When is the best time to observe Theta Tauri?

Theta Tauri is best observed from October through December, with peak visibility during November when it transits around midnight in the Northern Hemisphere.

Where is Theta Tauri located in the sky?

Theta Tauri lies in the constellation Touro at right ascension 04h 29m and declination +15° 58′.

What telescope do I need to split Theta Tauri?

Splitting Theta Tauri requires an aperture of roughly 60 mm or larger — the components are separated by about 268.3″ at magnitudes near 3.8. The companion is about 8.1 magnitudes fainter, so glare from the primary — not separation — sets the minimum aperture. Larger apertures and steady seeing help resolve the pair cleanly.

Theta Tauri — Estrela Dupla em Touro

HIP 20885; Theta1 Tauri; 77 Tauri

Magnitude 3.8^m DoubleStar Touro (Tau) Visível

Mapa Estelar + Lista + Plano

Sobre Theta Tau

Descrição

Theta1 Tauri is a G9 III yellow giant about 154 light-years away, the fourth-brightest member of the Hyades cluster at magnitude 3.84. It forms a naked-eye optical pair with Chamukuy (Theta2 Tau) across 5.6 arcminutes. Despite the close apparent pairing, the two Theta stars are roughly 20 light-years apart — but both are legitimate Hyades members.

Dicas de Observação

Theta1 and Theta2 Tau form an eye-catching pair just east of the main V, only about 5 arcminutes apart — one of the most accessible wide naked-eye doubles in the sky, visible even from urban skies. Binoculars clearly separate them and show their nearly matched yellow-orange colors. Best observed November through March.

História

The Theta designation was assigned by Bayer in 1603. The two Theta Tau stars are both classical Hyades members and have long been used as test subjects for cluster-membership criteria. No traditional name has been widely applied.

Curiosidades

Theta1 and Theta2 Tauri are a useful demonstration that even within a single open cluster, small spatial variations can create apparent double stars of physically unrelated origin. Their combined gravitational influence on local cluster dynamics has been mapped by Gaia's highly precise parallax measurements.

Observar

1Propriedades Físicas

Magnitude 3.84

Tipo Espectral G9III Fe-0.5 gigante

Cor da Estrela Laranja (B-V 0.95)

Distância 154 ly

2Posição e Identificadores

RA 04h 28m 34.5s

Dec +15° 57' 44.0"

Constelação Touro (Tau)

HR 1411

HIP 20885

HD 28307

SAO 93955

Bayer Theta1

Flamsteed 77 Tau

SIMBAD Wikipedia

3Facilidade de separação

Principal 3.8 mag Companheira 12.0 mag Separação 268.3″

Entrar e configure seu equipamento e local padrão para ver uma linha personalizada.

Telescópio	Bortle 3	Bortle 4	Bortle 5
Refrator 80 mm Refr. 80mm	Difícil	M. dif.+	M. dif.
Newton 150 mm Newt. 150mm	Médio	Difícil+	Difícil
Celestron C8 (SCT 203 mm) C8 203mm	Médio+	Médio	Difícil+