When is the best time to observe AR Lacertae?

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

Where is AR Lacertae located in the sky?

AR Lacertae lies in the constellation Lacerta at right ascension 22h 09m and declination +45° 45′.

What telescope do I need to follow AR Lacertae?

To follow AR Lacertae through its full brightness cycle (magnitude 6.1 to 6.8) you need any 7×50 or 10×50 binoculars — the star fades out of smaller apertures near minimum light.

AR Lacertae — Variable Star in Lacerta

Observable Variable Star Excellent (62/100)

Range: 6.08 - 6.77, Period: 2.0d, Type: EA/AR/RS

VariableStar Lacerta (Lac) Visible

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1Physical Properties

Magnitude 6.11

Range 6.08 - 6.77

Period 47.6 hours

Variable Type Eclipsing Binary (Algol-type)

Spectral Type G2IV+K0III

Star Color Orange (B-V 0.72)

2Position & Identifiers

RA 22h 08m 41.0s

Dec +45° 44' 31.0"

Constellation Lacerta (Lac)

HR 8448

HIP 109303

HD 210334

Variable ID AR Lac

SIMBAD

3How easy to follow?

Magnitude 6.1 – 6.8 mag Amplitude 0.7 mag Period 1.98 d Type EA/AR/RS

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Equipment	Bortle 3	Bortle 4	Bortle 5
Naked eye Naked eye	V. hard	V. hard	Imp.
50 mm finder 50mm finder	Medium	Medium	Medium
150 mm telescope 150mm scope	Medium	Medium	Medium

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)

5Light Curve

6Comparison Stars for AR Lac (6.1–6.8)

Nearby stable stars for estimating brightness (AAVSO)

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7

Size Comparison

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9

Spectral Classification

10

Hertzsprung-Russell Diagram

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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

Variable Star

EA 6.08 - 6.77V, RS CVn-type binary, 1.98319204d (period changes). Distortions in light curve possibly due to star | spots or to gas streams. Strong radio flare activity.

Spectroscopic Binary

1.9832d, K 116.1k/s, V0 -33.7k/s, msin3i 1.28, asini 3.17. Masses 1.2 and 1.3 solar. Mass loss from primary. | Close radio binary.

Spectral

Published classes range from F8, G2IV, G2Vn to G5IV for the earlier component, and K0IV to K2III for the later. Radio | emission source probably synchrotron emission.