitude 5.66

Range 5.55 - 5.76

Variable Type Semi-Regular Variable (Supergiant)

Spectral Type M1Ibep+B2pe+B3V

Star Color Red (B-V 1.38)

Distance 815 ly

2Position & Identifiers

RA 21h 19m 15.8s

Dec +58° 37' 25.0"

Constellation Cepheus (Cep)

HR 8164

HIP 105259

HD 203338

SAO 33318

Double Cat 14864

SIMBAD

3How easy to split?

Primary 5.7 mag Companion 9.3 mag Separation 4.6″

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

Easy Medium Hard Very hard Impossible

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

4Visibility

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Best season Jul – Sep (peak: Aug)

5Multiple Star System Quadruple D: optical

Components 4 (quadruple)

Component IDs AB

Separation 4.6″

Companion Mag 9.3

Companion Sp B2+B3

Position Angle 45°

Star Colors A: Red B: Blue

Discoverer STF2790

Notes

AB binary. B is B3V.

Separation over time

Measured 1831 → 2015 (184 y)

Separation drift 3.0" → 4.6" (+1.60")

Rate +0.0087" / y

PA drift 35° → 45° (+10°, +0.054°/y)

Slow change over generations — observable in lifetime comparisons.

Measured from the WDS observational archive. No orbital solution has been derived — most likely the period is too long to fit an orbit to the available measurement arc.

Eyepiece View

Telescope Eyepiece

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80x Dawes: 1.9″ TFOV: 0.6°

Seeing

Scale Realistic = true angular size

A: 5.7 · B: 9.3 · Sep: 4.6″ · PA: 45° · N up, E right

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

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Size Comparison

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Compare Stars

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Spectral Classification

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Hertzsprung-Russell Diagram

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Stellar Lifecycle

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Blackbody Spectrum

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Stellar Absorption Spectrum

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

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Stellar Fusion

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14Stellar Notes

Variable Star

Variable shell spectrum.

Spectroscopic Binary

75d period not confirmed by RV of the blue companion in the nonvariable VV Cephei system. The second component B2V, | 1.9 mag. fainter than primary. SKYLAB indicates cool star with hot companion. vsini secondary 50k/s. Resolved by | speckle interferometry 1986.45, sep. 0.09".

Group/Cluster

Cep OB2.

Dynamical

0.005".

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