21 Hydrae — Variable Star in Hydra
Good (56/100)
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1Physical Properties
Magnitude
6.11
Range
6.11 - 6.58
Period
7.7 days
Variable Type
Eclipsing Binary (Algol-type)
Spectral Type
A3III:m+A0V:
giant
Star Color
Yellow-white
(B-V 0.22)
2Position & Identifiers
RA
09h 12m 26.0s
Dec
-07° 06' 35.0"
Constellation
Hydra
(Hya)
HR
3655
HIP
45184
HD
79193
SAO
136662
Flamsteed
21 Hya
Variable ID
KW Hya
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3How easy to follow?
Magnitude
6.1 – 6.6 mag
Amplitude
0.5 mag
Period
7.75 d
Type
EA/DM
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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 | Hard+ | Hard+ | Hard+ |
| 150 mm telescope 150mm scope | Medium | Medium | Hard+ |
Easy
Medium
Hard
Very hard
Impossible
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
4Visibility
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Best season
Jan – Mar
(peak: Feb)
5Survey Image
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6Light Curve
7Comparison Stars for 21 Hya (6.1–6.6)
Nearby stable stars for estimating brightness (AAVSO)
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8
Size Comparison
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9
Compare Stars
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
EA 6.11 - 6.58V, 7.750d. Misnamed KM Hya in the 64th Name List of Variable Stars (IBVS 1581) and propagated in | IBVS 2015, the KM designation having previously been asigned to a faint star. HR 3655 has now been corrected to | KW Hya (IBVS 2681).
7.7504d, K 73.2k/s, V0 -4k/s, msin3i 1.59, asini 7.75. Primary, giant; secondary dA0?
Nearby in the Sky
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Visibility scores assume a 150 mm Newton at Bortle 4.
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