2015A&A...583A..98V


C.D.S. - SIMBAD4 rel 1.7 - 2021.06.16CEST00:43:58

2015A&A...583A..98V - Astronomy and Astrophysics, volume 583A, 98-98 (2015/11-1)

An early detection of blue luminescence by neutral PAHs in the direction of the yellow hypergiant HR 5171A ?

VAN GENDEREN A.M., NIEUWENHUIJZEN H. and LOBEL A.

Abstract (from CDS):

We re-examined photometry (VBLUW, UBV, uvby) of the yellow hypergiant HR5171A made a few decades ago. In that study no proper explanation could be given for the enigmatic brightness excesses in the L band (VBLUW system, λeff=3838Å). In the present paper, we suggest that this might have been caused by blue luminescence (BL), an emission feature of neutral polycyclic aromatic hydrocarbon molecules (PAHs), discovered in 2004. It is a fact that the highest emission peaks of the BL lie in the L band. Our goals were to investigate other possible causes, and to derive the fluxes of the emission. We used two-colour diagrams based on atmosphere models, spectral energy distributions, and different extinctions and extinction laws, depending on the location of the supposed BL source: either in Gum48d on the background or in the envelope of HR5171A. False L-excess sources, such as a hot companion, a nearby star, or some instrumental effect, could be excluded. Also, emission features from a hot chromosphere are not plausible. The fluxes of the L excess, recorded in the data sets of 1971, 1973, and 1977 varied (all in units of 10–10W/m2/µm) between 1.4 to 21, depending on the location of the source. A flux near the low side of this range is preferred. Small brightness excesses in uv (uvby system) were present in 1979, but its connection with BL is doubtful. For the L fluxes we consider the lowest values as more realistic. The uncertainties are 20-30%. Similar to other yellow hypergiants, HR5171A showed powerful brightness outbursts, particularly in the 1970s. A release of stored H-ionization energy by atmospheric instabilities could create BL emitted by neutral PAHs.

Abstract Copyright:

Journal keyword(s): ISM: molecules - HII regions - stars: variables: S Doradus - stars: individual: HR 5171A

Simbad objects: 9

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Number of rows : 9

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 44179 pA* 06 19 58.2185496 -10 38 14.706068 9.51 9.33 9.02     B9Ib/II 727 0
2 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2191 0
3 SNR G309.2-00.6 SNR 13 46.5 -62 54           ~ 62 0
4 GUM 48d HII 13 47.0 -62 35           ~ 7 0
5 HD 119796B * 13 47 09.9532405784 -62 35 15.989701100   9.64 8.45     B0Ibp: 7 1
6 HD 119796 s*y 13 47 10.8637055467 -62 35 22.954071288 10.24 9.05 6.80 4.74 3.54 G8Ia+ 125 0
7 V* V509 Cas LP* 23 00 05.1007915562 +56 56 43.348681058 8.01 6.68 5.13 3.96 3.11 G4_0 316 0
8 * rho Cas LP* 23 54 23.0339951270 +57 29 57.766930774 7.00 5.85 4.59 3.63 2.89 G2_0 367 0
9 NAME Centaurus Arm PoG ~ ~           ~ 74 0

    Equat.    Gal    SGal    Ecl

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2021.06.16-00:43:58

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