# 1998A&A...334..253F

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 Query : 1998A&A...334..253F

1998A&A...334..253F - Astronomy and Astrophysics, volume 334, 253-263 (1998/6-1)

Progressive dispersal of the dense gas in the environment of early-type and late-type Herbig Ae-Be stars.

FUENTE A., MARTIN-PINTADO J., BACHILLER R., NERI R. and PALLA F.

Abstract (from CDS):

We have carried out a systematic study of the environment of 14 Herbig Ae/Be (HAEBE) stars at millimeter wavelengths. Our data show that there is a progressive dispersal of the dense gas associated with these stars in their evolution to the main sequence. The efficiency of this dispersal is very different for early-type'' (B0-B5) and late-type'' (B5-A5) stars. While in early-type stars the mean gas density in a radius of 0.08 pc decreases by almost two orders of magnitude during their evolution to the main sequence, in late-type stars it decreases by less than an order of magnitude. Because of this different efficiency, there is no correlation between the ages of the stars and the Hillenbrands' infrared (IR) groups. Early-type stars evolve from the Hillenbrand's Group I to Group III in their way to the main sequence, while late-type stars evolve from Group II to Group I. Since the morphology of the parent molecular cloud seems to be strongly dependent on the age of the stars, we propose a new classification for both, early-type and late-type HAEBE stars. We refer as Type I stars to those immersed in a dense clump. These stars are associated with bipolar outflows and have ages ∼105yrs. We call Type III stars those that have completely dispersed the surrounding dense gas and are located in a cavity of the molecular cloud. Bipolar outflows are not associated with them and their ages are >106yrs. Type II stars represent the intermediate case, they are immersed in the molecular cloud but they are not at the peak of a dense clump. The advantage of this new classification is that it allows a simple and easy estimate of the evolutionary stage and age of HAEBE stars.

Journal keyword(s): stars: formation - radio-lines: ISM - stars: pre-main sequence - ISM: abundances - ISM: clouds - ISM: molecules

 Number of rows : 18
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 EM* LkHA 198 Ae* 00 11 25.8495450336 +58 49 28.713961920   14.65 13.79 14.03   B9e 222 0
2 BD+61 154 Ae* 00 43 18.2566590360 +61 54 40.139212716 10.83 11.13 10.60     B8eq 198 1
3 V* HK Ori Ae* 05 31 28.049808 +12 09 10.30212 11.82 12.235 11.716 11.632 10.56 A2?e+G0?e 186 1
4 EM* MWC 137 Ae* 06 18 45.5220873216 +15 16 52.244494608 12.89 13.30 13.759 11.67 10.31 sgB[e]d 236 1
5 EM* LkHA 215 Ae* 06 32 41.7730499472 +10 09 34.209036180 11.41 11.28 10.70     B7IIne 125 0
6 V* R Mon Ae* 06 39 09.9542000448 +08 44 09.539482632 10.76 12.46 11.85 10.96 10.25 B8IIIe 510 0
7 EM* LkHA 25 Ae* 06 40 44.6376365304 +09 48 02.151653868 12.745 13.03 12.88 12.545 12.386 B4Ve 136 0
8 HD 52721 Ae* 07 01 49.50977 -11 18 03.3219 5.88 6.65 6.59 7.52   B2Vne 210 0
9 V* Z CMa Ae* 07 03 43.1599411656 -11 33 06.209065836 10.51 9.99 8.80     B5/8eq+F5/7 556 3
10 DCld 264.3+01.5 DNe 08 54 42 -42 54.8           ~ 68 0
11 RCW 34 HII 08 56 28.1 -43 05 58   10.5 11.21     ~ 94 0
12 V* V391 Vel Or* 08 56 28.109952 -43 05 55.40028 12.61 12.71 11.73 11.50   O8/8.5V 81 1
13 V* PV Cep Or* 20 45 53.9540390184 +67 57 38.679941304   19.27 17.46 15.98 14.60 A5 264 3
14 HD 200775 Ae* 21 01 36.9205762896 +68 09 47.789578836 7.34 7.754 7.427 8.13   B2Ve 534 0
15 BD+65 1637 Ae* 21 42 50.1798725784 +66 06 35.186616864 10.21 10.56 10.53 10.29   B3IV-Vne 153 1
16 EM* LkHA 234 Ae* 21 43 06.8218113480 +66 06 54.202272804 13.65 13.61 12.73 11.98 11.20 B5Ve 283 0
17 EM* LkHA 233 Ae* 22 34 40.9923134958 +40 40 04.251892858   14.5       A7Ve 142 0
18 EM* MWC 1080 Ae* 23 17 25.5895018656 +60 50 43.444557384   13.24 11.542     B0eq 315 0

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2022.10.01-03:39:59