Optical spectroscopy offers the most direct view of the stellar properties
and the accretion indicators. Standard accretion tracers, such as Hβ,
Hα, and, Ca II triplet lines, and most photospheric features, fall in
the optical wavelengths. However, these tracers are not readily observable from
deeply embedded protostars because of the large line of sight extinction (Av
∼ 50-100 mag) toward them. In some cases, however, it is possible to
observe protostars at optical wavelengths if the outflow cavity is aligned
along the line-of-sight that allows observations of the photosphere, or the
envelope is very tenuous and thin such that the extinction is low. In such
cases, we can not only detect these protostars at optical wavelengths but also
follow up spectroscopically. We have used the HOPS catalog (Furlan et al. 2016)
of protostars in Orion to search for optical counterparts for protostars in the
Gaia DR3 survey. Out of the 330 protostars in the HOPS sample, an optical
counterpart within 2" is detected for 62 of the protostars. For 17 out of 62
optically detected protostars, we obtained optical spectra { (between 5500 to
8900 AËš) using the Aries-Devasthal Faint Object Spectrograph \& Camera
(ADFOSC) on the 3.6-m Devasthal Optical Telescope (DOT) and Hanle Faint Object
Spectrograph Camera (HFOSC) on 2-m Himalayan Chandra Telescope (HCT)}. We
detect strong photospheric features, such as the TiO bands in the spectra {(of
4 protostars)}, hinting that photospheres can form early on in the star
formation process. We further determined the spectral types of protostars,
which show photospheres similar to a late M-type. Mass accretion rates derived
for the protostars are similar to those found for T-Tauri stars, in the range
of 10−7 to 10−8M⊙​/yr.Comment: 9 pages, 5 figures accepted in Journal of Astrophysics and Astronomy
as part of the "Star formation studies in the context of NIR instruments on
3.6m DOT" special issu