When is the best time to observe R Aquarii?

R Aquarii is best observed from August through October, with peak visibility during September when it transits around midnight in the Northern Hemisphere.

Where is R Aquarii located in the sky?

R Aquarii lies in the constellation Aquarius at right ascension 23h 44m and declination -15° 17′.

What telescope do I need to follow R Aquarii?

To follow R Aquarii through its full brightness cycle (magnitude 5.8 to 12.4) you need a telescope of roughly 170 mm or larger — the star fades out of smaller apertures near minimum light.

R Aquarii — Variable Star in Aquarius

Observable Variable Star Excellent (74/100)

Range: 5.2 - 12.4, Period: 387.0d, Type: M+ZAND

Magnitude 5.8–12.4^m VariableStar Aquarius (Aqr) Visible

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1Physical Properties

Magnitude 6.36

Range 5.2 - 12.4

Period 387 days

Variable Type Mira (Long-period Pulsating)

Spectral Type M7IIIpe bright giant

Star Color Red (B-V 1.58)

2Position & Identifiers

RA 23h 43m 49.5s

Dec -15° 17' 04.0"

Constellation Aquarius (Aqr)

HR 8992

HIP 117054

HD 222800

SAO 165849

Variable ID R Aqr

SIMBAD

3How easy to follow?

Magnitude 5.8 – 12.4 mag Amplitude 6.6 mag Period 387 d Type M+ZAND

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Equipment	Bortle 3	Bortle 4	Bortle 5
Naked eye Naked eye	Imp.	Imp.	Imp.
50 mm finder 50mm finder	Imp.	Imp.	Imp.
150 mm telescope 150mm scope	Hard+	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 170 mm reflector.

4Visibility

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Best season Aug – Oct (peak: Sep)

5Survey Image

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6Light Curve

7Comparison Stars for R Aqr (5.8–12.4)

Nearby stable stars for estimating brightness (AAVSO)

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8

Size Comparison

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10

Spectral Classification

11

Hertzsprung-Russell Diagram

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12

Stellar Lifecycle

13

Blackbody Spectrum

14

Stellar Absorption Spectrum

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

15

Stellar Fusion

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16Stellar Notes

Variable Star

M 5.8 - 12.4v, 386.96d. Secular period change, and oscillations in 24y period, also in RV. Variable radio emission | and SiO maser. May be a symbiotic star embedded in expanding gaseous nebula. Dust cloud associated with red component. | Companion B2ep may be an accretion white dwarf. Merrill in 1935 and Payne-Gaposhkin in 1946 analyzed the composite | light curve of R Aqr and its companion, concluding that the companion varies from about 8 to 12p, perhaps by even 5m.

Spectral

Strong emission of He 10830 and FeXIII 10747. Spectrum varies M5e-M8.5e + pec.