Hi line analysis of Herbig Ae/Be stars using X-Shooter spectra

Title

Hi line analysis of Herbig Ae/Be stars using X-Shooter spectra

Creator

Shridharan B.; Mathew B.; Arun R.; Cysil T.B.

Description

Herbig Ae/Be stars are intermediate-mass pre-main sequence stars undergoing accretion through their circumstellar disk. The optical and infrared (IR) spectra of HAeBe stars show Hi emission lines belonging to Balmer, Paschen and Brackett series. We used the archival X-Shooter spectra available for 109 HAeBe stars from Vioque et al. (2018) and analysed the various Hi lines present in them. We segregated the stars into different classes based on the presence of higher-order lines in different Hi series. We discussed the dependence of the appearance of higher-order lines on the stellar parameters. We found that most massive and younger stars show all the higher-order lines in emission. The stars showing only lower-order lines have Teff< 12 , 000 K and an age range of 510 Myr. We performed a case B line ratio analysis for a sub-sample of stars showing most of the Hi lines in emission. We noted that all but four stars belonging to the sub-sample show lower Hi line ratios than theoretical values, owing to the emitting medium being optically thick. The Hiline flux ratios do not depend on the stars spectral type. Further, from the line ratios of lower-order lines and Paschen higher-order lines, we note that line ratios of most HAeBe stars match with electron density value in the range of 10 9 10 11 cm - 3 . The electron temperature, however, could not be ascertained with confidence using the line ratios studied in this work. 2023, Indian Academy of Sciences.

Source

Journal of Astrophysics and Astronomy, Vol-44, No. 2

Date

2023-01-01

Publisher

Springer

Subject

case B recombination; emission-line stars; Spectroscopy

Coverage

Shridharan B., CHRIST (Deemed to be University), Bangalore, India; Mathew B., CHRIST (Deemed to be University), Bangalore, India; Arun R., Indian Institute of Astrophysics, Bangalore, India; Cysil T.B., CHRIST (Deemed to be University), Bangalore, India

Rights

All Open Access; Green Open Access

Relation

ISSN: 2506335

Format

Online

Language

English

Type

Article

Identifier

https://doi.org/10.1007/s12036-023-09952-w

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