Contingut
Imatges
Carregar la teva Imatge
DSS Images Other Images
Articles Relacionats
Light Variations in the Candidate for Protoplanetary Objects HD 179821 = V1427 Aql in 1899-1999
We present photoelectric and photographic observations of the supergiantHD 179821 with a large infrared excess, a candidate for protoplanetaryobjects. Over, ten years of our UBV observations, the star exhibitedsemiregular light variations with amplitudes Delta V = 0.10 mag, B =0.15 mag, and U = 0.25 mag, as well as systematic color and lightvariations. From 1990 until 1996, the yearly mean U-B and B-V colorindices decreased by 0.25 and 0.15, respectively. After 1996, the motionof the star in the two-color (B-V)-(U-B) diagram upward and to the leftslowed down. The color excess that we derived from our observations, byassuming that the star's spectral type was F3I in the 1990s, is E(B-V) =1.0. The photographic observations of HD 179821 from 1899 until 1989show that its brightness mpg generally increased whilesignificantly fluctuating. An analysis of the observational datasuggests that HD 179821 is most likely a post-AGB star of intermediateor low mass.
| The variability of four yellow supergiants - Possible protoplanetary objects
Photoelectric UBV observations of four supergiants with a large IRexcess (IRAS 18095 + 2704, IRAS 19386 + 0155, and SAO 34504), possibleprogenitors of planetary nebulae, are presented. All of them exhibitedbrightness variations with amplitudes from 0.2 to 0.5 m over the period1990-1992.
|
Enviar un nou article
Enllaços Relacionats
- - No s'ha trobat enllaços -
Enviar un nou enllaç
Membre dels grups següents:
|
Dades d'Observació i Astrometria
| Constel·lació: | Aquila |
| Ascensió Recta: | 19h13m55.81s |
| Declinació: | +00°06'12.8" |
| Magnitud Aparent: | 8.76 |
| Moviment propi RA: | 30.4 |
| Moviment propi Dec: | -23.3 |
| B-T magnitude: | 9.827 |
| V-T magnitude: | 8.849 |
Catàlegs i designacions:
|
INHABITED SKY
