1. High-mass star formation

The main interest of my research is star formation in general and high-mass star formation in particular. My colleagues and I work on investigating from the early stages of high-mass star formation, when only the pre-stellar clouds of gas exists, to more developed stages where we can see outflows and ionized regions.

Accretion

One of the main interestest in my investigation is what is the role of accretion, particularly disk accretion, in high-mass star formation. I am interested on answering the following questions:

• How do high-mass stars accumulate most of their material? The original motivation for this question can be traced back 50 years ago, with the publication of an influential paper by Larson & Starrfield (1971). The main idea is to point out potential difficulties for accretion to work in high-mass star formation, namely, the high radiation pressure exerted by the forming star on the infalling material and the disruption of the protostellar nebula by action of the ionizing radiation. One natural way in which high-mass young stars could overcome these problems is by means of disk accretion.
  • Is disk accretion relevant for high-mass star formation? Colleagues and I have presented examples of collimated jets associated with high-mass young stellar objects. This sole fact seems to support disk accretion taking place, simply because there are no other more plausible explanations for the jet phenomena. However, it is pertinent to ask:
    • Do most high-mass stars accumulate most of their material through disk accretion?
    • Is there a mass limit up to which disk accretion works, but not for higher masses?
• What would be the other mechanism? Merging of lower mass stars has been recently revived as a viable hypothesis due to the apparent nature of the "explosive" outflows in Orion and DR21.

Prestellar phase

Early stages of star formation are also part of my interests. The question is related with the origin of the mass of high-mass stars.

• Is this mass confined in a massive core before the star is formed? Or does the young star and its envelope accumulating material as it evolves?

Discussions related with astronomy and astrophysics

1. The virial theorem applied to simple scenarios. We derive the widely used expressions of MacLaren et al. (1988) and discuss some of the assumptions.
2. The free falling cloud case.
   1. Pressureless collapse of homogeneous ellipsoidal clouds. The collapse of clouds of this shape is homologous and maintains the homogeneity of the cloud. Ellipsoids become increasingly more flattened, collapsing first in the direction of the shortest axis.
   2. Virial theorem applied to free-fall, pressureless, spherical collapse. We derive how expressions such as the virial ratio and virial mass behave.