Your question is regarding alienation of property in a Hindu Undivided Family.
In this case, as the Karta (Father) died without a will hence there will be intestate succession. Under a Hindu Undivided Family (HUF) if the Karta dies without a will, then the eldest son/daughter becomes the Karta of the HUF and the rest of the heirs become coparceners and gets their right in the property.
Among the many powers that the Karta of a Hindu Undivided family has like Right to receive and spend family income, Powers to manage family affairs, Power to settle family disputes, etc., he also has the power of alienation of joint family property.
Alienation of Property is Transfer of property inter vivos, such as by sale, mortgage, gift, license or lease (including perpetual lease)
The Power of alienation that Karta has is limited in nature as it can be exercised only with the consent of all family members.
When the coparcener does not give consent or is incapable of giving consent (is a minor), then the Karta can alienate property only for the following reasons: legal necessity, benefit of estate, or performance of religious or charitable purposes. This Alienation bind all family members, including minors.
Legal Necessity (Dev Kishan v. Ram Kishan, 2002) - Any necessity that can be sustained in law or justified in law. For example, pressure to pay off a debt is sufficient, even though creditors may not have filed a suit or threatened to do so. The test for legal necessity is that, What a reasonable, prudent person, entrusted with welfare of family and family property, will do.
Benefit of Estate (Balmukund v. Kamlavati, 1964)- By transfer of the joint family property or by its sale proceeds, the property or any other family estate is benefitted. Includes defensive actions for the protection of property from threatened danger or destruction, and other transfers to bring advantage or improvement in the family estate. The Karta must exercise due care and diligence.
Religious or Charitable purposes - Believed to bring peace, prosperity, and harmony to the family, its members and even departed ancestors like Hindu rites and ceremonies.
If Karta alienates the property without the consent of the coparceners, the coparcener who is dissatisfied is always free to demand partition of family property at any point of time.
Further, if the Karta alienates the HUF property for purposes other than the three mentioned above, without taking consent of all the other coparceners, the alienation becomes voidable at the instance of any one of the coparceners.
So as a coparcener now you have the right to can go to the court or ask your brother for partition as he cant pass property without consent.
I hope this solves your query.